Field scale comparative study on application of DAP, Urea and Humic acid on soil flora and crop productivity

Abstract

Humus is a generic term describing humic substances, which comprises of three distinct groups, namely: humic acid, fulvic acid and humin. Plant growth and health is positively influenced by an increase in the soil humus levels. A study on the effect of conventional chemical fertilizers viz. urea and diammonium phosphate (DAP) were compared with humic acid (HA), for the cultivation of Triticum aestivum and Zea mays, in a field of Junagadh District of Gujarat State. Compared to the DAP and urea treatment, HA treatment was found to increase the soil Rhizobium, phosphate solubilizing bacteria (PSB) and Azotobacter populations by 1.6, 2.0 and 2.3 folds. The soil treated with chemical fertilizers showed a marginal increase in the pH and electrical conductivity as compared to effect of HA. Soils treated with HA showed an increased moisture content as compared to the soil treated with DAP and urea; whereas the electrical conductivity was found to increase in DAP + urea treatment while HA treated soils showed a decrease in the electrical conductivity. Humic acid treatment was found to improve the soil bacterial flora, total nitrogen and total organic carbon content of the soil and thereby influences plant growth, fruit yield, decreases the need of conventional fertilizer, decreases the cost of crop productivity; thus making its use economically more feasible for the farmers.