氮、磷、钾在设施蔬菜土壤剖面中的分布及移动研究

N,P,K Distributions and Movement in Soils for Greenhouse and Outdoor Field

在山东省寿光市采集6个设施蔬菜和2个露地作物8 m深的土壤剖面样品,研究高施肥量条件下设施蔬菜土壤氮、磷、钾在剖面中的分布及运移。结果表明,设施蔬菜土壤硝态氮的含量远高于露地土壤,设施蔬菜表层土壤中硝态氮的平均含量是露地土壤的6.5倍,土壤中硝态氮的积累与设施种植年限和施肥量有关,设施蔬菜种植年限越长,土壤中硝态氮的含量越高,硝态氮在土壤剖面中淋洗下移明显,下移前锋已到达5￣6 m深处,对地下水构成了威胁。设施蔬菜土壤表层速效磷的含量比露地土壤高出几倍至几十倍,磷在剖面有向下层移动的现象,对地下水和地表水都构成了威胁。土壤速效钾含量与土壤质地有密切关系,土壤速效钾也有淋洗向下移动的现象。设施蔬菜土壤不仅氮淋洗严重,对地下水产生严重威胁,磷也具有淋洗下移的现象。

8 soil profiles including 6 from greenhouse and 2 outdoor field were taken to investigate N, P and K distribution and movement. We discovered that NH4-N content of upper layer and lower layer was similar in the profiles. The NO3-N content decreased with depth in the soil profiles. The upper layer averaged NO3-N content in greenhouse soils was 6.5 times more than that of field soil at the corresponding layers. The older the greenhouse was, the higher NO3-N content in its soil was. Nitrate leaching was evident in the soil profiles in our study. The front position of leaching NO3-N was to 5-6 m depth of soil profiles for the greenhouse, resulting in a dangerous threat to under ground water. The upper layer Olsen P content in the greenhouse soil was several to 40 times more than the outdoor field soil at same layer. It has been found that there was P movement from upper layer to down layer in the soil profiles, leading a danger trend to environment. In addition, K was also found to move from top layer to lower layer in our study. Soil available K content was more than 90 mg·kg^-1 in soil layer below 1 m depth.