Copper and Zinc Uptake by Pakchoi and Rice as Affected by Applying Manure Compost with Different Levels of Cu and Zn Concentrations

Cu and Zn are frequently added to livestock diets as additives to increase feed efficiency and production. This practice resulted in the higher contents of Cu and Zn in excrement of livestock. The aim of this study is to evaluate the effect of Cu and Zn concentration of manure compost and its application rates on the production and quality of pakchoi and rice. The pot experiments were conducted and the six manure compost were applied at 3 rates (20, 40, and 80 ton/ha), including the control and chemical fertilizer treatments. Results showed that the yield of the crops was enhanced by the compost application, and the Cu and Zn concentration in the edible part of crops were in normal range (pakchoi: Cu 1.8-10.4 mg/kg, Zn 39-160 mg/kg; rice grain: Cu 0.6-4.0 mg/kg, Zn 58-79 mg/kg). The potential risk of long-term manure compost application on soil quality was also evaluated. The total Zn concentration in soils may reach the regulation standard after 22 years of manure compost application at the rate of 40 ton/ha/year.