Response of Spring Wheat to Varied Nitrogen and Water Applications.

Water and nitrogen (N) are two key production inputs in most wheat cropping systems. 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. The proposed study aims to demonstrate that sensor-based technologies, utilized in combination with traditional practices such as soil testing and evapotranspiration (ET) monitoring, can substantially improve the management of N and water. Field studies were initiated in Idaho and Montana. Experimental plots were arranged in a split-plot design with 4 replications: four N levels (112, 168, 224, and 280 kg N ha^-1) and four water regimes (100%, 75%, 50% and 0% ET). Spring wheat (var. Alturas) was planted in March 2016 at 168 kg seed ha^-1. Irrigation was applied via subsurface drip system. Several crop physiological parameters including plant height, leaf area index, chlorophyll content, canopy spectral reflectance, above ground biomass, N uptake, water and N use efficiency and grain yield and quality was measured at early tillering, late tillering and anthesis. The project incorporates research and education focused on: 1) conducting field studies for determining the minimum N and water requirements for optimum wheat grain yield and quality, 2) developing a sensor-based system for identifying and distinguishing between N and water stresses, 3) developing an empirical model for predicting wheat yield and protein content in varying water × N interactions, 4) developing water and N use recommendations for growers based on the developed model, and 5) delivering extensive educational outreach focused on water and nutrient conservation and utilization of sensor-based technologies.