Studies On Utilization Of Saltish Water Under Straw Mulching

There are a great amount of salt and saltish water in many areas such as the north, northwest and coastland of China who is short of fresh water resource, especially in the saline soil areas. At present saltish water is not really regarded as a kind of resource that can be used, so exploitations of saltish water and studies on soil ecological effect and crop increase production after irrigated with saltish water has great significances in solving water crisis and guiding agricultural production.In the experiment on bases of previous saltish water utilization, the affection of saltish water on the germination and emergence of maize and cotton is studied and firstly soil and crop effects of irrigation with saltish water under straw mulching are inquired systematically. A mathematical model of transport of water and solute after irrigated with saltish water under straw mulching is formed and the regulations are studied. At last some measures such as straw mulching and irrigation with saltish and fresh water alternatively can be used to alleviate the negative effects.The results indict: (1) Saltish water can restrain the germination and emergence of maize and cotton to some degree, but if it is used to build soil moisture, the relative emergence ratio would reach 50-80%.The growth of cotton can be affected by irrigation with saltish water whenever the ground is mulched or not. During the seedling and flower stage, the plant height, leaf area, fresh weight and dry weight etc. would decrease along with the increase of mineralition degree of water. During the rainy season, because soil salt content drops gradually caused by the leaching function of rain and at the same time the salinity tolerance of plant enhances, the growth of cotton is restrained less by irrigation with saltish water than before. (3) Straw mulchingcan not only reduce the soil evaporation, conserve soil water and increase soil moisture content, but also restrain soil surface salification effectively and lighten the negative effect of saltish water on the growth of cotton. This proved that straw mulching is a good measure to exploit saltish water resource. (4) In compared with irrigation with saltish water all, irrigation with saltish and fresh alternatively can decrease soil salt content and increase cotton yield. Especially when fresh and 7g/L salt water are alternatively used to irrigate cotton, the yield only decrease 4.2% than that of irrigation with, fresh water. So irrigation with saltish and fresh water alternatively is also a feasible way to exploit saltish water. (5) Despite mulched or not, after irrigated with saltish water, soil water and salt movement concluds three obvious stages: Evaporation and salt accumulation in spring, Precipitation and eluviation in summer and Evaporation and salt accumulation in autumn. (6) Irrigation with saltish water probably causes soil secondary salinization, and some measures including prevention and harnessing must be taken and prevention measures should be put first. In the experiment mathematical model of water and solute transport irrigated with saltish water under straw mulching is formed and the regulations are studied. The results show that the calculation data are coincided well with the measured ones and if the parameters of soil water and solute transport are in harmony with the facts, it is possible to forecast the transport of soil water and solute. These can provide foundations in theory and practice for the exploitation of saltish water.