Temporal and spatial patterns of crop straw resources and their influencing factors in China

Clarifying the characteristics of the temporal and spatial changes in crop straw is of great significance to make the macro decision on the efficient use of straw resources and adjust the national planting structure adjustment. Based on the data from the National Statistical Yearbook, this study analyzed the main crop yields and grass-to-grain ratios from 31 provinces (municipalities and autonomous regions), and investigated the temporal and spatial distribution characteristics of crop sown area and straw resources and the associated main influencing factors during the past 20 years (1999-2018) in China. Results showed that rice, wheat, corn and soybean straw resources altogther accounted for 82.3%-88.3% of the national total straw amount, while other crops including millet, oil crops and cash crop straw resources accounted for 11.7%-17.7%. The main distribution of different straw resources were inconsistent across regions. Rice, wheat and soybean straw resources were mainly distributed in the middle and lower reaches of the Yangtze River, north China and northeast China, respectively. Corn straw resources were mainly distributed in north China and northeast China. In the past 20 years, the proportion of rice sown area remained stable at about 25%. The sown area of wheat decreased from 23.1% in 1999 to 18.7% in 2018, while the corn sown area increased from 20.8% in 1999 to 32.5% in 2018. The amounts of rice, corn, and soybean straw were positively correlated with their corresponding sown area. However, wheat straw was not related to its sown area. Overall, this study suggested that crop structure adjustment and straw resource utilization technology promotion in northeast China, north China, and the middle and lower reaches of the Yangtze River should be taken full consideration when optimizing the efficient use of national straw resources.