Determination and analysis on main harmful composition in excrement of scale livestock and poultry feedlots

In the last several decades,along with the rapid development of scale livestock and poultry industry in China,the increase of deleterious contaminants,such as heavy metals,residues of animal medicine,salinities,and maleficent bacteria,in the manures of livestock and poultry made up of the limiting factors which affected the healthy function of farmland soil,even brought about eco-environment risk.The main chemical composition of livestock and poultry manures from typical intensive farms from seven provinces or municipalities in China were measured.Results showed that manures riched in organic materials and inorganic minerals elements,such as nitrogen,phosphorus,potash,calcium,magnesium,iron,sodium,manganese,and cobalt.Moreover,the contents of some heavy metals(arsenic,copper,zinc,chromium) and salinities were high in livestock and poultry manures;The content of copper,zinc,chromium and arsenic was in range of 10.7—1591 mg/kg,71.3—8710 mg/kg,0—688 mg/kg and 0.01—65.4 mg/kg respectively in 55 samples of pig and chicken manures.Meanwhile,the antibiotics residues of tetracycline were detected in the manures.The average content of OTC,TTC and CTC for 32 samples of pig manure was 9.09 mg/kg,5.22 mg/kg and 3.57 mg/kg,(respectively,) and the average content of OTC,TTC and CTC for 23 samples of chicken manure was 5.97 mg/kg,2.63(mg/kg) and 1.39 mg/kg,respectively.As a result,the livestock and poultry manures must be harmlessly processed before land utilization.