引用本文:张 越,杨劲松,姚荣江.咸水冻融灌溉对重度盐渍土壤水盐分布的影响[J].土壤学报,2016,53(2):388-400. DOI:10.11766/trxb201506240156
ZHANG Yue,YANG Jingsong,YAO Rongjiang.Effects of Saline Ice Water Irrigation on Distribution of Moisture and Salt Content in Coastal Saline Soil[J].Acta Pedologica Sinica,2016,53(2):388-400. DOI:10.11766/trxb201506240156
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咸水冻融灌溉对重度盐渍土壤水盐分布的影响
张 越, 杨劲松, 姚荣江
土壤与农业可持续发展国家重点实验室(中国科学院南京土壤研究所)
摘要:
室内咸水冰融化试验设置2个处理:7.5 g L-1咸水冰(SIW(7.5))、15 g L-1咸水冰(SIW(15)),探究了咸水冰融化过程中的水量、水质以及离子组成的变化;土柱模拟试验设置同一灌水量(150mm),4个处理:淡水直接灌溉(FW)、7.5 g L-1咸水直接灌溉(SW)、7.5 g L-1咸水冻融灌溉(SIW(7.5))、15 g L-1咸水冻融灌溉(SIW(15)),对比分析两种灌溉水质(淡水、咸水)和两种灌水方式(直接灌溉、结冰灌溉)对土壤(粉砂壤土)水盐动态的影响。结果表明:咸水冰融化过程中,初期融出水量较大,但含盐量和钠吸附比(SAR)较高,后期融出水量较小,含盐量和SAR很低;融出水的离子含量变化与电导率(EC)变化表现相同的趋势;小于3 g L-1的水的融出率分别是SIW(7.5)= 25.46%和SIW(15)= 32.78%。FW处理下,土壤中水盐运动持续时间较其他3个处理长,土壤导水率降低最快,灌溉水入渗完成时表层土壤含水量达到33.88%,显著高于其他处理。四种处理下,0~15 cm土层土壤的含盐量平均值分别为FW=2.32 g kg-1 、SIW(7.5)=2.80 g kg-1、SIW(15)=3.87 g kg-1、SW=4.31 g kg-1。同等灌水量下,SIW(15)处理下土壤脱盐深度最浅。离子分析表明:FW和SIW(7.5)处理下,0~25 cm土壤的钠吸附比(SAR)下降明显,显著小于SW、SIW(15);然而FW处理下,土壤碱化特征最为明显。综合而言,在淡水资源缺乏而咸水资源相对丰富的地区,中度矿化度咸水结冰融水灌溉可以有效降低根层土壤盐分,满足农业生产的要求。
关键词:  滨海盐渍土  咸水冰  钠吸附比  电导率  入渗  总碱度
基金项目:国家科技支撑计划项目(2013BAD05B02)、国家自然科学基金项目(41171181)、江苏省农业科技自主创新资金项目(CX(15)1005-1)资助
Effects of Saline Ice Water Irrigation on Distribution of Moisture and Salt Content in Coastal Saline Soil
ZHANG Yue, YANG Jingsong, YAO Rongjiang
State Key Laboratory of Soil and Sustainable Agriculture,Institute of Soil Science,Chinese Academy of Sciences
Abstract:
Saline ice water irrigation must go through two processes: saline ice melting and melt-water infiltration, which determine the effect of irrigation together. An in-lab saline ice melting experiment was conducted using saline water, two in salinity (7.5 g L-1 and 15 g L-1) to investigate changes in quantity, quality and ion composition of the saline water during the ice melting process, and a simulated soil column irrigation experiment designed to have four treatments in irrigation water: Treatment FW (irrigation with fresh water), Treatment SW (irrigation with saline water 7.5 g L-1 in salinity), Treatment SIW(7.5) (irrigation with saline ice melted water 7.5 g L-1 in salinity), and Treatment SIW(15) (irrigation with saline ice-melted water 15 g L-1 in salinity), and two treatments in irrigation mode (irrigation with water directly and irrigation with ice), was also conducted to explore effects of irrigation with saline melt water on water and salt movements in the coastal saline soil(silt loam in texture). Results show that saline ice, regardless of salinity level, melted similarly in melting process with melt water higher in volume, salinity and sodium adsorption ration (SAR) at the initial melting stage and lower in the late stage, and ion content and electrical conductivity (EC) of the melt water displayed a similar pattern. Only about 25.46% and 32.78% of the melt water flowing out from saline ice, 7.5 g L-1and 15 g L-1 in salinity, respectively, during its thawing process was less than 3 g L-1, which was critical in soil salt elution. In Treatment FW of the soil column experiment, soil water and salt movement lasted the longest, soil hydraulic conductivity dropped the fastest and soil water content in the surface soil layer after the irrigation water completely infiltrated into the soil was the highest, reach 33.88%, followed by 30.16% in Treatment SIW(15), 29.40% in Treatment SIW(7.5) and 28.64 in Treatment SW. In the four treatments, mean soil salt content reached 2.32 g kg-1 in Treatment FW, 2.80 g kg-1 in Treatment SIW(7.5), 3.87 g kg-1 in Treatment SIW(15) and 4.31 g kg-1 in Treatment SW. Among the four treatments, the same in irrigation volume, Treatment SIW(15) was the lowest in salt leaching effect. Soil ion analysis indicates that SAR in the 1~25cm soil layer in Treatments FW and SIW(7.5) dropped significantly far below that in Treatments SW and SIW(15). In Treatment FW, the feature of soil alkalization was the most outstanding. All the findings indicate that the relationship between wetting front depth and time follows a power function in Treatments FW and SW, however, the wetting front depth is associated with time linearly in Treatments SIW(7.5) and SIW(15); the fast dropping hydraulic conductivity in Treatment FW is attributed to swelling and dispersion of soil particles; the lower SAR in the top soil layer in Treatments FW and SIW(7.5) is due to the water with lower SAR leaching. SAR is positively related to salt in the soil profile, and soil alkalization is positively correlated with pH. To sum up, in areas deficient in fresh water source, but sufficient in saline water source, moderately saline water subjected to freezing and thawing process can be used in irrigation to effectively lower salt content in the topsoil and to meet the demand of the agricultural production for water.
Key words:  Coastal saline soil  Saline ice  Sodium adsorption ration  Electrical conductivity  Infiltration  Total alkalinity