Temperature and stubble management influence microbial CO2–C evolution and gross N transformation rates

摘要: Few studies have examined the kinetics of gross nitrogen (N) mineralization, immobilization, and nitrification rates in soil at temperatures above 15 °C. In this study, 15N isotopic pool dilution was used to evaluate influence retaining standing crop residues after harvest versus burning on short-term N transformation constant 5, 10, 15, 20, 30, 40 °C. Gross mineralization calculated per unit organic carbon were between 1 7 times lower stubble burnt treatments than retained treatments. addition, significant declines microbial biomass (P=0.05) CO2–C evolution (P<0.001) associated with burning. Immobilization similar magnitude incubated 5 20 °C, but demonstrated divergence from 20 Separation immobilization turnover (MIT) high not due a lack available C substrate, as glucose-C added one treatment test assumption. Nitrification increased linearly temperature dominated over for ammonium 5 °C, 20 °C indicating that is often principal process controlling NH4+ consumption semi-arid soil. These findings illustrate MIT tightly coupled, consequently potential loss (as nitrate) considerably greater nitrification.