美国宾夕法尼亚州农业科研人员,在羊茅属、早熟禾属、草藤等牧草的活草皮上试种玉米,既获得较高产量,又保存了草地植被。具体做法是:在夏季草地收获一茬干草后,不犁翻土地就播种玉米。播后即喷施化学生长抑制剂和除草剂,除草剂的施用量应小于使牧草致死的剂量,即仅达到亚致死剂量。施药后能使牧草在6—8周内处于休眠状态。以后当牧草逐渐 Pennsylvania, United States agricultural researchers, corn on the living grass of fescue, blueberry, grass and other pasture grass, both to obtain higher yield, and save the grass vegetation. The specific approach is: after harvesting a first crop of hay in summer grassland, sowing corn without plowing the land. Immediately after sowing, chemical growth inhibitors and herbicides should be sprayed. The amount of herbicide used should be less than the lethal dose of forage grass, ie, only the sub-lethal dose. Herb can be dormant within 6-8 weeks after application. Later when the pasture gradually