Analysis On The Models And Price Ratio Of Northeast China Corn-soybean Rotation System In Heilongjiang Province

The Northeast Black Soil Region is the most important grain production region in China,the typical crop rotation system is corn?wheat?-soybean.Since 2008,under the stimulation of economic interests,the corn continued cropping model has been widely adopted by farmers,which reduces soil quality and increases greenhouse gas emissions.Adopting crop rotation system is useful in improving soil quality and reducing greenhouse gas emissions that is widely advocated by Chinese government.However,currently,the crop rotation system does not lead to widespread implementation.This was partly due to a lack of effective long-term policies to safeguard the farmers'interests for adopting crop rotation system.This paper aims to estimate future trend of organic carbon,greenhouse gas emissions and crop yield in different corn-soybean rotation system by using dndc model and to identify a reasonable price ratio between corn and soybean to safeguard the farmers'interests,which effectively encourage farmers to adopt corn-soybean rotation system.The main findings are as follows:?1?An economic benefit gap between corn and soybean and an uncertainty in the crop rotation system were the main reasons why the crop rotation system does not lead to widespread implementation.In 2016,the sown area ratio between soybean and corn was 0.6:1?0.4:1 for 2015?.The corn-soybean rotation system was widely adopted in the center and north of Heilongjiang,but the corn cropping model has not been widely adopted in the south of Heilongjiang.?2?According to the results of the DNDC model,compared with the corn cropping model,adopting corn-soybean rotation system has higher total nitrogen and a lower CO₂ emissions.In the south of Heilongjiang,when the corn-soybean rotation system is three years corn-one year soybean,the crops yield is highest.There is no significant difference in crops yield for different corn-soybean rotation system in the center of Heilongjiang.The corn yield in north of Heilongjiang is lowest,and planting soybean has a comparative advantage.Therefore,further crops rotation system in Heilongjiang should be as follows:1)south:two or three year's corn+one year soybean;2)center:one year corn+one year soybean;3)north:one year crops+two or three year's soybean.?3?In order to safeguard the farmers'interests for adopting crop rotation system,the reasonable price ratio between corn and soybean was 1:2.94.The local government should establish a subsidy standard based on the difference between reasonable price ratio and actual price ratio.In order to maintain the sustainability of adopting crop rotation system by farmers in Heilongjiang.First,the local government should pay ecological compensation to the farmers who adopting crop rotation system.Second,the local government should play a guiding role in this process and reasonably arrange rotation patterns.At last,the quality and yield of soybean needs to improve to increase the benefits of soybean cropping.