Open AccessLeaching with Subsurface Drip Irrigation under Saline, Shallow Groundwater Conditions
Author(s) -
Hanson Blaine,
Hopmans Jan W.,
Šimůnek Jirka
Publication year - 2008
Publication title -
vadose zone journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.036
H-Index - 81
ISSN - 1539-1663
DOI - 10.2136/vzj2007.0053
Subject(s) - drip irrigation , leaching (pedology) , leaching model , soil salinity , environmental science , groundwater , soil salinity control , saline water , irrigation , water table , hydrology (agriculture) , salinity , surface irrigation , evapotranspiration , soil water , soil science , agronomy , geology , geotechnical engineering , ecology , oceanography , biology
One option for coping with the high soil salinity levels caused by saline, shallow groundwater conditions along the west side of the San Joaquin Valley is to convert from sprinkler or surface irrigation methods to drip irrigation. Experiments in commercial fields revealed that subsurface drip irrigation of processing tomato ( Lycopersicon esculentum Mill. var. esculentum ) is highly profitable under these conditions compared with other irrigation methods. The experiments also showed that little or no field‐wide leaching occurred, based on the conventional or water balance approach to estimating the leaching fraction (LF), yet soil salinity measurements showed considerable leaching around the drip lines. Actual LFs could not be calculated because LF, soil salinity, soil water content, and root density all varied with distance and depth around the drip lines. Therefore, we conducted a numerical modeling study using the HYDRUS‐2D computer simulation model to evaluate leaching with drip irrigation under saline, shallow groundwater conditions for different amounts of applied water, water table depths, and irrigation water salinity, described by the electrical conductivity of the irrigation water (EC iw ). Results showed that LF values ranged from 7.7 to 30.9% as applied water amounts increased from 60 to 115% of the potential evapotranspiration (ET pot ) for the EC iw = 0.3 dS m −1 irrigation water, even though the water balance method showed no leaching for applied water amounts equal to or smaller than ET pot The spatially varying soil wetting patterns that occur under drip irrigation caused the localized leaching, which was concentrated near the drip line.