Using Canopy Temperature Sensing for Site-Specific Irrigation Management.

Water resources for crop production in semi-arid regions are limited, yet irrigated agriculture in these areas is critical to maintain farm profitability. Continuous canopy temperature monitoring with infrared thermometers (IRTs) mounted on a variable irrigation rate GPS guided sprinkler irrigation system and coupled with meteorological data can be used to monitor crop water status at the field scale level. ARS scientists at Bushland, Texas are using georeferenced maps of an integrated crop water stress index (CWSI) summed over daylight hours and pre-established CWSI thresholds to build prescriptions for site-specific irrigation management. Using the integrated CWSI as a plant feedback method for automated site-specific irrigation scheduling has resulted in favorable lint and grain yields and water use efficiencies (economic yield/evapotranspiration) for cotton and grain crops at well-watered to mild-stress levels. These responses were similar to yields and water use efficiencies produced with manual irrigation scheduling using weekly neutron probe readings and replenishing soil water depletion to field capacity. Plant feedback systems that continuously monitor crop water status provide indirect but timely information on soil water availability and predictability of yield.