| To address variability in crop yield caused by the soil moisture status, the soil hydraulic and physical properties must be quantified at geo-referenced locations and mapped. The variability map can also help in the development of soil management practices that might reduce leaching of essential plant nutrients, minimize potential ground and surface water contamination, and soil degradation.; An infiltration model was developed and used to estimate infiltration rates at geo-referenced locations within the field based on the volume balance technique, using flow rate into a furrow, flow cross sectional area, and the water front advance time along a furrow. Daily soil moisture tension and equivalent daily volumetric soil moisture content of the soil, in a referenced soil profile consisting of three layers, were used to estimate the daily moisture depletion in the layered soil profile. Evapotranspiration (ETc) was estimated from infiltration depth and daily depletion of measured soil moisture profile at geo-referenced locations.; Variability in soil hydraulic conductivity (coefficient of variation = 151%), initial infiltration rate (coefficient of variation = 89%), final infiltration rate (coefficient of variation = 70%), ETc for the duration of the study (coefficient of variation = 84%), daily ETc (coefficient of variation = 63%), were found for the field. Yield (coefficient of variation = 12%), and the soil compaction level (coefficient of variation = 7–22%) were also, found be variable in the field. High correlation exited between yield and hydraulic conductivity (coefficient of determination, R2, = 0.79); initial infiltration rate (coefficient of determination, R2, = 0.83), final infiltration rate (coefficient of determination, R2, = 0.92), daily ETc (coefficient of determination, R2, = 0.98), TCI (coefficient of determination, R2, = 0.86), SCP (coefficient of determination, R2, = 0.90), and bulk density (coefficient of determination, R2, = 0.97) in the field.; A power function was found to best describe the quantitative relationship between saturated hydraulic conductivity and force measured by the TCI and SCP whilst a linear function best described its relationship with bulk density.; Extensive field tests were conducted on a 20-acre furrow-irrigated plot planted to processing tomato to quantify and map variability in crop yield, soil hydraulic conductivity, infiltration rate, crop evaportranspiration (ET c), soil compaction level measured by TCI, SCP and bulk density. (Abstract shortened by UMI.)... |
