Copper content in animal manures and potential risk of soil copper pollution with animal manure use in agriculture

With the rapid development of livestock and poultry production and the wide abuse of copper as an additive in most animal feeds in China, the risk of soil copper (Cu) pollution due to the use of animal manure in agriculture has become more and more focused. The objectives of this study were to investigate the concentrations of Cu in pig, cattle, chicken and sheep manure and in a variety of animal feeds in Beijing and Fuxin, and to assess the potential risk of soil Cu pollution due to the use of these manures in agriculture. We collected 215 samples of animal manures and 210 samples of animal feeds. The results showed that the mean Cu concentrations in pig, cattle, chicken and sheep feeds were 131.7, 22.4, 29.0, and 11.3 mg kg−1, respectively. Copper concentrations in the respective manures were 699.6, 31.8, 81.8, and 66.85 mg kg−1. In addition, Cu concentrations in pig, cattle, and chicken manures were positively correlated to that in their feeds, respectively. The inventory of animal manures applied to land indicated that pig manure was the major source of Cu input both in Beijing and Fuxin. Calculation of the Cu loading rate showed that manure application might pose a potential risk to farmland according to the current standard issued by Chinese Ministry of Environmental Protection, especially in Beijing. This study may assist in understanding the risk of Cu from animal manure land application, aid in developing strategies to reduce the Cu input to agricultural lands and promote policies to protect soil quality.