INFLUENCE OF WHEAT-FEED GRAIN PROGRAMS ON RISKINESS OF CROP ROTATIONSUNDER ALTERNATE IRRIGATION LEVELS

Declining groundwater levels in parts of the Great Plains could lead t o reduced irrigation and a decline in the economies of those areas. Im proved irrigation efficiency has helped slow the rate of decline in aq uifer levels but adoption of limited irrigation and water conserving r otations could slow the decline even more. The objective was to estima te the riskiness and profitability of these alternatives with and with out farm commodity programs. Three water levels-rainfed, limited irrig ation (6 in./yr water allocation) and full irrigation (meet crop evapo transpiration demands) were established for continuous corn (Zea mays L.), winter wheat (Triticum aestivum L.)-corn-soybean [Glycine max (L. ) Merr.], and corn-soybean rotations. The profitability of each rotati on under each water level was estimated using results of field experim ents conducted since 1981 in west central Nebraska and cost estimates based on a typical center pivot irrigation system covering 126 acres. Stochastic dominance techniques were then applied to the data by using combinations of prices for corn, wheat, and soybean to generate cumul ative distribution functions. Profitability and riskiness were estimat ed with and without participation in the wheat and feed grain programs and with alternate acreage conservation reserve (ACR) levels. Results showed that the government program improved income levels and reduced income variation for each water level and all rotations. Program part icipation did encourage monoculture corn under full irrigation and und er limited irrigation with low ACR requirements. Under rainfed conditi ons the relative ranking of the three rotations was not changed by pro gram participation.