Impact of flood on soil quality of South Central laterites (AEU 9) of Kerala and mapping using GIS techniques

Abstract

A study was conducted to determine the soil quality and changes in the fertility status of soils after 2018 flood in Agro-ecological unit (AEU) 9 in Pathanamthitta district of Kerala and GIS maps were generated. A survey was conducted in the study area and seventy five geo referenced soil samples were collected from flood affected panchayaths. The samples were analysed for pH, organic carbon, N, P, K, Ca, Mg, S and micronutrients and GIS based thematic maps were prepared. The results of the study revealed that pH of soil falls into very strongly acidic, strongly acidic and moderately acidic categories after flood. Organic carbon and available K were increased and available P slightly decreased after the floods and widespread deficiency of available nitrogen were observed. Calcium and magnesium status also low in post flood soils. Among the micronutrients boron was highly deficient. The results outline the need for regular liming to control soil acidity and to alleviate Ca deficiency. The soils should be supplemented with Mg and B in addition to recommended dose of N, P and K fertilizers. Soil quality index of the post-flood soils of AEU 9 was calculated from eight parameters of minimum data set viz., organic carbon, bulk density, available K, available B, available S, sand percent and manganese. Majority of the soils had high soil quality index of more than 70.