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Temperature and stubble management influence microbial CO2–C evolution and gross N transformation rates
Journal article   Peer reviewed

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

F.C. Hoyle, D.V. Murphy and I.R.P. Fillery
Soil Biology and Biochemistry, Vol.38(1), pp.71-80
2006
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Abstract

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

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Source: InCites

InCites Highlights

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Collaboration types
Domestic collaboration
Citation topics
3 Agriculture, Environment & Ecology
3.45 Soil Science
3.45.112 Soil Carbon Dynamics
Web Of Science research areas
Soil Science
ESI research areas
Agricultural Sciences
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