连续施用鸽粪对菜心产量及重金属含量的影响

Heavy metal content and yield of flowering Chinese cabbage as affected by repeated application of pigeon manure

为提高饲料报酬，养殖业普遍使用微量元素添加剂，致使禽畜粪中重金属残留较高。根据养殖场鸽粪含氮量计算其用量，进行连续4茬菜心施用鸽粪田间试验，探讨其对菜心产量及重金属含量的影响。结果表明，与单施无机肥处理相比，鸽粪单施或与无机肥配施处理均降低第1茬和第3茬菜心产量，显著提高第2茬产量，对第4茬产量则影响不大。各施用鸽粪处理4茬菜心总产量比单施无机肥处理提高4．5％～17．4％。同时，施用鸽粪对菜心不同重金属含量影响不一。与单施无机肥处理相比，施用鸽粪处理提高了菜心As、Cu和Zn含量，降低了Pb、Cr和Cd含量。且菜心As和Pb含量随鸽粪施用茬数的增加而提高，Cd含量则显著下降，不同茬别间Cr、Cu、Zn平均含量则未表现出明显规律。建议在无公害或绿色农产品生产中避免一次性大量施用或连续施用养殖场禽畜粪肥。

Since microelement additives are commonly used in livestock to increase economic return of feeds, high heavy metal content in animal manure has been documented. 4 successive field trials of flowering Chinese cabbage were conducted to investi- gate the effect of repeated application of pigeon manure on yield and heavy metal content of flowering Chinese cabbage. The utili- zation rate of pigeon manure for the 4 crops was calculated by its N content. The results show that application of pigeon manure decreases yield in the first and the third crops, however, it significantly increases that of the second and has no significant effect on the fourth crop. Total yield of the 4 successive crops in all treatments with manure increases by 4.5% - 17.4% over single ap- plication of inorganic fertilizer. Pigeon manure has various effects on the content of different heavy metals in flowering Chinese cabbage. Cu, As and Zn contents are enhanced by pigeon manure application, however, that of Pb, Cr and Cd decreases. Moreover, As and Pb contents increase with increasing frequency of manure application, while Cd content decreases significantly. Those of Cr, Cu and Zn do not show any obvious pattern of change for the different crops. Mass application in one crop or repeated applications of animal manure heavily laden with heavy metals from livestock farms should be avoided in crop production.