The intensification of livestock and poultry production has led to increased animal wastes as by-products,which pose serious environmental problems.Aerobic composting and pyrolysis technologies have been used to eliminate or reduce the risk of spreading of pathogens,parasites and weed seeds in animal wastes.These techniques lead to stabilized products,such as composts and biochars.However,heavy metal contamination in manure and manure-derived biochars may lead to their accumulation in soil.Heavy metal uptake by plants from the soil and successive accumulation in human tissues through the food chain can be harmful to human health.In a pot experiment,fresh and composted swine manure and its biochar were applied to an acid soil(Plinthudult)at application rates of 1%and 3%to evaluate their effects on the growth of pakchoi(Brassica Chinensis L.)as well as the uptake of Cu and Zn.Swine manure and biochar addition to the soil both significantly increased soil pH.The pHs in soil treated with biochar were higher,while the pHs in soil treated with compost were higher than in soil treated with fresh manure.The Cu and Zn contents in soils treated with swine manure and biochar were higher than the control soil.The Cu contents in soils treated with the highest rate of 3%manure and biochar exceeded the permitted value in Chinese Environmental Quality Standards for edible agricultural products.The long-term use of manure and biochar can cause Cu and Zn accumulation in soils.Pot experiments revealed that the land application of swine manure and biochar may significantly increase the biomass of pakchoi.The contents of Cu and Zn in the shoot of pakchoi were higher than those in the roots.The higher addition rate of swine manure increased the contents of Cu in the shoot,whereas it decreased the contents of Zn.Lower addition rates of biochar significantly decreased the Zn contents in the shoot.However,the content of Cu in pakchoi shoots was below that required by the Chinese Food Hygiene Standard,whereas the Zn content exceeded the Chinese Food Hygiene Standard of 20 mg Zn/kg based on fresh weight.The uptake of Cu by pakchoi was significantly correlated with DTPA-Cu contents in the soil,and a highly statistically significant correlation(P<0.01)was obtained between Zn contents in the shoots and soil pH.