福建菜田氮、磷积累状况及其淋失潜力研究

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

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47.4±55.5 mg/kg,Olsen-P含量则为61.7±43.2 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-P42.8 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。

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.