低磷有机肥对土壤磷淋失及空心菜产量的影响

Effect of Phosphorus-Reducing Organic Fertilizer on Soil Phosphorus Leaching Loss and Water Spinach(Ipomoea aquatica Forsk)Yield

【目的】有机肥减磷对于调控菜地土壤磷素的淋溶风险具有重要意义,然而其阻控磷淋失和稳定蔬菜产量的潜力还不清楚。【方法】以不施肥和菜地常用高磷含量有机肥(TP 2.03%,HP)为对照,设置总磷含量为1.75%(MHP)、1.32%(MP)和1.06%(LP)3种低磷有机肥处理,进行空心菜设施栽培试验,考察不同处理对于土壤磷素淋溶、土壤磷含量及蔬菜产量的影响。【结果】空心菜生育前期(第一、二茬)是磷素淋失的关键时期,相比HP处理,低磷有机肥(MHP、MP、LP)处理土壤磷淋失强度第一茬分别降低4%、21%和31%(P<0.05),第二茬分别显著降低24%、34%和45%;土壤总磷含量第一茬分别下降6.8%、21.2%和19.2%(P<0.05),土壤有效磷含量分别下降0%、21.6%和20.0%(P<0.05);空心菜产量不显著降低,第一茬MP和LP处理植株磷含量显著降低。表观分析表明,低磷有机肥处理显著降低了有机肥磷在土壤中的遗存。以土壤总磷和淋溶水总磷浓度进行分段回归分析显示,本实验背景土壤磷淋失阈值为土壤总磷1.19 g kg^(-1)。【结论】低磷有机肥可以有效降低土壤磷淋失强度,显著降低土壤磷遗存,不显著降低蔬菜产量。以实验区土壤为参照,建议在土壤磷高于1.19 g kg^(-1)的土壤中使用磷含量小于1.75%的有机肥,在低于此值的土壤中使用磷含量大于等于1.75%的有机肥。

[Objective]Reducing phosphorus(P)content of organic fertilizer is of great significance to regulate the leaching risk of soil P in vegetable fields.But the potential of P-cutting of organic fertilizer is unclear to stabilize vegetable yield and decrease leaching loss.[Method]The field experiment was carried out,using high P organic fertilizer(HP,P 2.03%)as a contrast,high-middle P organic fertilizer(HMP,P 1.75%),middle P organic fertilizer(MP,P 1.32%),and low P organic fertilizer(LP,P 1.06%)were tested for the effect on soil P leaching loss,soil P content and vegetable yield.[Result]The early stage(the first and second crop)was the key period of P leaching loss.The leaching intensities of MHP,MP and LP reduced 4%,21%and 31%(P<0.05)compared with HP in the first stage,and 24%,34%and 45%in the second stage,respectively.The soil total P content decreased 6.8%,21.2%and 19.2%(P<0.05)in the first stage,respectively.The soil available P decreased 0%,21.6%and 20.0%(P<0.05),respectively.The vegetable yield did not decrease significantly.The vegetable P contents of MP and LP treatments decreased significantly in the first stage.This study indicated soil total P was an alternately index to analyze the intensity of soil P leaching in in situ field.The leaching threshold was 1.19 g kg^(-1),MP and LP were the low leaching risk treatment,MHP and HP were high leaching risk treatment.[Conclusion]The Preduction organic fertilizer may significantly lessened soil P leaching loss intensity,significantly decrease the legacy of P in soil and didn’t decrease significantly vegetable yields.Using the soil P threshold value,the P reduction value and application patterns of organic fertilizer P content are recommended.Thus,it is recommended to use middle P organic fertilizer(P 1.32%)in soil with high P(Soil total P>1.19 g kg^(-1)),and high-middle P organic fertilizer(P 1.75%)in soil with low P(Soil total P<1.19 g kg^(-1)).