盐碱化会引起土壤导水率的滞后现象
Salinity and sodicity can cause hysteresis in soil hydraulic conductivity
摘要：
土壤盐碱化和钠化可对土壤结构造成有害影响，对灌溉农业产生重要影响。然而，人们仍然缺乏关于盐碱化和钠化造成的土壤结构退化在多大程度上可以逆转的知识。我们研究的目的是考察溶质组成的历史对饱和导水率（Ksat）可逆性程度的影响。我们系统地研究了盐度（电解质浓度）和碱度（钠吸附比）对Ksat的影响，不同的粘粒含量的三种土壤。土柱实验产生滞后曲线，其中Ksat在初始衰减后不回到其原始值。我们开发的指数，量化Ksat退化和可逆性的程度，并发现，与我们的预期相反，高敏感性退化并不总是与低能力的恢复。测量土壤膨胀有助于我们辨别什么时候退化主要是由膨胀或粘土分散引起的。我们的研究结果强调，需要了解的滞后所造成的盐度和碱度，旨在更好地管理农业土壤的可持续长期使用。
英文摘要：
Soil salinization and sodification can cause detrimental effects to soil structure, with important implications to irrigated agriculture. Knowledge of the extent to which degradation in soil structure due to salinization and sodification is reversible is still lacking, however. The objective of our study is to examine the effects of the history of solute composition on the degree of reversibility in saturated hydraulic conductivity (Ksat). We systematically investigate the effects of salinity (electrolyte concentration) and sodicity (sodium adsorption ratio) on Ksat, for three soils of varying clay content. The soil column experiments yielded hysteresis graphs, in which Ksat does not go back to its original values after initial decay. We developed indices to quantify the degree of Ksat degradation and reversibility, and found that contrary to our expectations, high susceptibility to degradation does not always correlate with low capability of rehabilitation. Measurements of soil swelling helped us discern when degradation was mainly caused by swelling or clay dispersion. Our findings underscore the need of understanding hysteresis caused by salinity and sodicity, aiming at a better management of agricultural soils for sustainable long-term use.
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