Effects of Humic Acid and Crop Residues on Soil and Wheat Nitrogen Contents

This study was conducted with the aim of finding humic acid and crop residues effects on soil and wheat nitrogen at New Development Farm, University of Agriculture, Peshawar, Pakistan during winter 2009-2010. The experiment was laid out in RCB design having four replications. Different levels (1, 1.5, 2 and 2.5 kg ha-1) of Humic acid were applied at sowing time. Mungbean (5 tons ha-1), wheat straw (10 tons ha-1) and mungbean (2.5 tons ha-1) + wheat straw (5 tons ha-1) were incorporated 30 days before sowing. Our results showed higher mineral and total nitrogen (7.32 and 0.43, respectively) mg kg-1 in soil and also higher nitrogen in stem, leaves and grains (2.3, 4.6 and 21.1, respectively) mg kg-1 at maturity in those plots in which 2.5 kg ha-1 of humic acid was applied. Higher mineral and total nitrogen (7.04 and 0.5, respectively) mg kg-1 in soil and also higher nitrogen in leaves (5.5) mg kg-1 at pre-anthesis, while at maturity stage in stem, leaves and grain (5.5, 2.1, 4.2 and 20.8) g kg-1 was recorded in those plots in which 5 tons ha-1 mung bean was incorporated. Our experimental results suggest the use of 5 tons ha-1 of mungbean residues with 2.5 kg ha-1 of humic acid to improve soil fertility availability of more nitrogen in wheat plants to increase the crop yield and grains quality.