Why does Sanjiang Plain in Northeast China not belong to monsoon paddy field agriculture?

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

Second, the mechanization and scientific and technological level of monsoon paddy fields are relatively low. Farmers generally engage in manual labor. Although irrigation and threshing by electric power have developed rapidly in the past two decades, 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.