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首页> 外文期刊>Acta Agriculturae Scandinavica. Section B, Soil and Plant Science >Nitrification activities and N mineralization in paddy soils are insensitive to oxygen concentration
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Nitrification activities and N mineralization in paddy soils are insensitive to oxygen concentration

机译：水稻土的硝化活性和氮矿化对氧浓度不敏感

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摘要

Oxygen concentration is considered to be the most important factor influencing nitrification and mineralization rates in agricultural soils. However, the sensitivities of nitrification and N mineralization in paddy soils to oxygen concentrations are not well known. We examined nitrification activities and N mineralization rates of six paddy soils with pH ranging from 5.23 to 7.83 and incubated at 25 degrees C and 60% water-holding capacity in laboratory after ammonium was added at concentrations of 10, 30 and 50mgNkg(-1) of soil and the headspace gases were replaced with stock gases whose oxygen concentrations were 20%, 10% and 2%, respectively. The tested paddy soils had a very wide range of nitrification activities so that the nitrate ratio in inorganic N varied from >95% after 1 day incubation to<25% after 7 days of incubation. The nitrate ratio correlated with the soil pH. Nitrate content and its ratio, and mineralization rate were not suppressed when the oxygen concentration in the headspace decreased from 20% to 2%. Our results suggested that nitrifiers and microbial communities involved in N mineralization might have adapted to the environment with low oxygen concentration in paddy soils in which oxygen concentration is deficient during the flooding period. However, oxygen concentration would be even lower than 2% in paddy soils under the flooding conditions. Thus, the minimum oxygen concentration at which nitrification activities in paddy soils are suppressed needs to be explored further.
机译：氧浓度被认为是影响农业土壤硝化和矿化速率的最重要因素。然而，水稻土中硝化和氮矿化对氧浓度的敏感性尚不为人所知。我们检测了6种pH值为5.23至7.83的水稻土的硝化活性和N矿化率，并在25摄氏度和60％持水量下于实验室中以10、30和50mgNkg（-1）的浓度添加铵盐后进行了培养。分别用氧气浓度分别为20％，10％和2％的原料气代替土壤和顶空气体。所测试的稻田土壤具有非常广泛的硝化活性，因此无机氮中的硝酸盐比率从培养1天后的> 95％变为培养7天后的<25％。硝酸盐比率与土壤pH相关。当顶部空间中的氧气浓度从20％降至2％时，硝酸盐含量及其比例和矿化速率均未受到抑制。我们的研究结果表明，参与氮矿化的硝化器和微生物群落可能已经适应了稻田土壤中氧浓度低的环境，而该土壤在洪水期间氧浓度不足。然而，在洪水条件下，稻田土壤中的氧气浓度甚至会低于2％。因此，需要进一步研究抑制稻田土壤硝化活性的最低氧浓度。

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