|Author:||Andales, A. A. ; Ahuja, L. R. ; Peterson, G. A.|
|Book Group Author:||NA|
GPFARM is an ARS decision support system for strategic (long-term) planning. This study evaluated its performance for comparing alternative dryland no-till cropping systems and established limits of accuracy for eastern Colorado, using data collected during 1987-99 from an ongoing long-term experiment at three locations along a gradient of potential evapotranspiration (PET) (Sterling, low PET; Stratton, medium PET; and Walsh, high PET). The crop rotations, which included winter wheat, maize, sorghum (Sorghum bicolor), proso millet (Panicum miliaceum), and varying fallow periods, were wheat-fallow, wheat-maize-fallow, and wheat-maize-millet-fallow at Sterling and Stratton and wheat-fallow, wheat-sorghum-fallow, and wheat-sorghum-millet-fallow at Walsh. The ranges of relative error (RE) of simulated mean and root mean square error (RMSE) were total soil profile water content (RE: 0-23%; RMSE: 38-76 mm water), dry mass grain yield (RE: -27-84%; RMSE: 419-2567 kg ha-1), dry mass crop residue (RE: -5-42%; RMSE: 859-1845 kg ha-1), and total soil profile residual nitrate N (RE: -42-32%; RMSE: 26-78 kg ha-1). GPFARM simulations agreed with observed trends and showed that productivity and water use efficiency increased with cropping intensification and that Stratton was the most productive and Walsh the least. GPFARM (v. 2.01) was less suited for year-to-year grain yield prediction under dryland conditions but has potential as a tool for studying long-term interactions between environment and crop management system. Future development and applications of GPFARM must account for crop-specific responses to stress, detailed hydrology, better understanding of root uptake processes, and spatial variability to give more accurate grain yield predictions in water-stressed environments.
|Pages:||1510 - 1524|
arid lands, crop residues, crop yield, cropping systems, dryfarming, dry matter, evapotranspiration, fallow, maize, nitrate,no-tillage, plant water relations, roots, rotations, simulation models,soil water, sustainability, water stress, water uptake, water use, wateruse efficiency, wheat, Colorado, Panicum miliaceum, Sorghum bicolor,Triticum, Triticum aestivum, Zea mays, Panicum, Poaceae, Cyperales,monocotyledons, angiosperms, Spermatophyta, plants, eukaryotes, Sorghum,Triticum, Zea, Mountain States of USA, Western States of USA, USA, NorthAmerica, America, Developed Countries, OECD Countries, Great PlainsStates of USA, corn, crop rotation, dryland farming, fallowing,no-tillage systems, rotational cropping, soil moisture, zero tillage,Field Crops (FF005) (New March 2000), Plant Water Relations (FF062),Plant Production (FF100), Plant Cropping Systems (FF150), Mathematicsand Statistics (ZZ100)