DRIP IRRIGATION AS A SUSTAINABLE PRACTICE UNDER SALINE SHALLOW GROUND WATER CONDITIONS

摘要

Subsurface drainage systems cannot be used for addressing the saline, shallow ground waterrnconditions of the San Joaquin Valley, California because no drainage water disposal facilitiesrnexist in the valley. Thus, the salinity/drainage problem of the valley must be addressed throughrnimproved irrigation practices such as converting to drip irrigation. Experiments in fourrncommercial fields evaluated the effect of subsurface drip irrigation on processing tomato yieldrnand quality, soil salinity, soil water content, and water table depth. The HYDRUS-2D computerrnsimulation model evaluated leaching with subsurface drip irrigation under saline, shallow groundrnwater conditions. Drip irrigation of processing tomatoes was highly profitable under thesernconditions compared to sprinkle irrigation. No trend in tomato yield was found with soil salinityrnlevels. A water balance showed little or no field-wide leaching in the commercial fields, yet soilrnsalinity data and computer modeling clearly showed localized leaching around the drip lines.