Application of a Crop Model to Evaluate Cultural Practices and Optimize Dryland Grain Sorghum Yield

Abstract

Optimizing crop management practices for a specific location requires careful analyses of climate, soil, and crop varieties. The grain sorghum [Sorghum bicolor (L.) Moench] growth model, SORKAM, provides a means to simultaneously examine these factors for the sorghum crop. This study was conducted to see if SORKAM could identify profitable management practices (sowing dates, plant densities, and maturity groups) for eight sites in Texas. SORKAM grain yield estimates were within 15–40% of observed grain yields available from the sites evaluated. For locations in west Texas, where rainfall and soil moisture frequently limit growth, early-maturing cultivars sown early (1–15 April) were found to have the highest simulated grain yield (14–25 cwt/acre) and chance of profit. In central Texas, medium-maturing sorghum sown early to mid-March was found to have the highest simulated yield (30–50 cwt/acre) and chance for a profit, whereas in south and east Texas, late-maturing sorghum cultivars sown between 15 May and 15 June had the highest simulated yields (30–80 cwt/acre) and chance for profit. Except for south and east Texas, the optimum practices identified by the model agreed with the management practices generally followed. The model does not account for late season storm and insect damage that affect grain yield for late sowings in east and south Texas. The results from this study demonstrate that a crop model, such as SORKAM, may be used by producers, extension personnel, and crop consultants, to evaluate cultural practices that depart from those normally used over a range of climatic and edaphic environments.