Chemical transformation of Cu and Zn derived from swine faeces with composting and their movement to plant.

摘要

To evaluate the chemical transformation of Cu and Zn in swine faeces with composting, the rate of their chemical forms was compared before and after composting with swine faeces composts of chaff, rice bran and sawdust. The uptake of Cu and Zn by plants was also examined. Water-soluble and 0.1 M HCl-soluble forms of Cu and Zn, especially water-soluble Zn, were increased during swine manure composting. The increased availability of Cu and Zn was caused by mineralization of organic Cu and Zn in the manure. However, the formation of available Cu and Zn by composting did not increase their uptake by plants by standard application of the compost (20 t/ha). With 40 t/ha compost, however, the uptake of Cu and Zn was higher, indicated by the enhanced Zn content of plant leaves. It is suggested that for the prevention of plant contamination by heavy metals from swine faeces and their composts, the addition of inorganic Cu and Zn to blended feeds should be restricted and better uses, other than applicationto land, should be found for swine faeces and composts.