Pedogenic influence on profile distribution of total and DTPA - extractable micronutrients in rice growing hydric soils of Majuli river island, Assam, India

The rice-growing river floodplain ecosystems of Majuli island, India, have been recognized as a biodiversity hotspot with a high degree of variability in geomorphological forms and geochemical conditions for trace metals in hydric soils. Ten hydric soil series in rice-growing soils of Majuli island were studied with the aim of understanding the pedogenic influence on distribution and content of total and diethylenetriamine penta acetic acid (DTPA) extractable micronutrient cations (Fe, Mn, Cu and Zn) and their enrichment levels. The correlation analysis showed that these cations were closely linked with soil texture, organic carbon, cation exchange capacity and pH levels. The multiple regressions and cluster analysis was employed to identify the effect of river fed deposits on distribution pattern and lithological enrichment of metals. The contamination status was assessed through quantitative indexes with reference material. The negative geo-accumulation index values were used to conclude that these soils had been practically unchanged by anthropogenic influences. They showed moderate Cu contamination but were otherwise unpolluted (Pollution load index < 1) with respect to total elements under study.