论文部分内容阅读
碱茅屑植物种植改良河西硫酸盐土壤的机制在于：（１）碱茅属植物植被覆盖降低土壤蒸发（主要通过植物叶面蒸腾散水），相应地减少地表积盐。碱茅属植物草地的积盐速度比灌水裸地低３～７倍，在减少盐分向上转移中，植被起重要作用；（２）草地建植后的前期脱盐中，灌水起主导作用。在研究地区的１５３６．３ｇ／ｍ２总脱盐量中，由灌水淋溶向下的可溶性转移盐量占８９％，但无植物覆盖的裸地，仍能快速积盐，相反有植物覆盖者积盐速度慢、积盐量少，裸地的积盐速度为８．９～１１．４ｇ／ｍ２·ｄ，碱茅草地仅１．１～４．ｌｇ／ｍ２·ｄ；（３）碱茅属植物种植可改善盐渍土壤的物理状况。主要是降低土壤容重（３年生草地降低７．５％），土壤总孔隙度增加，土壤总团聚体增加２４．２％（３年生草地，０～１５ｃｍ土层）一２２．５％（ｌ５～３０ｃｍ土层），≥０．２５ｍｍ的水稳性团聚体增加１３．４％（牧草长势中等）一２２．６％（牧草长势良好），土壤透水系数增加３７．０ｍｍ／ｈ（４年生草地）一１４．４ｍｍ／ｈ（２年生草地）。
The mechanisms by which alkali fescue plants improve Hexi Sulfate soil are as follows: (1) The vegetation cover of the lower Phlomoplasma decreases the soil evaporation (mainly through the foliar evapotranspiration of plants), and reduces the surface area of salt accordingly. The rate of salt accumulation in the grassland of Phragmites australis was 3 ~ 7 times lower than that in the bare land of irrigation. Vegetation played an important role in reducing upward salt transfer. (2) In the early desalination of grassland, irrigation played a leading role. In the total desalination amount of 1536.3 g / m 2 in the study area, the amount of soluble salt transferred downward by irrigation leaching accounted for 89%, but the bare land without plant coverage could still rapidly accumulate salt. On the contrary, plant cover salt accumulation Slow, less salt accumulation, bare salt accumulation rate of 8.9 ~ 11.4g / m2 · d, alkali grass that only 1.1 to 4. lg / m2 · d; (3) Plantation of the genus Phoebe can improve the physical condition of saline soils. Mainly to reduce the soil bulk density (7.5 years of grassland in three-year reduction), the total soil porosity increased soil total aggregates increased by 24.2% (3-year-old grassland, 0 ~ 15cm soil layer) a 22.5% (l5 ~ 30cm soil layer), water-stable aggregates ≥0.25mm increased by 13.4% (grass growth medium) a 22.6% (pasture good growth), the soil water permeability coefficient increased 37.0mm / h (4-year-old grassland) A 14.4mm / h (2 years old grassland).