Of all the hydroponic growing media you can use water is cheap and the easiest to obtain. Water can be filtered, typically with an RO machine, and sterilized with UV or Ozone to create a clean and consistent substrate tailored to your growing requirements. Many hydroponic growers already understand the virtues of using, and more importantly reusing, water in hydroponic systems. So, why not go the whole hog, throw away your rock wool/soil/coco/clay pebbles and use water culture?!

What is Water Culture?

Deep water culture (DWC) – At its essence, a DWC system is made up of a container, lid and net pot. The container holds the nutrient solution (typically 2.5–4 gallons (10–15 liters)) and the lid supports a single plant growing in a net pot. Roots grow out the net pot and into the nutrient solution held in the container below. In the container, an air stone bubbles away to agitate the solution and keep dissolved oxygen levels high—essential in any DWC system. Shallow water culture (SWC) is based on the same principle but, yes you’ve guessed it, uses a lower volume of water.

Single vs. Recirculating

Single stand-alone systems are fairly cheap to buy and even more popular for DIY enthusiasts. Modular DWC systems, in which many containers are connected to a central reservoir, create an active system where the nutrient solution is able to cycle from the reservoir around all the pots, arriving back at the reservoir. Each has inherent issues. Stand-alone systems can be inconvenient to work with, while recirculating systems can spread problematic root diseases very quickly. The key is to operate the chosen water culture system properly, and you’ll be sure to get explosive results. Once you play around with DWC, you’ll most likely wish your system was modular and recirculating.

Q: Ok, lets start with the basics; what types of nutrients and additives work in DWC?

A: In my experience, pure synthetics of the highest solubility tend to work best. Especially formulations with well-balanced mineral ratios as well as being balanced on a molecular level. This tends to translate to a more pH stable nutrient solution that stays viable for longer periods of time.

Q: Where do you stand when it comes to Beneficial Biology in DWC systems?

A: There’s a bit of a fork in the road philosophically when it comes to“bennies” or no “bennies”. In my experiences both tend to work but I lean towards more of a sterile aqueous root zone. It is possible to use a more carbon-based substrate for a plant’s root crown cultivation. It’s this beneficial habitat that could harbor and allow colonization of a plant’s mutualistic organisms. The solution itself has little potential for colonization of anything other than bacteria, which while useful, don’t offer the benefits of fungi’s, which share a more direct relationship with the roots themselves.

Q: Are there any specific pH and EC requirements you recommend?

A: Depending on the nutrient, working with a pH between 5.5–6.5 works fine. If you want to be more specific 6.0–6.3 for veg, and 5.7–5.9 for flower. It’s in these pH ranges that the minerals most needed for the respective plant cycles are most available. With regards to EC, I generally recommend 50–75% of a nutrient manufacturers directed dosage for best results. Remember that lower EC can result in a higher intake of water into a plant’s tissue, which in turn speeds plant metabolism and increases nutrient transport.

Q: How often should growers change-out the nutrient solution? Are there signs they should look out for?

A: Depending on the type of nutrients, a 14–21 day change out schedule is typical. When plants are growing vigorously they can turn the nutrients over several times in that time frame. This is essentially “changing the nutes” by displacement from the top-off reservoir. If the nutes begin to fluctuate in pH or become murky, or if plants begin reducing nutrient usage this is usually a good time to purge the reservoir and mix a fresh batch.

Q: What is the ideal water temperature for DWC systems?

A: We’ve observed that no matter the ambient air temperature, plant roots tend to do best at 62–68°F (17–20°C). Above 72°F (21°C) the solutions dissolved oxygen (DO) holding potential quickly diminishes and below 60°F (16°C) plants tend to slow their metabolism in response to what is perceived as changing seasons. This said, growers could aid in fruit/flower ripening by reducing water temps toward the end of the reproductive cycle. Being able to dial in each zone of the plant (Leaf/Root) specifically often leads to an amplification of plant productivity.

Q: Speaking about DO, what is the best practice for monitoring and maintaining DO levels?

A: Keep nutrients cool and ppm’s at a modest level to ensure good DO saturation. Surface aeration and the implementation of air pumps and diffusers is an easy way to keep the solution agitated and moving. Manual as well as digital meters can be useful for those more meticulous souls. If you go digital buy high end as the budget meters (which still run several hundred dollars) are typically unreliable instruments in a pretty plastic housing.

Q: Can you run through your recommendations for propagating plants destined for DWC?

A: Establishing cuttings with an aeroponic cloner using 1/8th strength nutrients is ideal, preferably under mixed spectrum T-5 lighting. Propagating bare root plants suits DWC best. This offers an easier transition to water culture given there is no wicking substrate (rock wool, Sure To Grow) to hold excess moisture too close to the root crown.

Q: Is there an ideal water level to be maintained in the reservoir?

A: Start with the bare root submersed to the base of the rooted stalk, being sure to not submerse the stem or stalk tissue so as to avoid water logging. If using a wicking substrate, ensure the cube is approx. 1“ above water line; this may necessitate hand watering for a few days before the roots hit the water.

Q: What are the potentialities for plant steering using water level / amount of root zone exposed to the air?

A: With water as their growing media, growers can tailor nutrient solution parameters more specifically. Provoking plant responses such as essential oil production, fruiting and flowering are better manipulated when the substrate can be dialed in. For example, higher exposure of the root zone to atmospheric oxygen can help trigger a plant to increase oil production as a means to conserve water, and can also apply mild root stresses that are often interpreted by the plant as reproductive cues. While higher water levels can cause plants to focus more energy on vegetative production, particularly fan leaves, which in turn speeds transpiration and photosynthetic potential.

Q: Are there any specific pests or pitfalls DWC growers should watch out for?

A: Root diseases no doubt, Pythium, Fusarium, etc. These types of problems are most evident in water culture given the roots high profile, but are also typically found in most hydro methods currently practiced. In our experiences we’ve observed that once the variable causing the problem is removed (warm water, too high an EC, sludging inputs, etc.), it’s completely likely the plants will recover. In other words, root disease is not a death sentence, but a symptom of a problem needing to be addressed.

Q: I have heard from a few DWC growers that veg times can be significantly reduced, is this true?

A: Growers will need to make that call, but when dialed-in there is no faster way to grow plants—hydroponically or otherwise. A well-hydrated plant typically grows more quickly which will inevitably create shorter veg times and still achieve a premeditated harvestable plant size.

Q: Is DWC suitable for longer-term plants, such as donor plants? Commercially DWC is only used for lettuce and short-cycle plants, not for annuals.

A: Water culture is still a relatively new hydroponics method. Though first introduced in the 1930s by professor Gericke at UC Berkley, using water as a primary growth medium is still seen as somewhat impractical by commercial farmers. Due to the need to keep water conditions cool, it’s caused the bottom line to operate large-scale water culture facilities to be cost prohibitive.

Though with the recent improvements in cooling technology and increased efficiencies, I think we are likely to see a move toward water culture as a viable alternative to the current carbon substrate-based approaches presently being used for the growth of annual vegetables.

Especially as farmers discover the reduced volume of fertilizer inputs and the conservation of precious water that are key to water culture’s allure. This is an exciting time for water culture as what has been considered a black art is now emerging as a legitimate means of cultivating a variety of crops.

Ready for a revolution?

This article is the first in a two part series about aquaponics that will first describe aquaponic gardening, then focus on the practical details around the components of a thriving aquaponics system; from the fish, plants and bacteria to the grow beds, fish tanks and plumbing options.  Hopefully by the end of the next article I will have convinced some of you that aquaponics should be at least a part of your growing repertoire, and given you the tools you need to get started.

It seems appropriate that we start our journey together by answering the question: What is aquaponics?  At its most basic level aquaponics is the marriage of aquaculture (raising fish) and hydroponics (growing plants in water and without soil) together in one integrated system. The fish waste provides organic food for the growing plants and the plants naturally filter the water in which the fish live.  The third and fourth critical, yet invisible actors in the play are the beneficial bacteria and composting red worms.  Think of them as the Conversion Team.  The beneficial bacteria exist on every moist surface of your aquaponic system. They convert the ammonia from the fish waste that is toxic to the fish and useless to the plants, first into nitrites and then into nitrates.  The nitrates are relatively harmless to the fish and most importantly, they are the foundation of great plant food.  At the same time, the worms convert the solid waste and decaying plant matter in your aquaponic system into vermicompost which supplies the remaining micronutrients.

Here is the rest of the story

• Aquaponic Gardening enables home fish farming. You can now feel good about eating fish again.
• Aquaponic Gardening uses 90% less water than soil-based gardening.
• Aquaponic Gardening is four to six times as productive on a square foot basis as soil-based gardening.  This is because with aquaponic gardening, you can pack plants about twice as densely as you can in soil and the plants grow two to three times as fast as they do in soil.
• Aquaponic Gardening is free from weeds, watering and fertilizing concerns, and because it is done at waist height there is no back strain.
• Aquaponic Gardening is necessarily organic. Natural fish waste provides all the food the plants need. Pesticides would be harmful to the fish so they are never used. Hormones, antibiotics, and other fish additives would be harmful to the plants so they also are never used. And the result is every bit as flavorful as soil-based organic produce, with the added benefit of fresh fish for a safe, healthy source of protein.
• And if you are already a hydroponic gardener considering switching over to Aquaponic Gardening you can enjoy the following advantages:
  • Aquaponics has been shown to be more productive than hydroponics after the aquaponic bio-filter is fully established. (study by Dr. Nick Savidov, of the Crop Diversification Center South, Alberta Agriculture Food and Rural Development at Brooks, Alberta, Canada report in the “Aquaponics Journal,” 2nd Quarter, 2005)
  • EC (electrical conductivity) tracking is replaced by tracking of Ammonia, Nitrite and Nitrate.  Once your system is fully cycled you will only need to measure these about once a month or so vs. the much more frequent tracking of EC.
  • pH is much more stable, again once your system is fully cycled.
  • Fish feed is significantly less expensive than hydroponic nutrients.
  • You never dump out your nutrient solution!  Rather than having problems with chemical imbalance that you regularly experience in hydroponics, in an aquaponic system you are achieving a natural nitrogen balance that is the hallmark of a balanced eco-system.  I view the water in my system as a critical component that I have nurtured into the near perfect balance at which it stays for as long as I choose to run  my system (in my case, already years).
  • Best of all, you can say goodbye to pythium forever.  It is non-existent in aquaponics.

Types of Systems

AquaBundance by The Aquaponic Source

Deep Water Culture (DWC) is where most of the university research on aquaponics has focused.  This is especially true at the University of the Virgin Islands where Dr. James Rackocy has spent the past 30 years perfecting this growing technique.  In DWC, the fish are held in tanks separate from the plants.  The solid fish waste is removed from the water using a settling tank and clarifying filters before it is sent onto the plant raceways.  This prevents the plant roots from becoming coated with solid matter and suffocating.  The fish water then circulates through a raceway that is covered with floating rafts.  These rafts have holes in them to accept planted net pots whose roots dangle directly into the water.  Newly planted rafts are dropped into the beginning of the raceway.  The rafts progress along the raceway with each newly planted raft pushing the older rafts to the end of the raceway where they are pulled from the water and harvested.  DWC is an excellent aquaponic growing technique for commercial growers because it is relatively easy to plant, tend, and harvest a large number of fast growing plants such as lettuces and some herbs.  DWC also provides very stable water temperatures and pH levels because of the high volume of water required.  The downsides of DWC are that in filtering the solids you lose many of the micro-organisms required to grow healthy, larger, fruiting plants.  Also, while it has been done, it is difficult to grow larger plants to full size because of the challenges of getting enough oxygen to the larger root zone of a plant that lives its entire life in the water.

AquaBundance by The Aquaponic Source

Most media-based grow systems use a timer to turn the pump in the fish tank on and off.  A typical timer cycle is 15 minutes on followed by 30 – 45 minutes off and then the cycle repeats.  When the pump starts, water from the fish tank is pumped into the grow bed.  The grow bed fills with water up to about 10” or so.  This provides plenty of water and nutrients for the plants.  Hydroton or other media above this height are in the “dry zone” and stay dry all of the time.  When the water reaches about 10”, any additional water immediately returns to the fish tank through an “overflow” mechanism.  The returning water strikes the water surface in the fish tank; thereby creating turbulence which helps aerate the fish tank water.  When the timer turns off, the pump stops and the rest of the water in the grow bed returns to the fish tank.  This period of inactivity gives the roots a chance to dry out and “breath” the air – something they greatly appreciate.  Then, when the timer triggers the pump again the cycle repeats.

Fish

Every aquaponic system starts with the fish and there are a wide variety from which to choose. The most important thing to keep in mind is to use freshwater fish. But which fresh water fish to raise?  To figure this out, start by deciding whether you want to grow fish for food or for show.  If you are interested in growing edible fish, tilapia are most commonly used in aquaponics because they are a tasty, fast-growing fish that have low oxygen requirements and aren’t very fussy about their aquatic environment.   Tilapia are generally purchased at fingerling size (3 – 4”) and take 9 – 12 months to reach “plate” size (approximately 12” and 1.5 pounds).  Many other edible fish can be raised as well, including trout, catfish, and perch.  Don’t be afraid to try other species.  Just be sure that  when you create your fish environment, you plan for optimal water temperature, sociability, and diet for which ever species you have chosen. Trout, for example, require a tank environment similar to the mountain streams from which they come.  This means water temperatures at 55° or below and plenty of oxygen.  They are also carnivorous, so it is impractical to grow other species with them or represent a variety of ages and sizes in the same tank.
After you have chosen your species, you will have to decide how many fish to put into your tank. The safest stocking density is one pound of mature fish for every 5 gallons (19 liters) of water.  This works out to roughly one fish for every 3 gallons (11 liters) of water, depending on the size of the fish.  Another good general rule of thumb is to have a minimum of 50 gallons of water to grow an edible fish to plate size.  If you are inclined towards keeping your fish as pets instead of food, you can go with a much smaller aquarium and use any freshwater fish you would adopt from a pet store.

Plants

People are growing almost every kind of plant in aquaponic systems.  The main exception is acid-loving plants, like blueberry bushes. The converted fish waste creates a near perfect, complete plant food that can be augmented if necessary.  Occasionally iron, calcium and/or potassium nutrient deficiencies show up but all can be corrected using small quantities of minerals that are safe for the fish (I have only supplemented once in almost 2 years of growing).
In an aquaponics grow bed, there is very little competition for food, water, and oxygen.  This means you can space plants much closer than you can in soil – up to twice as dense.  The only real consideration regarding plant density is competition for light in the canopy of the mature plants.  Make sure to plan for the ultimate size of each plant vs. its neighbors so that each plant will get the sunlight or grow-light exposure that it needs.   If you make a mistake, however, don’t lose sleep over it.  The root ball of an aquaponically grown plant tends to stay fairly compact, making most plants generally easy to move around even when they are mature.

When deciding what to plant, avoid cultivating too many of one type and age of plant in a single grow bed. A monoculture in aquaponics often leads to a simultaneous harvest, and harvesting many plants at once can put a system off balance.  Remember, your plants are filtering the water for your fish so be sure to keep a steady supply of seedlings on hand to replace harvested crops.

Consider companion planting to fight pests, as well.  For example, planting marigolds in your system can help ward away some insects.  If you do get a harmful insect infestation on your plants we recommend using insecticidal soap and/or neem oil as a safe, organic way to solve the problem quickly.  Do so carefully, however, because the fish aren’t crazy about having even organic pest controls in their water.  Avoid “bug bombs”, even if they are approved for organic use.

Beneficial Bacteria (Microbes) and Worms

Bacteria are the engine of an aquaponic system. Without nitrifying bacteria converting the ammonia to nitrates, the fish would quickly die from ammonia toxicity and the plants would starve for lack of nutrition.  Nitrosomonas bacteria convert the poisonous ammonia into nitrites and then nitrospira bacteria convert the nitrites into nitrates.  The process where the bacteria are naturally established is called “cycling”, and takes about a month. We will go into the mechanics of how to initiate and speed up cycling in a later article, but know that after becoming established, bacteria will colonize on all surfaces of the system that stay in contact with the fish water.

Be careful not to use chlorinated tap water when filling a tank, as chlorine will kill the nitrifying bacteria in the system. To remove chlorine from tap water, use a dechlorinating filter, or top off your tanks on a frequent basis with only a very small amount of water (less than 5% of the water volume), or establish a separate de-gassing tank.  Chlorine will “off-gas” (i.e. the chlorine leaves the water as a gas) on its own within a couple days, and more quickly if you add aeration.  Chloramine is also harmful to nitrifying bacteria and the fish and, if present, must be filtered from the water.  Contact your municipal water supply to find out if there is chloramine in your tap water.

Like a fine wine, the bacteria in an aquaponics system will get better over time—becoming more stable and effective.  It takes about a month to become established in your system but after 6 months it will outperform any traditional soil based or hydroponic system.  Be sure to treat the bacteria in your system like the precious friends that they are by never letting your grow bed dry out, never exposing the bacteria to freezing temperatures for an extended period of time, and never allow the bacteria to come into contact with chlorine or chloramine.

If bacteria are the engine of an aquaponic system, worms are its secret weapon.  Now the secret is out!  Add composting red worms to your media-based aquaponics system after a few months to break down the solid fish waste into vermicompost.  Vermicompost is extremely beneficial for the plants.

Next Issue

In the next issue of Urban Garden magazine we will go through what you need to know to build a media based aquaponics system, including grow bed considerations, fish tank considerations, plumbing how-to (timer, siphon, and flush valve), and considerations around the media.  The third article will conclude the series with instructions on starting up and operating your system – cycling and starting up the bio-filter, adding the fish and plants, operating your system and maintaining it, and hints on spotting problems.  My goal is that by the time we are done taking this journey together you will have the knowledge you need to start on an aquaponic adventure of your own.

Borlaug grew up in a remote corner of rural Iowa – a place with twelve- grade one-room schools from which most youngsters dropped out by the eighth grade, a place with one car, no telephones, no electricity, but the Iowa Corn Song ,3 proudly sung like the Star-Spangled Banner at the start of every school day:

There was no future, other than growing corn, but “Norm Boy’s” grandfather had another vision, and inculcated the boy with a determination to obtain a higher education. He arrived at the University of Minnesota at age 20, “as a student athlete [whose] ability to do university work was questioned” 4 but left years later clutching a Ph.D in plant pathology,.

Assigned during World War II to Dupont, where he helped to develop DDT as part of the war effort, Borlaug was offered the sky, but given the choice between Dupont and sub-subsistence science for sub-subsistence Mexican farmers, he chose the. latter, working. with the Rockefeller Foundation, in a project to stave off a looming food crisis in overpopulated Mexico.5

THE AGRICULTURAL END OF FOOD PRODUCTION USES STAGGERING AMOUNTS OF WATER. AS AN ILLUSTRATION, HERE’S A RECIPE FOR A QUARTER-POUND CHEESEBURGER

The project goal was to breed strains of wheat that could withstand adverse climates, survive wheat’s fungal diseases, and produce prodigiously on dwarf plants, then convince tradition-bound farmers to adopt forthwith the new hybrids and the technology that accompanied them.. It was a race against time, and an extraordinarily demanding task in the pre-DNA era. Borlaug set up field operations in two locations with disparate climates and growing seasons so he could have plants accustomed to multiple climates, and could grow two generations of seedlings each year.

Borlaug shortly achieved his goal, and Mexico’s food crisis was over in a decade. On to Asia, where the same thing was happening: overpopulation, courtesy of modern medicine.. India was home to some of the poorest people in the world. Famine was widely forecast for the mid-seventies. It was the era of Ehrlich’s Population Bomb. Stanford professor Ehrlich was an icon for the rising environmental movement, but overnight, stubborn farm boy Borlaug appeared to prove him wrong. In a few short years, the Green Revolution turned a land of undernourished millions into the second largest wheat producer in the world. Borlaug became the hero of millions of peasants, and also of those who spoke for unlimited growth, and in the next twenty years The Population Bomb disappeared from the environmentalist lexicon, leaving the population boom unquestioned.

The Green Revolution, which was to go on producing wonder strains for other crops and other countries, had three central parts. The other two were irrigation and chemical fertilizer. These changed agriculture fundamentally, from a primarily solar-energy craft dependent upon local weather and soil conditions, to a fossil-fuel technology designed to force the land to produce mightily regardless of its natural limitations. Borlaug, summarizing in his Nobel lecture, warned that the new hybrids had not resulted in major yield improvements without both irrigation and “a strong responsiveness and high efficiency in the use of heavy doses of fertilizers.”6 Plentiful water, plentiful chemical fertilizer – that’s the secret to how in the last half century India – and California – turned arid lands almost instantly into wildly productive garden baskets. It may not be a sustainable solution, but at the time, the world needed a quick fix.

In his Nobel lecture, Borlaug talked proudly about how the new practices had given near-starving subsistence farmers surpluses they could sell, the money to buy oil-driven water pumps and tractors, and the influence to insist upon doors opening to the broader world. If you’ll permit me a broad brush, the Green Revolution had doubled and tripled grain production for multi-millions who had been on the brink of starvation, but turned locally self-sustaining agriculture into hydroponics. And it turned subsistence farmers, dependent on the whims of the soil, sun and rain, into small-time contractors dependent on the whims of the discount rate, the commodities markets and the petrochemical industry.

It weakened their umbilical cord to Mother Earth, and eased a process in which millions would find themselves drawn to seek their fortunes in the cities, providing cheap labor to run the Indochinese economic machine. But those were events far in the future when Borlaug performed his magic, and it’s hard to quibble when several hundred million people are about to die of starvation..

The agricultural end of food production uses staggering amounts of water. As an illustration, here’s the author’s recipe for a quarter-pound cheeseburger:

Ingredient /Water used in production

Lettuce (1/4 cup)…………………………0.8 gal

Bun (2 bread slices equiv) …………………….. 22.0 gal

Tomato (1 oz paste equiv) ……………………. 6.1 gal

Cheese (1 oz.)……………………………………… 58.3 gal

Ground beef (4 oz) ………………………………..641.2 gal

TOTAL………………………………… 728.4 gal

8-oz. Glass of milk……………………… 50.0 gal 7

The reason water consumption for meat and dairy products is so much higher than for vegetables and grain, is that, very approximately, it takes two pounds of grain to produce a pound of chicken, five pounds to produce a pound of pork, and ten pounds to produce a pound of beef.

The Green Revolution doubled the world’s irrigated acreage from 346 million acres to 690 million acres, and increased by a factor of nearly five its consumption of chemical fertilizer .8 Where does all the irrigation water come from? Wells, largely; as the World Bank has pointed out, groundwater comprises 97% of the world’s accessible freshwater reserves.9

Wells are a classic case of Garrett Hardin’s “tragedy of the commons” 10 – if the aquifer is shared by multiple individuals or multiple villages and there are no rules on how much anyone can use, then the users are individually, although not collectively, better off if they use as much as they want until the wells all run dry. So unless everyone follows the Golden Rule or there is an elaborate legal “groundwater management plan,” controlling how much everyone gets, the wells DO run dry. The first thing you need to begin fair and sustainable allocation of groundwater supplies is records of pumping from wells. They don’t exist. And farmers everywhere, from the one-acre plots of North China to the 1000-acre ranches of California, rebel against interference with their freedom. Even if there were the will and the way to adopt rational groundwater management programs around the world, the task would take many decades to accomplish – unless another farm-boy-savior-scientist comes down from the sky, to whom the farmers and bureaucrats can relate.

So where does that leave us? The United States is in a relatively good position because only one fifth of its grain production comes from irrigated land, but the figure is three fifths in India and four fifths in China.11 The world-wide picture is bleak:

* The annual overdraft from the U.S. Ogallala Aquifer, producing cattle and grain in quantity, is said to be about equal to total yearly flow of the Colorado River.12 It was declared by the USDA over a decade ago to be “near depletion,” with Texas having already lost 1.4 million acres of irrigated land and the irrigated land supported by the aquifer expected to be reduced 50% by2030, an acreage accounting for roughly 10% of US grain production.

* In China, the world’s greatest grain producer,13 pumping from a fossil aquifer in the North China Plain is relied upon to produce half the nation’s wheat and a third of its corn, approximately 40 million tons per year or 10% of the nation’s grain production; 14.

* Northern India is also overdrawing its groundwater supplies to maintain grain production. Although the overdraft is apparently much less severe than in China or the United States, nonetheless, if the current level of unsustainable groundwater overdraft continues, government experts have concluded that “India could face severe water shortages.”15

* Lester Brown, founder of the Worldwatch Institute, reports that fifteen nations containing half the world’s population, rely on groundwater overdraft for irrigation.16

These practices cannot go on for long, and in this writer’s opinion, water development and conservation are unlikely to come to the rescue. large surface reservoirs and desalinization are unlikely to save the day, because these projects do not ordinarily pay for themselves and for the foreseeable future governments are unlikely to be in a position to subsidize multi-billion-dollar investments in concrete and steel to feed the poor. As for water use efficiency, it might theoretically permit savings of anywhere from 10-40%, but implementation and enforcement have all the hurdles of groundwater management plans, plus the additional hurdle that tens of millions of farmers were taught decades ago that plentiful water was essential to high yields. Changes may occur, but they will most likely be incremental and slow. So dropping grain production appears inevitable in the US and China, and likely in much of the rest of the world, in the absence of major increases in acreage and/or yield per acre.

As for increased acreage, there is general agreement that the acreages have been at best essentially “flat” for decades17 and in any event it is hard to envision major investments being made in land development to feed the undernourished and virtually destitute bottom seventh of our population when the same land could be used, if at all, to produce beef or biofuels for the top seventh.

Yields? They are still increasing at approximately 1% per year, not enough to keep up with population increase; in fact, world per capita grain production peaked in 1986.18 Steady 1% per year yield increases cannot, of course, solve the problem of exhaustion of fossil aquifers, likely to occur close to the same time as exhaustion of the oil supply. There are disputes as to whether or how long genetic tinkering can continue to improve yields. Eventually we have to hit the maximum efficiency at which photosynthesis can occur, but there are radically different educated views as to how close we are.19

In Lester Brown’s view, “Unless population growth can be slowed quickly, there may not be a humane solution to the emerging world water shortage.”20 The statistics appear to show that he should have said population growth must be “reversed quickly,” rather than merely “slowed quickly.”

So when the aquifers run dry, a return to the days when agriculture was limited to natural precipitation, is inevitable. This means, on top of the present inability of yield increases to keep up with population increases, a relatively abrupt loss of at least 10% of production.

What about the fertilizer? That comes from mining operations, too. That is literally true of phosphorus, although it wasn’t before we came along. There are more phosphorus-rich bones walking the face of the earth than ever before in geological history; humanity is hoofing it around with 5 billion kg or 11 billion pounds of phosphorus ,21 which comes from mines,22 – NONE of it recycled. This has happened only since half of us moved to the cities, taking our personal wastes with us; petrochemical fertilizers replaced natural ones; and community sewers were invented. Mama Nature can’t afford this kind of progress for long.

In fact, the world phosphorus reserves are expected to be depleted within 25 to 70 years, depending upon where you are. Humanity will apparently go extinct for lack of phosphorus within a century unless we resume recycling,.23 This writer is unaware of any government plans anywhere, to do so.

And phosphorus isn’t the perceived serious problem. Nitrogen is. We have a reasonable amount of nitrogen in the air for the present, but the nitrogen has to be processed into ammonium nitrate or something comparable with a high energy input, and the starting material is natural gas, 5 % of which globally is used for production of nitrogen fertilizers.24 There are presently no alternatives. Natural gas accounts for 90% of the cost of nitrogen fertilizer, so the cost of the latter is pretty much proportional to the cost of the former.25 When the petroleum supply starts to go, fertilizer prices will spiral upward.

Of course nitrogen fertilizer can also be produced by nitrogen-fixing legumes, but that necessitates alternating between nitrogen-fixers and market crops. In his Nobel lecture Borlaug spoke of a dream of nitrogen-fixing grains being introduced in 1990 that would free peasant farmers from the need to purchase chemical fertilizers, but then, he said, he would wake up, disillusioned. It was only a dream. 35 years and 3 billion more people later, he would have to tell the New York Times, “This is a basic problem, to feed 6.6 billion people. Without chemical fertilizer, forget it. The game is over.”26

So at present, grain yield is not keeping up with the population, and things will get worse as fertilizer and water become expensive and scarce. Will a large part of the population die when they are curtailed? Not necessarily, because of how we allocate the use of the grain we produce.

To see the whole picture, we need to understand a little about the grain market, which is the dominant food market.. There are at this time three competing demands for the commodity: food (i.e. direct consumption by people), fodder, and fuel. Before fuel became part of the mix, the division between food and fodder was 60:40, with the “fodder” component capable if used as food, of providing the caloric needs of 3.5 billion people.27 But we are squandering the 40% “cushion.”

The mix in 2008 was said by Worldwatch Institute to be 47% food, 35% fodder, 18% fuel. The 18% figure may not be a 2010 reality, but no one claims less than 9%, and use of grain for bioalcohol is projected to double in the next decade.28 The 18% that we burn or apparently will burn is more than sufficient to fill the stomachs of the record 1 billion people who are undernourished today. Does it give you a warm and fuzzy feeling that we burn the grain that is sufficient to eliminate world hunger? Me neither. And If we engaged in a modest conservation program in our gasoline use and gave the saved grain to the hungry, no one would have to go hungry, at least for the moment The feed use is increasingly for beef, and the fuel use is primarily bioethanol – an attempt to use the “cushion” in world grain production to let the middle class, particularly in the

US and China, indulge in quarter-pounders and gas guzzlers for a few more years, while the poor’s burgeoning undernourished try to maintain themselves on an ever-slimmer portion of the grain production.

Feed and fuel compete with food not only for consumers, but for land. The EU has adopted a policy requiring 17% of its farmland to be devoted to biofuels in place of food.29 Land from Brazilian deforestation (which of course many of us would rather see not at all) could produce grain for food, could support range cattle, or could produce sugar cane (or grain) for ethanol. Not surprisingly, biofuel and beef are Brazil’s primary products from destruction of the rainforest.30 Food comes out as a poor third in competition with feed and fuel both for grain and for land. No wonder there were riots over bread in 2008.

“THE MIX IN 2008 WAS 47% FOOD, 35% FODDER, 18% FUEL. THE 18% THAT WE BURN IS MORE THAN SUFFICIENT TO FILL THE STOMACHS OF THE RECORD 1 BILLION PEOPLE WHO ARE UNDERNOURISHED TODAY. DOES IT GIVE YOU A WARM AND FUZZY FEELING THAT WE BURN THE GRAIN THAT IS SUFFICIENT TO ELIMINATE WORLD HUNGER?”

And we have hardly looked at the inevitable consequences of an agriculture dependent for more than half its productivity on fossil fuels, outside the control of one-acre farmers in the Third World or even of thousand-acre farmers in the US. Two of the simpler ties between fossil fuels and food are the costs of fertilizer and water for a typical Third World one-acre farm. With most of the cost of fertilizer(although varying widely year-to-year and place-to-place, $100/acre is a reasonable figure) coming from the cost of natural gas, its cost is going to go up rapidly as oil runs out and (if it happens at all) as the world starts to do something about global warming. And the cost of gasoline at $3/gallon for pumping the water from an -all-too-typical 500-foot-deep well sufficient to irrigate an acre for a year is about $200.31 So rising fossil fuel costs are likely on the near term to drive up fertilizer and water coss by hundreds of dollars per acre The Ogallala-Aquifer farmer may be able to “pass the cost along to the consumer”(Brace yourselves, Americans!), but the farmer in India or China or Bangladesh has mostly to pass the cost on to herself. Where will it come from? Less fertilizer, less water, less food, with one billion people hungry already. These are of course just illustrative costs, but he writer suspects they are more accurate than the assumptions made by the U.N. Food and Agricultural Organization in its food supply projections for the next decade, that the international community will invest $200 billion per year for technological improvements in agriculture, that oil production will meet demand and that its costs will hardly budge.32 So even if the world can produce enough food, most folks may soon be unable to pay for enough.

The story of how we got here is complex – a confluence of population boom, oil boom and bust, the tragedy of the commons, misallocation of resources between rich and poor, the almost-deliberate blindness of America to the consequences of biofuel production -. the list goes on. There is an ongoing academic argument about whether the plight of the poor is one of inequitable distribution “or” population, but it is quite clear at this point that the answer is “Both.” There is also a sociological factor – the separation of people from the land, which has allowed us to “commoditize” land, to block the recycling of phosphorus and nitrogen, to separate sustenance from daily life, to warehouse in China’s cities the millions who had recently been attached for millenia to the cycles of sun and rain and soil. Out of sight, out of mind. We will not treat the earth sustainably when we do not see it and feel it in our daily lives and know directly that what surrounds us is what keeps us and our descendants alive and healthy.

There are too many of us to go “back to the land,” but we must preserve the connection. In coming decades necessity will dictate that everyone produce their own food wherever and however they can, but more important, we must reconnect ourselves to the earth we have abused. You who put aside a little corner of your urban homestead where things green can flourish are preserving the connection as best you can, and must teach others to do likewise. You are preserving an essential thread to our past, which will, if we are lucky, allow us to have a future.

But it’s a slim thread.

It didn’t need to be this way. Norman Borlaug, far from viewing himself as the man who proved the doomsayers wrong, knew what was coming if we didn’t take care. In his Nobel lecture he described the Green Revolution as giving the world a “breathing space” until the year 2000, but then referred to an “impending doom” imposed upon us by the “Population Monster ,” and told his audience that”the frightening power of human reproduction must also be curbed; otherwise the success of the green revolution will be ephemeral only.”

Dr. Borlaug said in his lecture that whether and how we deal with the population problem is a”test of the validity of “sapiens” as a species epithet.” We have so far failed the test and squandered the thirty years he gave us. But the substantial fraction of the grain crop not used directly as food can, if we act quickly, allow us without famine to put ourselves on a sustainable population track, one recognizing that we don’t presently feed ourselves and that on the present track, things will get much worse. And of course no technical fixes can give the bottom seventh of the world population the wherewithal to pay for what they eat, so the looming food crisis will not just be fixed with a theoretical food supply for which they cannot pay. These things must happen. Is that likely? Probably not, given past history. But it is necessary.

Once again we 6.9 billion people are on our own, without leaders or guidance. But we know what we must do, as individuals and nations: we must avoid gasohol and beef, because we cannot take food from the mouths of the hungry; we must manage and conserve our diminishing water supplies, we must work to eliminate abject poverty so that people can pay for what they eat and we must begin to decrease our numbers by limiting ourselves to one child per family.33 There is no evidence that we can avoid famine otherwise. The Green Revolution was a one shot deal, because we cannot again double irrigated acreage or multipy use of chemical fertilizers by five; and because the Green Revolution was a program of the oil age, which is fast departing. Modest crop-yield increases may keep up with population growth for a while (although they haven’t for 25 years), but all indications are that the prices of what food there is will rapidly climb above the budgets of billions of us.

“Norm Boy,” the Iowa farm kid, died last year. He was 95.

………………………………….

The writer is a California-licensed attorney currently residing in Massachusetts. He has had professional experience trying without success to implement groundwater management in California’s vast agricultural San Joaquin Valley. Research and writing were supported by Urban Garden Magazine, which reserves copyright and all other republishing rights except the right to online submissions by the author. He wishes to thank Patricia Lemon and David Steele for invaluable editorial assistance.

1. This article will be published by Urban Garden Magazine in mid-August.
2. Bruce Alberts, President, NationalAcademy of Sciences
3. For the full lyrics, see http://www.netstate.com/states/symb/song/ia_corn_song.htmor http://iowareunionclub.com/iowacornsong.aspx
4. Mark Yudof, President, University of Minnesota.
5. Biographical information from Vietmeyer, Borlaug, Volume 1 (2004), unless otherwise indicated..
6. Dr. Borlaug’s Nobel lecture: http://nobelprize.org/nobel_prizes/peace/laureates/1970/borlaug-lecture.html
7. See Dr. Thomas Stein, sakia.org, 2007, http://www.sakia.org/cms/fileadmin/content/irrig/general/stein_2007_water_use_charts-units_converted.pdf for a general compilation of different foods and their water needs for production, together with a link for explanations as to how these were determined.
8. See chart, Global Education Project, Food and Soil, http://www.theglobaleducationproject.org:80/earth/food-and-soil.php. A hectare, a 100-meter square, is 2.2 acres. Spend an hour studying these charts, and you will know more than the average Ph.D. about modern agriculture.
9. World Bank, Groundwater, http://web.worldbank.org/WBSITE/EXTERNAL/TOPICS/EXTWAT/0,,contentMDK:21633297~menuPK:4620525~pagePK:148956~piPK:216618~theSitePK:4602123,00.html.
10. (Garrett Hardin, 1968 paper published in the journal SCIENCE (162:12431248). If you aren’t familiar with it, read it, and then go for a vacation and meditate on it for a week.
11. Lester Brown, Aquifer Depletion, 2006, http://www.eoearth.org/article/Aquifer_depletion
12. Patricia Muir, http://people.oregonstate.edu/~muirp/waterlim.htm
13. UN Food and Agricultural Organization (FAO), Agricultural Outlook 20102019 (2010)
14. Lin Shujuan, China’s water deficit ‘will create food shortage’, Science and Development Network, 2007, http://www.scidev.net/en/news/china-s-water-deficit-will-create-food-shortage-.html; and Lester Brown, WATER DEFICITS GROWING IN MANY COUNTRIES: Water Shortages May Cause Food Shortages, http://www.greatlakesdirectory.org:80/zarticles/080902_water_shortages.htm.
15. T. V. Padma, Thirsty Indian farming depleting water resources, Science and Development Network, http://www.scidev.net/en/news/thirsty-indian-farming-depleting-water-resources.html, quoting scientists from NASA and also citing the Indian Ministry of Water Resources..
16. http://www.eoearth.org/article/Aquifer_depletion,
17. See e.g. the graphs shown in Staniford’s article cited below.
18. Patricia Muir, http://people.oregonstate.edu/~muirp/waterlim.htm
19. Stuart Staniford, Food to 2050, The Oil Drum, http://www.theoildrum.com/node/3702, discussing both sides of the dispute. See also Grain Production, http://www.whole-systems.org/grain.html, and Science’s February, 2010 issue devoted to food security. http://www.sciencemag.org/cgi/content/full/327/5967/812
20. Lester Brown, WATER DEFICITS GROWING IN MANY COUNTRIES: Water Shortages May Cause Food Shortages, above.
21. http://www.random-science-tools.com/chemistry/chemical_comp_of_body.htm
22. UN Food and Agricultural Organization (FAO), Current world fertilizer trends and outlook to 2011/12, Table 4, ftp://ftp.fao.org/agl/agll/docs/cwfto11.pdf
23. For a recent and very readable discussion of the phosphorus situation, see D.A. Vaccari, Phosphorus: A Looming Crisis, Scientific American June 2009, www.ScientifiAmerican.com.
24. Wikipedia, Fertilizers, http://en.wikipedia.org/wiki/Fertilizer.
25. GAO, Domestic Nitrogen Fertilizer Production Depends on Natural Gas Availability and Prices, 2003, http://www.gao.gov/new.items/d031148.pdf.
26. K. Bradsher and A. Martin, The Food Chain: Shortages Threaten Farmers’ Key Tool: Fertilizer, New York Times, http://bigteaparty.com/fertilizer-soaring-foodprices-key-to-health-bad-for-environment/
27. United Nations Environment Program (UNEP), Food from Animal Feed, World Food Supply, http://www.grida.no/publications/rr/food-crisis/page/3565.aspx). R. Segelkin, US could feed 800 million people with grain that livestock eat, Cornell ecologist advises animal scientists, Cornell University Science News, 1997, http://www.news.cornell.edu/releases/aug97/livestock.hrs.html.
28. Worldwatch Institute, Vital Signs, Grain Harvest Sets Record, But Supplies Still Tight, 2009, http://www.worldwatch.org/vs2009.. The UN Food and Agricultural Organization says the figure is only 9% for biofuels at this time, but also says that the amount of grain being turned to alcohol will double in the next decade. OECD-FAO, Agricultural Outlook 2010-2019. So if 18% isn’t correct today, then it is likely to be correct in a decade…
29. X. Navarro, The European Commission says no to reviewing biofuel percentage goal, http://green.autoblog.com/2008/04/15/the-european-commissionsays-no-to-reviewing-biofuel-percentage/
30. OECD-FAO, Agricultural Outlook 2010-2019.
31. 1 gallon [U.S.] of automotive gasoline = 97,181,192.2530305 foot pounds. 1 acre pumping from 500 ft.: 3 acre-feet of water = 975,000 gal water x8 lbs/gal x 500 ft = 3,900,000,000 ft lbs/ 97,181,192.2530305 ft lbs/gal gasoline = 40.131 gal x $3/gal = $120, assuming a 100% efficient pump, or $200 assuming a 60% efficient pump.
32. OECD-FAO, Agricultural Outlook 2010-2019
33. There is a time lag of 30-40 years built into any population policy based upon birth control, because a rapidly-growing population over-represents the age group under reproductive age. Consequently, a “ZPG” birth rate does not result in ZPG for decades. Moreover, the water and energy problems imply that an overall population reduction is necessary.

By Nicholas C. Arguimbau
31 July, 2010
Countercurrents.org

Day 122

Although very short lived and sparse, the flowers of this black radish are very pretty.
The acrylic crocheted netting (left) has held up much better than the cotton trial. In fact it appears to be in good enough shape to wash, and be used again.

The radish appears healthy (right), and I have every reason to believe that the system could continue to support a plant almost indefinitely.

While I wouldn’t exactly call it ornamental, it is interesting looking, and taller than I expected. Someday people are going to quit teasing me about my crochet hydroponics; but not today.

Today, Gentle Reader I give you version three: I started with two plastic colanders from a dollar store, lashed them together, made a hole in the top, and filled with perlite. The encasing shell and wick are crocheted as one seamless piece.

Then I suspended the “ufo looking crochet thing” over the pond, with the wick dangling into the water.My current plan is to top water the perlite to keep it moist, then as the roots grow down to the wick, allow that to water the plant, until finally the roots reach the water, and it begins to function as a deep water culture. At which time, the perlite globe will not longer be supplying moisture, but air. Peace, love, and puka shells,

Grubbycup ]]> http://urbangardenmagazine.com/2010/05/crochet-hydroponics-part-5/feed/ 2 http://urbangardenmagazine.com/2010/04/hydroponic-recirculation-basics-part-3/ http://urbangardenmagazine.com/2010/04/hydroponic-recirculation-basics-part-3/#comments Sun, 25 Apr 2010 00:07:04 +0000 Urban Garden Magazine http://urbangardenmagazine.com/?p=4626 What all Hydroponic Growers Need To Know About Nutrient Recirculation

As we’ve learned in part 1 and part 2, in order to grow successfully in a hydroponic system, there are certain basics that always need to be kept in check: otherwise, plant performance inevitably suffers. After covering source water, nutrient and pH, world-renowned hydroponics expert Michael Christan breaks down the final ingredients of a healthy indoor growing environment: oxygen, light, temperature, humidity, air circulation and CO2.

Photos courtesy of AmHydro.

The 5 basics of recirculation and plant performance:

1. Pure source water
2. Balanced nutrient ions/anions (EC)
3. Optimum pH
4. Plentiful oxygen availability
5. Optimum light/temp/humidity/air circulation/CO2

The Importance of Oxygen

It’s obvious that loose, friable soil with organic matter and thriving microbes grows plants much better than tight, clay soil devoid of organic matter. The primary missing ingredient in the latter is air (oxygen) availability.

The air we breathe is composed of gasses: 78% nitrogen (N2), 21% oxygen (02), 0.9% argon (Ar) and 0.03% carbon dioxide (CO2). The one we’re focusing on in this article is oxygen. The action of microbes on organic matter in a loose soil produces air pockets as organic matter is mineralized. These oxygen pockets are crucial to the survival and rapid colonization of healthy microbial populations. When the organic matter in the soil is fully consumed by the microbes and plants have consumed all the minerals, oxygen becomes depleted and, if more organic matter is not reapplied, plant performance slows and pathogenic (anaerobic) microbes can colonize. This condition is best avoided.

In media-based recirculating systems, the O2 is in the media: e.g. rockwool, perlite, grow rocks. Plentiful air space is available even after water is drained from the media. Roots thrive in O2-rich pockets. They are able to produce prolific root systems and plentiful root hairs to increase surface area to better absorb available ions. This is the best reason for using media with porosity. Of course, flood and drain systems suck fresh air into the media when it drains, which is why it’s such a great irrigation system.

In water-based recirculating systems, NFT, DFT and Aeroponics, O2 availability is intrinsic to the design of the system. NFT is a flat-bottomed tube with a shallow nutrient stream moving slowly, keeping root hairs moist and absorbing O2 (see “NFT Gro-Tanks,” UGM009). Aeroponics is misting droplets of water, increasing the surface area many-fold for roots to grow prolific root hairs for ion absorption. It supersaturates the solution with O2. DFT uses air pumps and water temp to keep roots bubbled with 02 and oxygen rich.

The heart of a media-based or water-based recirculating system is the nutrient reservoir. This too requires oxygenation, especially when water temperatures rise. The use of air pumps and air stones on smaller reservoirs and pump-powered eductors (venturis) on larger reservoirs make a big difference in pathogen suppression (nasty fungi and bacteria don’t like O2). This agitation drives ethylene gas from the solution and increases the longevity of the nutrient. Be sure that, if there are reservoir lids, there’s room for air exchange with ambient air in the room or greenhouse. Many commercial growers use fresh outside air in their eductors to keep the nutrient solution optimum.

Dissolved Oxygen (DO) can be measured to determine solubility of oxygen in fresh water. Fresh water at 72°F (22°C) has a DO of 8.7 ppm; at 82°F (28°C) it drops to 8.1 ppm. Salt solutions are lower. As a rule of thumb, every increase of 1ppm in DO is equivalent to an 11°F (12°C) temp drop. The cooler the temp, the higher the DO. You don’t want cold water on plant roots, though. You want 72°F (22°C) water at your roots for most plants.

When we measured DO in our greenhouse reservoirs, we found that a 74°F (23°C) nutrient tank at an EC of 2 had a DO of 6.3 ppm (low because of salts and sitting still). When we turned on an eductor (venturi), which we do in ALL reservoirs, we received a reading of 7.6 ppm. BIG difference. That’s an increase of 1.3 ppm without changing temperature.

Then we add an in-line Mazzei injector in between the tank and the feeder pipe, which raises DO to 8.3 ppm. By the time the water had run down the NFT channel and 18 plants had their way with the O2, with some off-gassing occurring, there was an 8.1 ppm DO left in the nutrient solution going back to the reservoir. That’s what we’re after! Plants thrive at those DO levels. Makes ALL the difference.

Be careful: as water temperatures of salt solutions increase, you must mitigate by adding O2 in the reservoir as well as directly on the roots. If you can’t get the DO level up by mechanical means, then you will most likely require a water chiller, which is expensive but sometimes imperative. If you cannot bring water temps down or increase DO in the nutrient solution, your next action will be disease suppression or inoculating roots with beneficials to out-compete the pathogens that thrive in high temp, low DO water. If you do get a DO meter, get a good one. We use an Extech Model 407510.

Light

Photosynthetically Active Radiation (PAR) light is a fancy term for the wavelengths plants use to vibrate chloroplasts to power the engine of photosynthesis, a vaguely understood process in my opinion. It is said that PAR light is in the 400 to 700 nanometer wavelength range. No big deal if you’re outside or in a well-lit greenhouse. But if you are growing under HID light or using it as a supplement, it certainly is.

Color temperatures of lamps are measured in degrees Kelvin from a color rendering index (CRI). The blue/white side of the spectrum has higher Kelvin temp: 6000K-8000K (MH lamps). The yellow/red side of the spectrum has lower Kelvin temperature: 3000K (HPS lamps). As a rule, the higher the Kelvin temp, the more vegetative the growth. The lower Kelvin temps are used for supplemental and/or flowering light. Different bulbs have different combinations or blends of gasses for better PAR value. Plants can be finicky and prefer one blend of light more than another. Trial and error, sometimes, is the only way to find out what your plants really like.

High Intensity Discharge (HID) lamps produce light when the gases inside the fused alumina tube are heated to the point of evaporation by high voltage electricity. This process forces the metal gasses to throw off a barrage of photons partly in the PAR range. As the bulb burns over time, the metal gasses slowly change form and degrade out of the PAR range. It is not obvious, but plant performance can suffer from lack of the PAR light when there is no shortage of photons to the naked eye. To look at light as a possible limiting factor, keep track of the hours your bulbs have been burning. If you are over the recommended burn range as stated by the manufacturer, that could be what’s compromising your system. Rule of thumb with HPS bulbs is to replace them every 12 months, and MH bulbs every 9 months, with HPS burning 12 hour days, MH burning 18 hour days.

Outside it’s obvious what limits light, like trees. But in greenhouses, if the glazing is dirty, that’s a big deal and that situation just creeps up on you. Depending on what you’re growing and what time of year it is, a dirty film can cut out as much as 30% of available light. If you are using an 85% transmission film and have 30% attributed to dirt, that’s 55%, basically shade cloth. In situations where there is too much light and plants are unable to cope with the leaf temperatures or solar radiation, a white or metallic shade cloth is preferable to black, as black can radiate heat back down on the plant canopy. A simple mistake easily avoided by many growers in double poly greenhouses is that the inflation fan is pulling inside air in between the films, thereby creating moisture that blocks light. You can tell by the droplets in between the films, or a haze. It is always recommended to use outside air for inflation. Of course, all of this is dependent on location, latitude, geography, plant in cultivation and skill/experience of the grower. We cannot cover all those variables in a brief article.

Temperature

Plant response to temperature is pretty obvious. It’s visible. Plants stop growing when root temps hit 58°F (14°C). Air temp can actually be cooler than 58°F, but when roots are cool, growth slows and stops even when air temp increases. When temps are too high, say 95°F (35°C) plus, depending on RH, air flow, light, kind, size, and age of a plant, they may stop feeding and spend their energy evaporating water from their stomata to cool down. Temperature must be managed to keep plants transpiring and active in the sweet spot.

Most temp controllers are effective, turning on fans for increased air exchanges, but when temps are too hot outside, air conditioners must be used. As a variable, though, temperature control is straightforward. It’s common knowledge that insects like very consistent temperatures and no air movement. Find which temperatures are your best high and low, and vary them morning, daytime and night. Keep an inhospitable environment for the pests without sacrificing plant performance: another dance to master.

Humidity

The two ways of explaining humidity are relative humidity (RH) and vapor pressure deficit (VPD). Most people are familiar with RH and use hygrometers so, for the purposes of this article, I will use RH.

In my experience, this is the one variable that most growers need to be more aware of. The dance between temp/humidity directly affects transpiration rates as poor transpiration opens the plant organism to disease and mineral deficiencies.

RH is the amount of water vapor present in the air expressed as a % of the amount needed for saturation at the same temperature. Here’s what that means: if the humidity is too high, e.g. 95% at 75°F, plants cannot transpire or evaporate enough water to pull minerals up the vascular system even with stomata wide open. This usually results in calcium (Ca) deficiency (remember, Ca is a non-mobile element and must be constantly supplied to growing tips) and plant stress, which increases their vulnerability to fungal intrusion.

If humidity is too low, 50% at 75°F, stomata will open in an attempt to evaporate water because of the low pressure around the leaf, but then close up to conserve cell pressure in the leaf. Plants stress as they cannot take in CO2 with closed stomata and growth stops as the plant is just trying to survive without going into wilt (i.e. loss of leaf turgidity from which it’s difficult to recover). Again the plant is vulnerable to disease and insects. These two extremes points will create a high probability of crop loss.

As a rule, at 75°F (24°C), if RH is below 60% you must add moisture to get to 75% (which is ideal), but stay below 85% to avoid stress and disease. At 85°F (29°C), if RH is below 70% you must add moisture to get to 80% (which is ideal), but stay below 90% to avoid stress and disease. As temperature rises, air holds less moisture. Steer your plants within these parameters for optimum plant performance.

When RH is too low, use a fogger or humidifier coupled with outside air exchanges. When outside air is too warm and dry, you will have to use some form of air conditioner (if that is the only way) to drop the temperature to increase the moisture-holding capacity of the air.

When RH is too high, raise temperature to reduce moisture saturation of air coupled with outside air exchanges. If outside air has too high of an RH, you will need a dehumidifier to pull water out of the air.

Transpiration is king. Monitoring transpiration rates and keeping them optimum with temp/RH manipulation is crucial. If you are outside of the temp/RH safe zones and don’t use some mechanical method of bringing them under control, you will always be fighting the results of that variable being unchecked. This is where high quality environmental controllers come in handy

You can buy the most expensive nutrients, goodies and gadgets available to grow your crop, but if your plants are unable to transpire and you don’t know that, you had best learn quickly or get a day job

Air Circulation and CO2

No matter what kind of controlled environment you’re running, greenhouse or greenroom, air circulation is another key component that is often overlooked until mildew takes out your crop or your plants starve from lack of CO2. The great outdoors takes care of all this, but inside you have to provide the controls or fall prey to what you didn’t know you didn’t know.

Rule of thumb: 60 air exchanges per hour. Not only do you need to flutter your plants with gentle breezes from an oscillating fan or horizontal air flow (HAF) fans in a greenhouse, but you must freshen the air with air exchanges from outside, taking advantage of the 385 ppm ambient CO2. The raw materials that PAR light makes into carbohydrates are CO2 and H2O. CO2 furnishes the carbon and oxygen, while water furnishes the hydrogen for the carbohydrate (CH2O).

If air exchanges are frequent, 385 ppm CO2 is plenty unless you’re looking to accelerate growth by enriching your space with higher levels to, say, 1500 ppm CO2. Even if you are adding CO2, you still must exchange air. There are numerous ways to provide CO2: chemical reactions, gas bottles, gas generators and a variety of controllers and monitors depending on the size of the operation. For the purpose of this article, you just need to know that it is a basic component of the indoor growing environment, and be mindful that it’s always available. Without CO2, plants will not grow.

One of my teachers, Grenville Stocker in NZ, took me into one of his client’s lettuce/herb greenhouses and asked me, “Would you get a chair, sit down, read a book or hang out in here all day?” Actually, it was way too moist, not enough air movement, my shirt was sticky, and it was uncomfortably warm. I said, “No way.” He remarked, “How do you think those plants feel? The same way, I reckon, except they can’t leave.” Then he showed me powdery mildew in certain areas, a thrip infestation and tip burn in some of the lettuces. The plants did not look vital, they looked stressed. I noticed the HAF fans were down, because of a blown breaker that the grower had been meaning to fix for a week. He had an RH monitor but no controller to check humidity and spill air or add heat … AND he was doing only 1 air exchange per hour because it was cold outside. He wanted to keep temps up inside without turning on the heat, which would cost him money. I looked at the RH: it was 95%. Temp was 80°F but it felt like 90°F because of the humidity. His client was too busy to pay attention or take coaching, and he wasn’t even there. Grenville always tested me; he’d say, “What’s wrong with this picture?” Then he would point out a basic that was obvious once I saw it. Most problems were easy to correct once distinguished.

I found out later the grower lost 50% of his crop and the other 50% was barely marketable. Had he kept HAF fans working, increased his air exchanges and turned up the heat to drive off the humidity with the help of a controller, he would not have had crop and financial loss. Just that one error cost him a market: he couldn’t deliver, so a competitor moved in. The point I’m making is: don’t leave your plants in an environment you can’t handle being in yourself. Use meters and controllers, but always keep them honest by paying attention to what your skin says.

All the variables of light, temperature, humidity, air circulation and CO2 must dance together in a harmony that you must monitor and control to be successful and avoid crop loss. If you cannot distinguish which variable is out, you will be guessing what the problem is and perhaps taking actions that are detrimental. Next time a problem arises (which inevitably will happen) and you’re scratching your head as to what to do, go through this list and check off each one that you KNOW is in tolerance. These 5 basics could be what you didn’t know you didn’t know. Now that you do, dissect them and become competent with each one:

The 5 basics of recirculation and plant performance:

1. Pure source water
2. Balanced nutrient ions/anions (EC)
3. Optimum pH
4. Plentiful oxygen availability
5. Optimum light/temp/humidity/air circulation/CO2

For the content and experiences that allowed me to write these articles, I’d like to thank my teachers, Grenville Stocker (Stocker Hort), Jeff Broad (AutoGrow), Genaro Calabrese (ex partner), Grant Creevey (Accent Hydro) and all our clients and associates for sharing and being open to “figuring it out.” Controlled environment plant cultivation is infinitely beguiling; I am always learning a greater respect for being part of that process. Genaro’s motto: “Every plant, every day.”

Good luck and good growing.

Michael Christian, the president of American Hydroponics since 1984, is a hydroponic system designer and consultant to commercial growers worldwide.

It’s both. Water from the koi pond is filtered through a series of 4 wooden half-barrels.

In this way, I get both a cleaner pond, and attractive, almost maintenance-free plants.
Each barrel is slightly lower than the one before.

Pond water is pumped into to the top half barrel, and gravity takes care of the rest. These plants are obviously not nutrient starved. From the levels they get in these last two, I’d say the system could support another pot or two.

If I were to use a more traditional design, I would have pots that needed added fertilizer to do well, and a normal pond filter to remove unwanted elements from the koi pond.

By combining the two, not only do I avoid expenses like fertilizer and new filters, I avoid the work in adding and changing.

I do not claim this system to be maintenance free, but most of the time all it needs is simply clearing the pump intake, or removing plants so they don’t overgrow.

Peace, love and puka shells,

Grubbycup ]]> http://urbangardenmagazine.com/2010/04/half-cooked-thoughts-pond-filter-or-hydroponic-planter/feed/ 5 http://urbangardenmagazine.com/2010/04/what-is-permaculture/ http://urbangardenmagazine.com/2010/04/what-is-permaculture/#comments Thu, 08 Apr 2010 21:36:29 +0000 Urban Garden Magazine http://urbangardenmagazine.com/?p=4364 Javan Kerby Bernakevitch, a permaculture designer and teacher-in-training, introduces us to the principles and practice of permanent (agri)culture.

“Permaculture is revolution disguised as organic gardening.”
- Graham Bell, from Permaculture – A Beginner’s Guide

Permaculture is not organic gardening, and I am not a gardener. What I am is a permaculture practitioner who uses organic gardening, and many other tools, to design systems that work to water, feed, warm, house, and provide community, not to mention: make a garden.

So if permaculture isn’t just gardening, then what is it?

Permaculture is not the rain that falls, nor the roof that collects it or the catchment systems that stores it. Permaculture design is the relationship between these things. Permaculture is the match maker, creating passionate love affairs between rain and plants, humans and animals, and ultimately achieving systems that produce enough natural resources to provide for their own maintenance and reproduction.

Rainwater collection.

Imagine a ball that drops, hitting a lever that turns a wheel pulling on a string attached to a light bulb. Each step creates the necessary conditions for consequent steps which eventually will turn on the light bulb. Similar to well set-up dominoes. We can learn the skills to design whole systems that are focused on goals and fixing problems at the source, instead of focusing on the symptoms.

A backyard graywater filtration system that takes the sink, shower and washing machine water from the house, passes the water through a strainer, and then filters it through this man-made wetland bedded in 4 bathtubs that irrigates the gardens directly. Those irrigated beds produce 10-20% more than the non-graywatered beds.

Graywater filter.

With the light bulb glowing over your head you might have realized that practicing permaculture is not all that difficult. In fact, you probably are practicing it already and don’t realize it. Why? Because the knowledge contained under the umbrella of permaculture is not new; it combines the ancient and traditional knowledge of growing food with the modern science of ecology and new technology. Work in permaculture is self-evaluating: either it works or it doesn’t. The beauty of this movement is that, if you can learn from your errors, you can learn to design systems that work. You don’t have to wait for a committee to stamp your certificate or a teacher to baptize your understanding through tests.

“If you’re a scientist, you could liken it to a miraculous wardrobe in which you can hang garments of any science or any art and find they’re always harmonious with, and in relation to, that which is already hanging there.”
- Bill Mollison, the godfather of permaculture

Permaculture is a way of looking at the systems that sustain us, and designing them to have built-in endurance and sustainability to gain the highest output from the lowest input. It is not just the organic garden: the garden is just a piece of the bigger picture. A picture that includes the local climate, site topography, water access and drainage, capacity of the land and its users, where income is produced to finance the whole process and a host of other items. It is looking at the pieces of life and designing systems that produce the basic necessities needed to sustain and provide joy while creating rich, wealthy lives.

“Wealth is a deep understanding of the natural world.”
– Inuit definition

“I think it’s pointless asking questions like ‘Will humanity survive?’ It’s purely up to people – if they want to, they can, if they don’t want to, they won’t.”
- Bill Mollison

Bill Mollison, a disgruntled and highly motivated biologist, culminated a true “aha” moment with student David Holmgren in 1978 when they set out the seminal work Permaculture One. Coined as a combination of the words permanent and agriculture, and then permanent and culture, permaculture from its textual origins is about creating a world were we can live indefinitely. In this work, Mollison and Holmgren articulated their thoughts on sustainable living through a positive action movement in which anyone could be involved. The publication helped to create the first texts for the personal educational keystone of the movement: the Permaculture Design Certificate (PDC). Any keeners out there will be able to find PDC courses being offered in online and hands-on formats.

“If people want some guidance, I say, just look at what people really do. Don’t listen to them that much. And choose your friends from people who you like what they do – even though you mightn’t like what they say.”
- Bill Mollison

Contrary to the parental adage “do what I say, not what I do,” Mollison urges those interested to watch and see what is really happening. In a way, that’s how permaculture started. Working in wildlife relocation, Mollison realized that a forest needs no watering, weeding, fertilizing or other “outside care.” The forest is self-perpetuating. Mimicking the ecological principles he observed in the forest, he conceptualized that he could “make a system” that could produce food for human consumption. In essence, a food forest. This self-described “revelation” was understanding that there are beneficial interactions between living and non-living components. As people, we can assemble those components together to create beneficial connections and yields.

When Mollison asked an elderly Greek woman in a vineyard why she planted roses among her grapes, she replied: “Because the rose is the doctor of the grapes. If you don’t plant roses, the grapes get ill.” Accustomed to science, this answer did not sit well with Mollison. He began to research and found that the rose produces a certain root chemical that the grape root uptakes, which in turn repels the white fly (a pest for grapes). The story is the same from both Mollison and the woman’s perspectives: the grapes grow in community with the roses. However, the understanding behind the story changed. This story is where permaculture can be understood: in nature, organisms work in relation with one another. And using our commonsense we can observe these interactions, work out the commonsense or scientific understanding of what is happening, and reassemble the principle behind the interaction to create systems that feed, clothe, house, warm, and provide us with community.

Now in its fourth decade, the permaculture movement has spread like wildfire, creating a global grassroots community. Global in scope and adoption, permaculture has been able to specialize to meet specific needs. As permaculture is not an ideology, but rather an idea, it can change and adapt to any situation. In Haiti, permaculture practitioners were on the ground shortly after the earthquake, providing safe drinking water and human sanitation with a fraction of the budget of other aid organizations with twice the results. These efforts have grown from solid ethical building blocks that help guide the intentions of practitioners. These ethics, in order of priority and importance, are: Earth Care, People Care and Fair Share.

Earth Care

“We are sufficient to do everything possible to heal this Earth. We don’t have to suppose we need oil, or governments, or anything. We can do it.”
- Bill Mollison

“The Earth is a living, breathing entity. Without ongoing care and nurturing there will be consequences too big to ignore.”
- David Holmgren

Humanity has withdrawn so much of the natural capital from the earth’s savings account that we are no longer living off the surplus interest; we are now eating into the capital itself. We’re living on the savings, and they’re running low: it’s a lot like college without the getting-more-educated bit. From the north to south pole, to the tip of Mt. Everest and the bottom of the ocean, our environment is degraded and degrading at an alarming rate (imagine 1,000,000 fire alarms going off in a closed phone booth and you’re close to how serious the situation is). Synthesized chemicals at toxic levels can be found in every environment, in newborn children, and even in pollen (121 herbicides, fungicides and insecticides at last count); these are the very building blocks that support life.

Think of it this way: if you were hospitalized and depending on a medical life-support system, would you jiggle the plug, poke holes in the feeding tubes or pour toxic waste in the IV bag? Not unless you’re Keith Richards or a cockroach, and even then I think they’d both think twice about it … at least the cockroach would.

Earth Care is the top priority. Earth Care is our top priority. As a curmudgeonly 63 year old farmer from Manitoba advised, after I asked what I should grow on a certain piece of land…

Me: “What should we grow here-”

Him (cutting me off): “Soil.”

Me (frustrated but respecting my elder): “Right, I understand that, but in this micro-climate, what would be good to propagate-”

Him (cutting me off again): “Soil.”

Me (realizing there might be something he’s trying to tell me): “Okay, so you’re saying I should grow…”

Him (finitely stating): “Soil.”

At present, our greatest threat to humanity is not climate change (though that affects soil loss), nor pollution (this does affect soil loss), nor deforestation (now, that really affects soil loss). Our greatest threat is … soil loss. Without healthy ecosystems, soil is destroyed. Without soil, there is no food and, without food, the chairs around our global table become vacant. And it gets rather lonely sitting by oneself.

People Care

“I cannot save the world alone. It will take at least three of us.”
- Bill Mollison

Me, myself and I. Okay, and you too. And you can join, and … well heck, let’s invite everyone to the party. After ensuring that our life-support system is tended to, we turn to each other realizing that if the entire human species is on a planet with finite resources then we in turn all affect and effect each other. Like it or not, we are all in this together. In a closed system, the actions of one are felt by many, detrimental or beneficial alike. In permaculture, and life, everyone has something of value to bring to the party.

In a scarce economy, resilient employees embody the same strategy that ecology demonstrates: an organism that places itself in the most service to the whole, survives. We can see how helping friends and family survive supports our personal survival, and we may evolve a matured ethic that sees all humankind as friends and family and thus life itself as our ally. People care then turns into species care and we too have the “aha” moment that Sister Sledge had: “We are family.”

Fair Share

Remember kindergarten? No, not the dirt eating (which thankfully we don’t have to resort to … yet), but the idea of sharing. Well, sharing is back in style, sharing is the new khaki. With a new twist, fair share is also about abundance. Surplus is created either through an extraordinary amount of effort, which turns into a deficit of time and energy, or by limiting consumption. By conserving resources and setting limits to consumption, we can set our best course for survival to include others while creating the conditions to further the two ethics above.

The Prime Directive of Permaculture

“The only ethical decision is to take responsibility for our own existence and that of our children.”
- from The Permaculture Handbook, by Bill Mollison

Under the prime directive of permaculture, the three ethics (Earth Care, People Care and Fair Share) guide us to devise methods of applying them to our gardens, land, economies and nature. We can see permaculture as “the mechanism of mature ethical behavior, or how to act to sustain the earth” and our existence on it.

Well, if this hasn’t blown your mind yet then strap in for round two … how to go about applying and practicing intentional permaculture. From the prime directive and the ethics we spiral outwards to principles, strategies and, finally, techniques. These three are the holy trinity of permaculture in action.

Principles

Principles are beneficial as there are no penalties for error, only learning from errors, thereby leading to new ideas and methods. Now, here’s where the idea of permaculture being open-source really gets going: at a recent permaculture teachers’ training session, the facilitator (a long-time permaculture practitioner and teacher) stated that she knew of over 372 principles related to the movement. 372? Yup, 372. And by the time you start practicing permaculture, I’m sure you’ll have come up with a few more, or remember one that your grandma used to use. My Ukrainian Baba used to bellow from the top of the stairs when my brother and I were rough-housing: “Smarten up or I’ll throw you out, one by each!” The humor (or maybe it’s the genius) of this maxim lies in the translation to English: those parts that do not work with the overriding ecological principles at play (like my Baba’s patience, or the ability of the earth to absorb the pollution we are producing) are “thrown out, one by each.”

As you move further down this rabbit hole you’ll find many principles. However, I found permaculture best sampled like a good buffet, in sizable portions. David Holmgren, the other author to the first book of permaculture, continued down his own path and has produced some excellent work, including 12 concise principles that are easy to remember and to implement. Some of my personal favorites of his are:

Integrate Rather Than Segregate

The three sisters. Photo credit: Abri Beluga.

This principle has always wowed me by providing concrete examples of how to integrate plants together in communities or guilds that provide for the needs of other plants. The traditional example in North America is the “three sisters,” or maize (corn), beans and squash. Benefiting from each other, the maize provides the structure for the beans to climb (no poles needed). The beans fix nitrogen for the soil and the other plants, while the squash vines spread along the ground, blocking the sunlight that weeds need. The squash leaves are also a “living mulch,” creating a microclimate that retains moisture while the prickly hairs on the vines help deter pests. This guild integrates while utilizing the “waste” of the other plants, thereby touching on another great Holmgren principle: Produce No Waste (meaning that everything can have a use, even if we call it “waste”).

The Mollisonian Permaculture Principles that stand out for me are:

Work With Nature, Rather Than Against It

The revolutionary Masanobu Fukuoka (you’ll thank yourself if you read his The One Straw Revolution) once remarked, “If we throw nature out the window, she comes back in the door with a pitchfork.” When insecticides are used, the predatory insects (insectivores or cannibals, as I like to call them) are wiped out with the pests, ensuring that if an explosion of pests proliferate next year there will be no predators to keep their populations in check. Consequently, more insecticides are sprayed, tipping the scale even more. All pests are never killed and the survivors’ resistance is bred into a new generation, riding nature’s pitchfork aimed right at our food crops.

Visible through this window in the south side of a cob building is a frost peach growing on Vancouver Island. Peaches are not typically grown on Vancouver Island, but this tree is thriving because of the heat absorbed by the structure and the resulting microclimate.

The Problem is the Solution

Everything works both ways. It is only our perspective that judges a thing to be beneficial or not. If the south side of the greenhouse is constantly facing the sun, construct that side out of glass or plastic (salvaged, if possible) and, as the north side never receives sun, let’s construct that side out of a substance that has thermal mass (think of it like a thermal battery: it can up-take heat and return the heat to the surrounding area) like rock, cob (a traditional building material made up of clay, sand and straw), or something else that absorbs solar heat.

A greenhouse with south-facing glass and a north cob wall to retain heat.

Moving swiftly along strategies, like the ones below, are just like a handy number two Robertson screw driver or your Felco pruners: a tool to aid you on your permaculture journey.

When designing any site, be it a garden, a house, or even a driveway, here are the first three things to consider, in order:
1. Water
2. Access
3. Structure

1) Water – No matter where you travel or what you do, water is where the chemistry of life occurs. It’s also where some of your biggest headaches or joys can come from. First, consider where your water source is. Is it close to land that has a lot of sun in all seasons? What’s the land like around the water source? Where does it recharge from (underground, a stream that comes in from your neighbors’ property, precipitation)? Next, where does the water go? Does it drain on the land? Is that drainage seasonal or consistent year-round? If water is life, understanding the nature of your water on-site can save thousands of hours and just as many aspirin or cups of willow tea.

2) Access – As people, we design systems to water, feed, warm, house and provide us with community. If we design those systems first and then go to design access, we may find that the 6′-wide bed is too big for us to garden from the side. Considering how much a system will have to be “bumped” up against informs our decisions on how and where to construct that system. For example, chickens (the official permaculture mascot) need daily feeding (input) and collection of eggs (output). As keepers of this system, additional time and strain is endured if the chicken coop is placed far away from the house. Thus, if a system is “bumped” up against constantly, then placing that system closer to where we are increases the yields (outputs) while decreasing the work (inputs). This also applies to pathways, driveways, and other forms of getting to and away from systems.

3) Structures – Now that you know the water is draining on the north side of the hill and the best vehicle access is from the south, siting your structure can be made by an informed decision. In North America 40% of all energy consumed is by building and maintaining structures. With such huge amounts of resources inputted into your structure (house, greenhouse, tool shed), it’s important to site your structure where water is accessible and not threatening, and access is easy and not labor intensive.

“Permaculture is the end of the lawn virus, symptomatic of consumer culture.”
“You could say it’s a rational man’s approach to not sh*tting in his bed.”
- Bill Mollison

Or perhaps the definition is: “it’s sustainability, distilled, served straight up.” Or maybe it is just understanding that silver bullet solutions are best left to werewolves, proving that silver bullets are as fictitious as their intended fantasy targets. Catch-all solutions like pesticides and magic pills always have unintended side effects: it’s best to address the problem at its source.

As Geoff Lawton (the architect behind the Youtube video “Greening the Desert” — worth the time to watch) says, “All life’s problems can be solved in the garden.” Maybe permaculture is all about organic gardening … however, you’d do well to discard the definitions and just go out there and continue to garden, add in a sprinkle of permaculture, and be fruitful and mulch apply.

Javan Kerby Bernakevitch is an environmental educator, professional communicator, facilitator and editor. An O.U.R. Ecovillage resident on the West Coast of British Columbia, Canada, Javan continues to expand his knowledge and passion for sustainability through permaculture as a designer and teacher-in-training.

Join the discussion on how to incorporate permaculture principles into the indoor garden: post your comments and questions below!

Over in Europe, NFT has been the preferred hydroponic method among hobby growers for many years. Now finally, it seems, the word is beginning to spread to hobby growers over on this side of the Atlantic. But what’s the real deal with NFT? Does it truly offer all these promised benefits to hobby growers without any catches or compromises? Is it just suitable for salad crops or can it deliver when applied to heavy, fruit-laden annuals like tomatoes and cucumbers?

Our main man with a high yielding plan, Everest Fernandez, takes a first look at NFT Gro-Tanks and shares some of his hands-on experience.

WORDS: Everest Fernandez

NFT 101

Ok, don’t be shy. Raise your hand if you don’t know what the hell NFT is. No worries! We’ve all been there, and that’s what I’m here for I guess …

NFT stands for Nutrient Film Technique. It refers to a general method of growing plants hydroponically. In NFT nutrients are added to water just like any other hydroponics system and this solution is contained in a tank. Plants sit on a grow tray above the tank and the nutrient solution is pumped up to the tray. The tray is positioned so that it lies on a slight gradient. The nutrient solution flows constantly over the roots feeding them all the nutrients and water they need. Any nutrient solution that is not up taken simply flows back through a hole into the tank where it is re-circulated.

But What Are The Plants Growing In?

The roots of your plants are constantly bathed in an oxygen-rich nutrient solution. It forms a thin ‘film’ about 0.03 to 0.1 inches in depth. A thin layer of capillary matting called “spreader mat” is first placed over the tray. This helps to spread the flow of the nutrient solution evenly over the entire surface of the grow tray. We all know that roots hate light. That’s why they tend to stay under the ground in nature! Fortunately the root zone is protected with a piece of Correx (kind of like a cross between cardboard and plastic). Small holes are cut into the Correx, just big enough for the base of the plants to fit through. This also helps to prevent algae growth in the root zone or nutrient solution.

Cucumbers grown in an NFT system.

The thin nutrient film not only provides your plants with all the water and nutrients they need, it also gives them access to loads of oxygen – essential to maintain key metabolic processes in the root zone that regulate how efficiently your plants can feed. This is a key feature of NFT. There are always some parts of the root zone that have more access to oxygen than others – simply because they are higher up: these parts of the root zone help to supply lower parts with all the oxygen they require. This is just one aspect of plant physiology that NFT growers exploit to their advantage. When plants have access to all this water, nutrient and oxygen simultaneously the growth rates can verge on being scary.

Gro-Tanks vs. Gullies

NFT Gro-Tanks can accommodate a far wider root system than the NFT ‘gullies’ you may have seen on commercial hydroponic farms (commonly used to grow basil and other leafy greens) making them ideal for plants that produce abundant root systems such as tomatoes.

Go With The Flow

NFT Gro-Tanks often come supplied as a complete kit for hobbyists – including the right sized pump. Solution flow is generally unimportant but should normally be between 1 to 3 pints (400 ml and 1500ml) per min. Channels should be sufficiently sloped, normally not less than 1:50 but may be much steeper if set-up allows, so that there is no “pooling” in the channels.

Plant Stability

What about heavy, fruit-bearing plants like tomatoes? Surely without any growth media, the plants are simply going to keel over due to their own weight, right? Amazingly, the plants form such a thick mat of roots underneath the Correx that they are very well supported. That’s not to say that some top heavy varieties won’t benefit from some net supports – but that’s often the case across the board when you grow plants near to their maximum capacity!

Propagation

NFT growers start their seedlings and cuttings off in the regular way, perhaps propagating in rockwool cubes or another inert media (e.g. net pot with clay balls.) Aeroponic cloning machines can also be used. Just as with any other hydroponics system, it’s really important to ensure that your seedlings or cuttings have a sufficiently developed root zone before transplanting them into an NFT grow tank. Don’t just wait for one or two roots to poke out. Aim for a mass of roots first! A great tip is to use an air-pruning tray (see UGM005, page 28) to generate a compact, dense root zone that’s bursting to break free!

Everest’s NFT Grow-Tank Tips

Here are some of my special tips learned the hard way:

1) If you are using rockwool starter cubes, ensure that the ridges at the bottom of the cube are in line with the nutrient flow, not perpendicular to it. Otherwise your nutrient flow will be impeded.

2) No growth media around the root zone means less insulation and less protection from extremes in temperature – so you need to have your garden’s environment dialed in. The temperature of your nutrient solution is also crucial – but this is no different than with other hydroponic applications. Try to keep your nutrient solution at around 65°F for high levels of dissolved oxygen and optimum nutrient uptake.

3) Plants grown indoors under lights will take up water at a greater rate than they take up nutrient. Over time the EC (CF) of the solution will rise. Regularly top up your tanks with water or 50% strength nutrient solution. Keep your top up nutrient solution in a separate barrel rather than using water straight from the tap.

4) Maintain the pH of your nutrient solution at around 5.8 – check regularly as it can rise as the plants feed.

5) As a general rule, drain your nutrient solution and replace with a fresh batch every 7 to 10 days for optimum yields. Obviously bigger tanks can get away with less frequent changes whereas bigger plants prefer more regular fresh nutrients. For more information on nutrient change-outs make sure you read ‘Maximizing The Nutrient Environment’ by Lawrence Brooke (UGM004,005,and 006).

6) Do not let any light leak into the root zone. Ensure the holes in the Correx cover are just big enough for your plants to fit through. Cover the bases of your plants to prevent green algae forming – especially important if using rockwool cubes.

7) Thoroughly clean your tanks in between crops with a soap solution and rinse thoroughly.

Wait until roots are showing out of your starter blocks before inserting them into your NFT system. This is absolutely crucial!

9) Use a half strength nutrient solution to start your plants off, moving to two thirds to full dosage rate (as detailed on the bottle) after the first nutrient solution change (about 7 – 10 days after planting).

10) Take the opportunity to observe your plants’ root growth directly by simply lifting up the Correx cover!

11) Make sure you completely remove plastic wrapping from rockwool cubes or remove pots if using soil or coco. This allows the roots to access more oxygen.

12) NFT is a bare rooted growing technique. All but the smallest of plants will need additional support, i.e. yoyo’s or pea netting.

13) Cut lengths of spreader mat long enough to allow an overhang of a few inches from the channel into the tank. No trickling water sounds!

14) Don’t crowd them! Plants grow incredibly fast in NFT Gro-Tanks – many growers are overwhelmed!

Think NFT – Think Sushi!

NFT constantly provides plants with the opportunity to feed rather than other methods which just provide several opportunities to feed. It’s a bit like sitting in one of those once-trendy sushi conveyor belt restaurants all day, every day. You, like your NFT plants, can take what they want, when they want it, rather than having to wait for their next feed. As a result, you and your plants are going to end up very happy and heavy!

Planting out and Irrigation

First, mark your planting sites with a marker on the Correx sheet. Do not position any plant too close to the pump. Make the holes just big enough. The aim of the game is to allow your cuttings or seedling access to the nutrient film without letting light in through gaps. Lay a single layer of spreader mat over the grow tray. Run your pump 24/7, day and night. There’s no need to work out irrigation cycles and frequencies. Your plants will simply absorb as much or as little nutrient as they require. This is perhaps one of the most appealing aspects of NFT. You should be able to see obvious root activity within 24 hours of planting out. Root axes grow into the nutrient film. Fine root hairs will also grow around the propagation media.

Incredible Root Development

One of the best aspects of NFT growing is the ability to peer at the huge mat of roots that quickly develops underneath the Correx cover. It’s easy to assess the health of your plants – just look for a thick mat of white roots! Watch that the roots don’t get carried away and grow into the pump. (Unlikely, but it does happen.) Clean-up in between harvests is a lot less hassle than with media-based growing methods too, mainly because there is so little media to deal with. This makes NFT Gro-Tanks a great choice for the hobby grower who doesn’t want to endure the regular hassle, expense (and back ache!) of carrying endless bags of soil, coco or clay pebbles.

The Verdict?

Once I tried NFT I immediately saw the benefits, despite grossly overcrowding my Gro-Tanks with waaaay too many plants on my first few attempts. You live and learn. Since then I have come to appreciate that less is, indeed, more!

A greenhouse full of plants grown NFT-style.

Daniel Wilson invites us to rethink what gardening in earth vs. gardening in water really means to the sustainability of indoor gardening.

Allow me to paint you a picture…

It’s a beautiful day in Anywhere, USA. It’s 10:30 a.m. and somebody just woke up, had their herbal tea and is now ready to tackle a long day of transplanting young plants into 7 gallon containers of Sri Lankan coco. They hop into their biodiesel powered 4×4 and head straight for the local grow store to pick up the pallet of coco it’s gonna take to fill those 120 containers. After dropping a cool $1,500 for the medium and another $250 for containers, they load up their rig and jump back on the 101 and it’s off to work. Sound like anybody you know?

There’s obviously a fair amount of energy someone’s just expended and they haven’t even started “work” yet. It’s pretty obvious this is a labor intensive method, but it’s well worth it because they’re growing organically, right? Oh … they’re using synthetic coco fertilizers, run drain-to-waste? But don’t they live in the woods? What happens to the run-off? Thank goodness nutrients come in 5 gallon containers because we’re going to be getting through a whole lotta nutes using the drain-to-waste method, right? Okay okay … I’ll quit this righteous talk. But let’s take a minute to ask ourselves a far more relevant question:

Q: Is it really sustainable to continue shipping millions of pounds of growth media all over the planet?

The current practice of bagging soils and shipping it indiscriminately around the globe has helped propel container soil/coco growing to its current popularity in the indoor grow scene. Though this is, without a doubt, a productive technique, it certainly makes the business of growing in earth a very petroleumintensive practice. Most of the organic growers I talk to take great pride in the natural grow medium they use and feel it’s the ecologically appropriate way to garden … as nature intended. Very few growers consider the great costs incurred by transporting that bag of earth conveniently to their local garden shop. The trucking of this relatively abundant resource (earth) has become quite commonplace in both greenhouse and year-round gardening circles. We rarely give a second thought to the amount of energy the bag of earth we depend upon so much represents. In fact, many growers are so confident in the sanity of these perpetual shipping practices that they will buy brand new bags of earth for their next cycle of plants to follow this round. Alas, very few would consider the idea of composting their used grow medium to be used to generate future harvests.

That being said, we need to consider what would happen if the shipping of soils for thousands of miles just becomes impossible … due to regulations on shipping or even a reluctance of a region to want to give up its precious carbon source, perhaps seeing it a better idea to keep it local and grow food in it as opposed to trading it for money. I know, I know, some of this might seem pretty far out and unlikely but it’s these awkward questions that lead us into discussions which begin to propagate solutions for the future. The critical thinking necessary to tackle issues before they become an “issue” is what we need to strive for as a garden and farm-based civilization. Past populations both benefitted and suffered from the methods they preached and practiced. It’s only in hindsight that clarity begins to develop and we are able to steer a course for the better.

So this leads me to our next Q & A.

Q: What is the most sustainable grow medium for the future of indoor and greenhouse cultivation?

For this question there is no simple answer.

1) The renewability of coir fiber is promising, but unless coir is a local product we are still faced with the shipping issues.

2) Naturally derived soils are another obvious option but, as with coir, unless we can solve the shipping dilemma it too falls short with regard to its practicality over time.

3) Stone wool (aka rock wool) products are a mainstay of commercial growers and are a fairly sustainable option – but it takes intense amounts of energy and large factories to process into forms well-suited for plant cultivation. And there’s still the matter of shipping, as far as from Holland to California at times: yikes.

4) Regional soils offer a pretty attractive option as we could build soils from an area’s most naturally occurring resources. This might mean West Coast Soils, East Coast Soils, Deep South Soils … you get the gist. This would make for minimal shipping, and it just makes sense.

5) Expanded clay pellets are another option with a light and dark side. Though made out of naturally occurring inputs, it (like stone wool) is energy intensive to make and costly to ship. More often than not it’s coming all the way from Germany!

6) Local water sources all over the planet offer a reusable and renewable way of growing healthy food, fiber and medicine. It’s possible to pump water vertically from indigenous terrestrial aquifers, or when available, benefit from naturally occurring snow melt driven by gravity.

Is it really possible that water could be considered a viable alternative to growing crops in a conventional substrate? What about plant nutrition? This leads us to our next question …

Q: Besides Aquaponics, don’t most high performance water culture applications rely on inorganic nutrients to work most productively?

Hydroponic applications use mineral salts to provide plants with the nutrition they require to grow and bloom. Most hyper-oxygenated water culture methods tend to greatly increase the efficiency of nutrient uptake in the plants’ root zone. This, in turn, maximizes these naturally occurring earth elements by offering them to plants in their most available forms. Typically you can run your nutrient solution at 40%-70% strength when compared to regular application recommendations for any given nutrient. Combine this with the closed loop nature of the majority of water culture applications and you are feeding your crops and also managing our planet’s most precious resource in a responsible, efficient manner.

Q: Isn’t that still using petroleum-intensive inputs to grow plants? So what’s the difference between this and using petroleum to ship soils?

Most notably, the difference is the reduced emissions from the avoidance of burning fossil fuels to ship transcontinental distances. Besides, this efficient nutrient uptake and constant recirculation gets the most out of both the nutrient and the water. Dissolved minerals in solution make the need for a conventional growth substrate relatively unnecessary in modern gardening applications. This can result in another way for gardeners to save.

Now let’s really get down to the bottom-line with this whole water angle:

Q: Sure seems like it takes a lot of plastic to make a hydroponics system … don’t they make that out of petroleum too?

This is without a doubt the least sustainable aspect to any plastic-intensive hydroponics application. Keep in mind, though, that the majority of soil cultivation is in plastic soil pots … which are often not reused. Most hydroponics systems incorporate as much recyclable content as possible in the form of HDPE (which currently has a LEED rating), PP (Poly Propylene) and other relatively benign plastics. At the present time there are no viable substitutes for PVC & ABS plastics. Hopefully in the not-so-distant future, plant-based polymers may offer a more sustainable substitute. When a hydroponics system is designed and built professionally it should be something that can be used for many, many years. It’s only over this period of time that the practicality of using the plastic finally balances out the negative impact of the plastic itself. With that said, avoid hydroponic plastics if you’ve no intention of reusing it over and over.

Some Conclusions

Whether you’re a fan of soil or water as your grow medium, one thing is for certain: producing consistently good results has to be the common denominator in any crop production strategy. There’s no shortage of different time tested techniques to get sound results. The ever-evolving challenge is how we can achieve the results we expect without disproportionately depleting our planet’s natural resources.

LEDs replacing HID grow lights within the next decade is pretty unlikely, but we can make responsible substitutions as these new technologies become available. Modern water culture methods are one of the most implementable techniques we can use to reduce our carbon footprint as growers. Though not perfect, water culture provides a genuinely organic grow medium at the turn of a wrist. Put down that bag and pick up the hose.

Some final food for thought:

Plant life as we know it conceivably evolved in the oceans long before our earth’s mantle was broken down into what we now consider soil. It was only when single-celled organisms came to the rocky shores of these primordial continents that terrestrial plants even began to exist.With that said, all plant life has its most ancient DNA, which is still able and very willing to adapt back to water. So if the seas were the Petri dish that plant life developed in, isn’t the ocean essentially just a constantly circulating, well-aerated solution of H2O and dissolved salts? Sound familiar?

Below are some pictures of the way to PROPERLY install the ChillKing/IceBox combo—unlike what I had done previously.  Take note of the new hoses and worm-gear clamps used to secure everything.  Your local hardware store will stock a variety of typically cheap hoses.  The hoses from Hydro Innovations are industrial quality and tailored to their cooling and CO2 generator systems—-perfect diameter, inner and outer.  The most significant differences between HI’s hoses and the average water hoses are HI’s superior insulation and kink-resistance.  The vinyl black hoses kink and have no insulation.  Bad for chilling.

Removing my old hoses, I prepped the complete re-hosing by drilling through my garage wall.  With a quality hose setup, I removed all of the hack-job connectors which I previously utilized (see Chillaxing with Hydro Innovations, part 1).  The entire system is powered by an 1850 GPH submersible water pump sitting in my water reservoir.

After teflon-taping all hose bibs, because I am paranoid about leaks, I connected all of the hoses and cinched them with worm clamps.  From the ChillKing, we feed the cold hose into the first of two IceBoxes, then to the second IceBox.