Compost Key to Carbon Storage in Soil, Long-Term Study Shows

A 19-year study by scientists at the University of California, Davis, found that adding compost is key to storing carbon deep in semi-arid soils. The study compared soil carbon changes at 6-foot depth in conventional, cover-cropped, and compost-added plots of corn-tomato and wheat-fallow cropping systems. This research found that conventionally managed soils neither release nor store much carbon. Cover-cropped soils stored carbon only in the 12 inches nearest the surface, and they actually lost carbon at lower depths. However, when both compost and cover crops were added in an organic-certified system, soil carbon content increased 12.6% over the duration of the study, or about 0.07% annually. The study demonstrated significant carbon-storage potential in soils that have compost added.