Response of soil microbial Communities, inorganic and organic soil carbon pools in arid saline soils to alternative land use practices

• Published in: Ecological indicators 2023-06, Vol.150, p.110227, Article 110227
• Main Authors: Somenahally, Anil C., McLawrence, Javid, Chaganti, Vijayasatya N., Ganjegunte, Girisha K., Obayomi, Olabiyi, Brady, Jeff A.
• Format: Article
• Language: English
• Subjects: Gypsum amendment; Indicator for carbon sequestration; Saline soil microbial structure; Total soil carbon; Wastewater irrigation
• ISSN: 1470-160X; 1872-7034
• DOI: 10.1016/j.ecolind.2023.110227

•Climate-smart land-use practices were evaluated in arid saline soils for their impacts on carbon stocks and microbial community structure.•Organic carbon stocks were increased in bioenergy sorghum system under treated wastewater irrigation with gypsum amendment.•Inorganic carbon stocks showed negative relationship with organic carbon sequestration.•Unique prokaryotic community was assembled in treatments with higher organic carbon stocks.•Treated wastewater irrigation resulted in copiotroph dominated prokaryotic community and correlated to higher organic carbon stocks. Soil organic and inorganic carbon (SOC & SIC) and microbial community structure are key indicators of soil quality and productivity in arid-saline soils. Salinity stress and diminishing availability of freshwater (FW) for irrigation are major constraints for productivity and improving soil quality indicators. Using treated wastewater (TW) and implementing climate-smart cropping systems are promising alternatives to replace freshwater usage in intensive cropping systems, however, impacts on the microbial community and net-carbon sequestration potential are not clearly understood. This field study was conducted in an arid saline-soil to investigate soil microbial community structure and soil carbon contents under a combination of treatments comparing bioenergy sorghum (So) and switchgrass (Sg), two irrigation water sources (FW & TW), and gypsum amendment (GA), to a native-soil control. After three years of implementing these treatments, soil samples were collected and analyzed for total carbon (TC), SOC, SIC, microbial biomass-carbon (MBC) and microbial community structure. Results showed that TW increased microbial diversity and shifted the community structure towards copiotroph-dominated prokaryotes. Several predominant and responsive taxa were associated with divergent trends of SOC, SIC and salinity parameters. Both SOC and SIC pools were sensitive to treatments and demonstrated divergent trends, as contents of TC and SOC were higher in TW-treatments, but of SIC were significantly lower in several So_TW treatments. Treatment TW_So_GA assembled a distinctive microbial community structure, accumulated the highest content of SOC (7.66 g kg−1) but recorded the lowest content of SIC (6.63 g kg−1). The lowest content of SOC was observed in native soil (4.58 g kg−1) but contained the highest SIC (8.15 g kg−1). The study results revealed the agronomic systems with higher potential for increasing