Long-Term Effects of Fertilizer and Manure on Corn Yield, Soil Carbon, and Other Soil Chemical Properties in Michigan
Historically, manure has been used as a major source of nutrients for crop production. Manure is usually considered as a source of nitrogen (N) and, to a lesser extent, a source of phosphorus (P), potassium (K), and micro nutrients. One hundred years of continuous chemical fertilizer use on wheat, on a clay loam soil at the Rothamsted Experimental Station in England, has proven to be as effective as farm yard manure, producing equivalent grain yields. When nutrients are properly balanced, comparable corn silage yields can be obtained with either commercial fertilizer or manure. The soil carbon (C) level of the manured plots was directly related to the rate of manure applied. In 1982, after 20 annual applications of manure, soil C in the manured plots was significantly higher than nonmanured plots. The total soil N changes were very similar to soil C changes. The addition of manure significantly increased the soil N content.