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基于1980年吉林省第二次全国土壤普查剖面资料和2003—2006年的实测数据,估算了松嫩平原玉米带不同土壤类型农田表层(0—20 cm)土壤氮密度和储量,分析了该地区土壤氮密度的25a时空变化特征及其原因。结果表明,两个时期松嫩平原玉米带农田土壤氮密度的空间分布格局基本一致,中部高、边缘低,平均土壤氮密度变化不大,均为0.31 kg/m2,但25 a间不同土壤类型和土地利用方式的土壤氮密度变化趋势存在差异,暗棕壤、水稻土和沼泽土的氮密度上升,其它类型土壤的氮密度不变或下降,旱田的氮密度不变,水田的氮密度明显下降,25 a间研究区内的农田土壤总氮储量每年减少7.6×105kg。25 a间土壤氮密度的变化与1980年的初始值负相关,土壤氮密度的新稳定状态值为0.32 kg/m2。如保持1980年的土地利用方式和栽培耕作措施不变,该地区农田土壤总固氮潜力为5.18×106kg/a。但实际上,与固氮潜力相比,2005年该区农田土壤总氮储量偏低了1.20×108kg。因此,今后该区应多注重肥料的合理施用,加强农田管理,尤其是旱田改水田的管理。
Based on the data of the second national soil census in Jilin Province in 1980 and the measured data from 2003 to 2006, the nitrogen density and reserves in the soil layer (0-20 cm) of different soil types in the Songnen Plain were estimated. Spatial and Temporal Variations of Soil Nitrogen Density 25a and Their Causes. The results showed that the spatial distribution pattern of soil nitrogen density in the farmland of the Songnen Plain in the two periods was basically the same with high central and low edge and little change in average nitrogen density, both of which were 0.31 kg / m2. However, with different soil types The nitrogen density of dark brown soil, paddy soil and swamp soil increased while the nitrogen density of other soil types did not change or decreased, while the nitrogen density of dry soil did not change, and the nitrogen density of paddy field was obvious , And the total nitrogen storage in farmland in the study area decreased by 7.6 × 105kg per year in 25 years. The change of nitrogen density in 25 years was negatively correlated with the initial value in 1980, and the new stable state value of soil nitrogen density was 0.32 kg / m2. If the land use patterns and cultivation practices of 1980 were kept unchanged, the total nitrogen fixation potential of farmland in this area was 5.18 × 106 kg / a. However, in fact, compared with the potential for nitrogen fixation, the total nitrogen in farmland soils in 2005 was 1.20 × 108kg lower. Therefore, in the future, the district should pay more attention to the rational application of fertilizers and strengthen the management of farmland, especially the management of farmland conversion paddy fields.