Derek M. Heeren
Date of this Version
Bhatti, S. (2018). Variable Rate Irrigation Using a Spatial Evapotranspiration Model With Remote Sensing Imagery and Soil Water Content Measurements. MS Thesis. University of Nebraska-Lincoln.
Variable rate irrigation may help in intensification of agriculture by producing more yield per unit inputs. Real time spatial information about water balance components is important for designing VRI prescription maps. This work involved use of a spatial evapotranspiration model for studying spatial variability in an agricultural field at the Eastern Nebraska Research and Extension Center near Mead, Nebraska. Imagery from unmanned aerial systems and Landsat were used as input for the spatial evapotranspiration model. Other inputs into the model were soil water content measurements from neutron probes, weather data, crop data, previous irrigation prescriptions, and soil properties for the field. The work included comparison of VRI treatments with uniform irrigation and rainfed treatments in terms of yield potential and reduced water withdrawal. Uniform irrigation methods included uniform irrigation managed using soil water content measurements from neutron probe and rainfed treatment. The model was updated and improved during the study period in attempt to more accurately model water balance components and manage VRI. Mean total prescribed irrigation depth was significantly larger for VRI using Landsat than uniform treatments for soybean in 2017. It was significantly lower for VRI using Landsat than other irrigated treatments for soybean in 2018. Maize yield in 2017 was significantly greater for VRI using Landsat and uniform treatments than the rainfed treatment. No other significant yield differences were observed in 2017 and 2018. Future research may focus on inclusion of thermal infrared UAS imagery, and an advanced method soil water content measurements in the model.
Advisor: Derek M. Heeren