Climate change impacts on dryland cropping systems in the Central Great Plains,USA |
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| Authors: | Jonghan Ko Lajpat R Ahuja S A Saseendran Timothy R Green Liwang Ma David C Nielsen Charles L Walthall |
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| Institution: | (1) USDA-ARS Agricultural Systems Research Unit, 2150 Centre Avenue, Bldg D., Ft. Collins, CO 80526, USA;(2) USDA-ARS Central Great Plains Research Station, 40335 County Road GD, Akron, CO 80720, USA;(3) USDA-ARS, Office of National Programs, 5601 Sunnyside Ave., Beltsville, MD 20705, USA;(4) Present address: Chonnam National University, 300 Youngbong-dong, Buk-gu, Gwangju, 500-757, Republic of Korea; |
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| 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 projected CC on dryland crop rotations of wheat-fallow (WF), wheat-corn-fallow
(WCF), and wheat-corn-millet (WCM) in the U.S. Central Great Plains (Akron, Colorado) 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 Intergovernmental Panel on Climate Change (IPCC 2007) projections for Colorado. The CC for years 2025, 2050, 2075, and 2100 (CC projection years) were super-imposed on measured
baseline climate data for 15–17 years collected during the long-term WF and WCF (1992–2008), and WCM (1994–2008) experiments
at the location to provide inter-annual variability. For all the CC projection years, a decline in simulated wheat yield and
an increase in actual transpiration were observed, but compared to the baseline these changes were not significant (p > 0.05) in all cases but one. However, corn and proso millet yields in all rotations and projection years declined significantly
(p < 0.05), which resulted in decreased transpiration. Overall, the projected negative effects of rising temperatures on crop
production dominated over any positive impacts of atmospheric CO2 increases in these dryland cropping systems. Simulated adaptation via changes in planting dates did not mitigate the yield
losses of the crops significantly. However, the no-tillage maintained higher wheat yields than the conventional tillage in
the WF rotation to year 2075. 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. On average the CO2 increase enhanced wheat yields by about 30%, and millet yields by about 17%, with no significant changes in corn yields. |
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