A framework for modelling soil structure dynamics induced by biological activity

Abstract

Soil degradation is a worsening global phenomenon driven by socio‐economic pressures, poor land management practices and climate change. A deterioration of soil structure at timescales ranging from seconds to centuries is implicated in most forms of soil degradation including the depletion of nutrients and organic matter, erosion and compaction. New soil–crop models that could account for soil structure dynamics at decadal to centennial timescales would provide insights into the relative importance of the various underlying physical (e.g. tillage, traffic compaction, swell/shrink and freeze/thaw) and biological (e.g. plant root growth, soil microbial and faunal activity) mechanisms, their impacts on soil hydrological processes and plant growth, as well as the relevant timescales of soil degradation and recovery. However, the development of such a model remains a challenge due to the enormous complexity of the interactions in the soil–plant system. In this paper, we focus on the impacts of biological processes on soil structure dynamics, especially the growth of plant roots and the activity of soil fauna and microorganisms. We first define what we mean by soil structure and then review current understanding of how these biological agents impact soil structure. We then develop a new framework for modelling soil structure dynamics, which is designed to be compatible with soil–crop models that operate at the soil profile scale and for long temporal scales (i.e. decades, centuries). We illustrate the modelling concept with a case study on the role of root growth and earthworm bioturbation in restoring the structure of a severely compacted soil.

Anthropogenic Disturbances Shape Soil Capillary and Saturated Water Retention Indirectly via Plant Functional Traits and Soil Organic Carbon in Temperate Forests

“…Soil texture also shows no influence on soil water-physical properties across various circumstances [4,15,64], and the reason for this may be their low contributions when compared with other factors. Moreover, it is worth noting that there are other drivers affecting soil hydraulic properties crucially, such as root system and earthworm activities [65,66], although we barely mentioned them in this research. As such, soil structure is the consequence of multiple interactions of plant attributes and ecosystem processes, which underscores the necessity of an integrative understanding of biotic and abiotic drivers influencing soil water-physical properties.…”

Soil Macropores Affect the Plant Biomass of Alpine Grassland on the Northeastern Tibetan Plateau

“…Generally, low macropore contents are observed in degraded grasslands (Hu et al, 2020). Kravchenko et al (2015) proposed a feedback process in which more pores lead to stronger microbial activity, which promotes soil animal and plant activities and leads to the production of more pores (Meurer et al, 2020). In the 3D visualization, the ADS soil had almost no tubular or highly continuous large pores, while the other two grassland types exhibited many pores of this type (Figure 3); the pattern in ADS soil was caused by the reduced activities of soil animals and plant roots.…”

“…Therefore, the vegetation in alpine areas grows under unique soil conditions and harsh climate conditions. Due to differences in water and temperature conditions, soil animals, plants, etc., different grassland types vary in their influences on soil pore structure (Hu et al, 2016(Hu et al, , 2020Gao et al, 2020;Meurer et al, 2020); however, the effects of different soil macropore structures on soil properties and vegetation growth are not yet clear. Additional research is needed to clarify whether soil macropores have important influences on soil physicochemical properties and plant growth in alpine stony soils and to assess their ecological function in maintaining the sustainable development of natural grassland ecosystems.…”

2D Kinematic Quantification of Soil Particles around Growing Plant Root based on Optical Mechanics

“…5. The root passing through the soil directly changes the soil pore space and induces the soil particle displacement, which mainly occurs in the axial displacement in front of the root and the radial displacement near the root (Meurer et al, 2020).…”