滨海盐渍土原土滴灌水盐调控对土壤水力性质的影响

    Effect of water and salt regulations under drip irrigation on soil hydraulic properties in local coastal saline soil

    • 摘要: 为研究滨海盐渍土滴灌原土水盐调控不同处理对土壤导水率(K)、土壤孔隙大小分布常数(Gardner α)、土壤孔隙对水流贡献率等水力性质的影响,在滨海盐渍土上进行滤层及基质势(-5、-10、-15、-20、-25 kPa)处理的原土水盐调控试验。用圆盘入渗仪在-15、-6、-3、0 cm 4个连续增大的负压下进行入渗测定,并计算不同负压下导水率、土壤孔隙大小分布常数、孔隙级别对水流的贡献率。结果表明:经原土水盐调控后,各处理的饱和导水率、土壤孔隙大小分布常数较对照增大,在-6和-15 cm水头下的导水率较对照减少,在-3 cm水头下的导水率无明显变化规律。滤层处理下土壤的饱和导水率、-6 cm水头下的导水率、土壤孔隙大小分布常数较无滤层处理有显著提高;各处理土壤大孔隙对水流的贡献率大于对照处理,中等孔隙2及小孔隙对水流的贡献率小于对照处理。滤层处理是不同级别土壤孔隙对水流贡献率大小的主要影响因素,其中滤层的土壤大孔隙、中等孔隙1对水流的贡献率显著高于无滤层。可见,经原土水盐调控后,土壤饱和导水率、-6 cm水头下的导水率、土壤孔隙大小分布常数明显增加,土壤大孔隙增加,小孔隙减少,土壤结构得到改善。

       

      Abstract: In order to study the impact of filter and soil matric potential (-5、-10、-15、-20、-25 kPa) treatments on soil hydraulic conductivity K, Gardner α, and the contribution of pore size classes to flow in coastal saline soil, disc infiltration experiments at pressure heads of -15,-6,-3, and 0 cm were implemented. The results showed that, after local soil salt-water regulation, the hydraulic conductivity Ks and Gardner α were higher than that of the control (CK), and the K6, K15 were smaller than that of the CK, and K3 had no obviously changes. Through the tests of between-subjects effects with two factors of filter and soil matric potential treatments, filter treatment was the main factor to the hydraulic conductivity K, Gardner α, the Ksand K6, Gardner α of filter treatment was significantly larger than non-filter treatment. Contribution of macropores (>0.5 mm) to flow of filter and soil matric potential treatments was higher than CK, and the contribution of mesopores2 (0.25-0.1 mm) and micropores (<0.1 mm) to flow was less than CK, respectively. After the tests of between-subjects effects with two factors of filter and soil matric potential treatments, filter treatment was the main factor to the contribution of pore fraction to water flow. The contribution of macropores (>0.5 mm) and mesopores1 (0.5-0.25 mm) to flow under filter treatment had a significantly difference to the non-filter treatment (sig: 0.038, 0.014, respectively). The soil hydraulic conductivity Ks, K6 and Gardener α had a significantly increase, the contribution of large pore classes to flow increased too. The contributions of small pore classes to flow decreased after local soil salt-water regulation, so it was concluded that the soil structure was getting better after salt-water regulation.

       

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