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United States Department of Agriculture

Agricultural Research Service

Title: Modeling Alternative Cropping Systems for Central Great Plains Using Rzwqm

Authors
item Anapalli, Saseendran - COLO STATE UNIVERSITY
item Nielsen, David
item Ma, Liwang
item Ahuja, Lajpat
item Vigil, Merle
item Benjamin, Joseph

Submitted to: Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: April 15, 2004
Publication Date: April 20, 2004
Citation: Anapalli, S.S., Nielsen, D.C., Ma, L., Ahuja, L.R., Vigil, M.F., Benjamin, J.G. 2004. Modeling alternative cropping systems for central great plains using RZWQM. Proceedings of the International Workshop on Applications, Enhancements and Collaborations of ARS RZWQM and GPFARM Models. April 20-22, 2004. p.22-23.

Technical Abstract: The practice of a summer fallow period to conserve soil water and to reduce the chance of crop failure dominated dryland agriculture in the Great Plains in the 20th century. This conventional tilled (CT) winter wheat (Triticum aestivum L.)-summer fallow cropping system {WF(CT)} in the semiarid areas is known to have serious adverse impacts on the environment due to its associated potentials for wind and water erosion of agricultural soils and the consequent loss of soil organic matter and productivity. Field experiments oriented towards assessment and amelioration of the adverse impacts of the WF(CT) on the soil quality and productivity were established in 1990-92 at the USDA-ARS, Central Great Plains Research Station, Akron, CO. About 20 crop rotations both under conventional tillage and no tillage practices are being investigated. In this study we used the Root Zone Water Quality Model (RZWQM) of USDA-ARS to model 1)WF(CT), 2) winter wheat-fallow under no till(NT) {WF(NT)}, and 3) winter wheat-corn (Zea Mays L.)-fallow under NT {WCF(NT)} crop rotation systems from 1992 to 2002. All phases of the crop sequences (total=7) were available every year and thus modeled separately. Model predictions of soil water in different layers, total soil profile water content, and grain yield showed greater degree of accuracy than the predictions of leaf area index, evapotranspiration, and biomass. Higher soil water and crop yields measured in the WF (NT) rotation compared with the WF (CT) rotation were reasonably well reflected in the model simulations. Model simulations over the 11 year period showed a greater level of total carbon and fraction organic matter in the first 5 cm of the soil in the WF (NT) and WCF (NT) rotations compared with the WF (CT) rotation. While the model will need improvement for simulating biomass, ET, and LAI, the results of the study indicate that the model still possesses reasonable potential for simulating the alternative crop rotation systems in the Great Plains, as the present inaccuracies in predictions of these parameters are not large.

Last Modified: 10/20/2014
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