Submitted to: Sustainability
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/5/2013
Publication Date: 8/10/2013
Publication URL: http://www.ars.usda.gov/SP2UserFiles/Place/53102000/pdf_pubs/P2327.pdf
Citation: Alonso, M.F., Corwin, D.L., Oster, J.D., Maas, J., Kaffka, S.R. 2013. Modeling a sustainable salt tolerant grass-livestock production system under saline conditions in the western San Joaquin Valley of California. Sustainability. 5:3839-3857. Interpretive Summary: The reuse of drainage water on saline-sodic soils of California=s western San Joaquin Valley (WSJV) to produce forage has been proposed as a means of reducing drainage water volumes and reclaiming marginally productive soils. Modeling the growth and quality of forage (i.e., Bermuda grass) is a crucial aspect of assessing the viability and sustainability of this proposed degraded water reuse approach. The objective of this study was to predict the growth and quality of Bermuda grass under saline conditions as a means of estimating beef cattle stocking rates and potential daily weight gains. There is a reasonable fit of the model simulations to observed Bermuda grass yield and quality and beef cattle production for a 32.4-ha saline-sodic field in Kings County, CA located in the WSJV. Estimates indicate that it is possible to keep 1-1.2 beef cattle per ha with a weight gain of 1 kg each day, indicating the viability of the reuse of drainage water in the WSJV.
Technical Abstract: Salinity and trace mineral accumulation threaten the sustainability of crop production in many semi-arid parts of the world, including California’s western San Joaquin Valley (WSJV). We used data from a multi-year field-scale trial in Kings County and related container trials to simulate a forage-grazing system under saline conditions. The model uses rainfall and irrigation water amounts, irrigation water quality, soil, plant, and atmospheric variables to predict Bermuda grass (Cynodon dactylon (L.) Pers.) growth, quality, and use by cattle. Simulations based on field measurements and a related container study indicate that although soil chemical composition is affected by irrigation water quality, irrigation timing and frequency can be used to mitigate salt and trace mineral accumulation. Bermuda grass yields of up to 12 Mg dry matter (DM)·ha/1 were observed at the field site and predicted by the model. Forage yield and quality supports un-supplemented cattle stocking rates of 1.0 to 1.2 animal units (AU)·ha/1. However, a balance must be achieved between stocking rate, desired average daily gain, accumulation of salts in the soil profile, and potential pollution of ground water from drainage and leaching. Using available weather data, crop-specific parameter values and field scale measurements of soil salinity and nitrogen levels, the model can be used by farmers growing forages on saline soils elsewhere, to sustain forage and livestock production under similarly marginal conditions.