| Uneven distribution of precipitation in time and space in our country, An unreasonable water resources matching, which lead to the shortage of water resource utilization, especially in the field of agriculture where water consumption is the largest in China. At the same time, Because saline-alkali land more and widely distributed in China, If we make full use of the saline-alkali land, it will make a great significance for the food security and improving the agricultural productivity. Biochar is a low-density charred material, wood, crop waste biomass, plant leaves or other biomass waste produced by burning biomass under conditions of low temperatures and minimal oxygen.Biochar addition can increase soil porosity, lower bulk density and density,enhance the capacity of soil moisture, reduce the acidity of soil,increase the organic matter content, increase soil nutrient content, increase soil CEC and reduce the losses of soil nutrient. Biochar is likely to play a role in relieving the contradictions of China’s agricultural water and providing certain theoretical basis for the improvement of saline-alkali land.By indoor simulated test, this paper preliminary discusses the kinds of biochar, biochar addition amount, particle size of biochar on soil water and salt migration, to relieving the contradictions of China’s agricultural water and providing certain theoretical basis for the improvement of saline-alkali land, We get the following conclusions:1. Biochar addition can improve the soil water-holding capacity and capillary water upward movement. The soil water-holding capacity increases with the increase of content of biochar. Add small size biochar soil water-holding capacity is greater than the big size biochar and add bamboo charcoal soil water-holding capacity is greater than the wood charcoal. The phreatic water recharge is increased with the addition amount of biochar and Recharge rate change process with time meet kostiakov infiltration model. Biochar addition can obviously affect soil evaporation, but the different raw material and size of biochar, the different effect.At the low content(5%) of biochar,it can effectively restrain the soil evaporation.2. Biochar addition have significant impact on soil salt accumulated in the soil surface.but the effect is closely related to the biochar addition content. At the low content(5%) of biochar addition, it can effectively restrain the soil evaporation, reduce the salt accumulation amount in the surface soil,and with the increase of biochar addition content, increase the degree of the soil evaporation and the salt accumulation amount in the surface soil. The influence of biochar addition on accumulation process of different soluble salt ions in the surface soil is different. Biochar addition can increase the accumulation of Na+ and Cl-, reduce effectively the accumulation of Ca2+ and Mg2+, and enhance the SAR value. Biochar addition can improve the soil water and Soluble ion migration velocity, have no adsorption for soluble salt ions, Small particle size of biochar processing rate of soil water and salt migration is greater than the big size biochar, bamboo charcoal processing of soil water and salt migration rate is greater than the wood charcoal.3. The results showed that biochar addition can significantly reduce the moistube-irrigation cumulative infiltration and with biochar added, the greater the amount of the effect is more obvious.In a word, inhibit leap upward migration of soil moisture and promote the moistube-irrigation soil moisture sideways and downward migration. The water content of wetted region of moistube-irrigation increase with the increase of biochar addition. Biochar addition can improve the water-saving ability of moistube-irrigation. |
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