低洼盐渍区滴灌不同土壤水基质势对土壤盐分及速生杨生长的影响

Effect of Different Soil Matric Potentials on Distribution of Soil Salt and Growth of Poplar(Populus)by Drip Irrigation in Low-lying Saline Area

为探寻宁夏引黄低洼灌区植被快速构建模式,以速生杨为试验对象,设置-5,-10,-15,-20,-25kPa 5个滴灌土壤水基质势处理进行水盐调控试验。结果表明,低盐区呈椭圆状分布,且随灌水量增加而增大;基质势处理开始前强化淋洗阶段,盐分淋洗迅速,较初始值降低70.87%,单位脱盐灌溉水耗水率为41.7mm/(dS/m);基质势处理阶段,各处理整个土层盐分差异不显著,但0—40cm土层的ECe值和SAR有显著差异,且随基质势控制阈值的降低而线性增加。通过对速生杨树高、冠幅、株径、胸径及新稍生长量5个生长指标的主成分分析,发现-15kPa处理和-5kPa处理得分在均值以上,其余处理在均值以下。本着水资源高效利用的原则及盐分淋洗效果,确定-15kPa为本地区速生杨生态林构建的基质势控制阈值。

Irrigation districts in low-lying areas of Ningxia,where drawing water from Yellow River,suffered from salinization and poor ecosystem problems.Aiming to construct vegetation rapidly in these areas,experiments of water and salt management that chose poplar（Populus）as target plant included five drip irrigation treatments,in which controlled soil matric potential（SMP）higher than-5kPa,-10 kPa,-15 kPa,-20 kPa and-25 kPa respectively.Results showed low salinity zone,which enlarged as the irrigation water amount increased,appeared irregular oval.At the enhanced leaching stage that before the soil matric potential treatments was conducted,the salt leached rapidly with a decrease of 70.87% compared with the initial values and the water consumption per ECeunit（dS/m）decrease was 41.7mm.As the soil matric potential（SMP）treatments conducted,the ECeand SAR from 0to 40 cm depth soils had significant difference while significant difference was not showed in the whole depth soils.The ECeand SAR increased linearly as the soil matric potential controlled decreased.Principal component analysis of poplar＇s growth factors,including height,crown width,stem diameter,diameter at breast height（DBH）,and growth rate of treetop,showed the treatments of both-15 kPa and-5kPa got scores higher than the average value while others got lower scores than the average value.Based on principle of efficient water use and the effect of salt leaching,the-15 kPa could be used as a controlled SMP value to instruct the poplar ecology forestry construction in this area.