不同施肥模式对暗棕壤氮的形态及其在不同团聚体中分布的影响

目的]探讨传统施肥和测土配方施肥对暗棕壤中氮的形态及其在不同大小团聚体中分布的影响。方法]采用物理与化学相结合的方法对传统施肥模式和测土配方施肥模式下暗棕壤不同粒径团聚体中氮的分布和化学形态进行比较研究。结果]与传统施肥春秋两季相比，在测土配方施肥模式下，0~20 cm层土壤全氮平均减少了23.2%和20%，而20~40 cm层土壤全氮平均减少了48.8%。铵态氮对施肥模式变化极为敏感，在测土配方施肥模式下，秋季的铵态氮下降幅度明显高于传统施肥模式。传统施肥模式土壤氮素主要分布在0~0.25和0.5~1 mm 的团聚体中；而测土配方施肥模式土壤氮素主要分布在0.25~0.5和0~0.25 mm团聚体中。研究证实测土配方施肥模式减少了氮素面源污染的风险；测土配方施肥极大地影响暗棕壤中氮素的形态及其在不同大小团聚体中的分布。结论]该研究为辽河源头区面源污染和该地区的科学施肥提供科学依据。

Effects of Fertilization Patterns on Chemical Forms of Nitrogen in Dark Brown Soil and Its Distribution in Different Aggregates

Objective] This study was conducted to investigate the effects of tradition-al fertilization and formula fertilization by soil testing on the chemical forms of nitro-gen in dark brown soil and its distribution in different aggregates. Method] A physi-co-chemistry method was adopted in a comparative study on the chemical forms of nitrogen and their distribution in different-sized aggregates of dark brown soil under traditional fertilization and formula fertilization by soil testing respectively. Result] Compared with traditional fertilization in spring and autumn, the formula fertilization by soil testing averagely decreased, the total nitrogen in soil by 23.2% in spring and by 20% in autumn in the soil layer of 0-20 cm, by 48.8% in the layer of 20-40 cm. Ammonium nitrogen was so sensitive to the methods of fertilization that the content of ammonium nitrogen was reduced much more under formula fertitization by soil testing in autumn than under traditional fertilization. Nitrogen in soil under traditional fertilization pattern was mainly distributed in the aggregates of 0-0.25 and 0.5-1 mm, while in formula fertilization by soil testing it was mainly distributed in the aggregates of 0.25-0.5 and 0-0.25 mm. Conclusion] The study proved that for-mula fertilization by soil testing helped to reduce the risk of nitrogen pol ution and had huge effects on the chemical forms and distribution of nitrogen in different ag-gregates in dark brown soil.