The Sanborn field experiment: Implications for long-term soil organic carbon levels

Abstract

The Sanborn Field at the University of Missouri was established in 1888 in order to assess the long-term effects of various cropping practices, including crop rotation and manure application. As interest in biofuel production from crop residues continues to grow, as does the importance of studying the effects of removing crop biomass on active carbon and soil organic carbon. This study analyzed soil samples of various management systems from 1915, 1938, 1962, and 1988. Crop residues were returned to the field only after 1950. It was found that soil organic carbon equilibrium requires approximately 30 to 40 years to reestablish itself, and manure and residue in tandem restored soil organic carbon levels to 1915 levels and had a positive effect on active carbon. These results did not mirror those of monoculture systems. Additional research is suggested to further reveal the dynamics of active carbon and soil organic matter levels in relation to different long-term management practices, including crop residue removal.