Abstract
A pot experiment was carried out in a vinyl house with treatments of three organic materials and one fertilizer to assess the biodynamics of microbial biomass nitrogen and sulfur in organic matter amended soils and their roles in the yield of wheat cv. Shatabdi. The organic materials were dustbin waste, poultry litter and rice straw. The organic materials were added at a rate of 2% of the soil. In the fertilizer treatment, nitrogen was applied at a rate of 200 μg N g-1 soil as NH4NO3 and sulfur was applied at a rate of 15 μg S g-1 soil as MgSO4.7H2O. A basal dressing of 150 μg P and 188 μg K g-1 soil as KH2PO4 and 10 μg Zn g-1 soil as ZnO was added to each pot. The crops were harvested 30, 60 and 128 days after sowing. The organic matter amended soils induced higher amounts of biomass-C formation than that of the fertilizer treated unplanted soils. Higher amounts of biomass-C, -N and -S were found in the planted soils from day 30 and onwards compared to the unplanted soils. The fertilizer contributed the highest amount of inorganic N, which was significantly higher than that of the dustbin waste and poultry litter. The dustbin waste induced the highest amount of SO4-S, which was significantly higher than that of the fertilizer treated and poultry litter amended soils. In the soil amended with rice straw, inorganic N and SO4-S rapidly decreased by day 5 due to N and S immobilization. At the time of harvest, the highest amount of shoot dry weight of 34.4 g pot-1 was observed in the soils treated with fertilizer, which was significantly higher than that of 24.69, 22.64 and 3.26 g pot-1 in the dustbin waste, poultry litter and rice straw amended soils, respectively. A positive correlation was observed between the decrease in biomass-N or -S, N or S uptake and dry matter (shoot) yield of wheat. The critical shoot N and S concentrations in the wheat were 1.46 and 0.138%, respectively.
