Differences In Content of Soil Organic Matter Pools Under Varied Rates of Corn Residue Removal.

Organic matter is a crucial component of soil productivity, providing carbon for crops, maintaining soil sustainability, and is critical for soil biological, chemical and physical processes. Crop biomass is essential to maintaining soil organic matter (SOM). Corn residue is being evaluated as a possible feedstock source for biofuels production. Removal of a large proportion of corn residue for biofuel production could result in depletion of SOM. The impact this practice will have on the soil is unknown and methods for mitigating any negative effects need to be elucidated. Experimental treatments include three corn residue removal levels (low, mid and high); corn harvested for grain and all residue remains on the soil surface, corn harvested for grain, residue racked, baled and removed, and corn removed as silage respectively, all conducted under no-till soil management and within a two-yr corn/soybean rotation. In 2005 the plots were split and a fall/spring cover crop was included. This study will address the question of how C levels in relevant soil carbon pools are impacted by residue removal practices by isolating two important pools of SOC, humic acid (HA) and glomalin related soil protein (GRSP). HA and GRSP are extracted from separate soil subsamples and quantified. Carbon content of both operationally defined soil fractions will be compared among soils from each of the residue removal rates and between plots with and without a cover crop.