Microbial Activity Is Constrained by the Quality of Carbon and Nitrogen under Long-term Saline Water Irrigation
2018
Chahal, Shaminder Singh | Choudhary, O. P. | Mavi, Manpreet Singh
Most important, yet least understood, question, how microbial activity in soil under saline water irrigation responds to carbon (C) varying qualitatively (most labile form to extreme recalcitrant form) with or without maintaining C/N ratio was investigated in an incubation experiment. Soil samples from a long-term saline-water (electrical conductivity, EC ≈ 0, 6, and 12 dS m⁻¹)- irrigated field were incorporated with three different C substrates, viz., glucose, rice straw (RS), and biochar with or without nitrogen (N as ammonium sulfate, NH₄SO₄) and were incubated at 25 °C for 56 days. Cumulative respiration (CR), microbial biomass carbon (MBC), microbial biomass nitrogen (MBN), and dehydrogenase activity (DEA) concentrations decreased with increasing EC (P < 0.05), but less so in soils amended with glucose followed by RS and biochar. The addition of N to soils amended with different C substrates significantly decreased CR, MBC, DEA, and available phosphorus (P) concentrations at a given EC level.
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