Author
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Ayars, James |
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Submitted to: Journal of Crop Production
Publication Type: Book / Chapter Publication Acceptance Date: 6/1/2003 Publication Date: 7/1/2003 Citation: Ayars, J.E. 2003. Field crop production in areas with saline soils and shallow saline ground water in the san joaquin valley of california.. Journal of Crop Production. Vol. 7, No 1/2: pg 353-386. Interpretive Summary: Soil and water salinity are irrevocably associated with irrigated agriculture throughout the world. Origins of salt include naturally occurring geological deposits in the soil, accumulations from applied irrigation water, and from applied fertilizer. As soil salinity increases, plant growth and development is adversely affected until production is impossible. The despite salinity problems the west side of the San Joaquin Valley is one of the most productive agricultural areas in California. Sustaining current levels of productivity will be possible only if the drainage water disposal problem is solved. This chapter discusses the techniques available for managing irrigation in saline soils in the presence of shallow ground water. Two studies are discussed which demonstrate methods necessary for the long term sustainability of agriculture in a saline environment. The first project demonstrated the cyclic use of saline water and good quality water for irrigation when drainage was possible with a subsurface drainage systems. This resulted in no yield losses in both cotton and sugar beet. Results from the second project demonstrated the use of improved surface irrigation system, subsurface drip irrigation, and improved irrigation scheduling to increase use of shallow ground water by the crop to sustain agriculture in areas without drainage. The second experiment irrigation used only good quality water and salinity management was achieved during fallow periods with pre-plant irrigation and rainfall. The combination of lateral drainage and crop water use from shallow ground maintained the average water table depth below approximately 1.1 m. The use of pre-plant irrigation in fallow periods is a common practice in the San Joaquin Valley and careful management of pre-plant irrigation and the first seasonal irrigation are critical to preventing waterlogging. Technical Abstract: Salinity in soil and water is irrevocably associated with irrigated agriculture throughout the world and as a result requires that salt management becomes an integral part of the production system. With careful water management it is possible to sustain irrigated agriculture in areas with saline soil and saline ground water with and with out subsurface drainage. The results from two field projects conducted in an area with saline soils and saline ground water demonstrated the irrigation systems and management needed to sustain production of moderately salt tolerant and tolerant crops. The first study at Murrieta farms yields of cotton and sugar beets were maintained using both saline and non-saline water for irrigation when pre-plant irrigation and rainfall were adequate to maintain soil salinity. Wheat production was reduced in areas which used saline water for irrigation. Use of saline water containing toxic elements such as boron for irrigation pose a threat to the sustainability of the system. The second study evaluated the management of furrow and subsurface drip irrigation in the presence of shallow saline ground water. Careful management of the furrow system during pre-plant irrigation and the first irrigation of the growing season was required to prevent waterlogging. It was possible to manage the subsurface drip system to induce significant crop water used from shallow ground water. Rainfall and pre-plant irrigation were adequate at this site to manage soil salinity. |
