Effects of Guilspare requirement on soil evaporation and the vertical distribution of soil water and salt

The Tarim Desert Highway shelterbelt,436 kilometers long,locates in the hinterland of such an extreme arid environment in the Taklimakan Desert.Its main afforested species are Tamarix L.,Calligonum arborescens,and Haloxylon ammodendron,which are good windbreak and sand-fixation trees with strong salt and drought resistance.The strong soil evaporation and capillarity make soil salts from irrigation move upwards with soil water and accumulate on soil surface gradually,even form salt crusts,and then soil evaporation and irrigation management become focuses of the shelterbelt sustainable development.In order to explore suitable water-saving techniques for the Tarim Desert Highway shelterbelt,a simulative experiment with Micro-lysimeter(MLS) was conducted to research the effect of Guilspare under saline water irrigation on soil evaporation and vertical distribution of soil water and salts in the hinterland of Taklimakan Desert.In the study,a solution of 1.5 % v/v of the hydrophobic polymer Guilspare was sprayed to the aeolian soil surface at applied quantity of 0.5,1.0,2.0,3.0,4.0,5.0,6.0 and 7.0 L/m2,to text the inhibition on soil evaporation and effect on soil water and soil salt movement.The results show as follows:(1)Guilspare inhibits soil evaporation significantly and a logarithmic relationship was observed between its applied quantity and the accumulative soil evaporation,and at the quantity 4.0 L/m2 the daily evaporation of the blank(CK) was higher than that of other treatments in the early days while lower in the later days,and at the quantity 4.0 L/m2 the daily evaporation of CK was always more than the treatments;(2)the inhabitation of the treatment 6.0 l/m2 was maximum and differed from other treatments(7.0 L/m2 except) significantly at P 0.05,and in addition,the maximum inhibition was not arrived in early days but on the 10th day after the irrigation beginning;(3)Guilspare weakened the evaporation intensity at first phase obviously,the weakened degree had close relations with applied quantity and was maximum at 6.0 l/m2;(4)Soil water and soil salinity are most important factors to limit sand-fixation trees growth.Therefore,soil moisture and soil electric conductivity of soil surface,0-2 cm,2-6 cm,6-10 cm and 10-14 cm soil layer were analyzed.According to analysis results,under the same initial moisture content,both the moisture and extract electrical conductivity(7.0 L/m2 except) decreased at the soil surface(0-2 cm) while increased at 2-6 cm and 6-10 cm soil layers with increasing Guilspare.Basically,the results are helpful for the development of high-efficient water saving irrigation techniques and the establishment of reasonable irrigation strategies,and provide scientific references for the greening and water management along the whole Tarim Desert Highway shelterbelt.