Impacts of Land Use Changes on Selected Soil Physical and Chemical Characteristics under Pineapple Cropping Systems in Matara District, the Low Country Wet Zone of Sri Lanka

Abstract

The present paper investigated the impacts of land use change on physical and chemical characteristics of soil. A land, originally inhabited by native secondary forest, later converted to pineapple cultivation was selected for collection of representative soil samples from the 0-15 cm depth. A closely forest land was used as the reference. Soil texture, bulk density, aggregate stability, pH, total nitrogen, available soil P, exchangeable K and organic matter (OM) content were determined following standard methods. According to the results, significant variations in OM, soil pH, aggregate stability and available P were observed among forest and cultivated lands. The distribution of particle size revealed a decrease in larger particle size and an increase in smaller particle size following the conversion of natural forest to other land cover. Land use changes from forest to pineapple cultivation resulted in decreased aggregate stability, soil pH and organic matter content. The highest (17.3 mg kg-1) mean available P was recorded in the old pineapple land followed by forest land (15.0 mg kg-1) whilst the lowest in the new pineapple land (12.4 mg kg-1). However the values of bulk density, total nitrogen content and exchangeable K content of forest and cultivated lands were not significantly different (p ≤ 0.05). Based on the results, it can be concluded that regular monitoring of soil properties is essential to maintain soil health, enhance agricultural productivity and sustain agro-ecosystems