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  • Is liming soil a strategy f...
    Barton, L.; Gleeson, D.B.; Maccarone, L.D.; Zúñiga, L.P.; Murphy, D.V.

    Soil biology & biochemistry, 07/2013, Letnik: 62
    Journal Article

    Nitrous oxide (N2O) emissions in semi-arid regions are often greater following summer rainfall events when the soil is fallow, than in response to N fertiliser applications during crop growth. Nitrogen fertiliser management strategies are therefore likely to be ineffective at mitigating N2O emissions from these cropped agricultural soils. Here we examined the influence of raising soil pH on N2O emissions, nitrification rates, and both nitrifier and denitrifier populations following simulated summer rainfall events. The soil pH was raised by applying lime to a field site 12 months before conducting the laboratory experiment, resulting in soil of contrasting pH (4.21 or 6.34). Nitrous oxide emissions ranged from 0 when the soil was dry to 0.065 μg N2O–N g dry soil−1 h−1 following soil wetting; which was attributed to both denitrification and nitrification. Increasing soil pH only decreased N2O emissions when losses were associated with nitrification, and increased amoA gene copy numbers. We propose increasing soil pH as a strategy for decreasing soil N2O emissions from acidic soils following summer rainfall in semi-arid regions when emissions result from nitrification. ► We investigated if liming decreased soil N2O emissions following summer rain. ► N2O emissions were attributed to both denitrification and nitrification. ► Raising soil pH decreased N2O emissions from nitrification. ► Raising soil pH increased ammonia oxidising bacteria (AOB) gene copy numbers. ► There was no change in AOA or denitrifier gene copy numbers with soil pH.