Soil Carbon and Nitrogen Dynamics After Corn Stover Harvest.

Biofuel production from plant biomass seems to be a suitable solution to mitigate fossil fuel use and reduce greenhouse gas emissions. Corn (Zea mays) is a highly promising crop for biomass production. However, stover harvest could negatively impact soil properties. Changes in the quantity of corn residue returned to the soil, as well as management practices, could have an effect on soil C and N. The objective of this study was to investigate C and N dynamics under different cultivation practices and two soil types. Soil samples were collected from two locations with different soil types (loamy sand and silt loam) in central and northern Alabama. A laboratory incubation experiment was performed in which soil samples were analyzed for total C, N and inorganic N during a 60 days period (0, 30 and 60 days), and C mineralization (30 and 60 days). Carbon and N content in the northern site (1.30% and 0.12%, respectively) were significantly higher than those in the central site (0.64% and 0.04%, respectively). For the silt loam, in plots where the stover was harvested, C content (1.23%) was lower than plots that stover was retained (1.38%). In both soil types, NO₃^- content increased significantly during the 60 days period of the experiment. Carbon mineralization significantly increased only for the northern location between 30 and 60 days of incubation (272-288 mg of C per kg of soil). Information from this study suggests that differences in C and N dynamics resulting from stover harvest are soil dependent.