Since the early 1900s, soil scientists have recognized that soil particles combine to form larger aggregates (see definitions in Table 1 of many terms used Mechanisms that drive soil structural changesĪggregates are the fundamental building blocks of mineral soil they have long been examined for their role in governing soil water infiltration, plant-available water holding capacity, and root growth (e.g., Yudina and Kuzyakov, 2019 Dexter, 1988 Blevins and Frye, 1993 Nimmo, 2004 Nemati et al., 2002 Skvortsova, 2009).
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Soil structure dictates the character and pace of many critical zone (CZ) processes such as chemical weathering, groundwater flow, and carbon cycling that both govern and respond to Earth’s climate (Fig. Soil structure is the size, shape, and arrangement of solid particles and pores (Brewer, 1964 Letey, 1991 Rabot et al., 2018). Section snippets Embracing the dynamic nature of soil structure in the Anthropocene This recognition highlights the importance of addressing these proposed questions, which will promote a predictive understanding of soil structure. From these efforts, four fundamental questions emerge: 1) How do rates of soil aggregate formation and collapse, and their overall arrangements, interact in the Anthropocene to regulate CZ functioning from soil particle to continental scales? 2) How do alterations in rooting-depth distributions in the Anthropocene influence pore structure to control hydrological partitioning, biogeochemical transformations and fluxes, exchanges of energy and carbon with the atmosphere and climate, regolith weathering, and thus regulation of CZ functioning? 3) How does changing microbial functioning in a high CO 2, warmer world with shifting precipitation patterns influence soil organic carbon dynamics and void-aggregate profile dynamics? 4) How deeply does human influence in the Anthropocene propagate into the subsurface, how does this depth relate to profile structure, and how does this alter the rate at which the CZ develops? The United Nations has recently recognized that 33% of the Earth's soils are already degraded and over 90% could become degraded by 2050. We further argue that modelers and empiricists both are well-poised to quantify and incorporate these dynamics into their studies. We argue that the variable nature of soil structure, and its dynamics, need to be better understood and captured by land surface and ecosystem models, which currently describe soil structure as static. Though it is well known that soil structure can change with wetting and drying events, often oscillating seasonally, the dynamic nature of soil structure that we discuss is a systematic shift that results in changes in its hydro-bio-geochemical function over decades to centuries, timescales over which major changes in carbon and nutrient cycles have been observed in the Anthropocene. Here we review the nature of soil structure, focusing on its co-evolution with the plants and microbes that live within the soil, and the degree to which these processes have been incorporated into flow and transport models. The network of pores provides storage space for at least a quarter of Earth’s biodiversity, while the abundance, size and connectivity of the pore space regulates fluxes of heat, water, nutrients and gases that define the physical and chemical environment. A key aspect of the way soil functions results from its structure, defined as the size, shape, and arrangement of soil particles and pores. Changes in soil and its ability to perform a range of processes have important implications for Earth system function, especially in the critical zone (CZ)-the area that extends from the top of the canopy to the bottom of groundwater and that harbors most of Earth’s biosphere.
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Torrent j cole forest hills drive live skin#
Soils form the skin of the Earth’s surface, regulating water and biogeochemical cycles and generating production of food, timber, and textiles around the world.