|Milner, Maribeth - UNIVERSITY OF NEBRASKA|
Submitted to: International Conference on Precision Agriculture Abstracts & Proceedings
Publication Type: Proceedings
Publication Acceptance Date: July 22, 1998
Publication Date: N/A
Technical Abstract: Crop yield can be reduced due to a high water table in closed depressions or to inadequate water on summit and back slope positions during dry periods. When rooting depth is not limited, relatively high water tables supply extra water to crops. The objectives of this study were to develop relationships between terrain parameters and aeration stress or soil water storage; and to determine the effect of aeration stress or soil water storage 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. Each point was furthered classified as to whether or not it was influenced by tiles. Yield was measured in six or seven transects for each crop, divided into 25 sections each 20 m long. Predicted available soil water storage was slightly less than that measured at a midslope site, partly because predicted evaporation was slightly higher than measured. In a wet year predicted aeration stress correlated with corn yields but not soybean yields. In a drier year soil water storage correlated with both corn and soybean yields.