Submitted to: American Society of Agricultural Engineers Meetings Papers
Publication Type: Other
Publication Acceptance Date: July 11, 1998
Publication Date: October 15, 1998
Citation: WILLIAMS, R.D., DANIEL, J.A., STARKS, P.J., GARBRECHT, J.D. 1998. SIMULATION OF CLIMATE CHANGE IMPACT ON WINTER WHEAT PRODUCTION IN CENTRAL OKLAHOMA. AMERICAN SOCIETY OF AGRICULTURAL ENGINEERS MEETINGS PAPERS. Paper No. 98-2187. P. 7. Interpretive Summary: Most analysis of climate data show an increase of 0.5 degree C in the mean global temperature over the past 100 years. Such information is not useful in examining the impact of climate change on a local area. This paper presents the analysis of changes in temperature and precipitation in local weather data and uses those trends to simulate their rpotential effects on future crop production, water resources and soil erosion. Trends in the historical data from a winter-wheat field in Central Oklahoma showed a slight increase in annual precipitation, while both the mean annual maximum and minimum temperature slightly decreased, from 1950 to 1990. These weather trends were used in a computer model to simulate winter wheat production for an additional 40 years using conventional tillage practices typical for the area. Overall, the increased precipiation increased the chance for erosion, nutrient loss, and pesticide movement from the winter-wheat field. One factor shown by this simulation is the increase in drainage which increases the possibility of nutrient and pesticide leaching through the root zone. Using this approach, the potential impact of climate change can be targeted for small, local areas. In addition, alternative management practices and/or cropping systems can be simulated in a similar manner to determine which systems could be more effective under changing climate conditions.
Technical Abstract: Local effects of global warming are difficult to predict with General Circulation Models (GCMs) since they encompass large land areas. However, historical climate data can be used to simulate climate change impacts on small areas. Trend analysis of historical data and a stochastic weather generator (CLIGEN) were used to develop a possible climate change scenario for a 2.4-ha experimental, conventional winter wheat watershed. Trends in climate data showed an increase in average annual precipitation from 79 to 117 cm/y. Management practices and watershed characteristics were parameterized for the GLEAMS model. Over the 40-year simulation period precipitation, runoff and percolation increased by 34%, 68%, and 65%, respectively. Increases in runoff and percolation increased the potential for erosion and pesticide loss. Soil loss increased from 82 t/ha without climate change to 131 t/ha with climate change. Simulations of chlorsulfuron showed an increase in runoff and percolation losses from 6 t 7 g/ha and 9 to 11 g/ha, respectively. However, the pesticide loss was less than 1% of the material applied over the 40-year simulation.