不同养分管理措施下常年菜地磷、钾养分径流流失特征

Runoff characteristics of phosphorus and potassium from a perennial vegetable field under different nutrition managements

为研究不同养分管理措施下菜地磷、钾养分径流流失特征,采用田间小区试验方法,设置对照(CK)和有机肥配施不同用量化肥处理(N0,化肥氮空白;CON,习惯施肥;OPT,优化施肥;OPT+N,优化增氮;OPT+P,优化增磷;OPT+NPK,优化增氮磷钾)。结果表明,不同处理下可溶性总磷、颗粒态磷和总磷径流浓度分别为0.015～0.500、0.004～0.623 mg·L^(-1)和0.093～0.876 mg·L^(-1),施磷明显增加径流水可溶性磷浓度,对总磷和颗粒态磷浓度影响较小。不同处理径流水总磷浓度均不同程度超地表水Ⅴ类标准(GB3838—2002),且施磷量最高的OPT+NPK处理总磷超标率高达56%。总磷年流失负荷为4.37～4.93 kg·hm^(-2),施肥处理磷流失负荷均低于对照,不同处理间总磷流失负荷无明显差异。不同处理的钾径流浓度为4.7～83.0 mg·L^(-1),年流失负荷为176.9～331.7 kg·hm^(-2),流失系数为4.5%～15.7%。施钾显著增加菜地钾的流失负荷,施钾量最高的OPT+NPK处理钾流失负荷最高,肥料N/K2O比例最高的OPT+N处理钾流失负荷最低。研究表明,不同养分管理措施下菜地磷径流损失无明显变化,而OPT+N处理钾流失负荷及流失系数均最低,蔬菜实际生产中氮、钾合理配施有利于降低钾的流失。

A plot experiment with treatments of different combinations of organic and inorganic fertilizers was conducted in a perennial vegetable field.Seven treatments in this experiment including control(CK)and OM combined with different rates of inorganic fertilizers i.e.no fertilization of inorganic nitrogen(N0),conventional fertilization(CON),optimum fertilization(OPT),nitrogen addition upon OPT level (OPT+N),phosphorus addition upon OPT level(OPT+P),synchronous addition of nitrogen,phosphorus and potassium upon OPT level (OPT+NPK).The concentration of dissolved phosphorus,particulate phosphorus and total phosphorus were 0.015~0.500,0.004~0.623 mg L^-1 and 0.093~0.876 mg L^-1 ,respectively.Application of phosphorus fertilizer increased the content of dissolved phosphorus in the runoff,whereas it showed little effect on the particulate phosphorus and the total phosphorus.The total phosphorus concentration in different treatments exceeded grade Ⅴ(GB 3838-2002)in some runoff events.In particular,it was estimated that 56% of runoff samples in the OPT+ NPK treatment exceeded the grade Ⅴ standard,which was higher than that in other fertilizer treatments although a general exceeding phenomenon were also observed.The runoff load of total phosphorus in vegetable field was 4.37~4.93 kg·hm^-2 .There was no significant difference among different treatments.Unusually,runoff load of total phosphorus in fertilizer treatments were less than that in the control treatment.Runoff concentration of potassium in different treatment was 4.7~83.0 mg L^-1 .The runoff load of potassium ranged from 176.9 to 331.7 kg· hm^-2 ,with corresponding runoff coefficients of 4.5%~15.7%.Application of potassium fertilizer increased the runoff load of potassium.The highest and the lowest runoff load of potassium was recorded in the treatment of OPT+NPK and OPT+N,respectively.It is worthy noted that the highest N/K2O ration in OPT+N treatment instead of other treatments was found.In summary,no significant variations of phosphorus runoff losses occurred under different nutritional managements.However,a lower potassium runoff load and runoff coefficient were found in the OPT+N treatment.A suitable N/K2O ration should be adapted in the agricultural production in order to reduce the runoff loss of potassium.