内陆干旱区不同灌溉制度对盐碱地滴灌土壤盐分离子分布的影响

通过田间试验研究覆膜滴灌条件下不同灌溉制度对土壤盐分分布的影响。试验通过控制滴头正下方20 cm处的土壤基质势下限进行灌溉,共设5个水平的土壤基质势处理:-5 kPa(S1)、-10 kPa(S2)、-15 kPa(S3)、-20 kPa(S4)和-25kPa(S5),每个处理重复3次,按随机区组布置。结果表明:不同土壤基质势控制对盐渍土中盐分分布有显著影响,不同土壤盐分离子的分布各不相同。其中Na+与Cl-容易被淋洗,两个生长季后,各处理土壤中Na+与Cl-含量有显著降低,并且土壤基质势控制越高淋洗效果越好。SO42-与HCO3-的淋洗效果主要受离子浓度影响,第一年淋洗效果较第二年明显。Mg2+与Ca2+不易随水移动,各处理无明显差异。经过两个生长季的灌溉淋洗,各处理土壤SAR值与全盐含量均有显著降低,根区内SAR值与全盐含量的降低幅度均在50%以上。研究结果对内陆干旱区盐碱地水盐调控和灌溉制度的制定具有理论意义和应用价值。

Effect of Different Irrigation Regimes on the Distribution of Soil Salt under Drip Irrigation on Saline and Alkaline Soil in Inland and Arid Region

Field experiment was conducted to investigate the effect of different irrigation regimes on the distribution of soil salt under mulch drip irrigation on saline and alkaline soil in inland and arid regions.The experiment included five treatments,in which controlled the soil matric potential(SMP) higher than-5 kPa(S1),-10 kPa(S2),-15 kPa(S3),-20 kPa(S4) and-25 kPa(S5),respectively,at 20 cm depth immediately under emitter.All treatments were repeated three times with the experimental plots following a complete randomized block design.Results showed that there was a significant effect of SMP threshold on the soil salt distribution and the different salt ions had the different characteristics of movement and distribution under mulch drip irrigation.Na+ and Cl-are easy to be leached and the content of which decreases considerably in the soil after two growing seasons.The average contents of Na+ and Cl-in the soil profile decreased with the increasing SMP threshold.SO42-and HCO3-contents in the soil were influenced by their concentration in the soil and there were more considerable differences among the five treatments for these two ions in the first year than those in the second year.Since it's hard for Mg2+ and Ca2+ to move with water,there was no significant difference among the five treatments on the distribution of these two ions.The SAR and TDS values in the soil decreased considerably and the decreasing rate of the two values in root-zone were all above 50% for each treatment.