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

Abstract

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.

Pedogenical Distribution of some Micronutrients in Prevailing Sub Great Soil Group in Iraq

“…𝑌(𝑃1) = 39.31 + 0.13𝑋 𝑌(𝑃2) = 70.01 + 0.03𝑋 𝑌(𝑃3) = 21.59 + 0.03𝑋 𝑌(𝑃4) = 27.12 − 0.03𝑋 𝑌(𝑃5) = 80.42 − 0.14𝑋 𝑌(𝑃6) = 78.55 − 0.05𝑋 𝑌(𝑃7) = 74.18 − 0.01𝑋 𝑌(𝑃8) = 70.81 + 0.05𝑋 The soil content of total iron ranged between 2.41 and 4.91% with a significant difference in the distribution of the weighted averaged for this element, the lowest content was recorded at Pedon P3 reached 2.47%, whereas the highest content was recorded at Pedon P6 site reached 4.77%, with a clear correlation of this element content with the soil content of clay, these results were compatible with what was observed by Bhaskar et al (2017). The following equations illustrate the total iron content distribution with depth in the studied soils: 𝑌(𝑃1) = 3.01 + 0.002𝑋 𝑌(𝑃2) = 2.76 + 0.014𝑋 𝑌(𝑃3) = 2.46 + 0.0002𝑋 𝑌(𝑃4) = 2.77 + 0.006𝑋 𝑌(𝑃5) = 3.88 − 0.012𝑋 𝑌(𝑃6) = 2.38 − 0.255𝑋 𝑌(𝑃7) = 4.69 − 0.0002𝑋 𝑌(𝑃8) = 2.87 + 0.009𝑋 The bioavailable content of micronutrients in the studied soils Table (3) shows that the available manganese content ranged between lowest content of 2.6mgKg -1 at Bk horizon for Ramadi pedon (Typic Calciorthids) and the highest content of 15.8mgKg -1 at Cw1 horizon in Delmj marsh pedon (Aquollic Salorthids), with significant differences in this element's weighted average content between selected pedons for the study.…”

“…The analysis of 5673 soil samples collected across the Haryana state showed a wide variability in status of available micronutrient deficiency in soils. Bhaskar et al (2017) studied soil series in rice-growing soils of Majuli island, to understanding the pedogenic influence on distribution and content of total and bioavailable (Fe, Mn, Cu and Zn) and their enrichment levels. The correlation analysis showed that these elements were closely linked with soil texture, organic carbon, cation exchange capacity and pH levels.…”