Changes in Soil Carbon Associated with Corn Residue Removal.

Removal for corn residue as a possible feedstock for the biofuels industry has left many producers with a number of unanswered questions.  These include what impact will this have on the following crop and also the impact on soil quality associated with this practice.  A field study was established in 2000 to address these and other questions. 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.  There was no difference in soybean yield following corn residual.  Short-term (5 years) soil organic carbon levels decreased for the high residue removal treatment compared to the low residue removal treatment at all of the sampling depths.  Surface soil carbon analysis from samples collected in 2008 shows that increase residue removal decreased soil carbon content, but the presence of cover crops in each residue removal options improved soil carbon content, compared to the no cover crop management.  These samples will be compared to 2000, and 2003 samples and changes in soil carbon will be reported.  Although it appears that removal of corn residue did not have a negative impact on the following crop (soybean) yield, there was a negative impact of soil carbon under a no-till situation when residue was removed from the production practice. Additional research is underway to evaluate the impact of residue removal on other measures of soil quality, and also crop mineral nutrition.