Will Wetter Water Make Fatter Wallets? Evaluating Soil Surfactants in Irrigation

摘要

Growers concerned with drainage, runoff, and localized dry spots in the Pacific Northwest are considering adding soil surfactants during irrigation based on claims that these wetting agents improve infiltration, water distribution uniformity, and soilmoisture retention. Growers are requesting independent studies on the cost effectiveness of these materials. Experiments are being conducted at Washington State University in uniformly prepared soil columns to investigate the effects of surfactants on soil-water properties of sandy and silt loam soils. The infiltration rate, water holding capacity, and unsaturated hydraulic conductivity were compared for soil columns irrigated with and without several types of soil surfactants. To date, no statisticaldifferences between treatments have been found. Capillary rise experiments remain to be conducted, and some sand columns are still being processd. Researchers have concluded that new tests will need to be designed with problem-soil conditions before results can help advise the irrigation practices of regional growers of difficult-to-irrigate crops such as high-value vegetables and beans.