Irrigation with Rainfall Harvesting for Spring Wheat with Plastic-Film Mulching in Semi-arid Areas

Compared with no irrigation, irrigating a mount of 30 mm has an great effect on the yield of spring wheat with plastic-film mulching. During the jointing stage, 30 mm irrigation increased yield by 371.1 kg/hm² and water use efficiency by 11.2%. Taking precipitation distribution into consideration, the jointing stage is the best water-supplementing period of rain-collecting and water-saving irrigation of spring wheat with plastic-film mulching. About 30, 60, 90 and 120 mm irrigation water at one irrigation increased the grain yield by 23.4%, 68.7%, 105.5% and 98.3%, and water use efficiency was raised by 16.3%～67.2%. Irrigation efficiency is 16.1 kg/(mm·hm²), 21.6 kg/(mm·hm²), 22.1 kg/(mm·hm²) and 15.43 kg/(mm·hm²), respectively. So the optimal irrigation amount of spring wheat with plastic-film mulching is 60mm at one time.