Applying Compost In Mainstream Agriculture

BioCycle July 2004, Vol. 45, No. 7, p. 26

An overview of practices, application rates, end product quality, farm economics and grower education to achieve biological soil balance.

Ralph Jurgens

THIRTY YEARS AGO, we started out at New Era Farm Service in Tulare, California making 1,000 tons of compost that first year. Back then, compost was not promoted for mainstream agriculture but only for use on backyards. We got this kind of reaction – “You must be a hippie if you’re making compost because it would never work in the real world.”

Today, 30 years later, we are manufacturing between 80,000 and 100,000 tons annually – applying mostly on central California conventional and organic farms, but also retailing compost all over the state, even into Oregon and Washington (some 1,500 tons). We even ship quite a bit into Hawaii for agricultural applications there. When we talk about being too expensive to use compost hauled those distances, it is really compared to what goals are sought. The best solution, of course, is to “keep it local and keep the cost down as much as possible.” That’s why I help growers become better composters because it’s crazy for us to send compost to Washington and Hawaii where there are other good composters whom we can educate to do the process correctly.

Within a 60-mile radius of my office here in the central San Joaquin Valley, there are 1,000 dairies – generating more than four million tons of manure annually. We work with ten of the larger dairies, composting three types of manure on leased sites – milk cow manure, dry (or nonlactating) cow manure and lagoon manure.

All the manures 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 C02 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 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.

Currently, New Era is working with close to 400 growers, who farm well over 1,000,000 acres of which 283,000 acres are using “Biologically Influenced Fertility” inputs and of the 283,000 acres, 35,000 acres are certified organic. The standard charge for applying our finished, stable compost is $14 per ton (plus freight). with the premium blends costing up to $18-25 per ton. All applications are based upon soil and tissue analysis. Our sales last year at New Era were around $4-6 million.

Our growers – both conventional and organic – are seeking to balance the farms’ fertility system and increase nutrient uptake. Their goals are to increase uniform production, crop quality, flavor, and storageability. They seek to lower fertility costs and improve the environment. Whether organic or conventional, these are the goals of the farmer. In a biologically influenced fertility system, it is a matrix of inputs, not just compost by itself. It is the value of using organic matter such as fresh carbon and then applying compost as a media for stable amounts of humus and organic matter.

Most of our application rates are two tons per acre. At two tons per acre, you cannot see the compost on the ground once applied, but there is a good balance. Biological farming is a complex system, but when done correctly, it helps to build good soil and structure, increasing crop quality.

In the chain of soil 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 25 percent water, 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. 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 (over-watering 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.

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 – depending upon soil pH. 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 are 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 base our blending foundation according to soil type and microbial balance.

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 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 a 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 of 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.

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.

As evident from the information supplied here, agronomist Ralph Jurgens of New Era Farm Service in Tulare, California brings a confident quality to the utilization and application of compost in agriculture.

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