中文摘要：

结合野外调查取样，采用Bremner法测定下辽河平原两种类型（草甸土型和滨海盐渍土型）水稻土有机氮组分含量。结果表明：①两种类型水稻土均以酸解氮为主体。草甸土型水稻土酸解氮含量显著高于滨海盐渍土型水稻土（P〈0．01），其分配比例则显著低于滨海盐渍土型水稻土（P〈0．01）。②两种类型水稻土酸解各组分氮含量及其分配比例的分布规律不同，其差异因酸解氮组分的不同而异。草甸土型水稻土表现为未知态氮〉氨态氮〉氨基酸态氮〉氨基糖态氮，滨海盐渍土型水稻土则表现为氨基酸态氮，未知态氮，氨态氮〉氨基糖态氮；草甸土型水稻土酸解氨态氮与氨基酸态氮总量及其分配比例显著低于滨海盐渍土型水稻土（P〈0．01），酸解未知态氮含量及其分配比例则显著高于滨海盐渍土型水稻土（P〈0．01）。③两种类型水稻土酸解氮含量均与其土壤有机碳、全氮含量呈显著正相关（P〈0．01）。因此，该地区两种类型水稻土有机氮组分含量及其分配比例的显著差异是影响土壤氮素有效性的重要因素。

英文摘要：

Contents of fractions of organic nitrogen （N） were measured with the Bremner method. Results showed that in two types of paddy soils （meadow soil and coastal saline soil） 1） acid hydrolysis N was the dominant fraction of organic nitrogen in two paddy soils. The content of acid-hydrolyzable N in meadow paddy soil was significantly higher than coastal saline paddy soil （P 〈 0.01）, while the distribution proportion of acid-hydrolizable N in meadow paddy soil was significantly lower than that in coastal saline paddy soil （P 〈 0.01）. 2） The contents and distribution proportion of the fractions of acid-hydolyzable N were different in two paddy soils. In meadow paddy soil, the organic N followed the order： unknown N 〉 ammonia N 〉 amino acid N 〉 amino sugar N, while in coastal saline soil that was amino acid N 〉 unknown N 〉 ammonia N 〉 amino sugar N. The total contents and distribution proportion of acid-hydolyzable N and amino acid N in meadow paddy soil were significantly lower than those in coastal saline paddy soil （P 〈 0.01）, while the content and distribution proportion of acid-hydrolysable unknown N in meadow paddy soil were significantly higher than these in coastal saline paddy soil （P 〈 0.01）. 3） The acid-hydrolyzable N in two types of paddy soils was positively correlated with soil organic C and total N significantly （P 〈 0.01）. Therefore, the significant differences in the contents and distribution proportion of the fractions of organic N were the main factors that affected the availability of soil N in two types of paddy soils in this region.