Author(s):

Akhila Nand Dubey and Priyankar Raha

Abstract: Nitrogen leaching is major problem resulted to low fertilizer use efficiency. Humic acids (HAs) are proposed as a chelating / complexing agent to minimize these losses. The aim of the work was to evaluate the effect of different type of humic acids on ammonical nitrogen vertical movement from the Gangetic alluvial soil. A vertical soil column leaching experiment was carried out in the laboratory with seven different treatments of three different layers (yellow, brown and black) of lignite coal originated and purified humic / fluvic acid [i.e. 0.0 (H₀), 10 (HY₁), 20 (HY₂), 10 (HB₁), 20 (HB₂), 10 (HK₁) and 20 (HK₂) mg HA 500g^-1 soil] in soil. The vertical soil column studies were carried by spiking the ammonium chloride solution through (2000 mg NH₄⁺) on the top of the saturated soil columns followed by constant water head flow at definite time interval (1,2,3,4,5,6,10 & 24 hours). It was observed that the amount of leachates and ammonical concentration from humic / fulvic acid treated soil was comparatively low in which addition of black humic acid (10 & 20 mg) followed by brown humic acids as compared to control. In addition, the break through curve (BTC) of NH₄⁺ leaching through different soil columns were drawn with respect to relative concentration (C₀/C₁) of NH₄⁺ leachate against the pore volume (Pv) of the soil columns within the period (1 to 24 hours) of leaching. The chelation / complexation of nitrogen in the form of NH₄⁺ by humic substances (containing –carboxyl & phenolic hydroxyl group on surface) originated from lignite coal was the basic cause of the diminishing ammonical nitrogen vertical movement through soil column.

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