| At the present, soil saline-alkali and secondary salinized soil phenomenon has become a serious environmental problem in the world. The main methods of controlling saline-alkali soil are mechanical method, chemical and biological. The mechanical methods are digging ditches to drain salt or use of water for leaching salt out. Chemical methods use chemicals to improve the soil. Although mechanical and chemical methods have made obvious achievement in a long term, they are very expensive and have many problems: such as soil erosion, water pollution, slitting up and decrease in the physical and chemical quality of the soil. So the utilization scope is limited. To control the salinization of soil, especially inland salinization, many people have proved that biological method is the most effective method; it can improve the soil quality. But most plants can not live in salinity condition. Some plants that can live in saline conditions are weeds, but have lower economic value. With the rapid development of science and technology, use biological methods to improve salinized land can conserve water and soil; it will become one of the sustainable and stable methods. Biological methods usually use salt tolerant forage to improve the saline-alkali land. Research has shown that salt tolerant forage can improve saline-alkali land effectively. This research mainly emphases physiological aspect, salt on tolerant mechanism, salt tolerant adaptability and yield etc. These researches are seldom about planting in farmland, but especially Chinese herb medicine has developed in recently years. Main research on herb medicine has taken introduction and planting adaptability in saline-alkali land, such as introduction of Eucommia ulmoides Oliv. introduction and fine variety selection of Lycium barbarum L., and artificial Ephedra cultivation in saline-alkali land. This article researched the tolerance and control ability of Astragalus membranaceus Bge. in saline-alkali land in different cultivation condition. Astragalus membranaceus Bge. is one kind of Chinese herb medicine. It belongs to leguminous plant, and its property is sweet, a little bit warming. It strengthen the heart, diuresis, diminish inflammation, disinfect, increase immunity ability affect etc. It is one kind of no poisonous and widely used herb medicine. The task of this article is to research the movement state of salt and water in secondary saline-alkali land, and different densities, fertilization, ages of As tragalus membranaceus Bge's salt improvement effect, and chose one of effective, scientific biological method to develop herb medicine in saline-alkali land.1)Chinese herb medicine has good salt control effects, and the effects are related with different species.2) Among 5 densities of Astragalus membranaceus Bge. D1: spacing in the rows 15cm; D2: spacing in the rows 20cm; D3: spacing in the rows 25cm; D4: spacing in the rows 30cm;CK: uncovered land, pH value decreased when density increased, result shows Astragalus membranaceus Bge. can decrease pH value and the affect has positive correlation with densities. Four soil layers of CK soil soluble salt distributed according to high in up and down layer. But after plant Astragalus membranaceus Bge. high salt layer distributed in 20-40cm layer. In Astragalus membranaceus Bge land Ca+,Mg2+ and Na+decreased and K+ increased,K+ / Na+ increased this will be good for improving the saline-alkali land. Distributed according to lowest in up layer---lower in middle layer-----high in down layer, this distribution is not the same with positive ion, it means cover of Astragalus membranaceus Bge does not change the regulation of Cl- and SO42- go up layer with water evaporation. It decreased water evaporation speed and quantity and absorbed some Cl- and SO42- , so Cl- and SO42- decreased in up layer. The highest yield of Astragalus membranaceus Bge. is and other growth index are best in, D3 is the best density among the 5 densities.3) Salt content is related with different time, the highest salt content appe...
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