Organic Gardener's Composting by Steve Solomon

Sheet Composting

Decomposition happens rapidly in a hot compost heap with the main agents of decay being heat-loving microorganisms. Decomposition happens slowly at the soil's surface with the main agents of decay being soil animals. However, if the leaves and forest duff on the floor of a forest or a thick matted sod are tilled into the topsoil, decomposition is greatly accelerated.

For two centuries, frontier American agriculture depended on just such a method. Early pioneers would move into an untouched region, clear the forest, and plow in millennia of accumulated nutrients held as biomass on the forest floor. For a few years, perhaps a decade, or even twenty years if the soil carried a higher level of mineralization than the average, crops from forest soils grew magnificently. Then, unless other methods were introduced to rebuild fertility, yields, crop, animal, and human health all declined. When the less-leached grassy prairies of what we now call the Midwest were reached, even greater bounties were mined out for more years because rich black-soil grasslands contain more mineral nutrients and sod accumulates far more humus than do forests.

Sheet composting mimics this system while saving a great deal of effort. Instead of first heaping organic matter up, turning it several times, carting humus back to the garden, spreading it, and tilling it in, sheet composting conducts the decomposition process with far less effort right in the soil needing enrichment.