Replanting strategies for grain sorghum under risk

Risk analysis of replanting strategies for grain sorghum at three Kansas lo cations was conducted using stochastic dominance techniques. Yield data wer e simulated for seven planting dates, six seeding rates or target plant pop ulations, and three maturity classes over a 33-year period using weather da ta for each year at each location. The results showed that optimal planting dates, seeding rates, and maturity classes vary by location and risk prefe rence. In northeast and southcentral Kansas, planting at later rather than earlier dates was preferred as risk aversion increased. In southwest Kansas , generally no change occurred in the preferred strategy as the level of ri sk aversion increased. Early- and medium-maturing hybrids and low-to-modera te seeding rates often were selected. Late-maturing hybrids never were sele cted by risk-averse managers. The degree of risk aversion did not significa ntly affect the selection of a replanting strategy for southcentral and sou thwest Kansas, but did for northeast Kansas. However, whether managers repl anted immediately or delayed, replanting varied with the replanting decisio n date and degree of risk aversion. Replanting on the first replanting deci sion date in southwest Kansas rather than delaying 2 weeks or more was pref erred by all risk-averse managers. More strongly risk-averse managers in th e northeast and all risk-averse producers in southcentral Kansas preferred to delay replanting of damaged stands, in some cases by 2-4 weeks after the decision date. Results also showed that when a stand was damaged late in t he season, the expected yield from the damaged stand had to be lower than t hat from a stand damaged early in the season in order for replanting to occ ur, Price changes had only minor impacts on the preferred replanting strate gies. A higher crop price caused replanting to occur more often, because th e yield reduction of a damaged stand required for replanting to be economic ally feasible grew smaller as the price increased. (C) 1999 Elsevier Scienc e Ltd. All rights reserved.