Soil Quality of a Semi-Arid Pasture Irrigated with Reverse Osmosis Wastewater—A Case Study from Northern New Mexico

Soil quality indicators were assessed in two adjacent fields in northern New Mexico near a reverse osmosis (RO) facility. One field has been cleared of native vegetation, sowed with a pasture mix and irrigated with saline RO wastewater (electrical conductivity (EC) of 2.73 dS/m) (WW) for two years. An adjacent field of non-irrigated, undisturbed native vegetation (NV) that received only natural rainfall was sampled for comparison and assumed to be representative of baseline values. Measurements included mean weight diameter, dry aggregates > 2 mm (D > 2 mm), dry aggregates < 0.25 mm (D < 0.25 mm), wet aggregate stability, permanganate oxidizable carbon, soil organic matter, EC, pH, sand, silt and clay contents, and chemical parameters. The wastewater irrigated field had more favorable soil quality indicators than the non-irrigated field, presumably due to the pasture mix and irrigation. However, the EC is higher in the WW irrigated field and will affect long-term utilization of the land for cropping, unless good soil salinity management is implemented.