Least limiting water range (LLWR) is a range in soil water content not limiting root growth, which integrates the effect of soil water retention, aeration, and penetration resistance. This study aimed to assess the effect of different long-term fertilization treatments on LLWR in the surface layer of a Vertisol. Soil samples were taken from six long-term fertilization treatments including no fertilization (Control), inorganic fertilization (NPK), inorganic fertilization plus low amount of straw (NPKLS), inorganic fertilization plus high amount of straw (NPKHS), inorganic fertilization plus pig manure (NPKPM) and inorganic fertilization plus cow manure (NPKCM) for measuring LLWR. Results showed that in comparison with the Control, the manure treatments (NPKPM and NPKCM) increased soil organic carbon content (SOC) more pronounced than the straw treatments (NPKLS and NPKHS). However, the water stable aggregates (WSA_0.25) in the manure treatments was much smaller than the straw treatments. Soil water content at field capacity (θ_FC) was significantly higher in the manure treatments (NPKPM and NPKCM) than the other treatments. However, soil water content at soil penetration resistance of 3 MPa (θ_PR) was significantly lower in the straw treatments than in the manure treatments. The LLWR in the manure treatments had sharper decline with bulk density than the other treatments. In comparison with the Control and NPK treatments, the straw treatments significantly increased the LLWR, but manure treatments did not, probably resulting from positive relation between SOC and penetration resistance at a given soil water content and less favorable effect of the manures on soil aggregation than the straw. The S index was significantly increased by the NPKCM treatment relative to the Control, and positively correlated with the SOC. The variation of WSA_0.25 instead of SOC could explain the change of LLWR under different fertilization treatments effectively. These observations imply that the LLWR could assess the effect of organic fertilizations on soil physical quality more comprehensively.

最低限水范围 (LLWR) 是一个不限制根系生长的土壤含水量范围，它综合了土壤保水、通气和渗透阻力的影响。本研究旨在评估不同长期施肥处理对 Vertisol 表层 LLWR 的影响。土壤样品取自不施肥（Control）、无机施肥（NPK）、无机施肥加少量秸秆（NPKLS）、无机施肥加大量秸秆（NPKHS）、无机施肥加猪六种长期施肥处理。粪肥 (NPKPM) 和无机施肥加牛粪 (NPKCM) 用于测量 LLWR。结果表明，与对照组相比，与秸秆处理（NPKLS 和 NPKHS）相比，粪便处理（NPKPM 和 NPKCM）增加了土壤有机碳含量（SOC）。然而，水稳定聚集体（WSA_0.25 ) 在粪肥处理中远小于秸秆处理。在字段容量（土壤含水量θ _FC）是粪便处理（NPKPM和NPKCM）比其他处理显著更高。然而，土壤渗透阻力为 3 MPa ( θ _PR) 秸秆处理显着低于粪肥处理。与其他处理相比，粪便处理中的 LLWR 随堆积密度的下降幅度更大。与 Control 和 NPK 处理相比，秸秆处理显着增加了 LLWR，但粪肥处理没有增加，这可能是由于在给定的土壤含水量下 SOC 和渗透阻力之间存在正相关关系，而且粪肥对土壤团聚的有利影响低于稻草。相对于对照组，NPKCM 处理的 S 指数显着增加，并与 SOC 呈正相关。WSA _0.25的变化代替 SOC 可以有效解释不同施肥处理下 LLWR 的变化。这些观察结果意味着 LLWR 可以更全面地评估有机肥对土壤物理质量的影响。