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Title: GPFARM Evaluation Across a No-Till Dryland Agroecosystem Landscape Catena

Author
item Ascough Ii, James
item Andales, Allan
item McMaster, Gregory
item Ahuja, Lajpat

Submitted to: ASA-CSSA-SSSA Annual Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 9/8/2006
Publication Date: 11/15/2006
Citation: Ascough Ii, J.C., Andales, A.A., Mcmaster, G.S., Ahuja, L.R. 2006. Gpfarm evaluation across a no-till dryland agroecosystem landscape catena. ASA-CSSA-SSSA Annual Meeting Abstracts. Indianapolis, IN. 11/15/2006.

Interpretive Summary:

Technical Abstract: Title: GPFARM Evaluation Across a No-Till Dryland Agroecosystem Landscape Catena Authors: James C. Ascough II, Allan A. Andales, Gregory S. McMaster, and Lajpat R. Ahuja Address: USDA-ARS, ASRU, 2150 Centre Ave., Bldg. D, Suite 200, Fort Collins, CO 80526 GPFARM is a USDA-ARS decision support system (DSS) for strategic (long-term) planning. This study evaluated GPFARM performance for comparing alternative dryland no-till cropping systems and established limits of accuracy for eastern Colorado locations. Data used in the GPFARM evaluation were collected in 1987 through 1999 from an on-going long-term experiment at three locations along: 1) a gradient of potential evapotranspiration (PET) [Sterling, low PET; Stratton, medium PET; and Walsh, high PET]; and 2) across summit, sideslope, and toeslope landscape positions at all three sites. Crops included winter wheat (W) [Triticum aestivum (L.)], corn (C) [Zea mays (L.)], sorghum (S) [Sorghum bicolor (L.) Moench], proso millet (M) [Panicum miliaceum (L.)], and varying fallow (F) periods; crop rotations included WF, WCF, WCMF, WSF, and WSMF. Ranges of relative error (RE) of simulated mean and root mean square error (RMSE) were calculated for total soil profile water content, dry mass grain yield, dry mass crop residue, and total soil profile residual nitrate-N. GPFARM simulations agreed with observed trends and showed that productivity and water use efficiency increased with cropping intensification and downslope landscape position.