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氮素矿化是土壤氮循环的重要环节,土壤氮矿化参数对于正确评价土壤供氮潜力和指导土壤氮素管理有重要意义。采用35℃淹水厌氧短期培养法研究了中亚热带典型红壤丘陵区五种土地利用方式土壤氮素的矿化作用。利用双一级动力学模型(双氮库模型)对矿化过程进行拟合与比较,并利用土壤理化性质对氮矿化动力学参数进行估测。结果表明,土壤氮素快速矿化主要在淹水培养前7 d,于28 d矿化曲线即趋于平稳;双氮库模型能很好的拟合氮矿化作用。菜地、稻田、荒地、林地和茶园土壤的易矿化氮库矿化势分别为85.9 mg/kg、184.4 mg/kg、64.5 mg/kg、37.0 mg/kg和11.4 mg/kg,其占全氮的比率分别为5.77%、8.65%、4.42%、3.31%和1.25%,其易矿化速率常数分别为0.31、0.58、0.15、0.07和0.17(1/d)。应用双氮库模型拟合的易矿化氮库矿化势和易矿化速率常数与土壤全氮、微生物生物量碳、微生物生物量氮、p H和碳氮比有显著相关性;利用全氮及p H两变量能较好地预测氮矿化势和矿化速率常数,但土壤微生物生物量碳对氮素矿化动力学参数估算具有更关键作用。
Nitrogen mineralization is an important part of soil nitrogen cycle. Soil nitrogen mineralization parameters are of great significance to correctly evaluate the potential of soil nitrogen supply and to guide soil nitrogen management. Soil nitrogen mineralization under five land use patterns in a hilly red soil region of subtropical China was studied using an anaerobic short-term culture at 35 ℃. The mineralization process was fitted and compared using the double-first-order kinetic model (dual nitrogen pool model), and the kinetic parameters of nitrogen mineralization were estimated by using soil physical and chemical properties. The results showed that the mineralization curve of soil nitrogen rapid mineralization tended to be steady at 7 d before flooding and 28 d before rapid mineralization. The model of double nitrogen reservoir could well fit the nitrogen mineralization. Potentials of readily available mineral nitrogen in vegetable fields, paddy fields, wastelands, woodlands and tea plantations were 85.9 mg / kg, 184.4 mg / kg, 64.5 mg / kg, 37.0 mg / kg and 11.4 mg / kg, The ratios of nitrogen to mineralization were 5.77%, 8.65%, 4.42%, 3.31% and 1.25%, respectively. The rates of easy mineralization were 0.31,0.58,0.15,0.07 and 0.17 (1 / d), respectively. The mineralization potential and the rate of susceptibility to mineralization fitted by the dual-nitrogen pool model are significantly correlated with soil total nitrogen, microbial biomass carbon, microbial biomass nitrogen, p H and carbon to nitrogen ratio. Both nitrogen and p H variables can better predict the nitrogen mineralization potential and mineralization rate constants, but soil microbial biomass carbon plays a key role in estimating nitrogen mineralization kinetic parameters.