Soil Quality Assessment under Different Land Uses in Pokkali Lands of Kerala

Abstract

Pokkali lands represent waterlogged coastal saline areas of Ernakulam, Thrissur and Alappuzha district of Kerala characterized by a unique farming system named after the renowned saline tolerant rice cultivar “Pokkaliâ€. Rice cultivation followed by prawn farming is the predominant eco-friendly land use system practiced here traditionally by the farmers. The unsustainable monoculture of prawn has gained momentum recently and resulted in severe soil quality deterioration and ecological imbalance. Hence this study was undertaken to evaluate the soil quality of acid saline Pokkali soils under different land uses. Initial survey was conducted in Pokkali area and five panchayats were selected from Ernakulam district, Kerala in which all the land use systems under the study were covered. The land use systems were, i) rice alone ii) rice – prawn iii) prawn alone iv) fallow and v) mangroves. Surface soil samples were collected from the selected panchayaths representing five land use patterns and were characterized for physical, chemical and biological attributes. From these data, minimum data set which highly influenced the quality of the soil was selected. The highest soil quality index (4.92) was observed in rice- prawn land use system in Nayarambalam panchayat and least value (2.07) was observed in prawn alone land use pattern in Kottuvally panchayat. The observed soil quality index value was in the order, rice- prawn> rice alone> fallow> mangrove> prawn alone. Based on the relative soil quality index value, all land uses were categorized into three groups, i.e. poor, medium and good. Rice- prawn land use system in Nayarambalam panchayat was the only one land use system coming under the ‘good’ category.