Submitted to: CRC Book: Agricultural Sys Models in Field Research and Technology Transfer
Publication Type: Book / Chapter
Publication Acceptance Date: 10/3/2001
Publication Date: 2/15/2002
Citation: Interpretive Summary: Computer models are available that simulate various components of agricultural systems (e.g., crop growth and development, plant water and nutrient use, movement of water in soils, etc.). Many of these models have not been tested under the varying available water conditions in the central Great Plains. This chapter evaluates three models [Root Zone Water Quality yModel (RZWQM), CROPGRO-Soybean, and CERES-Maize] for simulations of corn and soybean production under a range of water availability conditions in northeast Colorado. RZWQM has a generic plant development module with detailed soil water balance, while CROPGRO-Soybean and CERES-Maize have detailed plant development modules with a more general soil water balance component. Consequently, a second objective of the chapter was to determine how much benefit is gained from detailed crop growth and development components vs. detailed water balance components. RZWQM simulated corn and soybean yield acceptably under all water availability conditions, and provided better simulation of soil water content than CROPGRO-Soybean and CERES-Maize. Predicted corn yields from CERES-Maize did not respond to irrigation. CROPGRO-Soybean predicted soybean yield better than RZWQM. The data presented in this chapter should encourage field scientists to use models as a tool to analyze their experimental results and gain a better understanding of the effects of environment on crop productivity.
Technical Abstract: Models of plant growth and development exist but have not been widely tested under the water-limited conditions of the central Great Plains. The models use differing algorithms for quantifying the water stress which affects plant growth and yield. This chapter evaluates three models [Root Zone Water Quality Model (RZWQM), CROPGRO-Soybean, and CERES-Maize] for simulations of corn and soybean production under a range of water availability conditions in northeast Colorado. Models were calibrated against data from one water level in one year, and then evaluated with data from other water levels in the same year and in other years. RZWQM gave satisfactory yield predictions for both corn and soybean across the range of water availability provided. RZWQM provided better simulation of soil water contents than CROPGRO-Soybean and CERES-Maize. Predicted corn yields from CERES-Maize did not respond to irrigation. Soybean yields were generally better predicted by CROPGRO-Soybean than RZWQM. Water stress was better predicted by RZWQM than by the other two models. This study clearly showed the weaknesses and strengths of each model, and should encourage field scientists to use models as a tool to analyze their experimental results while promoting technology transfer via system models.