BioCycle Magazine

Compost Users Forum: The Applied Thoughts Of A Compost Theorist

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Courtesy of BioCycle Magazine

WITHIN a 60-mile radius of my office here in central California, there are 1,000 dairies — each having an average of 2,000 cows. They generate over four million tons of manure annually, so we are pretty much in the manure business whether we want to be or not. Somebody has to manage this material and help the farmers utilize it properly, fulfilling its potential monetary value. That’s what we accomplish by making compost out of manure and applying it to farm fields.

For the past 25 years, I also have been highly involved in sustainable agriculture, more specifically, integrated biological farming systems. We deal with the “below portion” of the soil as well as the top portion of the crops being grown. The key to these sustainable systems is organic matter and its management.

At New Era Farm Service, we have been specializing in custom blending compost to meet the soil’s specific needs. It is hard for me to tell growers to put ten tons of compost on and it will take care of all their problems because it may or may not. It depends on the soil structure itself, and on the nutrient loading capacity of the crop. For example, perhaps the soil needs additional calcium to help hold its platelet-like structure apart, allowing for better air flow and water percolation or movement. Calcium plays a real key role in keeping soil pliable so that the microbes in compost can survive.

Composting Approach

Three types of dairy manure are used in our composting operations — milk cow manure, dry (or nonlactating) cow manure and lagoon manure. All have different C:N ratios and NPK content. Milk cow manure always has more straw; dry cow manure has the least amount of straw and nutrients; and lagoon manure after drying is extremely high in fiber and potassium, and has 80 percent carbon, which blends into an ideal C:N ratio of 25:1. We also inject liquid lagoon water into compost windrows so we are totally recycling everything that we possibly can from a dairy. Once we get the water content up, then we aerate, turn and monitor the entire process. We are really keen on making sure that our oxygen and CO2 levels are balanced. We also buy a lot of green waste and blend that into the windrows on a custom basis, depending on what the soil needs (e.g. perhaps a phosphate loading mechanism).

Our composting sites are located at two dairy operations. The first, about two miles from our office, is a 60-acre site adjacent to the dairy, with capacity to process 60,000 tons of dairy manure in windrows. The second site, 12 miles west of Tulare, is on a 40-acre parcel adjacent to the dairy, and has capacity to process 40,000 tons of manure. All of the manure is purchased from surrounding dairies and usually not hauled over five miles to our composting sites.

It usually takes 90 to 120 days for our controlled composting process. The finished compost should be uniform in particle size (to aid in precision application and uniform availability), stable, and dark brown in color (not black). Finished compost that is black in color usually indicates the composting process was too hot (above 158°F) for periods of time and has actually burned rather than biologically digested the organic matter.

New Era Farm Service is currently retailing approximately 150,000 tons/year of finished dairy manure compost. Some years, we produce up to 215,000 tons, depending on whether it is a good crop year for our growers.

Utilizing Compost In The Chain Of Life

If we are going to make a compost product that is high in humus and beneficial organisms, we have to understand soils — not only their physical and chemical aspects, but their biological fertility. In the chain of life, in microbial ecology, microbes eat at the table first. They are at the beginning of the first part of the chain, and we want to make sure we take care of these microbes because they release the nutrients for the plants. A fertile soil is a chemical self-feeder. The more we can build soil fertility, the more we can increase organic matter and convert it to humus — and the better the soil will act as a chemical self-feeder. Typical soils should be 30 to 50 percent water, 20 to 25 percent air, 45 to 47 percent mineral, and two to five percent organic matter. Then we have the living organisms, which should be at a level of at least one percent.

The key to microbial vitality is the air-moisture relationships. If there is too much air and not enough moisture, microbes will die due to a lack of moisture. And if there is too much moisture in relation to air the microbes will die due to a lack of oxygen. I like to ask my growers what is the most important ingredient for proper microbial viability — organic matter (as food), heat (to keep warm), moisture (water intake) and last but not least, air. Then I ask them how long they can live without food, heat, too little or too much water, or without air. Without food, heat or water, they might live up to four days. With too much water, they could drown. And without air, they could only last several minutes (how long can you hold your breath). The point is that in all microbial systems, air is by far the most important ingredient for microbial viability.

We teach growers how to use organic matter, encouraging them to buy compost and use it in their system. But if we don’t make them aware of air-moisture relationships and management, then the job we ask them to do can fail. Paying close attention to water practices (overwatering pushes out oxygen) is absolutely critical in sustainable farming systems because it can regulate the survivability of the microorganisms.

The soil colloidal mineral (cation exchange) balance is also very important in its ability to regulate air flow and moisture management. A soil high in percent saturation of calcium (70 to 80 percent) and with an optimum balance of 10 to 15 percent magnesium, two to five percent potassium, and .5 to two percent sodium, is usually a good candidate for optimum organic matter management and microbial viability. When the soil’s percent saturation of magnesium becomes greater than 15 to 20 percent and calcium is lower than 65 percent, the soil can seal and cut off oxygen supply to both the soil microbes and plant, thus affecting crop quality and health. Compost applications alone may or may not work due to the sealing effect, but by adding a calcium source with compost, we can assure better flocculation and air flow, allowing compost and its microbial viability to work better and longer for optimum soil and crop health.

Custom Blending

Once the compost is done based upon analytical data and we determine what the soils’ limitations are, we custom blend our compost for each grower, e.g. a 50:50 blend of compost and gypsum, or a mix of 75 percent compost and 25 percent limestone. If the pH is high, it needs calcium. If they need additional potassium, is it cheaper to add potassium to the compost or is it cheaper to add more compost to the soil structure? If they need more phosphate, we look at the cost of phosphate versus the economics of adding phosphate from compost. A dry ton of our particular compost consists of 25 pounds of nitrogen, 30 pounds of phosphorous, 60 pounds of potassium and 50 pounds of calcium. Therefore, by avoiding supplemental phosphate and potassium the savings add up when five tons/acre of our compost is applied.

Everything we do is specifically blended for the field. We always want to look at the soil first. Testing is critical. We base everything on analytical data, salt testing, tissue testing and water analysis. That information is compiled and then we try to custom blend from there. We even look at biological assays and microbial reserves and then try to find something there.

A typical scene in our area would show dairymen using raw manure at fairly high rates. What is wrong with this approach? There may be no problem during the growing season, however at the end of the growing season, there can be an uneven release of nitrogen and phosphate, inhibiting the crop from maturing. For example, we worked with a cotton grower that split an 80-acre field down the middle. On one side, he put on his normal application of ten tons/acre of raw dairy manure plus an additional 150 units of nitrogen (via UN-32), and had a yield of 1,300 lbs/acre of cotton (2.6 bales/acre). (Due to the late nitrogen release from the raw manure application, the top cotton crop was too green and would not open, even after two defoliant applications). On the other half of the field, the grower applied two tons/acre of New Era Dairy Compost plus 150 units of nitrogen (via UN-32) and had a yield of 1,440 lbs/acre (2.8 bales/acre) with one defoliation. This was an increase of 100 lbs/acre of cotton at $.68/lb (or $68/acre) plus one less defoliation (a savings of $15/acre), yielding a net increase of $83/acre. The raw manure cost this grower $8/ton delivered and spread ($80/acre), whereas the New Era compost applied at a rate of two tons/acre cost $48/ton delivered and spread. This grower now has 1,000 acres under our compost and soil fertility system. In the field where raw manure was applied, the early root development was suppressed due to salt content (the compost has less of a salt load, providing the cotton plants a healthier start).

Cover Crops, Commercial Fertilizers, Micronization

Cover crops are essential as part of a sustainable farming system. I am the first one to say — as one of the largest composters in the state of California — that you do not buy your organic matter, you grow it. You use cover crop systems, rotational systems, and then you use compost, a well-made compost that is a biological inoculum and also a nutrient recycler. By putting compost over a cover crop, whether it is two or three tons, there will be a tremendous positive effect. In our biological system, we also are using the organic matter as an beneficial insect habitat. Every fifth row has a different kind of cover crop that will be blooming all the time to attract beneficial insects. This cuts down on pests and diseases. The key is developing a healthy root mass by growing the cover crop and then applying compost over the top.

We also have experimented over the years blending fine ground compost at very small rates with commercial fertilizer. I always was led to believe that blending commercial fertilizer with compost would kill the microorganisms. But the results showed otherwise. We applied 500 pounds/acre of a fertilizer (15 percent each of N, P and K). Then on half the field, we added 40 pounds of screened regular ground compost. It was our first indication that we could apply compost closer to the root and increase the efficiency of the commercial fertilizer. This practice does not build soil fertility but it does increase the efficiency of the chemical fertilizer being put on. What we learned is that the compost released the phosphate more efficiently.

What we are trying to do by using small amounts of compost is increase the microbial environment around the root zone, making sure those organisms around that root zone can pick up nutrients more efficiently. Therefore, the value of compost becomes greater in small amounts. This knowledge became a key to our compost marketing program. When we were trying to expand our market, the limitation is trucking. Most everyone says we can only haul our compost 20 to 40 miles to still make a profit. Our work with using small rates of compost application led us to experiment with the micronization process. Micronizing takes the particle size of any given product, e.g. 100 mesh, down to 300, 500 or even 1,000 mesh by using an air mill classifier and laser light process that keeps a given material within its air chamber, fracturing the material until it reaches a given size. Most micronization plants grind the product and the heat friction created raises the temperatures high enough to kill most of the biological organisms found in compost. The air mill process we are using does not grind the compost during micronization. The processed compost is bagged and can be shipped globally, helping us get over the transportation hurdle presented by our “regular” compost.

Micronized compost can be applied dry, or at 1,000 mesh, it can be made into a liquid slurry and put onto the plant as well as put directly into the seed bed. The liquified compost can go through any irrigation system (drip, fan jet, sprinklers or flood and furrow). This approach enables compost application in the middle of the growing season right around the root zone to enhance root growth — at a cost of about $20/acre — but giving higher yields to growers. Overall, however, the use of micronized compost does not replace a good fertility program — it only can enhance one.

Experience And Analytical Data Optimize Results

Over the years, I’ve developed a few guiding principles that I stress to growers. Based on my experience, compost is a key element in transitioning farmers from conventional to biological methods, but growers also need to balance nutrients for optimum production. When one element is deficient, its absence affects uptake of other elements. For example, nitrogen is critical to growth of plants and living cells. But one of the most common problems is overfertilization with nitrogen, which results in higher magnesium availability, but lowers uptake of potassium, calcium and other nutrients. The end result is rapid cell wall expansion, which leads to weak cell walls and crops that are susceptible to pest attack.

In a biological system, where we are introducing thousands of microbes by applying compost, air and moisture have to be present in the right quantities for the microbes to perform well. If soil is completely compacted or too wet or too dry, you can apply the best compost in the world and get disappointing results.

The organic matter in compost is a food source for the organisms we’re trying to promote. Our goal is to educate and equip the grower with a cost-effective fertility program which meets the needs of the current crop and improves the quality and productive capacity of the soil.

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