Effects of long-term application of organic manure and chemical fertilizer on the contents of Zn, Mn, Fe and Cu in soil were studied. The results show that the organic manure is a good resource of Zn, Fe and Cu. After long-term application of organic manure, the available Zn increased 8 times from 0.2 to 1.6 mg/kg; avai- fable Fe increased by 63.9% from 5.32 to 8.72 mg/kg; and available Cu increased by 17.5% from 1.14 to 1.34 mg/kg. Part of increased nutrients came from organic manure, and part from the decomposition and mineralization of soil Zn, Fe and Mn because the soil pH was decreased due to the decay of organic manure and roots. Correlation coefficients of pH decrease and available Zn and Fe increase were -0.907^** and -0.981^** respectively, while correlation coefficients of pH decrease and total soil Fe and Mn decrease were 0.864^** and 0.791^** respectively, ahowing a close correlation between the availability of Zn, Fe and Mn and the pH of Soil.