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

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.