小麦、玉米一年两熟是华北平原最重要的种植制度。由于全年热量条件难于满足一年两熟的要求,鲁、豫和冀南多采用麦垅套种玉米的办法,但在京津地区,由于农业机械化程度较高,为了解决两茬作物争热量的矛盾,前几年多采取冬小麦复种早熟玉米的办法,秋分节是种麦的适期,夏玉米必须赶在9月下旬收获。近几年来,由于农业科技工作者的努力,在热量更为紧张的华北北部边缘地带的 Wheat, corn two crops a year is the most important planting system in the North China Plain. Due to the year-round heat conditions are difficult to meet the requirements of two crops a year, Shandong, Henan and Henan more use of maize intercropping corn approach, but in Beijing and Tianjin areas, due to the higher degree of agricultural mechanization, in order to solve the two crops crop heat Contradiction, a few years ago to take the method of multiple cropping of early wheat, early autumn is the appropriate period of wheat, summer corn must catch in late September harvest. In recent years, due to the efforts of agricultural scientists and technicians, on the more intense northern edge of northern China