七十年代以来,在我国西南地区丘陵旱地发展了一种以增产玉米为中心的小麦、玉米、甘薯(红苕)间套种耕作制度,也称为旱三熟制。其中以四川省种植面积最大,达1,500多万亩,占该省丘陵旱地的三分之一。云南、贵州和广西部分丘陵旱地也在试验推广。 Since the 1970s, an inter-crop farming system has been developed in the hilly drylands of southwestern China, where wheat, maize and sweet potato (red mulberry) are mainly used as yield-increasing corn, also known as dry farming system. Among them, Sichuan Province has the largest planted area of ​​more than 15 million mu, accounting for one third of the hilly drylands in the province. Some hilly drylands in Yunnan, Guizhou and Guangxi are also experimentally popularized.