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Title: Climate change impacts on dryland cropping systems in the central Great Plains, USA

Author
item Ko, Jonghan
item Ahuja, Lajpat
item ANAPALLI, SASEENDRAN - Colorado State University
item Green, Timothy
item Ma, Liwang
item Nielsen, David
item Walthall, Charles

Submitted to: Climatic Change
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/15/2011
Publication Date: 8/9/2011
Citation: Ko, J., Ahuja, L.R., Anapalli, S., Green, T.R., Ma, L., Nielsen, D.C., Walthall, C.L. 2011. Climate change impacts on dryland cropping systems in the central Great Plains, USA. Climatic Change. 111:445-472.

Interpretive Summary: The likely doubling of atmospheric CO2 and associated warming within the next century may affect agricultural production through changes in evapotranspiration, plant growth rates, plant litter composition, and nitrogen-carbon cycling. However, the effect at any given location will depend on the magnitude of change and response of the crops, forage or livestock species, and location-specific management. In order to understand the effects and recommend remedial measures in the U.S. Great Plains, we investigated the likely impacts of GCM projected CC on dryland crop rotations of wheat-fallow (WF), wheat-corn-fallow (WCF), and wheat-corn-millet (WCM) at Akron, Colorado, USA. Simulations were done using the CERES V4.0 crop modules in RZWQM2. The CC scenarios for CO2, temperature and precipitation were based on a synthesis of IPCC (2007) projections for Colorado. The results of this investigation indicated that in the event of a climate change (the scenario adopted for analysis), the negative effects of enhanced temperatures would dominate over the positive impacts of atmospheric CO2 increases on crops in the dryland cropping systems. Consequently, wheat yields were projected to decrease to some extent in all of the cropping systems analyzed (WF, WCF and WCM). However, corn and millet yields in all the crop rotations analyzed were found to decrease more significantly (within 95% confidence intervals). As an adaptation strategy to ameliorate the yield reduction under the climate scenario investigated, simulations using early planting dates up to 30 days from the historical dates did not show any promising results.

Technical Abstract: Agricultural systems models are essential tools to assess potential climate change (CC) impacts on crop production and help guide policy decisions. In this study, impacts of GCM projected CC on dryland crop rotations of wheat-fallow (WF), wheat-corn-fallow (WCF), and wheat-corn-millet (WCM) at Akron, Colorado, USA were simulated using the CERES V4.0 crop modules in RZWQM2. The CC scenarios for CO2, temperature and precipitation were based on a synthesis of IPCC (2007) projections for Colorado. For simulations of possible climate change impacts on the cropping systems, the CC for years 2025, 2050, 2075, and 2100 (CC projection years) were super-imposed on measured baseline climate data collected during the long-term WF and WCF (1992-2008), and WCM (1994-2008) experiments at the location. For all the CC projection years, the decline in simulated wheat yield compared to the baseline was not significant (p>0.05) in all cases but one. However, wheat yield in WF under no-till for year 2100, and corn and proso millet yields in all rotations and projection years declined significantly (p<0.05). Simulated adaptation via changes in planting dates did not mitigate the yield losses of the crops significantly. Overall, the projected negative effects of rising temperatures on crop production dominated over the positive impacts of atmospheric CO2 increases in these dryland cropping systems. For comparison, possible effects of historical CO2 increases during the past century (from 300 to 380 ppm) on crop yields were also simulated using 96 years of measured climate data (1912-2008) at the location. During the period, on average the CO2 increase enhanced wheat yields by about 30 % with no significant changes in corn yields.