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Submitted to: Meeting Abstract
Publication Type: Abstract Only Publication Acceptance Date: 10/2/2006 Publication Date: 10/29/2006 Citation: Suarez, D.L. 2006. Soil salinity and farming sustainability related to crop yield and quality. Meeting Abstract. Opportunities and Challenges in Agricultural Water Reuse, Santa Rosa, CA October 29-31, 2006. Interpretive Summary: Technical Abstract: Increasing demands on our fresh water supplies means that irrigated agriculture will need to reuse drainage water and treated municipal and industrial waste waters for irrigation. These waters are invariably higher in salinity than the initial fresh waters, with the added salinity often being primarily sodium and chloride. The waters generally contain increased levels of alkalinity (thus elevated pH) and often contain elevated concentrations of minor elements such as boron that may adversely affect crop growth. Existing water quality guidelines were developed to avoid infiltration problems and potential yield loss under all circumstances, thus they are useful to delineate potential problems but are overly restrictive in many instances. Despite limitations, proper crop selection and management practices enable beneficial reuse of these waters with minimal reduction in yield. Where winter rains and leaching occur, soil salinity is reduced during the early stages of crop growth, which are generally the most salt sensitive stages. Advances in knowledge of plant salt response suggests that increased salt tolerance can be developed for salt sensitive and moderately salt tolerant crops such as rice and tomatoes, and that high quality forage can be grown with saline water. Traditional plant breeding and molecular techniques are particularly promising where yield reduction is related to specific ion toxicity to sodium and chloride. Crop selection should be based on profitability rather than relative yield loss. Because salt tolerant crops are generally lower value crops, and often lower yielding crops, it should not be assumed that they are optimal for irrigation with moderately saline waters. Despite some yield loss moderately salt tolerant crops such as alfalfa may out-produce more salt tolerant crops such as wheatgrass at salinities up to 15 dS/m. Additional benefits of moderate salt stress to crops may be increased product quality. Many plants adapt to salt stress by enhanced accumulation of secondary metabolites such as soluble solids, sugars, organic acids, and proteins, thus increasing quality and marketability. For example salinity stress increases sugar and dissolved solids content of tomatoes and melons, increases content of beneficial antioxidant compounds in strawberries and increases oil and particularly the desired lesquerolic acid in lesquerella. Sustainable reuse of these waters will require careful monitoring of field conditions. New remote sensing technology can be used to provide rapid and inexpensive detailed field salinity assessments and evaluate the need for amendments. Reuse of these waters provides not only beneficial utilization, substituting for high quality waters, but also minimizes the environmental impact associated with direct discharge of waste waters. |
