基于^(15)N示踪的库尔勒香梨园土壤无机氮残留分布特征

Distribution characteristics of soil inorganic nitrogen residues in Korla Fragrant Pear orchard based on ^(15)N tracing

为给香梨园氮肥的应用提供参考,以6年生库尔勒香梨园土壤为对象,采用^(15)N同位素示踪技术,研究果实成熟期香梨园土壤剖面(0～120 cm)残留无机氮(N-NO_3^-和N-NH_4^+)的分布特征。结果表明,库尔勒香梨果实成熟期0～120 cm各土层硝态氮含量为8.94～11.96 mg/kg,铵态氮含量为6.92～9.88 mg/kg,无机氮积累量为45.06～54.16 kg/hm^2,土壤剖面各土层中土壤无机氮残留总量随着土层深度的增加逐渐下降。0～60 cm土层深度各土层的^(15)N-NO_3^-或^(15)N-NH_4^+残留量占^(15)N残留总量的比例显著高于60～120 cm各土层(P <0.05),表明^(15)N-NO_3^-和^(15)N-NH_4^+主要富集于果园土壤上部(0～60 cm)。^(15)N肥料残留的^(15)N-NO_3^-和^(15)N-NH_4^+在0～60 cm土层最多,分别为2.21、1.57 g,占^(15)N-NO_3^-残留总量的63.14%和^(15)N-NH_4^+残留总量的69.17%。在库尔勒香梨园土壤中,^(15)N肥料无机氮残留率高达20.67%,主要以硝态氮形式存在于土壤中,残留率为12.54%,以铵态氮形式被土壤固持的残留率为8.13%。

In order to provide some references for N fertilizer application in Korla Fragrant Pear orchard,a 6-year Korla Fragrant Pear orchard was selected as study object,distribution characteristics of inorganic nitrogen(N-NO3^-and N-NH4^+)residues in soil profile(0-120 cm)were researched at fruit maturity stage by using the 15N isotope tracing technique.The results showed that nitrate nitrogen content in each soil layer of 0-120 cm soil profile ranged from 8.94 mg/kg to 11.96 mg/kg at fruit maturity stage of Korla Fragrant Pear,and ammonium nitrogen content ranged from 6.92 mg/kg to 9.88 mg/kg,and inorganic nitrogen accumulation ranged from 45.06 kg/hm2 to 54.16 kg/hm2.Total amount of soil inorganic nitrogen in each soil layer was decreased gradually with soil depth increasing.Percentage of 15N-NO3^-or 15N-NH4^+residues in each soil layer accounting for total amount of 15N residual in 0-60 cm soil depth were significantly higher than those in 60-120 cm soil depth(P<0.05).It indicated that 15N-NO3^-and 15N-NH4^+were mainly concentrated in upper part of orchard soil(0-60 cm).15N-NO3^-and 15N-NH4^+were the highest residual amount(2.21 and 1.57 g)in 0-60 cm soil layer,which were 63.14%and 69.17%accounting for 15N-NO3^-residues and 15N-NH4^+residues,respectively.Inorganic nitrogen residual rate of 15N fertilizer was as high as 20.67%in soil of Korla Fragrant Pear orchard,which mainly existed in the form of nitrate nitrogen,and its residual rate was 12.54%.The other part was ammonium nitrogen,and its residual rate was 8.13%.