B. 1. Compost Food Web Information

All of the information in this section applies to compost made by thermal composting, by worm-driven processes (cold-composting), or by static composting. Differences in microbiology between these different ways of reaching the same end-product, as far as the plant is concerned, are in The Biology of Compost book, written by Dr. Elaine Ingham. Please see our product page for information about the book.

Compost is used for one of the following reasons, generally:

1. To add organisms to the soil. This is not just bacteria, but fungi, protozoa, nematodes and often microarthropods. Compost serves as an inoculum of all these organisms, if the compost is made correctly.
2. To add foods to feed bacteria, fungi, protozoa , nematodes and microarthropods.
3. To add structure to the soil. Many composts contain physical structure components like kor (cocnut fiber), clay, fiber, and chunks of wood. These impart physical structure that allows oxygen to move through the material. It is very important to maintain these air passageways into the compost.

Many people think of compost as a source of enzymes, hormones, and plant growth promoting materials. But while those materials are important, they do not last long in soil, or in compost.

What is the “life-expectancy” of enzymes, hormones and other good-food resources for bacteria or fungi to consume in compost, or soil? Unless the organic matter is absorbed on the surface of clay or organic matter – and thus protected from uptake by the plant or more difficult for the bacteria or fungi to access – these nutrient-rich compounds will be consumed by something within minutes. One more caveat - normal biology has to be present. If the enzymes has been separated into sterile conditions, then of course it won’t be used as food. But as soon as any protein or sugar (all enzymes are proteins, all hormones contain sugars and/or protein in their structure) is put into a habitat where bacteria or fungi are actively growing, that food is going to be gone.

What makes enzymes, hormones, and plant-growth-promoting materials? The bacteria, fungi, protozoa, nematodes and microarthropods. So, really, what you want to be adding is the biology, because they will make more of the enzyme you want. Or the hormone. Make certain that the compost contains the right set of bacteria, fungi, protozoa and nematodes so the process you want will occur. If you buy really good compost, the microarthropods will be present too.

There is a “best food web” for each combination of crop type, climate, region, soil type, amount of organic matter and water supply. The ideal food web balance for row crops in Arizona is different than the ideal balance for fruit trees or grapes in California (see SFI Approach, Succession and the Soil Foodweb) LINK

So, make or buy compost that will make a habitat appropriate for your plant to grow. In general – and this is a huge generalization – annuals need bacterial-dominated soil to maintain pH, form of N, soil structure, and nutrient cycling correct for those plants. Perennials need fungal-dominated soil to maintain pH, form of N, soil structure and nutrient cycling correct for the long-lived plants. Exceptions? Sure. But in general, this holds true everywhere we are looking at this all over the world.

Now, if growing plants in soils where the biology isn’t right, you can get plant growth, by using the toxic chemicals to try to overcome the diseases that will attack the stressed plants, by using chemical salt inputs to try to feed the plants the inorganic nutrients they need. But the plant is not healthy, it is stressed, and the food it makes is not the best for human consumption.

Can we increase production of plant material in un-healthy systems? Sure. But at what cost to water quality? What cost to human nutrition? To the quality of our lives? The long-term impacts are going to be staggering.

So, when trying to decide what compost is needed, and when trying to determine what compost to buy, understand your purpose in using compost very clearly.

The tests you need then should be come clear.

• For example, if you want to know what organisms you need, you need to do a full foodweb analysis. If you don’t know what part of the food web may or may not be “out of whack”, you have to figure that out first.
• You also need to know if the biology is lacking, or a chemical lack is preventing plant growth. Biology can’t solve the plant’s problems if all the calcium in your soil has leached away, or is tied up on the carbonates, clays, or organic matter in your soil. You might need to add some form of calcium first, and get the biology back to make sure that calcium STAYS in your soil.
• If you have done a foodweb analysis in the past, and know your soil lacks fungal activity, for example, then all you need to assess is fungal activity and total fungal biomass. Perhaps mycorrhizal colonization as well, since this assay includes disease encountered on the root system, as well as insect feeding damage.
• If your problem has been root-feeding nematodes in the past, then perhaps you just need to assess whether addition of the biology has out-competed, inhibited and consumed those root-feeders.

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