Geoestatística aplicada ao estudo da caracterização de atributos químicos do solo quanto à salinidade.

Abstract

The objective of this work was to study the spatial variability of the Electrical Conductivity of the saturation extract (EC), Sodium Absorption Relation (SAR) and Exchangeable Sodium Percentage (ESP) in an alluvial soil affected by salts. The soil samples were collected in an area of 134 ha in the Project of the Sume Irrigated Perimeter, at 0-15; 15-30; 30-60 and 60-90 cm depth intervals in a systematic grid sampling of 250x250 m, with a total of 51 sample points. The data was treated and analyzed by classical and geostatistic procedures. High variability for EC (CV= 185.4%), SAR (CV- 141.49%) and ESP (CV = 118.49%) was observed through the classical statistic. Through the semivariograms, obtained by the geostatistic analyzes, it was found that all the variables studied showed high variability at all depth intervals and also that the variability for the EC was the highest followed by the SAR and ESP. The EC of the 0-15cm depth interval has a moderated spatial dependence. For the other intervals it was weak. For the SAR, the spatial dependence was weak for all the depth intervals studied. The variability of the Exchangeable Sodium Percentage was weak for the two first intervals (0-15 and 15-30cm) and moderated for the last two ones (30-60 and 60- 90cm). Al the variables showed spatial dependence ranges, which could be used in the future for the management of the salt affected soils.