Modeling a Sustainable Salt Tolerant Grass-Livestock Production System under Saline Conditions in the Western San Joaquin Valley of California

Máximo Alonso,John Maas,James Oster,Stephen Kaffka,Dennis Corwin

doi:10.3390/su5093839

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.

Highlights

The semi-arid western San Joaquin Valley (WSJV) has large areas with shallow, saline water tables that limit crop choice, reduce productivity, and has led to land idling or abandonment
The validated model was used to estimate the system’s performance under likely combinations of irrigation amounts and frequencies, irrigation water salinity, fertilization and stocking rates that could occur in the WSJV
Simulations with irrigation volumes of 80% ETc predicted 7,100 kg dry matter (DM)·ha−1, whereas irrigation volumes of 60% ETc yielded less than 6,500 kg DM·ha−1, at a fertilization rate of 300 kg N·ha−1

Summary

Introduction

The semi-arid western San Joaquin Valley (WSJV) has large areas with shallow, saline water tables that limit crop choice, reduce productivity, and has led to land idling or abandonment. The amount of land affected in this way is reported to vary up to 200,000 ha, depending on rainfall and irrigation water delivered to the region [1,2]. To farm this land sustainably, subsurface drainage is required. Current practices for the disposal of saline drainage water in the WSJV are not sustainable. Growers rely on natural drainage to create a positive salt balance in their fields [14,15]

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Conclusion