Microbial biomass and activity in alkalized magnesic soils under arid conditions

摘要: Abstract The effects of salinity and Mg 2+ alkalinity on the size activity soil microbial communities were investigated. study was conducted along border area alluvial fan Taolai River. Thirty samples taken which had an electrical conductivity (EC) gradient 0.93–29.60 mS cm −1 . Soil pH ranged from 8.60 to 9.33 correlated positively with /Ca ratio, exchangeable percentage HCO 3 − +CO 2− varied considerably 3.04 61.31, average 23.03. Exchangeable generally exceeded 60% a positive correlation averaged 1.63 cmol kg usually did not exceed 2.0 cmol kg Microbial biomass, indices activities hydrolases negatively or percentage. Biomass C, biomass N, quotient (the organic C present as C), N total potentially mineralizable FDA hydrolysis rate arginine ammonification decreased exponentially increasing EC. C/N tended be lower in soils higher alkalinity, probably reflecting bacterial dominance alkalized magnesic soils. metabolic ( q CO 2 ) showed quadratic relationship EC, indicating that resulted progressively smaller, more stressed less metabolically efficient. Consequently, our data suggest are stressful environments for microorganisms.