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Title: CROP YIELD VARIABILITY AS INFLUENCED BY WATER IN RAIN-FED AGRICULTURE

Author
item Logsdon, Sally
item Prueger, John
item Meek, David
item Colvin, Thomas
item MILNER, MARIBETH - LARSON SYSTEMS
item James, David

Submitted to: International Conference on Precision Agriculture Abstracts & Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 7/22/1998
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Crop yield is reduced due to high water table in closed depressions or to inadequate water on summit and backslope positions during dry periods. When rooting depth is not limited, relatively high water tables supply extra water to crops. The objectives of this study are (1) develop relationships between terrain parameters and aeration stress or total water available, and (2) determine the effect of aeration stress or total water on crop yield. Soil water and water table depths were measured periodically at fourteen locations for 4 yrs in a field with both corn (Zea mays L.) and soybean (Glycine max (L.) Merr.) each year. Bowen ratio evaporation measurements were made in the corn and soybean sections. Terrain analysis (TAPES-G) was used to extrapolate soil water and water table depth information to the whole area (33.2 ha divided into 15 m grid). The drainage area output was modified to better describe landscapes dominated by closed depressions rather than overland flow. The area was further classified as influenced or not influenced by tile drains. Yield was measured in six or seven transects for each crop, divided into 25 sections each 20 m long. Predicted aeration stress correlated with yields 3/4 of the time in wet years, and predicted total water (stored plus upward movement from water table) correlated with yield 2/3 of the time. Work is continuing on use of SRAD and WET programs to examine predicted variation in evaporation at different landscape positions, and to relate this to predicted total water.