Journal of Global Agriculture and Ecology

This study evaluates soil fertility and nutrient dynamics in two contrasting tropical wetlands of Kerala, India - Ashtamudi (estuarine) and Kuttanad (below–sea-level), with emphasis on agricultural implications. Surface soil samples were analysed for pH, electrical conductivity, organic carbon, and available nitrogen, phosphorus, and potassium using standard methods. Descriptive statistics, independent samples t-test, Pearson correlation, principal component analysis, and nutrient index values were applied to identify dominant fertility patterns and controlling factors.

Soils of both wetlands were acidic, but Ashtamudi soils exhibited significantly higher electrical conductivity and greater spatial variability in nutrient concentrations, reflecting estuarine influence. Kuttanad soils were more uniformly acidic due to prolonged flooding. Correlation and PCA results showed that organic carbon strongly controlled nitrogen and potassium availability, while phosphorus availability was closely linked to soil pH. Nutrient index analysis revealed low nitrogen but high phosphorus status in Ashtamudi soils, whereas Kuttanad soils showed relatively balanced nutrient status under acidity constraints. The findings indicate that wetland soils are agriculturally differentiated mainly by salinity and acidity regimes rather than absolute nutrient levels. Site-specific nutrient and soil acidity management is therefore essential for sustainable wetland agriculture.