As most of you may have noticed, compost is a hot new topic in agriculture. There are a number of cities, stockyards and chicken ranchers touting their products to the tree fruit industry, as well as any other high value per acre crop. You have a range of products available. They are generally produced from organic waste materials, such as livestock manure, sewage solids, wood chips, straw livestock bedding, tree leaves, and lawn clippings. Due to the variability in the original substances going into the compost mix, and the complexity of the composting process, each batch is slightly to wildly different from previous batches.
Producers sometimes try to follow set mixtures, but product variability is almost certain.
Important variables include nutrient content and moisture content. As you sometimes buy these products by weight, be well aware of how much water you are purchasing. Nutrient content is often quite low, often only 1-2 percent by weight. They have potential for improving some aspects of soil quality when used at high rates over the short term, but do not work well as traditional plant nutrient sources. Nutrient release will occur slowly as the compost is further broken down by soil organisms, often over a two or three year period.