Microbial Activity Is Constrained by the Quality of Carbon and Nitrogen under Long-term Saline Water Irrigation

• Published in: Communications in Soil Science and Plant Analysis Vol. 49; no. 11; pp. 1266 - 1280
• Main Authors: Chahal, Shaminder Singh, Choudhary, O. P., Mavi, Manpreet Singh
• Format: Journal Article
• Language: English
• Published: Philadelphia Taylor & Francis Ltd 17.06.2018
• Subjects: Ammonium; Ammonium compounds; Ammonium sulfate; Biological activity; Biomass; Carbon; Carbon/nitrogen ratio; Charcoal; Electrical conductivity; Electrical resistivity; Glucose; Incubation period; Irrigation; Irrigation water; Microbial activity; Microorganisms; Nitrogen; Phosphorus; Saline soils; Saline water; Soil; Soil amendment; Soil investigations; Soil water; Straw; Substrates; Sulfates
• ISSN: 0010-3624; 1532-2416; 1532-4133
• DOI: 10.1080/00103624.2018.1455852

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 [ap] 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.