Variability of Soil Quality Indicators In New Mexico Vineyards.

A study was conducted to assess the variability of selected soil quality indicators of vineyards in New Mexico. Three established vineyards located in Deming (6.7 ha), Las Cruces (0.9 ha) and Alamogordo (3.8 ha), NM were selected for this study. Twenty five geo-referenced soil samples were collected at depth (0-0.3 m) from each sampling site to assess the variable nature of different soil measurements. Soil measurements from collected samples included soil organic matter, soil nitrate-nitrogen content, Olsen phosphorus, ammonium acetate extractable potassium, calcium, magnesium, sulfur, pH in 1:1 soil/water slurry, soluble salts, cation exchange capacity and micronutrients (manganese, boron, copper, iron and zinc). Variability in measurements was analyzed using the coefficient of variation (CV) and was classified as follows: CV of < 15%: least variable; CV of 15–35%: Moderately variable; and CV of > 35%: highly variable. The CV for individual indicators depended on the measured variable and location. The CV of vineyard measurements in Deming varied from 1.7% - 56.5%, in Alamogordo from 2.7%-105.5%, and in Las Cruces from 2.5% - 75%. Measurements were generally least variable at the Deming site, while they were most variable at the Alamogordo site. Measurements showing high levels of variation across sites included nitrate-nitrogen, sulfur and manganese concentrations. Indicators exhibiting low levels of variability across sites included soil organic matter, soil pH, extractable potassium and boron concentration. Soluble salt was highly variable at the Alamogordo site with a range of measurement between 1.2 and 19.2 dS/m. A map of the soluble salts in Alamogordo showed distinct parts of the vineyard having high soluble salts compared to the rest of the field. The high degree of variability of some of the measured soil quality indicators may justify the division of vineyards into distinct zones for soil sampling, in order to enable adequate management practices that are based on soil test results.