Assessing salinity impacts on crop yield and economic returns in the Central Valley

Abstract

Salt accumulation in the root zone can impair crop yields and profitability. This study utilized a biophysical model to evaluate the economic and environmental impacts of groundwater salinity on the yields and profits for four crops (alfalfa, almonds, table grapes, and processing tomatoes) across California's Central Valley. The model analyzed five different levels of groundwater/irrigation water salinity, which ranged from 0.5 to 5.5 dS/m, with up to 12 mm/day of irrigation water for simulation. The results showed that the model's relative yield prediction was best for alfalfa, while the profits prediction was best for almonds. The study also found that an irrigation water salinity level of 5.5 dS/m could cause a decrease in the relative yield of almonds by up to 40%. The spatial component developed for the model indicated that yield and profits would vary based on soil type and water salinity across the Valley. At a daily irrigation rate of 3 mm, no profits were predicted. When the daily irrigation was increased to 6 mm/day, profits of up to $1000/ha were possible for alfalfa and processing tomatoes. Profits for almonds and grapes reached up to $15000/ha at 9 mm of daily irrigation. The study emphasized the importance of considering irrigation water quality in water allocation and trading decisions, as it significantly impacts crop profitability. The methodology developed in this study can be applied to other regions facing similar challenges of water scarcity and salinity.