亚洲一区欧美在线,日韩欧美视频免费观看,色戒的三场床戏分别是在几段,欧美日韩国产在线人成

To explore the role of sand column in improving the saline soil, a series of experiments combining soil column simulation and field monitoring were carried out. The results indicated that the average water infiltration rate of the soil column reached to 0.132mm/min in three washing repeats with the help of sand columns, which was 1.73times higher than that of the soil column without sand columns. And the salinity decreased from 3.78% to 0.51% with sand columns, which was 1.45times higher than that of the soil column without sand columns. Moreover, the former’s pH value decreased by 0.12 compared with the latter’s after washing. Similar results could be found in the field contrast experiments. The increase in density of the sand column could enhance the desalination rate and the evenness of salt washing, and also inhibit the growing of pH value. The desalination rate reached to 83.9% and the vertical evenness difference was 3.9% with sand columns at an interval of 0.67m in field contrast experiments. But without sand columns, the desalinating rate was just 53.2% and the vertical evenness difference stood at 33.1%. The pH value decreased by 0.59 with the sand columns. To a certain degree, there was a correlation among the salt content, pH value and the water infiltration rate. The salinity went down with the increase of pH value and water infiltration rate. With all factors taken into consideration, the 0.67 m interval of sand column was the best. 