Soil quality indicator response to tillage and residue management on semi-arid Mediterranean cropland

No-tillage (NT) practices for raided cereal production in semi-and Mediterranean soils can conserve water and increase crop productivity, but producers are reluctant to adopt NT because of potential increases in penetration resistance and bulk density. We hypothesized that understanding soil quality could encourage NT adoption, but methods for selecting and assessing soil quality indicators needed to be developed for this region Our objectives were to (1) identify the most sensitive indicators for evaluating long-term tillage and residue management within this region using factor analysis, and (2) compare soil quality assessment using those indicators with traditional evaluations using changes in water retention, earthworm activity and organic matter stratification ratio Several soil physical, chemical, and biological indicators were measured within conventional tillage, minimum tillage, and NT (with and without stubble burning) treatments that represent a wide agro-climatic area in NE Spain. Sampling depth and management treatments significantly affected several indicators when evaluated individually and collectively Principal component analysis identified three factors that accounted for 75 and 85% of the variation in soil measurements for 0-5- and 5-15-cm depth increments Only two factors per depth showed significant differences among the four treatments. For both depth Increments, one factor grouped soil physical attributes, and the other organic matter and biological properties. The indicators with the greatest loadings were identified as the most sensitive in each factor. These were penetration resistance, particulate organic matter (POM) and total organic matter within the 0-5 cm layer, and aggregate stability and POM within the 5-15-cm increment. Factor scores were positively correlated to soil water retention, earthworm activity and organic matter stratification, which were all greater in NT, regardless of stubble management We conclude that (1) multivariate analyses are useful for selecting appropriate soil quality indicators, and (2) that adopting NT on Mediterranean semi-arid cropland can have several positive effects on soil quality within this region (C) 2010 Elsevier B.V All rights reserved