consequences of different management of barley (hordeum vulgare l.) residue on microbial biomass carbon, organic carbon and total nitrogen indices in soil

.soil microorganisms are important agents in nutrient cycling and energy flow. they are extremely sensitive to environmental changes. soil microbial biomass has been proposed as an index of soil stress and disturbance. the objective of this study was to determine the effects of barley (hordeum vulgare l.) residue amounts, burning, nitrogen fertilizer levels and tillage management on organic carbon, total nitrogen and microbial biomass carbon, after 90 days. the experiment was carried out based on a completely randomized design with a factorial arrangement with two replications. the treatments included two levels of barley residues (3 and 6 t.ha-1), burning (without and with stubble burning), urea fertilizer (0 and 125 kg.ha-1) and tillage systems (no-till, conventional tillage). results showed that 6 t.ha-1 barely residue treatment increased organic carbon, total nitrogen and microbial biomass carbon in comparison with 3 t.ha-1, while stubble burning significantly decreased all these parameters. tillage treatment also significantly decreased organic carbon and microbial biomass carbon whereas had no effect on total nitrogen. the nitrogen fertilizer had no effect on microbial biomass carbon, whereas organic carbon and total nitrogen positively affected by urea application. the results of this experiment showed that no-tillage system along with crop residue retention of 6 t.ha-1 and without stubble burning systems would be the most effective management to protect and promote soil organic carbon, total nitrogen and microbial biomass carbon.