Submitted to: Soil and Water Conservation Society Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: August 4, 2004
Publication Date: October 10, 2004
Citation: Hatfield, J.L., Prueger, J.H., Sauer, T.J. 2004. Spatial and temporal variation of water use in corn-soybean cropping systems of the midwest. [CD-ROM]. Minneapolis, MN: Soil and Water Conservation Society Proceedings.
Crop production in the Midwestern United States is dependent upon adequate rainfall during the growing season and a completely recharged soil profile by early spring. Patterns of crop water use by corn and soybean during the growing season is related to the soil water holding capacity and the precipitation events. Observations of yield within fields demonstrated the interactions of soil water holding capacity and effective precipitation. Studies have been conducted across central Iowa in corn and soybean fields since 1991 to examine the patterns of crop water use as affected by crop, soil type, and crop residue management. Different methods to measure crop water use have been used based on energy balance techniques with Bowen ratio, flux gradient, or eddy correlation methods. Crop residue reduces the soil water evaporation rate in the spring and increases soil water storage. Tillage increases soil water evaporation and can remove as much as 25 mm from the upper 100 mm of the soil profile during crop planting and emergence. Spatial variation in crop water use exists within fields and is the primary factor causing crop yield variation. Current cropping systems are based on the precipitation pattern and changes in these patterns induced by climate change will affect the efficiency of precipitation use. Understanding the crop water balance and the causes of variation will provide for more effective soil and crop management practices.