Spatial and Temporal Variability of Soil Water Content in Leveled Fields.

Precision irrigation in time and space stands as a promising way of managing crop irrigation water in a more sustainable way. While precision irrigation is at its infancy stage, farmers and crop practitioners often doubt the existence of spatial variability of soil water content in leveled fields (slope of 1% or lower). The objectives of this study were to quantify the spatial and temporal variability of soil water content in leveled fields. Neutron probe readings were acquired at 5 depths over a whole crop growing season at two sites from north eastern Colorado. A total of 41 and 31 locations were monitored at site 1 and 2 respectively. Moran’s I and semivariograms were used to study the data. Results showed that up to 87% of measured soil water content locations across leveled fields can be in a different management class than the field’s average. In general, the spatial and temporal variability of soil water content observed in this study was conducive to the implementation of water management zones because it was variable in space with long spatial range, doubled with long temporal dependency.