Soil Water Balance Calculation Using a Two Source Energy Balance Model and Wireless Sensor Arrays Aboard a Center Pivot.

Recent developments in wireless sensor technology and remote sensing algorithms, coupled with increased use of center pivot irrigation systems, have removed several long standing barriers to adoption of remote sensing for real time irrigation management. One remote sensing based algorithm is a two source energy balance (TSEB) model, which only requires a single view of directional brightness temperature, routinely available meteorological variables, and basic crop phenology. The TSEB calculates the energy budget of the soil and canopy separately, providing calculation of evaporation (E), transpiration (T), and evapotranspiration (ET). The TSEB was tested where directional brightness temperature was measured by wireless sensor arrays aboard a center pivot, and ET was calculated and applied to a soil water balance. The calculated soil water balance was compared to that derived from direct measurements of the soil water profile using field-calibrated neutron probes. This application of the TSEB combined with wireless sensors may provide an operational method to calculate the soil water balance of center pivots, which could improve irrigation scheduling and thus crop water productivity.