不同利用方式下土壤有机氮素矿化特征的研究

采用长期淹水密闭培养-间歇淋洗法(30℃),测定了长期(16年)定位的水田、旱地和林地土壤有机氮素的矿化氮数量,利用一级反应动力学模型对有机氮素的矿化过程进行了拟合,并探讨了不同利用方式下土壤有机氮素的矿化特征。结果表明,3种利用方式下土壤有机氮素的矿化过程均可用一级反应动力学模型很好地拟合;任意两种土壤利用方式之间的N0值差异均达1%显著水平,水田与旱地、林地之间的k值差异均达1%显著水平,而旱地与林地之间的k值差异则达5%显著水平,林地土壤氮素矿化势最大(72.96 mg kg-1),约为旱地和水田土壤的1.3倍和7.4倍,水田土壤氮素矿化速率最大(0.0908 d-1),约为旱地和林地土壤的4.1倍和2.3倍;旱地和林地土壤供氮能力大小相接近,分别为88.24 mg kg-1和89.11 mg kg-1,约为水田土壤的2倍左右。由此可见,长期(16年)不同利用方式对土壤有机氮素矿化特征影响显著,水田土壤可供矿化的有机氮数量最少且矿化时间最为短暂,旱地土壤可供矿化的有机氮数量较多且矿化时间最为缓慢持久,林地土壤可供矿化的有机氮数量最多且矿化时间较为缓慢持久。

Long-term Effects of Different Land Use Patterns on Mineralizing Characteristic of Soil Organic Nitrogen

The effects of different long-term(lasting 16 years) land uses(paddy filed,upland and forest land) on soil nitrogen mineralization were measured by the submerged incubation method(30 ℃) in this paper,and the mineralized process of soil organic nitrogen was fitted with first-order kinetic equation,the characteristic of soil nitrogen mineralization was discussed for different land uses.Results showed that first-order kinetic equation could preferably fit the mineralized process of soil organic nitrogen under three land uses.The differences of nitrogen mineralization potential(N0) between land uses reached significant levels(P<0.01),and the same trend was also found for mineralized rate constant(k)(P<0.05.N0 of forest land was highest(72.96 mg kg-1),which was about 1.3 times of upland and 7.4 times of paddy field.The highest k was observed in paddy field(0.0908 d-1),which was about 4.1 times of upland and 2.3 times of forest land.The soil N supplying capacity of upland was approximate to that of forest land,which were 88.24 mg kg-1 and 89.11 mg kg-1,respectively,being about 2 times that of paddy field.Therefore,the effect of different long-term(lasting 16 years) land uses on the characteristic of soil organic nitrogen mineralization was significant.The quantity of available mineralized organic nitrogen was lowest and the mineralization time was shortest for paddy field soil.The quantity of available mineralized organic nitrogen was highest and the mineralization time was longest and the most permanent for upland soil.The quantity of available mineralized organic nitrogen was highest and the mineralization time was relatively long for forest land soil.