Wednesday, November 15, 2006
231-15

The Impact of Using On-Site and Off-Site Soil Data on Simulated Soil Moisture and Crop Yield.

Larry Guerra, The Univ of Georgia, 1109 Experiment Street, Griffin, GA 30223-1797, Axel Garcia y Garcia, Univ of Georgia, 1109 Experiment St, Griffin, GA 30223, Ayman Suleiman, Univ of Jordan, Dept of Land, Water and Environment, Faculty of Agriculture, Amman, Jordan, and Gerrit Hoogenboom, 1109 Experiment St., University of Georgia, University of Georgia, Dept. of Biological & Agricultural Eng., Griffin, GA 30223-1797.

One of the most important input constraints in crop model applications is the availability of soil data for specific locations. Soil profile information is often scarce and/or incomplete. In order to avoid this limitation, the use of soil data collected from a different location but with the same soil type is a common practice in crop simulations. However, accurate and representative soil data are especially important where the estimates from the crop models are used for decision support, strategic planning and policy development. The objective of this study was to evaluate the performance of a cotton model for simulating soil moisture and yield using both on-site and off-site soil data as inputs. An experiment was conducted at the Stripling Irrigation Research Park in southwest Georgia to study growth and development of cotton under irrigated and rainfed conditions. Soil samples at seven depths down to 1.5 m were collected in the field to determine the values for key soil variables in model inputs. Crop growth and development and soil moisture at different depths were collected every two weeks. Yield and yield components were also collected at final harvest. We then used the Cropping System Model (CSM)-CROPGRO-Cotton to simulate soil moisture and yield. This study demonstrated the importance of local soil data for a more accurate simulation of soil moisture and its potential impact on crop yield. However, if soil profile information is not available for a particular location, available profiles for several locations with the same soil type could be considered but a sensitivity analysis should be conducted.

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