Enhancement of soil water holding capability is of great interest for the management of agro-ecosystems to increase water use efficiency and crop yields. Application of organic amendments has been reported to affect the wet range of the soil water retention characteristic (SWRC, pF ≤ 4.2) differently and knowledge of the impact on the dry range of the SWRC (pF > 4.2) is limited. In this study, we evaluated the effect of 33 years application of inorganic fertilizer and organic amendments, including wheat straw, cow and pig manure on the full range of the SWRC of a Vertisol. Results showed that long-term application of inorganic fertilizer did not significantly affect soil water retention. The addition of organic amendments, i.e. wheat straw, pig or cow manure in combination with inorganic fertilizer significantly increased the wet range of the soil water retention, which was attributed to improved soil structure by increased SOC content. However, plant available water content was not significantly improved by organic amendments. Application of organic amendments decreased or had no effect on soil water retention at pF > 5.5, indicating the hygroscopic water was less impacted by SOC content. Our results showed that the effects of organic amendments mainly improved the retention of the capillary water but not the adsorption of hygroscopic water. This provides new insights on the understanding of water behaviors in Vertisols.

提高土壤持水能力对管理农业生态系统以提高用水效率和农作物产量具有重大意义。据报道，使用有机改良剂会不同程度地影响土壤保水特性的湿润范围（SWRC，pF≤4.2），并且对SWRC干燥范围的影响（pF> 4.2）的知识有限。在这项研究中，我们评估了33年间施用无机肥料和有机改良剂（包括小麦秸秆，牛粪和猪粪）对Vertisol整个SWRC的影响。结果表明，长期施用无机肥料不会显着影响土壤保水率。添加有机改良剂，例如麦秸，猪粪或牛粪肥料与无机肥料的结合显着增加了土壤保水的湿润范围，这归因于SOC含量的提高，土壤结构得到改善。但是，有机改良剂并未显着改善植物体内的水分含量。当pF> 5.5时，施用有机改良剂减少或对土壤保水没有影响，表明吸湿性水受SOC含量的影响较小。我们的结果表明，有机改性剂的作用主要提高了毛细管水的保留能力，但没有改善吸湿水的吸附能力。这为了解Vertisols中水行为提供了新的见解。有机改良剂并未显着提高植物的有效水分含量。当pF> 5.5时，施用有机改良剂减少或对土壤保水没有影响，表明吸湿性水受SOC含量的影响较小。我们的结果表明，有机改性剂的作用主要提高了毛细管水的保留能力，但没有改善吸湿水的吸附能力。这为了解Vertisols中水行为提供了新的见解。有机改良剂并未显着提高植物的有效水分含量。当pF> 5.5时，施用有机改良剂减少或对土壤保水没有影响，表明吸湿性水受SOC含量的影响较小。我们的结果表明，有机改性剂的作用主要提高了毛细管水的保留能力，但没有改善吸湿水的吸附能力。这为了解Vertisols中水行为提供了新的见解。