Assessment of Soil Quality and Nutrient index in Agroecological Unit 7 of Kerala and Mapping Using GIS

Abstract

Aims: Soil quality assessment is valuable for agricultural production. In this study, 150 soil samples at 0-15 and 15-30 cm depths were collected from Kaipad land (Agroecological unit 7) of Kerala to assess the quality and nutrient index. Study Design: Survey, collection of sample and principal component analysis. Place and Duration of Study: Department of Soil Science and Agricultural Chemistry, College of Agriculture, Vellayani between 2020 and 2021. Methodology: Soil samples were collected from AEU 7 and analyzed for physical, chemical and biological indicators for evaluating soil quality. Principal component analysis (PCA) was carried out with 13 soil parameters which resulted in 6 principal components and a minimum data set (MDS) of nine parameters (pH, EC, organic carbon, available N, Mg, K, B, P and Zn) with eigen values greater than 1, which were used for computing soil quality index. Nutrient index was computed for organic carbon, available N, P and K. Thematic maps on SQI and NI were prepared using geographical information system (GIS). Results: The results revealed that the Kaipad soils (AEU 9) are sandy clay loam in texture, extreme to strong acid condition (pH 3.5- 5.0), high in organic carbon, low in available N and K, medium in available P, deficient in available Ca, Mg and B. Majority (88%) of the soils are rated medium in soil quality. Relative soil quality index ranged between 47.5 and 76.3 per cent in the Kaipad soils with a mean of 61.0 per cent. Conclusion: The soils of Kaipad (AEU 7) under different agricultural land uses experiences various constraints to crop production like extremely acidic pH, high electrical conductivity, . nutrient deficiencies of N, K, Ca, Mg, B and toxicities of Fe and Al. Examining the relationships of soil parameters by principal component analysis indicated that nine soil parameters such as pH, EC, organic carbon, available N, Mg, K, P, Zn and B have significantly contributed to soil quality index, which are the important key indicators of soil quality. The soil quality index was medium for Kaipad soil. Nutrient index was high for organic carbon, low for available N, medium for available P and low for available K.