福建菜田氮磷积累状况及其淋失潜力研究

本文通过采集460个福建菜田代表性耕层土样，采用土壤测试和土柱渗漏水模拟试验的方法研究菜田土壤硝态氮和Olsen P含量状况和淋失临界指标及其淋失潜力。结果表明，耕层土壤硝态氮含量为47.455.5 mg/kg，Olsen-P含量则为61.743.2 mg/kg， 其中瓜果类蔬菜种植地土壤硝态氮和Olsen-P含量明显高于叶菜类和根茎类蔬菜种植地。 应用双速率转折点建模法，得到氮、 磷淋失临界指标X0分别为土壤硝态氮76.3 mg/kg和Olsen-P 42.8 mg/kg。 淋失临界值相当于或略高于满足蔬菜营养的农学指标。当土壤硝态氮或Olsen-P含量低于X0时，随着其含量增加，渗漏水硝态氮或总磷浓度以线性方式缓慢增加，反之，则以非线性形式急剧增大。土壤硝态氮和Olsen-P含量高于其X0的土样数分别占17.9%和81.3%， 表明这些样点具有较高的氮、 磷淋失潜力，是氮、 磷污染控制的关键地块。 瓜果类菜田土壤硝态氮和Olsen-P含量高于其X0的土样数分别占到32.3%和96.3%，淋失潜力明显高于叶菜类和根茎类菜田，是氮、 磷污染控制的优先区域。

N and P accumulation status and their leaching potential in vegetable fields in Fujian Province

Soil tests and leakage water simulation experiment using earth pillar were used to study NO^-₃-N and Olsen-P content and their leaching in 460 vegetable field samples,  which were collected from the topsoil of typical vegetable fields in Fujian province. Soil test results show that the NO^-₃-N and Olsen-P contents in the top soils were averaged 47.4±55.5 mg/kg and 61.7±43.2 mg/kg respectively. Thereinto,  the NO^-₃-N and Olsen-P content in the fields growing melon and fruit vegetables was apparently higher than those in the fields growing leaf and tuber vegetables. Calculated with the double-velocity turning point model,  the critical index of double-velocity turning point X₀ of N and P leaching is 76.3 mg/kg for NO^-₃-N and 42.8 mg/kg for Olsen-P,  which is equivalent or a bit higher than the agricultural indices for the satisfactory vegetable nutrition. When the NO^-₃-N or Olsen-P contents in soil were lower than their X₀,  the NO^-₃-N or total-P concentration in leaching water increases slowly in a linear way,  when the NO^-₃-N or Olsen-P contents in soil exceeds its X0,  the NO^-₃-N or total-P would increases rapidly in non-linear way. There are 17.9% and 81.3% of soil samples with their NO^-₃-N and Olsen-P content exceeded their X₀ respectively,  indicating the high N and P leaching potential. In the melon and fruit vegetable fields,  in about 32.3% and 96.3% of soil samples the NO^-₃-N and Olsen-P contents exceeded their X₀ respectively,  indicating their N and P leaching potential were apparently higher than the leaf vegetable and tubers vegetable fields. More attention should be taken on the melon and fruit vegetable fields to control N and P pollution.