Soil Quality Assessment in the Post-flood Scenario of South Central Laterites of Ernakulam District, Kerala, India

Abstract

Kerala was hit by a terrible flood in 2018, wreaking havoc on the agricultural economy and taking lives. The flood caused great damage to Ernakulam district, especially in Agro-Ecological Unit (AEU) 9 which comprises the South Central Laterites. The AEU 9 represents midland laterite terrain with typical laterite soils. An initial survey was conducted in the flood-affected areas and twelve panchayats were selected. Geo-referenced composite soil samples were collected from different panchayats and were characterized for physical, chemical and biological properties. Principal component analysis (PCA) was performed for 23 soil attributes which resulted in 7 principal components (PCs) and a minimum data set (MDS) was developed using selected indicators i.e., available calcium, available sulphur, available iron, available nitrogen, available zinc, available boron, bulk density, microbial biomass carbon and soil moisture. After the development of MDS, the soil indicators were converted to unit-less scores ranging from 0 to 1 using non-linear scoring function methods. The highest soil quality index was observed in Sreemoolanagaram (0.79) and the lowest in Karumaloor (0.55). Based on the relative soil quality index (RSQI) value different panchayats were categorized into three groups, i.e., poor, medium and good. The RSQI values of less than 50% are categorized as poor, 50-70% as medium and more than 70% as good. No panchayat in the flood-affected area was found to fall in the good category and 50% of the panchayats were found to have poor RSQI.