Effect Of Phosphorus Application Methods On Higher Phosphorus Use Efficiency In Pepper And Chinese Cabbage

Vegetables are the main crops but faces high P fertilizer input and low phosphorus use efficiency（PUE）which large surplus of soil P leads to high risk of P loss.Solving the problems of high P input and high risk of P loss is an important need of current agricultural production,and tapping the method for PUE is a key problem.In this study,root box and field experiments were carried out in the red soil in Yunnan,aiming to reveal the spatial matching and root response of different soil layers of P fertilizer with pepper root system;and evaluate the effects of different P application methods on PUE,soil apparent P surplus（APS）,environmental risks and economic effects of crop rotation system,and provide scientific guidance for P fertilizer reduction in pepper-Chinese cabbage rotation system.The main results of this paper are as follows:（1）The root box test showed that application of P fertilizer significantly increased pepper biomass compared to no P fertilizer,with no effect on P concentration in all parts.P fertilizer increased P accumulation in aboveground parts of pepper,but there was no significant effect between P application treatments.P fertilizer application significantly promoted the root growth P of pepper in the corresponding soil layers.Application at 5-10 cm and 10-15 cm soil layers significantly promoted the root growth of pepper and significantly reduced the root-top ratio.Acid phosphatase activity was more than twice as high as alkaline phosphatase activity,and application of P fertilizer to deeper soils increased acid phosphatase activity.The in situ enzyme profile showed that phosphatase activity in pepper roots was higher than that in non-root systems.（2）Field experiments showed that application of P fertilizer could increase pepper yield,but had no effect on P concentration of each part of pepper.P fertilizer increased P uptake in peppers,while there was no significant effect between P application treatments,and the harvest index of peppers increased in the second year.The drill of N and P could induce root growth of pepper,but there was no significant effect between P application treatments.Compared with traditional fertilization,fruit biomass could be significantly increased.The soil Olsen-P of drill of P was at the same level as that of conventional.P zero surplus with drill fertilization can reduce the amount of P fertilizer input while ensuring the yield of pepper,improve PUE,and reduce APS.Therefore,P zero surplus with drill fertilization(100 P₂O₅ kg ha^-1)is a more suitable P application.（3）Field experiments showed that the two-year trend was consistent in all indicators of Chinese cabbage.The application of P fertilizer had no effect on the yield,but it significantly increased P concentration in the aboveground of Chinese cabbage.P fertilizer increased aboveground P uptake,but there was no significant effect between P application treatments.The PUE of drill of P was significantly higher than other P application methods,and the APS was negative in both years.Therefore,for Chinese cabbage,P zero surplus with drill fertilization(100 P₂O₅ kg ha^-1)is a more suitable P application.（4）In the current pepper-Chinese cabbage rotation system,the application of P had a yield-enhancing effect on pepper,but not on Chinese cabbage.Based on the phosphorus index（PI）,the environmental risk of applying P fertilizer in reduced amounts to the cavity is low.Considering only the economics,P with broadcast(150P₂O₅ kg ha^-1)is more appropriate.P zero surplus with drill fertilization(100 P₂O₅ kg ha^-1)reduces the overall input of P fertilizer and increases PUEa,while also ensuring its economic effect.