长期施用有机肥对土壤及不同粒级中酸解有机氮含量与分配的影响

Contents and Distribution of Forms of Organic N in Soil and Particle Size Fractions after Long-term Fertilization

通过 14年 2 9茬稻 麦水旱轮作田间试验 ,研究长期连续定位施用有机肥料对土壤及不同粒级土壤颗粒中各形态有机氮含量与分配的影响。结果表明 ,长期施肥后土壤酸解有机氮总量比对照增加 10 %～ 34%。施肥对不同形态有机氮的影响取决于肥料类型 ,单施化肥处理酸解铵态氮增加最大 ,其它形态氮素变化较小 ;化肥与有机肥配合施用后 ,酸解铵态氮明显下降 ,氨基糖态氮显著增加 ,氨基酸态氮含量也增加。从形态分布上看 ,土壤中以氨基酸态氮和酸解未知氮占优势地位 ,铵态氮次之 ,氨基糖态氮最低。长期施用有机肥后氨基糖态氮占土壤总氮的比例超过酸解铵态氮 ,同时还使得土壤中非酸解氮的比重增加。土壤不同粒级中酸解氮的含量高低顺序为 :0～2 μm >2～ 10 μm >5 0～ 10 0 μm >10～ 5 0 μm粒级。长期施入土壤的肥料氮同化进入各粒级中不同形态氮的数量因肥料种类而异 ,化肥氮主要进入 0～ 2 μm的粘粒 ,有机肥氮则同化进入各粒级中的氨基糖态氮及 2 μm以上各粒级的氨基酸氮中。土壤各粒级中均以氨基酸氮比重最大 。

The objective of the research was to study the effect of long term fertilization on the contents and distributions of different forms of organic N in soil and particle size fractions to clarify soil nitrogen inherent fertility. Samples were taken from the top 20cm after 14 years application of chemical fertilizer and organic manure. The particle size fractions (0～2μm, 2～10μm, 10～50μm and 50～100μm ) were isolated without chemical pretreatment by ultrasonic dispersion in water followed by sedimentation syphonation. The contents of forms of organic N in bulk soil varied with fertilizer species. The soil treated with ammonium sulfate gave the highest NH 3 N and lowest amino sugar N content in all treatments. The highest content of amino sugar N and amino acid N were found in the treatment of pig manure. The distribution of acid hydrolysable N within size fractions was in the order as follows: 0～2μm>2～10μm>50～100μm >10～50μm. Most of the chemical fertilizer N remained in soil was distributed in particle size fraction 0～2μm while most of the manure N remained was transferred into amino sugar N in each size fraction and amino acid N in the size fractions >2μm during the process of humification.