SIMULATIONS OF CROP RESPONSES TO CLIMATE CHANGE - EFFECTS WITH PRESENT TECHNOLOGY AND CURRENTLY AVAILABLE ADJUSTMENTS (THE SMART FARMER SCENARIO)

If climate changes, farmers will have to adapt to a new set of climate constraints. In this paper we examine the efficacy of strategies for dealing with climate change that are currently available to farmers and that are inexpensive to use; we refer to this group of strategies as 'adjustments'. Adjustment schemes of various kinds were identified for us by agricultural experts in the Missouri-Iowa-Nebraska-Kansas (MINK) states. These can involve changes in land use, changes in variety and crop selection, changes in planting and harvesting practices, and changes in fertility and pest management. Using the erosion productivity impact calculator (EPIC) model on a small set of representative farms, we tested adjustments of these kinds. The simulations show that earlier planting, longer-season cultivars and the use of furrow diking for moisture conservation would offset some of the yield losses induced by climate change in warm-season crops. Longer-season varieties of wheat (a cool-season crop) and shorter-season varieties of the perennials wheatgrass and alfalfa were also effective. The adjustments to climate change diminished yield losses in all crops but irrigated wheat. Despite the positive effects of adjustments, however, yields of all dryland warm-season crops remained lower than control levels. The adjustments also increased demand for irrigation water. Carbon dioxide enrichment had the same incremental effect on crop yields with or without adjustments (see the fourth paper in this issue), except in the case of alfalfa and sorghum, where a CO2-adjustment interaction was found. We conclude that currently available techniques would partially offset the yield reductions caused by a 1930s-like climate, but that in most crops the yield reductions would still be substantial.