Changes In Organic Carbon And Nitrogen Of Morrow Plot Soils Under Different Treatments, 1904–1973

摘要: ABSTRACT The Morrow Plots, which were established in 1876 at Urbana, Illinois, are the oldest experimental plots America, and they contain longest continuous corn (Zea mays L.) plot world. This paper reports changes content of nitrogen organic carbon dark-colored soil on Plots during 70 years, 1904 to 1973, under different cropping systems treatments. In comparison with culture, crop rotations retarded decline carbon. However, without treatment did not maintain soils a high state productivity. Crop rotation plus appropriate fertilization produced highest yields also maintained levels.