Unsaturated Zone Soil Water Modeling for Furrow and Drip Irrigated Field for Arid New Mexico.

Furrow or drip irrigation water that infiltrates and percolates below the crop rooting zone is important for groundwater recharge in agricultural zones with shallow aquifers. The objective of this study was to characterize soil moisture response to irrigation and to carry out a water balance analysis for the two irrigation systems. Two onion fields were instrumented to measure soil moisture, temperature and salinity. Soil samples were collected to characterize the soil physical properties such as texture, bulk density, saturated hydraulic conductivity, and soil moisture retention. These data were used to calculate velocity of propagation of the wetting front, water fluxes, evapotranspiration, percolation and water balance. Water transport was simulated after each of the six irrigation events using Hydrus-1d. Field-measured results showed relatively low levels of propagation of the wetting front, water flux and shallow groundwater response in the drip irrigated field. However, in the furrow irrigated field, higher values for wetting front propagation, water flux, and water level response were observed. Water balance analysis showed that drip irrigation system was better than the furrow system of irrigation for maintaining moisture and salinity levels. Additional modeling efforts are underway and results will be presented during the conference.