Effects of climate change and elevated CO2 on cropping systems: model predictions at two Italian locations

The potential effects of future climate change were investigated, correspon ding to a doubling of atmospheric CO2 from 350 to 700 ppm, on agricultural production of four different cropping systems at two Italian locations, Mod ena and Foggia. Climate change scenarios, derived from two general circulat ion models (GCMs), were used as weather input to a soil-plant growth simula tor, CropSyst. This model was recently modified to include the effects of e levated CO2 on crop photosynthesis and transpiration. Six different crops i n total were simulated at the two Italian sites. At Modena, a 3-year maize- maize-wheat rotation and a 2-year soybean-barley-summer sorghum rotation we re studied. At Foggia, a 2-year sunflower-wheat-fallow rotation, and a 2-ye ar wheat-fallow-spring sorghum rotation were simulated. Results suggested t hat the combined effects of elevated atmospheric CO2 and climate change at both sites would depress crop yields if current management practices were n ot modified. Specifically, predicted warmer air temperatures accelerated pl ant phenology, reducing dry matter accumulation and crop yields by 10-40%. By investigating adaptation strategies, it was found that a combination of early planting for spring-summer crops and the use of slower-maturing winte r cereal cultivars succeeds in maintaining crop yields at current levels at both sites. For irrigated maize and soybean production at Modena, 60-90% m ore irrigation water was required under climate change to keep grain yields at current levels. This implies that adaptation to climate change may be l imited for irrigated crops, depending on site-specific water availability. (C) 2000 Elsevier Science B.V. All rights reserved.