Abstract The least limiting water range (LLWR) is a modern and widely used soil physical quality indicator based on predefined limits of water availability, aeration, and penetration resistance, providing a range of soil water contents in which their limitations for plant growth are minimized. However, to set up the upper and lower limits for a range of soil physical properties is a challenge for LLWR computation and hence for adequate water management. Moreover, the usual LLWR is given in terms of the soil water content in which only for field capacity and permanent wilting point, the matric potential range is known. In this paper, we present a procedure for calculating LLWR using Genuchten’s water retention curve parameters and introducing the least limiting matric potential ranges of agricultural soils, which we named LLMPR, defined as the range of matric potential for which soil aeration, water availability, and mechanical resistance would not be restrictive to plant growth. Additionally, we calculated the minimal air-filled porosity, field capacity, permanent wilting point, and limiting soil penetration resistance thresholds which define the upper and lower limits of LLWR and LLMPR. Finally, we present some application examples using experimental data (from cultivated and forest soils) and developed an algorithm for their calculation in the R software. The calculated soil physical restriction thresholds were sensitive to changes in soil structure and clay content and were changeable rather than fixed. Based on experimental data, our calculations with the calculated parameters showed that an increase in LLWR and its corresponding LLMPR could be achieved with improvements in soil structure. Higher water content at field capacity, as well as a larger soil penetration resistance threshold to a given root elongation rate were observed in the structured in comparison to the cultivated soil. The LLWR and LLMPR as presented in this study was computationally implemented as an R function (R software), named llwr_llmpr, and in an interactive web page, both available in the R package soilphysics, version 4.0 or later, available from https://arsilva87.github.io/soilphysics/ or CRAN ( http://cran.r-project.org/web/packages/soilphysics/index.html ).

中文翻译：

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具有计算物理限制阈值的农业土壤的最小限制水和基质潜力范围

摘要 最低限水范围 (LLWR) 是一种现代且广泛使用的土壤物理质量指标，它基于预先定义的水分可用性、通气性和渗透阻力限制，提供了一系列土壤含水量，其中它们对植物生长的限制最小。然而，为一系列土壤物理特性设置上限和下限对于 LLWR 计算以及充分的水管理来说都是一个挑战。此外，通常的 LLWR 是根据土壤含水量给出的，其中仅对于田间持水量和永久枯萎点，基质势范围是已知的。在本文中，我们提出了使用 Genuchten 保水曲线参数计算 LLWR 的程序，并引入了农业土壤的最小限制基质势范围，我们将其命名为 LLMPR，定义为土壤通气、水分可用性和机械阻力不会限制植物生长的基质势范围。此外，我们计算了最小充气孔隙率、田间持水量、永久枯萎点和限制土壤渗透阻力阈值，这些阈值定义了 LLWR 和 LLMPR 的上限和下限。最后，我们展示了一些使用实验数据（来自耕地和森林土壤）的应用示例，并开发了一种在 R 软件中进行计算的算法。计算出的土壤物理限制阈值对土壤结构和粘土含量的变化很敏感，并且是可变的而不是固定的。根据实验数据，我们对计算参数的计算表明，随着土壤结构的改善，可以增加 LLWR 及其相应的 LLMPR。与耕作土壤相比，在结构化土壤中观察到更高的田间持水量以及对给定根伸长率具有更大的土壤渗透阻力阈值。本研究中介绍的 LLWR 和 LLMPR 通过计算实现为 R 函数（R 软件），名为 llwr_llmpr，并在交互式网页中，两者都可在 R 包 soilphysics 4.0 版或更高版本中获得，可从 https:// arsilva87.github.io/soilphysics/ 或 CRAN ( http://cran.r-project.org/web/packages/soilphysics/index.html )。与栽培土壤相比，在结构化土壤中观察到对给定根伸长率具有更大的土壤渗透阻力阈值。本研究中介绍的 LLWR 和 LLMPR 通过计算实现为 R 函数（R 软件），名为 llwr_llmpr，并在交互式网页中，两者都可在 R 包 soilphysics 4.0 版或更高版本中获得，可从 https:// arsilva87.github.io/soilphysics/ 或 CRAN ( http://cran.r-project.org/web/packages/soilphysics/index.html )。与栽培土壤相比，在结构化土壤中观察到对给定根伸长率具有更大的土壤渗透阻力阈值。本研究中介绍的 LLWR 和 LLMPR 通过计算实现为 R 函数（R 软件），名为 llwr_llmpr，并在交互式网页中，两者都可在 R 包 soilphysics 4.0 版或更高版本中获得，可从 https:// arsilva87.github.io/soilphysics/ 或 CRAN ( http://cran.r-project.org/web/packages/soilphysics/index.html )。