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Title: Short-term sustainability of drainage water reuse: Spatio-temporal impacts on soil chemical properties

Author
item Corwin, Dennis
item LESCH, SCOTT - UNIV CALIFORNIA RIVERSIDE
item OSTER, JAMES - UNIV CALIFORNIA RIVERSIDE
item KAFFKA, STEPHEN - UNIV CALIFORNIA DAVIS

Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/10/2007
Publication Date: 8/1/2008
Citation: Corwin, D.L., Lesch, S.M., Oster, J.D., Kaffka, S.R. 2008. Short-term sustainability of drainage water reuse: Spatio-temporal impacts on soil chemical properties. Journal of Environmental Quality. 37:S8-S24.

Interpretive Summary: Greater urban demand for finite water resources, increased frequency of drought resulting from erratic weather, and increased pressure to reduce drainage water volumes have intensified the need for drainage water reuse in arid and semi-arid agricultural areas. Drainage water reuse would be particularly useful on the west side of California’s San Joaquin Valley (WSJV) where no drainage water disposal outlet exists. To dispose of drainage water evaporation ponds are used, which could remove as much as 34,000 ha of land from productivity in the WSJV. A 10-year study has been developed to determine if the quality and productivity of forage grown on previously low-productivity, saline-sodic soils of the WSJV can be maintained at sufficiently high levels to be sustainable when irrigated with drainage water. A preliminary short-term (5 yr) evaluation is made of the sustainability of drainage water reuse from the perspective of the impact on soil chemical properties crucial to the soil’s intended use of producing forage for livestock. Results of the preliminary evaluation are very positive. Drainage water reuse is shown to not only reduce drainage volumes thereby mitigating the need for non-productive evaporation ponds, but an alternative water resource asset becomes available that can be used to economic advantage by reclaiming non-productive saline-sodic soils and bringing them back into agricultural production. Even though the extrapolation of short-term results points to a positive prognosis, the long-term sustainability (i.e., 10 years or more) of drainage water reuse in California’s Central Valley needs to be evaluated because of the potential for the slow accumulation of detrimental trace elements (i.e., molybdenum and selenium).

Technical Abstract: Greater urban demand for finite water resources, increased frequency of drought resulting from erratic weather, and increased pressure to reduce drainage water volumes have intensified the scrutiny of water used for irrigated agriculture in arid zones throughout the world. A study was initiated in 1999 on a 32.4-ha saline-sodic field (Lethent clay loam series; fine, montmorillonitic, thermic, Typic Natrargid) located on the west side of California’s San Joaquin Valley (WSJV) with the objective of evaluating the sustainability of drainage water reuse from the perspective of impact on soil quality. A preliminary 5-year evaluation is presented. Geo-referenced measurements of apparent soil electrical conductivity (ECa) were used to direct soil sampling at 40 sites to characterize the spatial variability of soil properties (i.e., salinity, Se, Na, B, and Mo) crucial to the soil’s intended use of growing Bermuda grass (Cynodon dactylon (l.) Pers.) for livestock consumption. Soil samples were taken at 0.3-m increments to a depth of 1.2 m at each site in August 1999, April 2002, and November 2004. Drainage water varying in salinity from 3–5 dS m-1 has been applied to the field. An analysis of the general temporal trend shows that overall soil quality has improved with leaching of B from the top 0.6 m of soil; salinity and sodium from the top 1.2 m, but primarily from 0–0.6 m; and Mo from the top 1.2 m. Short-term sustainability of drainage water reuse is supported by the results. However, since April 2002 Se has started to accumulate and Mo has reappeared in the surface soil indicating that continued monitoring is essential to evaluate the long-term sustainability of drainage water reuse in the WSJV.