The technology exists for farms of all sizes and types to produce their own fertilizer, often using the biological farm waste they generate as the raw material — and it's not composting.
Building a covered aerobic bioreactor to convert biowaste like poultry manure or the leftovers from the garden into benign plant food might be among the best alternatives to expensive synthetic fertilizer or composting. And, it provides plants with beneficial micronutrients not available in synthetics.
Dr. Nick Savidov, a researcher at Alberta's Lethbridge College, says that continued human existence on the planet depends on farmers adopting this practice of nutrient recycling versus depending upon synthetic fertilizers.
"The fact is that if we don't learn how to recycle nutrients and water, we are doomed. We will start dying off from hunger," says Savidov. Formerly a senior research scientist with Alberta Agriculture, he is now working in the Aquaponics program at Lethbridge College.
Dr. Savidov says we are running out of critical, non-renewable fertilizers like phosphorus. According to the most recent survey conducted by the International Fertilizer Development Centre (IFDC), 85 per cent of all phosphorus rock reserves on the planet, which are used to produce phosphorus fertilizers are located in just one area — in Morocco and the Western Sahara.
Today, given the cost of synthetic, inorganic fertilizers, and with concerns about how these fertilizers are manufactured, many farmers are looking for organic alternatives. They usually turn to raw manure or compost. Both have their challenges. While raw manure may be readily available, it is a slow-release plant food and costly when considering the transportation and application costs to the actual nutrient benefit delivered to plants. Plus, it smells bad and has the potential to leach nasty pathogens into waterways, which makes enemies of the neighbors and opens up all kinds of liability issues.
Composting is a better alternative. Properly composted manure is odorless and generally non-toxic, while holding its nutrient value. But it takes months to manufacture, and because the composting process does not always produce a consistent product, Savidov says, pockets of the compost may still contain pathogens.
That is not the case with the aerobic fermentation process in a controlled, bioreactor environment that produces mineralized nutrients in water.
Savidov believes that his approach — to use the aerobic fermentation process to convert biowaste into mineralized, benign, liquid plant food in a matter of weeks rather than months, provides farmers with a faster safer sustainable approach to generate their own plant food in a form that plants can gobble up quickly.
"In my opinion, the setup of an on-farm aerobic fermentation system for a smaller farm operation is not just possible and worthwhile, it is a necessity," he says. It delivers many benefits, from providing an alternative to applying unsafe organic waste, to cutting down food production expenses and introducing sustainable, environmentally-friendly practices on the farm.
An aerobic bioreactor is not expensive, space-age technology, and it’s something that Savidov says small farms can benefit from, whether they are growing cash crops or simply want to grow their own food using safe, organic nutrients.
"To be honest, it's not really an absolutely new system," he says. "It's using bits and pieces of what is already used in the agriculture industry to treat manure."
The aerobic bioreactor can simply be a septic tank filled with water and equipped with an agitator. An oxygen concentrator connected to the tank provides a regular supply of oxygen to the beneficial microorganisms inside. Raw material like poultry manure or food waste is fed into the tank, creating a slurry. Intense mixing and added oxygen encourages biological conversion over time. There is no odor produced during the process. After about three weeks, the conversion is mostlycomplete and the benign, highly concentrated, nutrient-rich liquid is removed from the bioreactor. Filtration separates the solids from the liquids. The solids are returned to the bioreactor for further treatment, while the liquid stream is ready to use as organic fertilizer.
There are many ways that this liquid fertilizer can be used on a small farm. Savidov and his research team tested the fertilizer, converted from poultry manure, in a soil-less greenhouse environment to raise tomatoes and grow tree seedlings. The results were remarkable. Greenhouse tomatoes delivered 15 per cent higher yields compared to the use of synthetic fertilizer, and tree seedlings doubled in height in two months.
The liquid fertilizer could also be used in a drip or broadcast sprinkler system to feed plants on a larger scale, such as a market garden, hay land, or a field producing high value cash crops like potatoes or peas, or even cereal grains. The economics come down to three factors: access to a cheap supply of raw material, the amount of pre-processing required to create a consistent liquid fertilizer and a bioreactor designed to match the needs of the farm.
Savidov's research team determined that one tonne of poultry manure with between 50 and 60 percent moisture content processed through their bioreactor yields about 10 cubic metres of concentrated liquid plant food.
What is aerobic fermentation?
There are two types of microorganisms that can convert raw biological waste such as manure or food waste into benign, ready-to-use, plant food. One type works best in an oxygen-free environment through a process called anaerobic digestion and another works best is an oxygen-rich environment through a process called aerobic fermentation.
Either conversion process is a form of nutrient recycling.
Depending on the raw material used, conversion to usable, benign plant food using the aerobic fermentation method takes place within two to three weeks versus three months to a year for composting.
Dr. Nick Savidov at Alberta's Lethbridge College predicts that the cost of a farm-based aerobic fermentation system, "should not exceed much more than the price for a regular septic tank installation, but that depends on the size."
Through a little ingenuity, a modest upfront investment, and help from experts like Dr. Savidov, it is possible to set up an aerobic fermentation system on a farm. Although there are no current commercial suppliers of complete aerobic fermentation systems, all the components are readily available to set one up.
For a small farm, Dr. Savidov suggests two, 1000 to 2000 litre, aerobic bioreactors equipped with agitators. The cheapest option for a bioreactor of this size are High Density Polyethylene (HDPE) tanks, which sell for about $1000 to $2000 each. Savidov says tank agitators are in the same price range. A small oxygen concentrator to supply both tanks sells for between $500 and $2000. After conversion, Savidov recommends connecting the mineralized nutrients to a 2000 to 4000 litre accumulating and feeding tank. At this point, the contents are ready to use as plant food. Savidov says the cost of this system should not exceed $6000 to $10,000 per farm.
A front-end grinder to create a more consistent feedstock, especially when using more fibrous raw materials, is a good investment to encourage more complete and faster conversion in the bioreactor. A filtration method to capture the solids in the converted plant food should also be considered so the solids can be re-processed, and to avoid blockage in drip or sprinkler fertilization systems. Almost any organic waste from the farm can be used in the bioreactor. However, feedstock containing high levels of lignin such as wood chips should be avoided in the bioreactor, as it takes considerably longer to break down. Cattle manure can be used after fractionation and separation of the fibre.
Food safety is an important consideration when operating the bioreactor. The raw material should be stored in a separate building from the bioreactor, and the transportation and addition of the raw material to the bioreactor should be carefully managed to avoid potential pathogen contamination further downstream within the system.
Fertilizer from B.C. farmer's bioreactor supports vegetable and fish enterprise
B.C. farmer, Matthias Zapletal, knows that using a bioreactor to produce his own organic fertilizer works because he has been operating one on his farm for the past six years.
He uses the fertilizer from his custom-built bioreactor to feed his commercial plant crop in his greenhouse and market garden, although in reality, it can be used in any growing environment.
Zapletal cautions those wanting to set up a bioreactor, however, that it requires daily system monitoring and management to ensure that the microorganisms in the bioreactor stay healthy and happy.
Before you start . . . Expert advice on setting up a bioreactor
At first, it may sound like a micro-biology degree is required to successfully build and operate a bioreactor. That would help, but talking to a micro-biologist is the next best thing.
For those wanting more information and mentoring in setting up an aerobic fermentation system that includes a bioreactor, you are encouraged to contact Dr. Nick Savidov at Lethbridge College.
Dr. Savidov says short of having a micro-biologist for a friend, he and his team at Lethbridge College are probably the best technical experts available. They recently built a complete bioreactor at the College and are happy to provide tours of the facility. He is also available to speak to groups interested in this nutrient recycling method.
In future, he is working with the Department of Biological Sciences at the University of Lethbridge to develop a course, which he believes will be about two years in development. He is also discussing the possibility of developing an online course at Lethbridge College to teach best practices and protocols for building and maintaining an aerobic fermentation system and would like to establish a demonstration farm.
In the meantime, feel free to contact Dr. Nick Savidov at nick.savidov@lethbridgecollege.ca, or for someone actually using a bioreactor in a commercial setting, contact Matthias Zapletal at matthias@northernbioponics.ca.
- Tony Kryzanowski