Why doesn't Sanjiang Plain in Northeast China belong to monsoon paddy field agriculture?

One is climate. Monsoon paddy fields are mainly distributed in tropical, subtropical and temperate monsoon climate zones, and the temperature is high all year round or in summer. The northeast plain is in the middle temperate zone, belonging to the temperate monsoon climate, with four distinct seasons, warm and rainy summer and cold and dry winter. The average temperature in July is 21~ 26℃;

Second, the mechanization and technology level of monsoon paddy field are low. Farmers generally engage in manual labor. Although electric irrigation threshing has developed rapidly in recent twenty years and the use of chemical fertilizers and pesticides has gradually increased, on the whole, the mechanization level and scientific and technological level of monsoon paddy field agriculture are still relatively low. While the northeast plain is higher.