不同施肥对城郊菜地土壤质量、叶菜镉及养分含量的影响

通过田间试验研究不同施肥处理对广州市郊菜地土壤质量、叶菜可食部分Cd含量和养分含量的影响。结果表明:与75kg N/hm2处理相比,150kg N/hm2处理没有显著提高叶菜产量,且后者叶菜地上部分Cd含量较前者有不同程度提高。N用量为75kg/hm2时,硝酸铵+磷酸二氢钙+硫酸钾配施处理的芥菜和小白菜产量较高,矿质养分含量较高,Cd含量较低,且土壤肥力和质量得到维持。因此,在试验条件下,以硝酸铵+磷酸二氢钙+硫酸钾配施处理且N,P2O5,K2O用量分别为75,21.75,67.5kg/hm2时有利于改善叶菜品质和安全;而精制有机肥可能提高土壤和叶菜可食部分Cd含量的风险。

Effect of Fertilization on Soil Quality,Leafy Vegetable Cadmium and Nutrient Contents in Suburban Farmland

Effect of different fertilizers application on soil quality,cadmium,total N,P and K concentrations in the shoots of two leafy vegetables was investigated at two different field trial sites in suburban vegetable fields of Guangzhou.The results showed that there was insignificant difference for leafy vegetables yields between the fertilization treatments of 150 kg/hm2 N and those of 75 kg N/hm2,and shoot Cd contents of the 75 kg N/hm2 treatments were less than those of the 150 kg N/hm2 treatments.Combined fertilization of NH4NO3+Ca(H2PO4)2+K2SO4 not only obtained higher yields and mineral nutrients,but also had lest shoot Cd contents and kept soil quality.Therefore,fertilization of NH4NO3+Ca(H2PO4)2+K2SO4 at doses of 75,21.75,67.5 kg/hm2 respectively,was beneficial in proving safety quality of leafy vegetables,while refined organic fertilizer might cause the risk of increasing Cd contents in soil and shoots of leafy vegetables.