猕猴桃园氮素投入特点及硝态氮累积和迁移特性研究

为指导果园科学施肥及合理评价施肥对环境的影响,2014年对该区域的陕西省周至县俞家河小流域氮素投入状况进行了调查,并采集猕猴桃园土壤样品进行测定,评价了猕猴桃园土壤硝态氮(NO_3~--N)累积及降雨对坡地猕猴桃园NO_3~--N迁移特性的影响。结果表明:该区域猕猴桃园氮素投入量过高,盈余量高达1195 kg·hm~(-2),0~200 cm土壤剖面NO_3~--N累积量高达827kg·hm~(-2),且52.1%的NO_3~--N累积在100~200 cm土层;对于坡地猕猴桃园,坡下部0~200 cm土壤剖面NO_3~--N累积量明显高于坡上部,在经过一个雨季后,0~200 cm土壤剖面NO_3~--N发生明显的向深层土壤淋溶现象且坡下部与坡上部0~200 cm土壤剖面NO_3~--N累积量差异增大。俞家河小流域猕猴桃园大量氮素盈余,造成土壤NO_3~--N过分累积,在集中降雨条件下,NO_3~--N出现明显的向深层土壤淋溶且可能存在顺坡向下迁移的趋势,不仅造成氮肥的损失,而且对地表及地下水环境构成潜在威胁。

Nitrogen inputs and nitrate accumulation and movement in soil of kiwifruit orchards

The northern slope region of the Qinling Mountains is the main growing area of kiwifruit in Shaanxi Province. However, inadequate application of nitrogen(N) in kiwifruit orchard is very common. Therefore, studying N plant utilization and movement in soil is of great significance for achieving balanced fertilization and evaluating the effect of N fertilization on the environment in this region. A survey was conducted in Yujiahe catchment in 2014 to assess the status of N inputs. Soil profile samples in 0~200 cm depth from mature kiwifruit orchards were collected to examine the accumulation and movement of NO₃^--N in the soil profiles of sloping kiwifruit orchard. Excessive applications of N were very severe in the catchment. The surplus of N applied was high up to 1195 kg·hm^-2 with residual NO₃^--N being 827 kg·hm^-2 in the 0~200 cm soil profile, of which 52% of N was accumulated in 100~200 cm soil profile. The accumulation of NO₃-N in the 0~200 cm soil profile was dependent on the locations within an orchard:more NO₃-N was accumulated in the lower part than in the upper one of a slope. After a rainy season, NO₃-N was leached to deeper part of the soil profile. It is concluded that excessive additions of N to kiwifruit orchard in Yujiahe catchment results in high accumulation of NO₃^--N in the soil. The NO₃-N leaching in soil profiles during the rainy season is also severe. Nitrate leaching not only wastes N fertilizer resource, but also increases potential risk to the quality of both surface and groundwater.