Developing Efficient Deficit Irrigation and Nutrient Management Strategies for Spring Wheat Grown in Southeastern Idaho, USA.

Sustainability of wheat production in semi-arid regions of the Western U.S. is threatened by limited water availability and inefficient use of irrigation water and fertilizers. Consequently, there is an urgent need to develop more efficient deficit irrigation and nutrient management strategies that would optimize cost, yield, quality, and efforts for wheat production in this region. An ongoing field work study is being conducted in Idaho and Montana to i) determine the minimum N and water requirements for optimum wheat grain yield and quality, ii) develop a sensor-based system for identifying and distinguishing between N and water stresses, and iii) develop an empirical model for predicting wheat yield and protein content in varying water × N interactions. Experimental plots are arranged in a split-plot design with 4 replications, four N levels (56, 112, 170, and 225 kg N/hec) and four water regimes (100%, 75%, 50% and 0% evapotranspiration (ET)). Spring wheat was planted early April with row spacing of 30 cm. Irrigation is applied through surface drip systems where water amounts for different irrigation treatments is controlled by varying irrigation duration. Soil volumetric water content is measured in each plot prior to –and after each irrigation application at 30 cm depth intervals. Several crop physiological parameters including plant height, leaf area index, canopy temperature, chlorophyll content, canopy spectral reflectance, biomass weight, N uptake, water and N use efficiency and grain yield and quality will be measured at early tillering, late tillering and anthesis growing stages. Besides preventing environmental degradation, the results of this study will enhance our knowledge about efficient N and water management practices in terms of agronomic advantages (improved grain yield and quality), economic benefits (reduced fertilizer use and improved water savings) and socio-economic benefits (improved awareness through education, and enhanced confidence in effective resource stewardship).