长期施肥对石灰性潮土氮素形态的影响

EFFECT OF LONG?TERM FERTILIZATION ON THE FORMS OF NITROGEN IN CALCAREOUS FLUVO?AQUIC SOIL

采用Bremner1 965年提出的土壤氮素分级方法 ,对 1 6年肥料长期定位试验中的耕层以及剖面各层次土壤的氮素形态进行了分级。结果表明 ,施用化肥不能提高耕层土壤各形态氮的含量 ,对土壤氮素的组成也无明显的影响 ;有机肥和化肥配合施用 ,耕层土壤各形态氮的含量都有不同程度的提高 ,其中氨基酸态氮的增加最为明显。有机无机肥配合施用 ,可提高土壤氮素的储量和质量 ,不仅对耕层土壤氮素的含量和组成有影响 ,而且对耕层以下土壤各形态氮的含量也有一定的影响。一般随着有机肥用量的增加 ,下层土壤各形态氮含量的增加幅度也越大 ,而且影响深度也更深。在本试验条件下 ,施肥对氮素形态的最大影响深度为 30cm左右。

In this research, method for soil nitrogen fractionation proposed by Bremner (1965) was adopted to study the transformation of nitrogen in the soil of long term fertilization experiment which has lasted for 16 years. The main results are as follows: When only chemical fertilizer was applied, the content of forms of nitrogen was slightly decreased. Even in the N treatment that the amount of nitrogen application had largely exceeded that the plant could used, but the extra N couldn't accumulated in the soil. Neither chemical fertilizer application had the effect on the content of soil nitrogen, nor had the effect on the nitrogen composition. Application of manure with chemical fertilizer significantly increased the contents of all forms of nitrogen, especially the content of amino acid N. The composition of nitrogen was also affected. Furthermore, application of manure with chemical fertilizer also affected the contents of forms of nitrogen in soil profile, as the amount of manure application increased, the contents of nitrogen forms increased, and the deeper layer of soil profile was affected. In the condition of our experiment, the deepest depth that fertilization affect was about 30 cm.