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Simulated Impacts of Crop Residue Removal and Tillage on Soil Organic Matter Maintenance
- Dalzell, Brent J., Johnson, Jane M.F., Tallaksen, Joel, Allan, Deborah L., Barbour, Nancy W.
- Soil Science Society of America Journal 2013 v.77 no.4 pp. 1349
- Glycine max, Zea mays, continuous cropping, conventional tillage, corn, crop residue management, crop residues, crop rotation, edaphic factors, models, no-tillage, roots, soil depth, soil erosion, soil organic matter, soil sampling, soybeans, Minnesota
- Cellulosic biofuel production may generate new markets and additional revenue for farmers. However, residue removal may cause other environmental problems such as soil erosion and loss of soil organic matter (SOM). The objective of this study was to determine the amounts of residue necessary for SOM maintenance under different tillage and removal scenarios for corn-soybean (Z. mays - G. max, respectively) and continuous corn rotations for a site in west-central Minnesota. We employed a process-based model (CQESTR) to evaluate current management practices and quantify SOM changes over time. Results showed that conventional tillage resulted in SOM loss, regardless of the amount of residue returned. Under no-till, the amount of residue was important in determining SOM accumulation or depletion. For the upper 30 cm of soil, average annual rates of 3,650 and 2,250 kg crop residue ha-1 yr-1 were sufficient to maintain SOM for corn-soybean and continuous corn rotations, respectively. Soil OM in soil layers below 30 cm was predicted to decrease in all scenarios as a result of low root inputs. When considered over the upper 60 cm (maximum soil depth sampled), only continuous corn with no-till was sufficient to maintain SOM. Results from this work are important because they show that, for the scenarios tested here, no-till management is necessary for SOM maintenance and that determining whether SOM is accumulating or depleting depends upon the soil depth considered. At current yields observed in this study area, only continuous corn with no-till may generate enough residue to maintain or increase SOM. [REAP publication].