Farmers pack wheat straw in the fields in Beigaoli Village in Xingtang County, north China's Hebei Province, June 14, 2018. Farmers here pack wheat straw as materials for power plants. (Xinhua/Zhang Haiqiang)

Farmers pack wheat straw in the fields in Beigaoli Village in Xingtang County, north China's Hebei Province, June 14, 2018. Farmers here pack wheat straw as materials for power plants. (Xinhua/Liang Zidong)

Wheat straw packs are seen in Beigaoli Village in Xingtang County, north China's Hebei Province, June 14, 2018. Farmers here pack wheat straw as materials for power plants.(Xinhua/Liang Zidong)

Farmers pack wheat straw in the fields in Beigaoli Village in Xingtang County, north China's Hebei Province, June 14, 2018. Farmers here pack wheat straw as materials for power plants.(Xinhua/Liang Zidong)