Date of this Version
University of Nebraska–Lincoln Office of Research and Economic Development (2010). Proceedings of the 2010 Water for Food Conference. Lincoln.
Highlights of Research and Educational Programs Related to Agricultural Water Management in Nebraska
Farmers are challenged to use water more efficiently while maximizing net return, Suat Irmak said. Researchers at the University of Nebraska– Lincoln (UNL) are investigating ways to improve agricultural practices and minimize water loss.
Center pivot irrigation research is designed to measure and understand crop response to water and chemigation under limited and full irrigation settings with the goal of determining how much farmers can reduce irrigation while maintaining high yields.
Irrigation treatments investigated range from dryland conditions to 50 percent irrigated to fully irrigated, and measurements include biomass production, kernel weight and other grain quality parameters. Other research addresses the effect of irrigation frequency on crop yield, water use efficiency and soil evaporation for corn under subsurface drip irrigation. Four years of results indicate that, in most cases, high-frequency irrigation leads to higher yields than low- or medium-frequency irrigation.
Additional research on crop water stress aims to determine, in part, how much stress the crop can withstand without a reduction in economical yields. A crop water stress index is determined from continuous canopy temperature monitoring using infrared thermometers from a few days after emergence to physiological maturity, coupled with microclimate variables, such as temperature and humidity.
Irmak and his colleagues also are improving models to separate evapotranspiration (ET) into evaporation and transpiration. By obtaining field measurements of stomatal conductance, researchers can develop a model to estimate transpiration. Such measures could be used to better analyze water use efficiency and other agricultural production indices. “We can do a pretty good job estimating or measuring soil moisture, rainfall or snowfall, but I think we have a long way to go to accurately quantify evapotranspiration,” Irmak said.
Irmak established the Nebraska Water and Energy Flux Measurement, Modeling and Research Network to measure ET for a variety of vegetative surfaces, including irrigated and rainfed crops and grasslands, crops under different conservation practices and invasive species. Twelve network instruments have been collecting data continuously throughout Nebraska for several years. One finding showed that disk-tilled fields averaged 7 percent higher ET rates than no-till fields during the past 18 months.