Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/13/2010
Publication Date: 8/1/2010
Publication URL: http://hdl.handle.net/10113/48120
Citation: Wienhold, B.J., Gilley, J.E. 2010. Cob removal effect on sediment and runoff nutrient loss from a silt loam soil. Agronomy Journal. 102:1448-1452. Interpretive Summary: Corn cobs have been proposed for use in biofuel production. They are a potential feedstock because they are easy to collect, transport, and store. The effect of cob removal on soil erosion and fertilizer nutrient loss is not well understood. This study applied artificial rainfall to plots where cobs were removed or retained within a field where the remaining residue was removed or retained. Loss of soil and nutrients in runoff was measured. Runoff began more quickly after rainfall was initiated in plots where residue was removed than in plots where residue was retained. Runoff also began more quickly in plots where cobs were removed than in plots where cobs were retained. Soil loss was 30% greater when residue was removed than when residue was retained. Cob removal did not negatively affect runoff, soil, or nutrient loss.
Technical Abstract: The cob fraction of corn (Zea mays L.) residue has been identified as a potential feedstock for ethanol production. Cobs can be harvested during the same operation as grain, are more dense, and are easier to store and transport than other crop residue components. The role of the cob in soil and water conservation is largely unknown. A rainfall simulator study was conducted in an irrigated corn field in Nebraska having replicated strips where corn residue was removed (6.0 ± 1.0 Mg ha-1 residue remaining, 49.5% cover) or retained (12.9 ± 1.0 Mg ha-1 residue remaining, 77% cover). Duplicate plots were installed in each strip and cobs were removed from one and retained in the other. Simulated rainfall was applied for 30 min. at a mean rate of 83 mm hr-1 to plots at antecedent moisture and 24 hrs later at near saturated soil moisture conditions. Time to initiate runoff, runoff and sediment loss, and water quality parameters were measured. Residue removal reduced the time to initiate runoff (195.9 ± 1.0 vs. 239.5 ± 4.8 sec.) and increased sediment loss (0.36 ± 0.02 Mg ha-1 vs. 0.27 ± 0.01 Mg ha-1). Cob removal reduced time to initiate runoff during the antecedent run but not during the saturated run. Residue removal and rainfall treatment (antecedent vs. saturated) affected runoff water quality parameters (NO3-N concentration, pH, soluble P concentration, and NO3-N loss). Cob removal did not affect runoff, sediment loss, runoff pH, NO3-N, NH4-N, or soluble P loss. Cob removal when adequate stover was retained did not negatively affect erosion and runoff nutrient loss.