Soil Health Assessment of Three Semi-Arid Soil Textures in an Arizona Vineyard Irrigated with Reclaimed Municipal Water

The depletion of freshwater supply is occurring at a faster rate than it is being replenished. The agriculture sector is the largest consumer of freshwater for irrigation and production-related processes. The use of reclaimed municipal water for the irrigation of crops offers a sustainable alternative solution for reducing the dependence of agriculture on freshwater. However, the long-term and continuous use of reclaimed water may contribute to soil salinity and sodicity limitations in agriculture production. The chemical and microbial properties of three different soil textures (all Alluvial soil with 60% clay: pH 8.6; 30% clay: pH 8.2; and 20% clay: pH 7.9) were evaluated in a vineyard irrigated using reclaimed water (126 mg/L Na⁺, 154 mg/L Cl⁻, 7.6 water pH, and 1.2 dS/m EC_w). The results indicate that the reclaimed irrigation water significantly (p < 0.05) increased the pH (by 0.4 to 18%), nitrate-N (over 100%), electrical conductivity (EC) (over 100%), and sodium absorption ratio (SAR) in these arid soils. A significant decline in microbial respiration (48 to 80%) was also documented in the three different soil textures that received reclaimed water. Although using reclaimed water for crop irrigation may be a substitute for using limited freshwater resources and offer a partial solution to increasing water security for wine grape production, the development of innovative technologies is needed for the long-term use of reclaimed water to counter its undesirable effects on soil quality.