Carbon-driven eco-agriculture without nitrogen deficiency

A farmer grew crops by adding only organic material with a high C:N ratio (40) to the soil for 30 years. He focused on the role of carbon in increasing the number of microorganisms. This idea was based on the concepts of 1) indirect crop management via microorganisms and 2) providing carbon to microorganisms for energy. Here, we name this practice “carbon -driven eco-agriculture” (CDEA). We determined the effect of CDEA on a laterite soil vegetable field in Sao Paulo for 4 years. The yield exceeded the national average. Soil aggregates formed to 29 cm thickness, and the microbial activity was one order of magnitude higher than that in a conventional control field. The output/input ratios of carbon and nitrogen were 1.88 –2.35 and 3.58–6.00, respectively, indicating a sustainable system for these elements. Incorporating high-C:N-ratio (>20) organic material results in nitrogen deficiency. However, our results indicate that large numbers of microorganisms provide crops with sufficient nitrogen at low concentrations. This method overcomes the yield limitation of chemical fertilizer application and reverses soil degradation.