Association between Physical Quality and Chemical Fertility of Lateritic Soils under Dry Dipterocarp Forest and Cultivation

Abstract

ABSTRACT Physical quality and chemical fertility of lateritic soils under different types of land use were assessed and tested for their relationship. Six land-use types that have been continuously applied to similar lateritic soils (Plinthic Paleustults) were included in this study. These types of land use are (1) dry dipterocarp forest, (2) 6-year sugarcane, (3) and (4) 6-year rotating forage/sugarcane, (5) 6-year rubber plantation, and (6) 6-year mixed legume-maize cropping. The soil water retention curves and available water capacity were determined as well as S-index, a single indicator of soil physical quality, was estimated by using the parameters of the van Genuchten equation. Relevant fertility parameters were also analyzed to evaluate the fertility level. The results showed that all selected types of land use influenced the physical status and chemical fertility of lateritic soils. Dry dipterocarp forest and rubber plantation enhanced the S-index of 0.044 and 0.047, respectively, which were higher than those soils influenced by other agricultural practices (0.034–0.039). The good physical quality, as indicated by S-index, is significantly correlated (p < 0.05) with increasing available potassium and positively correlated with available phosphorus, base saturation percentage, and available water capacity. Our results imply that S-index is a useful indicator of soil physical quality associated with chemical fertility for Thai lateritic soils.