An International Survey of Soil Carbon and Nitrogen on Smallholder Farms.

Auburn University is working on a six-year project with Heifer International to determine the carbon (C) sequestration potential of small farms in eight countries of the Americas, Africa, Europe and Asia. Initial data suggest there was considerable variation in C concentrations at different depths among soils in different countries. At 0-10 cm soil depth, C amounts ranged from about 20-50 Mg/ha across the countries, and nitrogen (N) ranged from about 1-6 Mg/ha. At 10-20 cm depth, soil C amounts ranged from about 15-45 Mg/ha, while N ranged from about 1-3 Mg/ha. The data also show there is variation in soil C stocks under similar crops within countries. For example, mass of soil C under different Bhoma Rhodes grass fields in Kenya ranged from 25-43 Mg C/ha. Soil bulk densities varied considerably from farm to farm, and the mass of soil C varied along with it.