减量施磷对温室菜地土壤磷素积累、迁移与利用的影响

Effects of Reduced Phosphorus Fertilization on Soil Phosphorus Accumulation, Leaching and Utilization in Greenhouse Vegetable Production

【目的】针对过量施磷问题,定位研究日光温室蔬菜生产磷肥减施潜力,明确适宜施磷范围。【方法】以北方温室蔬菜主栽种类黄瓜和番茄为研究对象,采用冬春茬黄瓜-秋冬茬番茄种植模式,在基础土壤有效磷(Olsen-P)40.2 mg·kg^(-1)下,设计不施磷肥(P0)、减量施磷(P1)和农民常规施磷量(P2)3个磷肥用量水平。P0、P1、P2处理对应黄瓜单季施磷肥(P_2O_5)0、300、675 kg·hm^(-2),番茄单季施磷肥(P_2O_5)0、225、675 kg·hm^(-2)。3年6季定位研究蔬菜生产磷素盈亏、土壤有效磷供应与迁移,分析产量变化,推荐合理施磷范围。【结果】(1)农民常规施磷量年盈余磷480.0 kg P·hm^(-2)·a^(-1),每盈余磷100 kg P·hm^(-2)主根区0—20 cm土层Olsen-P增加2.7mg·kg^(-1),3年0—20 cm土层Olsen-P平均含量70.2 mg·kg^(-1),2010年番茄季0—20 cm土层磷素饱和度(DPSM3)为80%,磷素土壤深层迁移明显。(2)减量施磷较农民常规磷量下降61.1%,3年磷素盈余量下降71.0%—77.3%,0—20 cm土层Olsen-P含量下降18.6%—43.5%,3年均值为49.3 mg·kg^(-1),接近瓜果类蔬菜Olsen-P农学阈值,关键生育期磷素吸收量无显著变化,产量保持在中高水平不降低;经过3年种植,0—20 cm土层DPSM3下降21个百分点,20—60 cm土层Olsen-P平均含量下降9.3%—30.1%,减施磷肥有效缓解了土壤磷素深层迁移。(3)不施磷肥导致土壤磷素亏缺,蔬菜从土壤中每攫取磷100 kg P·hm^(-2),P0处理0—20 cm土层Olsen-P含量下降3.4 mg·kg^(-1),3年0—20 cm土层Olsen-P平均含量30.5 mg·kg^(-1),虽产量没有显著降低,但是2008年番茄高产下(140 t·hm^(-2))磷素吸收量较P1、P2处理下降19.8%—30.0%,产量呈降低趋势。(4)依据上述推荐:土壤有效磷含量≥40 mg·kg^(-1)的温室,冬春茬黄瓜产量水平170 t·hm^(-2)下施用P_2O_5不宜超过300 kg·hm^(-2),秋冬茬番茄产量水平100 t·hm^(-2)下施用P_2O_5不宜超过225 kg·hm^(-2)。【结论】华北平原温室蔬菜生产减施磷肥潜力较大。对于种植一段时间(≥3年)的温室,较农民常规减施磷60%,可以显著改善磷素盈余状况,缓解土壤有效磷积累,降低土壤磷素深层迁移量,保证黄瓜番茄持续中高产水平生产。

[Objective]Excessive application of phosphorus fertilizer is commonly observed in vegetable production in China. The purpose of this study was to investigate the potential of phosphorus fertilization reduction in vegetable production and recommend appropriate phosphorus rates for cucumber and tomato.[Method]Cucumber and tomato were widely cultivated in North China, and thus were taken as the research objects. In this study, cropping model was the winter-spring cucumber and autumn-winter tomato double cropping system. The basic Olsen-P level was 40.2 mg·kg^（-1）. Three treatments were designed in this experiment, including a non-phosphorus control（P0）, a reduced phosphorus rate（P1） and a farmers＇ conventional phosphorus rate（P2）. In cucumber season, the amounts of P_2O_5 applied in P0, P1 and P2 treatments were 0, 300, 675 kg·hm^（-2）, respectively. The corresponding phosphorus amounts in the tomato season were P_2O_5 0, 225, 675 kg·hm^（-2）, respectively. The apparent phosphorus balances, soil phosphorus availability and movement and yield changes among 3 years were collected and analyzed to find out the appropriate phosphorus rates.[Result]（1） Phosphorus surplus was P 480.0 kg·hm^（-2）·a-1 and the average Olsen-P content in 0-20 cm soil was 70.2 mg·kg^（-1） in P2 treatment during 3 years. Due to the surplus application, the Olsen-P in 0-20 cm soil increased by 2.7 mg·kg^（-1） when phosphorus surplus increased by P 100 kg·hm^（-2）. The DPSM3 was 80% at 0-20 cm depth in P2 treatment and phosphorus leached obviously to deeper soil.（2） Compared to P2 treatment, the phosphorus application rate decreased by 61.1% and the phosphorus surplus among 3 years reduced by 71.0%-77.3% in P1 treatment; the Olsen-P contents decreased by 18.6%-43.5% with the average of 49.3 mg·kg^（-1） among 3 years, which was close to the critical value of the fruit vegetable production; the average of Olsen-P content decreased by 9.3%-30.1% at 20-60 cm soil depth, and the DPSM3 decreased by 21 percentage point, which indicated lower phosphorus leaching in P1 treatment, and no yield reduction was observed.（3） The Olsen-P in 0-20 cm soil decreased by 3.4 mg·kg^（-1） when phosphorus uptake increased by P 100 kg·hm^（-2） in P0 treatment. The average Olsen-P content in 0-20 cm soil was 30.5 mg·kg^（-1） in P0 treatment. Although no yield decrease was observed, the phosphorus uptake in 2008 tomato season decreased by 19.8%-30.0% in P0 treatment.（4） Based on this results, when the soil Olsen-P was above 40 mg·kg^（-1）, less than 300 kg·hm^（-2） P_2O_5 was recommended for cucumber with yield level of 170 t·hm^（-2）, and not more than 225 kg·hm^（-2） P_2O_5 was recommended for tomato with yield level of 100 t·hm^（-2）.[Conclusion]The reduction of phosphorus fertilizer exhibited a great potential in the greenhouse vegetable production in North China Plain. For greenhouse planted for more than 3 years, 60% phosphorus could be saved and significantly decrease the phosphorus surplus, lessen available phosphorus accumulation, reduce phosphorus leaching and keep vegetable yield at high level.