Relationship Between Achnatherum Splendens Growth Development And Moisture-salinity Migration Under Drip Irrigation In The Severe Soil Salinity Of Abandoned Farmland

The experiment was started on severe soil salinity of abandoned farmland, non-irrigation, drip irrigation and flood irrigation was chosen. Moisture-salinity migrations, the root weight density in non-irrigation, pre-irrigation and post-irrigation were studied in order to reflect the characteristics of moisture-salinity migration and the root space-time distribution of Achnatherum splendens. Research on abandoned farmland, the establishment year and the second year determined soil physical and chemical indicators and root weight density, the aim was to show the soil improvement between years and the root distribution. With "S" shaped curve sampling method, periodic determinated Achnatherum splendens aerial parts and root fembers in order to summarize the development characteristics of each component. The main conclusions list as follows,1. Non-irrigationWith the time increasing, the moisture content decreased, salt accumulated to the surface and the root content gradually reduced in the surface but increased in the depth. Compared with the second year and the establishment year, the content of soluble salt deceased, but the content of organic matter, alkali-hydrolysable nitrogen, available phosphorus and available potassium was increased in the second year compared to that of the establishment year. Root content in 0-30 cm was less than that of the establishment year.2. IrrigationThe distribution law of moisture:In drip-irrigation, moisture distributed around the water dropper. And with the irrigation frequency increasing, the wetting front moved down, moisture content increased in the deep layer. Horizontal wetting front was always less than the vertical wetting front. In flood irrigation, water was increased along with soil depth, and the rate of increase was greater than drip irrigation. In both irrigation methods, moisture content near to the Achnatherum splendens root was a little less than the surrounding. Moisture content from 0 cm to 40 cm had greater variation than other soil depth.The distribution law of salt:the soil salt followed the movement of soil moisture, that is, in irrigation, salt was migrated away from the drip irrigation zone and accumulated in the middle, but in flood irrigation, comparing the pre-irrigation and post-irrigation, salt in the soil depth had returned to the ground.Root distribution:in drip irrigation, root content increased with the growth time of Achnatherum splendens and root distributed into the depth in vertical direction, and avoided high-salt accumulation zone in horizontal direction. In flood irrigation, root distributed into shallow depth in vertical direction, but trended to develop between the two lines in horizontal direction.In both irrigation methods, the law of salt content between years was that the second year<the establishment year< abandoned farmland. Organic matter and alkali-hydrolysable nitrogen were increased year-to-year, but available phosphorus and available potassium were slightly reduced. Root content in 0-30 cm of the second year was less than that of the establishment year.Throughout the trial period, the growth velocity of Achnatherum splendens showed as "fast-slow-fast-slow" in drip irrigation but "fast-slow-fast" in flood irrigation. The aerial parts and root fembers and their material accumulation of Achnatherum splendens trended to increase. At the end of growth, the aerial part in drip irrigation was higher than that in flood irrigation, but in contrast with root fember.