The Study On Correlation Between Soil Carbon Input Level,soil Organic Carbon Content And Crop Yield In Farmland

This paper explored the soil organic carbon saturation by analyzing the soil organic carbon content,carbon input level,nitrogen input level and crop yield in 36 long-term test sites in six regions of Northeast China,North China,South China,Northwest China,Southwest China and the middle and lower reaches of the Yangtze River.The aim was provided a theoretical basis for evaluate soil carbon sequestration potential and carbon input level under crop target yield by studied the relationship between soil organic carbon content,carbon input level and crop yield in different regions.The main results were as follows:(1)In the long-term experiment of the survey,the soil organic carbon balance value showed a saturation phenomenon after the curve increases and approaches the fixed value with the increase of farmland carbon input level(2)The carbon input level of farmland was 10000 kg/hm2 in the northeast,north,south,northwest,southwest and middle and lower reaches of the Yangtze River,the soil carbon sequestration potential was 13.45,-13.79,1.71,17.96,8.49,2.59 g/kg,respectively.In the case of carbon-free input,soil carbon sequestration potential was negative.In the northeast region,the soil exhibited carbon source characteristics at 0~10000 kg/hm2 carbon input level,and other regions indicated the characteristics of carbon sink with the increase of carbon input level.(3)Crop yield and soil organic carbon content,crop yield and carbon input showed a parabolic trend.Under the condition of a certain soil organic carbon content,crop yield and nitrogen input level demonstrated a parabolic trend.With the increase of organic carbon content,it was increased the yield of wheat in Northwest China,corn and late rice in Southwest China,wheat and corn in North China Plain,and middle and lower reaches of the Yangtze River,and the growth rate slowed down.