Soil chemical quality in irrigated agricultural areas

Abstract

Soil quality assessment in irrigated perimeters of the northeast region of Brazil is required for correctly applying management practices. However, univariate statistical analyses often mislead the interpretation of results. This study was carried out in the Piauí irrigated perimeter in Sergipe state, and aimed to apply multivariate analysis to evaluate the effect of different land uses (passion fruit; pepper; passion fruit + pepper intercropping; and pasture) on soil chemical quality. Soil samples were collected from the 0-15, 15-30, and 30-45 cm layers. Soil chemical attributes such as pH, organic matter, CEC, sum of bases, percent base saturation, P, K+, Ca+2, Mg+2 and Na+ were determined. Multidimensional ordination analysis was used to group the soil chemical attributes according to their relative importance in each agricultural use. The results showed that cultivation of pepper alone or associated with passion fruit improved soil chemical quality, probably due to greater soil cover and higher fertilizer inputs. The use of multivariate analysis was efficient in separating soil use effects as a function of soil chemical attributes. For instance, the results showed that Ca, Mg, CEC, base saturation, OM and pH were responsible for improving the pepper and pepper + passion fruit cultivation areas. In addition, it showed that conventional cultivation and irrigation of passion fruit can increase soil salinity.