Structural characterization of soil biochar amendments and their comparative performance under moisture deficit regimes

Abstract

Biochar has a propitious role in the agricultural lands as a sustainable soil management and drought mitigation approach. The present research work aims at evaluating the structural characteristics of wheat straw, rice straw, sugarcane bagasse, and wood shaving biochar in clay loam and sandy loam soil at a rate of 0, 10, and 20 tons ha−1 and their comparative role for improving soybean growth, biomass water content, apparent water productivity, Zn, Mn, and Fe status under three moisture conditions (75%, 50%, and 40% of field capacity). Wood shaving and sugarcane bagasse biochar amendments in sandy loam soils caused favorable adjustments in the BET surface area, pore surface area, pore volume, pore radius, water-holding capacity, EC, and pH. However, in clay loam soil, there was traced a decline in BET (N2) surface area and other pore properties, while the highest soybean shoot and leaf fresh and dry biomass were recorded with 10 tons ha−1 wood biochar in both types of soils under optimum and moisture-deficit conditions. Apparent water productivity with 10 tons ha−1 wood biochar in soybean plants under 75%, 50%, and 40% moisture was 77%, 137%, and 157% higher, respectively, than that in control in the clay loam soil, while 153%, 149% and 135% higher, respectively, than that in control in the sandy loam soil. In both types of soils, soybean leaves with 10 tons ha−1 sugarcane bagasse biochar under all three moisture regimes had the highest Zn concentration. Under deficit moisture leaf, Mn concentration was found to be increased in wood biochar amendments and the highest Fe concentration was found with 20 tons ha−1 rice straw biochar amendments in both types of soils, while under 40% moisture with most biochar treatments, leaves had high Fe concentration.