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ISWS Research Report 127PDF


Title:Long-Term Variations in Seasonal Weather Conditions and Their Impacts on Crop Production and Water Resources in Illinois
Author(s):Changnon, Stanley A.; Wistanley, Derek
Subject(s):Climatic data
weather data
water quality
ground water
surface water
water resources
climate change
impacts of weather
Abstract:This study reports the results of an analysis of long-term records of corn yields, water resource conditions, and seasonal weather conditions in Illinois and found major temporal shifts and important spatial variations in the types of seasonal weather conditions that have positive and negative impacts on yields and water conditions. Nineteen different types of corn-weather seasons (May–August) occurred during 1901–1997, of which nine types accounted for most of the high corn yields (highest 20 of the 97 values) and eight types produced most low yields (lowest 20 values). An assessment of the years with either high or low yields revealed three findings about the distributions of the corn-weather seasons creating these extremes: 1) some types were uniformly distributed throughout the century; 2) others were unevenly distributed over time, some occurring only in the century’s early decades and others only in the last few decades; and 3) certain types varied greatly regionally. Yield responses to certain seasonal types varied over time. The findings helped establish that changes in farming practices, corn varieties, and agricultural technology all affect how a given type of growing season affects corn yields. Sizable regional differences in yield outcomes from a given set of weather conditions, a result of varying soil and climate differences across Illinois, further revealed how impacts f similar seasonal weather conditions can vary spatially. These two conclusions revealed the importance of using weather effects in defining seasonal extremes. Seasons harmful to corn yields and the state's water resources were prevalent in three decades: 1911–1920, 1931–1940, and 1950–1960. Seasons with the best weather effects were prevalent in 1901–1910 and 1961–1967. The last 37 years have had the best seasonal conditions of the century as a result of slightly cooler temperatures and higher precipitation. Results reveal the difficulties in projecting impacts of future climate conditions.
Issue Date:1999
Series/Report:ISWS RR-127
Genre:Technical Report
Date Available in IDEALS:2015-04-24

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