The Irrigation System Of The Typical Crop Under Mulched Drip Irrigation With Different Brackish Water In Hetao Irrigation District In Inner Mongolia

with the development of economy and society, the water shortage is becoming increasingly prominent. The conflict of using water between industry and agriculture exacerbates. It will be a trend to develop water-saving irrigation in the future agricultural irrigation. In recent years, the area of water-saving irrigation rapidly develops in Inner Mongolia. That of spray irrigation is 45.28 hm-,and that of mulched drip irrigation is 46.86hm2. As a water-saving technology, mulched drip irrigation has a rapid development in present agriculture.with a great promotion and a large application. However, the water using coefficient of mulched drip irrigation is less than 0.9 in Inner Mongolia, partly less than 0.8. It is far from the level of 0.9 to the design specifications. Therefore the experimential study of the filed under mulched drip irrigation carried out in Hetao Irrigation District in Inner Mongolia, which provides a basic theory and a technical support for the development of a large area under mulched drip irrigation.The research showed that mulched drip irrigation could appropriately increase the crop planting density because of the superior condition of water and fertilizer. When planting density increased by about 15 percent, the yield increased the most, by about 5 percent.The crop yields varied widely in different hydrological years. There was a good correlation between irrigation amount and yield under mulched drip irrigation, which was in line with the change of parabola. The irrigation amounts which measured by the maximized yield were different in different hydrological years. That showed that the irrigation amount in the average year was 23mm less than that in the average year, but 23mm more than that in the wet year. There were 9 times irrigation for sunflower in the growth period in the average year, while 14 times for maize, with the same irrigation quota of 22-25mm. The irrigation amout in different hydrological year had a difference of about 23mm.That meant the irrigation frequency had a difference of 1 in different hydrological years. There had a change about the crop coefficients under between the mulched drip irrigation and the traditional surface irrigation. The crop coefficients under the mulched drip irrigation were larger in the initial growth and the maturity periods. while smaller in the fast growth and the middle growth periods.Under the mulched drip irrigation, the irrigation quota was less, with no significant deep percolation. The water and the nutrients could directly reach the crop root zone. Thus it greatly improved the efficiency of water and nutrients. The mulched technology could effectively prevent the surface evaporation. Campared with the surface irrigation, the water use efficiency significantly improved under the mulched drip irrigation. It was up to more than 0.92. The water was saved by about 26%. while the fertilizer 15% to 30%. There had a consistency in the growth indicators. But because the planting density improved, the crop yield under mulched drip irrigation was larger than that under surface irrigation. Considered the indexes of the crop yield、tilities and fertilizer, the profit under mulched drip irrigation increased by more than 4500RMB/hm2.The mulched drip irrigation influenced by the temperature and the frequency of the irrigation water. The ground temperature under the mulched drip irrigation was lower by 0.6℃-1℃ than that under the surface irrigation in the tillage layer during the growth period. Because the irrigation quota under the mulched drip irrigation was less, there was less or no rinse water during the whole irrigation cycle in the situation that the soil matric potential was higher. The salinity brought in by the irrigation water mostly accumulated in soil, except some absorbed by the crop. It caused the higher salinity appeared in the soil root zone and the mulched outside. Therefore, in the formulation of the irrigation system under the mulched drip irrigation, the water and salinity regulation should be considered according to irrigation water quality. If necessary, the irrigation to wash salt could be taken.