施磷对苦麦菜生长及土壤磷素淋失的影响

Effect of phosphorus application on growth of bitter Chinese lettuce and soil phosphorus leaching

利用网室土柱模拟试验,研究了不同磷用量[0、0.05 g.kg-1(土)、0.10 g.kg-1(土)、0.20 g.kg-1(土)]对苦麦菜产量、磷素吸收和利用及土壤磷淋失的影响。结果表明,施磷显著增加苦麦菜产量、促进植株对磷的吸收。苦麦菜产量在低磷水平[0.05 g.kg-1(土)]时最高,为每个土柱186.29 g。随磷用量增加,苦麦菜产量和磷肥利用率明显降低,植株吸磷量无明显变化。施磷显著增加土壤磷淋失量,且随磷用量增加,不同形态磷淋失量均显著增加。同一磷处理颗粒磷淋失量高于溶解态磷。不同磷用量条件下土壤各形态磷的淋失率均低于0.1%。低量施磷条件下溶解态磷在施磷后第10 d出现第1次淋失高峰;中量和高量施磷条件下溶解态磷在施磷后第10 d和第40 d分别出现2次淋失高峰。土壤总磷和颗粒磷淋失高峰期在施磷后第40～50 d出现。施肥后第60 d,土壤总磷、溶解态磷和颗粒磷淋失浓度均明显降低。综合考虑苦麦菜产量、磷素吸收和利用及土壤磷淋失量等因素,苦麦菜以0.05 g.kg-1(土)的施磷量为佳。

A soil column experiment was conducted in net room to study the effects of different phosphorus levels [0,0.05 g·kg？1（soil）,0.10 g·kg？1（soil） and 0.20 g·kg？1（soil）] on phosphorus uptake,utilization and yield of bitter Chinese lettuce and on soil phosphorus leaching.The results showed that phosphorus application significantly increased yield of bitter Chinese lettuce and also promoted phosphorus absorption by the plant.The highest yield（186.29 g per column） was observed under low phosphorus level [0.05 g·kg？1（soil）].With increasing phosphorus level,yield and phosphorus use efficiency decreased significantly.There was no significant change in phosphorus uptake under different phosphorus levels.It was also noted that leaching of total phosphorus increased significantly with increasing phosphorus level.Under the same treatment,particulate phosphorus leaching was higher than dissolved phosphorus.The leaching ratios of phosphorus in different forms in all the treatments were less than 0.1%.Dissolved phosphorus leaching was highest at 10 days after phosphorus application under low phosphorus level.The second highest leaching occurred at 40 days after phosphorus application under moderate and high phosphorus level.High leaching of total phosphorus and particulate phosphorus were observed at 40～50 days after phosphorus application.Leaching of total phosphorus,dissolved phosphorus and particulate phosphorus drastically decreased at 60 days after phosphorus application.In terms of plant yield and phosphorus uptake,phosphorus use efficiency and soil phosphorus leaching,low phosphorus application [0.05 g·kg？1（soil）] was suggested for bitter Chinese lettuce in the region.