ANALYSIS OF SOIL WATER FLUCTUATIONS IN A LOAMY SAND UNDER IRRIATED POTATO

Authors: Starr, Gordon; COOLEY, E - DOOR CTY SOIL&WATER CONS; LOWERY, B - UNIV WISCONSIN-MADISON; KELLING, K - UNIV WISCONSIN-MADISON

Submitted to: Soil Science Society of America Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/4/2004
Publication Date: 5/1/2005
Citation: Starr, G.C., Cooley, E.T., Lowery, B., Kelling, K. 2005. Analysis of soil water fluctuations in a loamy sand under irriated potato. Soil Science Society of America Journal. Volume 170(2); pages 77-89

Interpretive Summary: Irrigated potato production in the Central Sands Region of Wisconsin suffers from rapid drainage of water and it is difficult to optimize water applications under these conditions. Water content was measured every fifteen minutes at many locations in and below potato hills in an effort to understand where the water is moving and how irrigation can be managed more effectively. Trickle irrigation was tested as an alternative to the more conventional sprinkler method. We analyzed indicators of soil drainage, soil wetting, and soil drying that help us evaluate the two systems and determine where improvements can be made. It was determined that a very dry zone right in the middle of the potato hill and very fast drainage between hills were problems for sprinkler irrigation. The results for drip irrigation showed that system might be made more effective by using less water. The results of this study should be useful to farmers, scientists, engineers, and irrigation salespeople who are involved in improving irrigation water management.

Technical Abstract: Irrigated potato production in the Central Sands Region of Wisconsin suffers from rapid drainage and concurrent chemical and nutrient transport to groundwater. Soil water content time series were measured across potato hills in sandy soil using time domain reflectometry to evaluate water storage, flow, and uptake patterns under drip and sprinkler irrigation. Indicators were developed for water storage, drainage, uptake, and wetting patterns. The sprinkler system leads to drainage losses beneath the furrow whereas the drip system leads to water losses at the base of the hill. The sprinkler system was unable to wet the center of the hill. A model of water uptake was fit to a composite of the daily cycle with acceptable results (R2 = 0.27-0.72) in the potato hill, but uptake was virtually undetectable at the base and furrow locations. Uptake peaked around 3:12 p.m. at the shoulder, 4:45 p.m. at the toe, and 6:40 p.m. at the center of the hill. Management practices targeted at wetting the hill center under sprinkle and optimizing water application amounts under drip would likely improve water use and production efficiency under these conditions.