Long-Term Effects of Crop Residual and Inorganic Fertilizers on Yield and Soil Organic Matter for a Winter Wheat-Maize System in North China Plain

Long-term effects of inorganic and corn stalks organic nutrient sources on yield, soil organic carbon(SOC) and the relationship between crop yield and SOC were investigated in Dry-Land Farming Institute of Hebei Academy of Agricultural and Forestry Sciences, Hengshui, Hebei Province, China from 1981 to 2005. Hengshui is a part the North China Plain and the dominant cropping systems are Winter wheat-maize rotations. Recently the use of organic manure with grain crops has almost disappeared. This could reduce soil fertility and crop productivity in the long run. There were sixteen treatments applied to both wheat and maize seasons: Inorganic fertilizers as main plots and corn stalks as subplots and the main plot and subplot all have four levels expressed A and B respectively. So there are sixteen treatments with three replicates were set (A1,A2,A3,A4)*(B1,B2,B3,B4). After more than 20 years crop yield and SOC decreased in treatment of without fertilizers and only applicate corn stalks just sustain it. Combine application of inorganic fertilizers and corn stalks increase SOC and crop yield very strongly. For crop yield the more fertlizers the more increase. But the SOC will decrease as the more inorganiac fertlizer application and increase with the increase of corn stalks.