不同施氮水平对库尔勒香梨园土壤无机氮分布的影响

Effects of different nitrogen application levels on distribution of soil inorganic nitrogen in Korla fragrant pear orchard

为给香梨种植生产过程中氮肥的合理施用提供科学依据,以树龄为6 a的库尔勒香梨树为试材,在香梨年生长周期内的不同时间段,采用土钻分层取土法取样,研究了不同施氮水平下香梨园土壤无机氮的含量分布及累积特征。结果表明:施氮对库尔勒香梨园土壤中无机氮的含量和累积均有显著影响,同时土壤中无机氮的含量因土层深度和香梨生育时期的不同而发生变化。不同施氮处理下,土壤中无机氮的分布均具有表聚效应,硝态氮还具有明显的向下淋洗的作用,但铵态氮的淋洗作用较弱;土壤中无机氮的含量随着氮肥施入量的增加而增加,但随着香梨生育期的推进这种影响逐渐减弱;在库尔勒香梨年生育末期,施氮处理N1PK、N2PK和N3PK的0~120 cm土层土壤中无机氮的总累积量与不施氮处理N0PK的相比分别增加70.81、74.39和133.39 kg·hm^(-2);施肥处理中的N1PK和N2PK处理之间差异不显著,而其与N3PK处理间的差异均较为显著。文中因此建议,为了减少土壤中无机氮的累积,降低硝态氮向下淋洗污染地下水和环境的风险,库尔勒香梨园的施氮量应控制在300 kg·hm^(-2)以内。

In order to provide some scienfic basises for reasonable application of nitrogen fertilizer in planting and production of Korala fragrant pear, 6 years Korla fragrant pear was taken as experimental materials, some soil samples were collected by soil-drilling method in different grades of whole growth period of Korla fragrant pear, and content distribution and accumulation characteristics of soil inorganic nitrogen were studied under different nitrogen application levels. The results showed that nitrogen application had significant effects on contents and accumulations of soil inorganic nitrogen in Korla fragrant pear orchard, and contents of inorganic nitrogen in soil were changed with soil depth and growth periods of Korla fragrant pear. Distributions of soil inorganic nitrogen had a surface aggregation effect in Korla fragrant pear orchard soil under different nitrogen treatments, and nitrate nitrogen also had a significant downward leaching effect, but ammonium nitrogen had a weaker leaching effect. Content of inorganic nitrogen in soil was increased with nitrogen fertilizer application increasing, but the effects were gradually weakened with growth developing of Korla fragrant pear. At the end of the annual growth period, compared with the treatment NoPK, the total inorganic nitrogen accumulations of the treatment N IPK, N2PK and N3PK in 0-120 cm soil layer were increased by 70.81, 74.39 and 133.39 kg-hrn- 2, respectively. In the fertilization treatments, difference between the treatment N^PK and N2PK was not significant, but differences between the two treatments and the treatment N3PK were more significant. Therefore, in order to reduce the accumulation of inorganic nitrogen in soil and reduce the risk of contaminating groundwater and environment caused by nitrate leaching, the amount of nitrogen application should be controlled within 300 kg.hm - 2.