Composting has undergone a great deal of refinements in recent years and many composting operations have finally become viable businesses with good long term markets and business potential. While experimentation for the purpose of overall improvement in compost continues, there are some already proven concepts that may not have widespread dissemination.

There are a series of problems or situations in composting looking for an answer. The first problem that may be encountered by a composting site may be odor if any manure or other rotting bio-solids are used as an input. A second problem follows from the first in that the material can rapidly lose ammonia N into the atmosphere. A third problem is the presence of E coli in some manure. A fourth problem is the loss of nutrients through leaching or run off during rainfall; a fifth problem is the loss of carbon into the air in the form of CO2 and finally there is the issue of how much true humus is formed, both the active faction and long term stable types. All of these problems/situations can be mitigated.

Mitigating these issues requires the use of additional materials in the compost mix. The nutrient content of these additive materials usually has a cost that is less than ½ the nutrient value in the market place, but adding to the final cost of compost can still cause a marketing problem if the final price is perceived as too high. Compost producers are dealing with a perception that the major value of the compost is micro-organism content and humus with a small dose of stable N thrown in. The more innovative composters are adding materials with higher calcium, potassium, phosphorous, sulfur, nitrogen and trace minerals to the basic composting materials. Some are added during the composting process and others may simply be blended in to make a final value added product that can match the nutrient needs of the grower’s soil. Both compost products and end users need to be educated as to the value of good, value-added compost.

Making a value-added final product can be very cost efficient and timesaving for growers of all sizes in terms of spreading. Having what amounts to a complete fertilizer imbedded into a compost offers great marketing potential to those that realize that compost is about the only option there is to recovering heavily farmed soils that used conventional programs up to this point. With the current cost of commercial fertilizer it is almost a no brainer to switch to a natural fertility program using quality compost loaded with nutrients from natural or NOP sources that have nutrient costs that are half the market costs of conventional fertilizers.

Some of the more common compost additives are: Hi-Cal Lime, Gypsum, Clay Soil or Clay Deposit Material, Chilean Nitrate of Soda (16-0-0), Feather Meal (14-0-0), Green Sand (7% K), Wood Ash (0-0-2), K-Mag (0-0-21-11 Mg-22 S), Sulfate of Potash (0-0-50), TN Brown Phos (23% P2O5), Meat & Bone Meal (8-13-2), KS Plus, (0-0-8-24S) and Humates. The advanced composters would also have a series of separate trace mineral available for blending such as Boron, Zinc, Copper, Manganese, and Iron.

Four of the above materials deserve special attention because of new information concerning their use, their problem solving ability and the fact that they may not be as familiar as some others in the marketplace.

The first one to consider is humate. It would seem counter productive to add humate material to a process which is supposed to be producing humus from raw material inputs. However, Dr. Paul Reed Hepperly of The Rodale Institute has shown that adding small amounts of a humate material, clay and gypsum to the composting process created some very stable long chain humus substances. Since US soils have had a continuous degradation of the stable humus, this would offer a chance to rebuild long term sustainability to US farmland at a faster rate.

Dr. Hepperly used  a ratio of 7:2:1 of 14 yd³ leaves, 4 yd³ manure and 2 yd³ clay plus the addition of 110 #’s of humate material and 90 #’s of gypsum. Other highly mineralized clay deposits are also available, mostly in the Western US. There are raw agricultural Gypsum mines in MI, IA, and UT, but other distant locations might have to deal with pelletized gypsum that might not be cost effective. There are multiple sources of dry humate material or soluble powders available in the US marketplace. The clay, gypsum, and humate additives also decrease the soluble components that can leach from the compost rows and are the major source of environmental concerns.

The second material is wood ash. This is not your typical ashes coming out of a wood burning stove. This particular ash results from a unique firing process that only uses natural untreated wood. The ash is re-fired a second time. The resultant material has extreme hydroscopic (water absorbing) qualities, albeit a lower final K value. Since water scarcity is a world wide problem already, the wood ash material offers a chance to continuously bring moisture out of the atmosphere as plant roots interacting with the ash material remove moisture from the ash.

This special ash comes out of an electrical generating plant. Whether or not your local plant is using such a process would be up to you to find out. Plants burning treated wood, coal, tires, etc. would not be suitable.

The third material is a unique deposit formed in a volcanic plume millions of years ago called KS Plus. It is listed as an average composition of 0-0-8-24S-1Fe. The uniqueness is not evident from the numbers. There is a naturally occurring Thiobacillus bacterium that continuously oxidizes the elemental S into Thio-Sul and other active S compounds as well as SO4. These compounds give the sulfur much more activity than a straight SO4 from gypsum, ammonium sulfate, 0-0-50, or K-Mag. There are also significant quantities of Silica and some expensive traces like Molybdenum, Cobalt & Nickel.

In relation to compost, it offers the site operator a chance to absorb all of the odor and volatile ammonia compounds from manures or other “rotting” bio-solids within 48 hours if it is mixed into the material upon arrival at the site. Because of the rapid acidification of the manure, E coli and other “bad guys” are quickly eliminated. Because of the alum content, there is less soluble leachate to escape from the pile. This is usually mixed at 20-30% of volume of KS Plus to manure. The wetter the manure the less KS Plus is needed to get the desired reaction. From that point on, all the nutrients in the KS Plus are integrated into the finished product resulting in a higher Ca, N, S, & K content. Because of the presence of S in the composting or digesting process, more of the available N will be formed into longer chain, higher quality amino acids. This will give better N utilization curves, virtually eliminating any N loss when the compost is applied.

Standard composting lore usually avoids the use of elemental S in the composting process due to the fear that Hydrogen Sulfide gasses could be produced. The HS gasses have a bad odor and could kill beneficial micro-organisms. No such effect has been observed using KS Plus.

As an alternative, the KS Plus could be added directly to the manure “on farm” and have the adsorption take place in pits, piles etc. before the manure is transported to the compost site. Obviously, the grower could also use KS Plus to treat any on farm manure before spreading. Dr. Hepperly found up to 80% manure nitrogen was lost as ammonia during the first two weeks. Adding KS Plus can immediately stop this loss. If treated in a pit, KS Plus can precipitate out P to mitigate the major reason given for restricting manure application.

The fourth material is TN Brown Phosphate. This unique “reactive” phosphate allows a composter to increase the amount of available, but not water soluble, P in the mix. Run-off of soluble P from raw manure is a major factor in water contamination. The TN Brown can be composted right in or blended at the end and still hold the same available, but not soluble characteristics. TN Brown Phosphate also contains lots of trace minerals. Current availability by a state lab test shows 10-12%. Total P2O5 is about 23%. This reactive phosphate also confounds those users thinking that the numbers on a CEC test tell the whole story. Large applications of TN Brown may not show significant P1 or P2 increases, yet the P2O5 is definitely there and the availability is there by lab test and crop response. CSI has seen quite a few instances when the CEC # for P2O5 was low yet the LaMotte availability was much higher.

There is really no limit to the type of materials that can be composted or blended into compost. Using local materials is always the best option, but sometimes it makes economic and agronomic sense to bring in unique sources of major and minor minerals that offer unique chemical and biological properties. Their use will depend on the marketplace. A composter can offer them as the first step or the composter may have a grower requesting additives as the first incentive to bring in the unique materials.

One of the supply problems for composters is that animal manures tend to be concentrated in specific areas of the US. One doesn’t need manure to make compost, but manure does offer a unique set of bacteria and unique nutrient content. In areas that don’t have manure, the special additives offer a chance to make up for some of the nutrients. Bacteria can come from commercial sources or from local healthy soils such as fence rows and woodlots.

If the fertilizer industry can justify N made from Russian natural gas, then the composting industry can justify asking growers to ship complete fertilizers longer distances as well. In fact, it is time for some areas of excessive manure or those that area manure deficient to cooperate and possibly subsidize both composting and shipping to mitigate the problems of manure contamination in one area and the loss of soil fertility in another.

Let’s hope that compost making and use continues to expand. Let’s also hope that more composters can develop their skills and offerings to meet the growing demand for one time annual applications of complete nutrient composts for the full spectrum of crops grown in the US.