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Title: Use of a Cropping System Model for Soil-Specific Optimization of Limited Water

item Ahuja, Lajpat
item Ma, Liwang
item Nielsen, David
item Trout, Thomas

Submitted to: International Conference on Precision Agriculture Abstracts & Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 7/1/2009
Publication Date: 7/20/2009
Citation: Ahuja, L.R., Anapalli, S.S., Ma, L., Nielsen, D.C., Trout, T.J., Andales, A.A., Hansen, N.C. 2009. Use of a Cropping System Model for Soil-Specific Optimization of Limited Water. International Conference on Precision Agriculture Abstracts & Proceedings.

Interpretive Summary: Agricultural system models are potential tools for the synthesis and integration of site-specific information on the various components of the agricultural system for input management. Saseendran et al. (2008) calibrated and validated the CERES-maize v4.0 model for corn production in Rago silt loam soil at Akron, Colorado and used it with long-term weather data (94 years), and developed site-specific limited water irrigation management scenarios. In this paper, we extended that study further and developed soil-specific water management scenarios for the Nunn clay loam and Julesberg sandy loam soils commonly occurring in the region. The limited water management strategies developed varied considerably between the three soils. The study highlighted the potential of agricultural system (cropping system) models for site-specific synthesis and integration of soil-crop-water-atmosphere information for decision support in precision agriculture.

Technical Abstract: In the arena of modern agriculture, system models capable of simulating the complex interactions of all the relevant processes in the soil-water-plant-atmosphere continuum are widely accepted as potential tools for decision support to optimize crop inputs of water to achieve location specific yield potential while minimizing environmental (soil and water resources) impacts. In a recent study, we calibrated, validated, and applied the CERES-Maize v4.0 model for simulating limited-water irrigation management strategies for corn in a Rago silt loam soil at Akron, Colorado. The results showed that, for different levels of irrigation, optimum production and WUE with minimum N losses were found when 20% of the available irrigation supply was applied during the vegetative (V) stage and 80% during the reproductive stage (R) (split irrigation strategy). We also found that the number of irrigations could be reduced and the water significantly saved if irrigations were initiated at 80% depletion of the plant available soil water (PAW) (later than commonly practiced). In this paper, the above model was used to evaluate similar limited irrigation management strategies for two other soil types (Nunn clay loam and Julesburg sandy loam) commonly occurring in the area. For the Nunn clay loam and Julesberg sandy loam soils, the water-level production functions, optimum irrigation levels, and WUE responses were similar. However, for the Julesberg sandy loam soil, our best results were found with the 20:80 split irrigation between V and R for all irrigation levels. For the Nunn clay loam soil, our best irrigation strategies were 20:80 split between the V and R stages for irrigations below 300 mm and above 600 mm, and 50:50 split between the stages for irrigation levels between 300 and 600 mm. For the late initiation of irrigation, optimum yields were achieved when water was applied at 60% depletion of PAW for the Nunn clay loam soil, and at 70% depletion of PAW for the Julesburg sandy loam soil.