长期施肥对河西灌漠土有机氮组分及剖面分布的影响

Effects of Long-term Fertilization on Forms and Profile Distribution of Soil Organic Nitrogen in Irrigated Desert Soil

采用1965年Bremner提出的土壤有机氮分级方法,对25年有机肥与化肥定位试验中的土壤各剖面层次有机氮组成进行分级。结果表明,长期施用化肥和有机肥对河西灌漠土不同剖面土壤全氮和有机氮各组分有显著影响,施肥对不同形态有机氮的影响取决于肥料种类。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。不同土层间土壤有机氮各组分含量的差异主要存在于0～100cm土层,100～180cm差异较小,180cm以下差异很小。与单施化肥相比,在0～100cm土层,有机肥与化肥配合施用后显著提高了土壤全氮和酸解性氮的含量。在酸解性氮中,氨基酸态氮和酸解未知氮显著增加,在0～40cm土层氨基糖态氮含量也有所提高。与不施肥相比,施用氮肥显著提高了0～200cm所有土层的土壤全氮、酸解性氮与非酸解性氮的含量。在酸解性氮中,化学氮肥显著提高了0～200cm所有土层氨态氮的含量,对氨基酸氮、氨基糖氮和酸解未知态氮影响较小。

Organic nitrogen （N） forms in in-igated desert soil profile were quantified in a 25-year fertilization trial using the method proposed by Bremner in 1965. Results showed that soil total nitrogen and organic nitrogen fractions in soil profile were significantly influenced by long-term application of chemical fertilizer and manure and varied with fertilizer species, the contents of total N and organic N forms were decreased with layer depth, but the ration of organic N forms to total N didn＇t had obvious rule. The differences of organic nitrogen forms were mainly in 0 - 100 cm soil layer under different fertilizer species. Organic nitrogen forms were small differences in 100 - 180 cm soil layer, but below 180 cm soil layer the difference was no obvious. At various soil layers, acidic hydrolysable N was the main components of the organic N. Compared with application of N and P fertilizers, manure with N fertilizers greatly increased the contents of total N and acid hydrotysable N in 0 - 100cm soil layer. Of the forms of acid hydrolysable N, amino acid N and hydrolysable unidentified N were significantly increased. Amino sugar N was increased also by manure with N and P fertilizers in 0 - 40 cm soil layer. At all the soil layer of 0 - 200 cm, N application significantly increased total N, acid hydrolysable N and nonhydrolysable N. Compared to the plots without N addition, N fertilizer significantly increased ammonium N but little affects amino acid nitrogen amino sugar N and hydrolysable unidentified N.