Field Water Consumption And Control Of No-tillage With Mulch Soil-Crop System For Double Cropping Region In North China

The main problem of summer corn's production in North China is water management problem. Uneven rain distribution by time in North China often causes draughts in summer corn's growth periods, which threatens stabilization of summer corn's production and affects summer corn's yield. Field experiments in Yucheng County (Shandong Province) and Jingxian County (Hebei Province) were practiced in 1997-2000. Taken soil and crop as a whole system, this paper discussed water management and control for summer corn under no-tillage with mulch (NT) on the basis of soil water status, characters of summer corn's growth and water consumption. Results got below: 1. Water consumption character was changed for the changing soil water status and summer corn's growth under NT. (1) From the whole water consumption, the difference was not significant among treatments. Many years'experiments indicated that water consumption of NT was less18mm than that of conventional tillage (CT) and less 4 mm than that of direct drilling (DD). In dry years, NT could save more water. (2) From water consumption compose view, NT reduced soil evaporation and increased crop transpiration especially in summer corn's mid-later stage. Therefore, NT reduced water use for non-production consumption and increased water use for production consumption, which was benefit to yield improving. (3) From soil evaporation and crop transpiration phases view, soil evaporation reduced was mainly in young corn stage and the effect was significantly and transpiration increased was mainly in summer corn mid-late stage. (4) Yield could improve10% and WUE could increase 15% under NT, compared with DD and CT. NT could increase yields more than 10%. If CT got the yields higher as NT with WUE of CT, CT would consumed more water about 52mm than NT; with same methods, DD would consumed more water about 33.89mm than NT. Compared with conventional tillage, NT increased WUE about 15%. 2. High yield region, middle yield region and low yield region were partitioned on the basis of water consumption character of summer corn in NT soil-crop system and water resources status in North China Plain. Water control scenarios were put forward based on field water consumption characters in NT soil-crop system. In high yield region, high yield and high WUE was main object. The water control method was fully satisfying summer corn's water requirements and irrigating according to the actual precipitation condition. In middle yield region, limited irrigation was practiced and water consumption decrease while yield was not decreased more, on other words, water supply must meet to summer corn's critical stage such as elongation and tasseling stage. In low yield region, "life-maintaining water"should be guaranteed and other construction should be enforced. 3.NT altered soil surface condition for mulch cover and without tillage. NT improved available soil water for summer corn growth. Stronger "source and pool"and sound crop structure were built in NT system. NT reduced soil evaporation and increased transpiration, which improved summer corn's yield and WUE; so, NT is a good way to solve the unstable yield problem for summer corn.