Soil Water and Salinity Distribution after Irrigation Under Different Farming Practices.

To better understand effects of farming practices on soil water and salinity distributions after irrigation, a field experiment was conducted with soil water content and salt concentrations measured before irrigation and 4 times after irrigation. Obtained data were applied to calibrate and validate HYDRUS-2D/3D to be used to simulate soil water and salt transport for different farming practices that included conventional tillage (T), tillage with plastic mulching (TM), ridge (R), and ridge with plastic mulching (RM). Results indicate that HYDRUS-2D/3D provides a powerful means to accurately simulate water and salt transport. Soil water and salt distributions were significantly affected by farming practices.  While T led to an increase of water storage capacity down to a depth of 40 cm when compared to R, R proved beneficial with regard to salt leaching. Plastic mulching before irrigation showed adverse effects on soil water storage and salt leaching but it reduced the amount of salt movement to the aquifer measured 10 days after irrigation by up to 20.3% (TM versus T) and 15.6% (RM versus R). In addition, plastic mulching reduced evaporation. Water use efficiency (WUE) and salt leaching efficiency (SLE) were determined to quantitatively evaluate the difference between farming practices.