Effect of Corn Stover Harvest on Soil Quality Indicators and Irrigated Corn Yield in the Southern Great Plains.

Corn fields have been identified as a potential source of crop residue to serve as cellulosic feedstock for ethanol plants. However, residue harvest can have a negative impact on soil quality, which can reduce crop productivity and potential for soil carbon sequestration. The objectives of this study were to evaluate the effects of full and partial corn stover removal and the use of winter cover crops on the soil physical properties, soil carbon storage, and irrigated corn yield in no-till and strip-till management systems. Three years (2010-2012) of canopy cover, biomass yield, grain yield, soil carbon, hydraulic conductivity, bulk density, and soil water content at -10 kPa, -33 kPa, and -1500 kPa were collected at the Oklahoma Panhandle Research and Extension Center at Goodwell, OK. The treatments consisted of three strip-till treatments that differ only on amount of residue removal (ST0, ST50, and ST100), strip-till with 100% removal and a cover crop of winter wheat planted after corn harvest (ST100 + CC), and no-till with all reside removed (NT100).  The experiment was in a randomized complete block design with four replications. Only ST0 and ST100 + CC maintained soil coverage >30% throughout the experiment, the minimum level required to reduce soil erosion. In the first two years of the experiment, grain yield was not affected by tillage and residual removal; while in 2012, ST100 + CC had highest grain yield while ST100 had the lowest yield. The soil physical properties were highly variable from year to year with no steady trend. However, the ST0 treatment showed significantly greater increase in soil carbon, while the rest maintained their soil carbon throughout the study period.