灌溉方法对保护地土壤有机氮组分及剖面分布的影响

Effect of Different Irrigation Methods on Forms and Profile Distribution of Soil Organic Nitrogen in Protected Field

用Bremner有机氮分组法测定了连续7年采用不同灌溉方法灌溉的保护地土壤各剖面层次有机氮组分含量。结果表明,土壤全氮及有机氮各组分含量均随土层深度的增加而降低,但有机氮各组分占全氮的比例随土层深度增加的变化却无明显规律。用3种灌溉方法灌溉,不同土层间土壤有机氮各组分含量的差异主要存在于0～50 cm土层,50 cm以下差异很小;相同土层,土壤有机态氮含量均以酸解氮为主,且酸解氮中各组分绝对含量和相对含量的大小排列顺序均为,未知态氮〉氨态氮〉氨基酸态氮〉氨基糖态氮。在0～80 cm土层,土壤酸解氮占全氮的比例大多在58%～60%之间,只有渗灌处理0～10 cm,10～20 cm及沟灌处理0～10 cm土层酸解氮占全氮的比例较低,分别为34.21%,50.75%和48.02%;而非酸解氮占全氮的比例大多在32%～36%之间。3种灌溉方法相比较,除个别层次外,酸解氮中氨基酸态氮、氨基糖态氮及氨态氮占全氮的比例在各土层中滴灌和渗灌处理均高于沟灌处理,而酸解未知态氮和非酸解氮占全氮的比例则为沟灌处理高于滴灌和渗灌处理。

The content of organic nitrogen（N） forms in soil profile were determined by using the method proposed by Bremner in 7 years protected field with different irrigation methods.The results indicated that the content of total N and organic N forms were decreased with layers＇ depth,but the ration of organic N forms to total N didn＇t had obvious rule.The difference of soil organic nitrogen forms was mainly in 0～50 cm soil layers under three irrigation methods,but below 50cm the difference was no obvious.At the same layer,acidic hydrolysable N was the main components of the organic N,the order of the content of acidic hydrolysable N forms and proportion to total N was unknown N 〉 ammonia N 〉 amino acid N 〉 amino sugar N.At 0～80 cm soil layer,the proportion of acidic hydrolysable N to total N was mostly 58%～60%,but they were lower at 0～10cm and 10～20 cm of subsurface irrigation and 0～10 cm of furrow irrigation,the content respectively were 34.21%,50.75% and 48.02%.The proportion of non-acidic hydrolysable N to total N was 32%～36%.Compared with three irrigation methods,except for a few layers,the proportion of amino acid N,amino sugar N and ammonia N to total N in various layers of drip irrigation and subsurface irrigation were higher than furrow irrigation;but the proportion of unknown N and non-acidic hydrolysable N to total N of furrow irrigation were higher than drip irrigation and subsurface irrigation.