Synergies between cover crops and corn stover removal

The potential harvest of corn stover as a feedstock for biofuels to meet government mandates has raised concerns about the agronomic impacts of its removal from fields. Furthermore, in order to meet these mandates, larger quantities of stover will be required. As a result, increased attention has been placed on sustainable agronomic practices, such as cover crops. While cover crops may offer desirable benefits, adoption comes at a cost. The objective of this study was to determine the extent to which cover crop costs could be compensated by additional stover removal and additional agronomic benefits from the use of cover crops. To meet the objective, we took three distinct approaches: (1) benefit-cost analysis, (2) integrated model analysis, and (3) representative farm analysis using the linear programming model PC-LP. Each approach was a different take on the same issue; however, each provided different information. First, we estimated cover crop costs and agronomic benefits and employed benefit-cost analyses, including stochastic analysis in @RISK. Second, we tested cover crops with stover removal for 24 Indiana farms using PC-LP. Cover crop costs ranged from $81.76/ha to $172.50/ha, with variability being driven by differences in the seeding rate and seed cost. Agronomic benefits included reduced erosion, which was calculated using a newly created integrated modeling system. The mean estimated reduced soil erosion with a cover crop and no residue removal was 0.72 metric tons/ha. An analysis of cover crop agronomic benefits resulted in private benefits (on-site) ranging from $91.45/ha to $192.07/ha, and $97.63/ha to $198.27/ha from society's perspective. These benefits were highly influenced by added or scavenged nitrogen (N) from the cover crop. For sensitivity we eliminated the benefit from added N and reevaluated the results. Without the N credit, benefits ranged from $74.72/ha to $134.62/ha. Benefit-cost analyses when considering the agronomic benefits of cover crops resulted in a range of a net loss of $11.09/ha to a net benefit of $87.32/ha for the private perspective. The integrated modeling system results indicated that, on average, while holding soil erosion constant, an additional 4.01 metric tons/ha of stover could be removed if a cover crop were used. Accounting for cover crop costs and stover removal, a benefit-cost analysis suggested that at a farm-gate stover price of $66.14/metric ton, net benefits ranged from a loss of $3.78/ha to a net benefit of $86.93/ha. At a farm-gate stover price of $88.18/metric ton, mean net benefit ranged from $158.81/ha to $249.52/ha. Results from the farm model (PC-LP) indicated that cover crops, along with increased stover removal, impacted crop rotations, increased the total amount of stover harvested, and had the potential to increase farm profits. (C) 2014 Elsevier Ltd. All rights reserved.