Modeling the Impact of Biopores on Root Growth and Root Water Uptake

Abstract

Core Ideas A 3D soil–root model was used to investigate root–biopore interactions. Known effects of biopores on root growth, i.e., increased root length and depth were reproduced. Despite reducing root–soil contact, biopores led to increased water uptake in dry periods. Biopores had a larger impact on water uptake for more compact and less conductive soils. Roots are known to use biopores as preferential growth pathways to overcome hard soil layers and access subsoil water resources. This study evaluates root–biopore interactions at the root‐system scale under different soil physical and environmental conditions using a mechanistic simulation model and extensive experimental field data. In a field experiment, spring wheat (Triticum aestivum L.) was grown on silt loam with a large biopore density. X‐ray computed tomography scans of soil columns from the field site were used to provide a realistic biopore network as input for the three‐dimensional numerical R‐SWMS model, which was then applied to simulate root architecture as well as water flow in the root–biopore–soil continuum. The model was calibrated against observed root length densities in both the bulk soil and biopores by optimizing root growth model input parameters. By implementing known interactions between root growth and soil penetration resistance into our model, we could simulate root systems whose response to biopores in the soil corresponded well to experimental observations described in the literature, such as increased total root length and increased rooting depth. For all considered soil physical (soil texture and bulk density) and environmental conditions (years of varying dryness), we found biopores to substantially mitigate transpiration deficits in times of drought by allowing roots to take up water from wetter and deeper soil layers. This was even the case when assuming reduced root water uptake in biopores due to limited root–soil contact. The beneficial impact of biopores on root water uptake was larger for more compact and less conductive soils.

Soybean Agronomic Performance and Soil Physical Attributes Under Tractor Traffic Intensities

“…These results are in accordance with Foloni et al (2006), who concluded that an increase in soil penetration resistance in the surface layer could stimulate lateral root proliferation, which is thinner and capable of growing in small diameter soil pores, reaching higher depths. It occurs especially in consolidated no-tillage areas, where there is the natural formation of biopores that allows for higher root growth and, consequently, access to water in deeper and wetter soil layers, mainly in those more compact and less conductive (Landl et al, 2019).…”

Linking root structure to functionality: the impact of root system architecture on citrate‐enhanced phosphate uptake

“…Landl et al . (2019) used a coupled root growth model and water uptake model to determine the role of biopores on RSA and water uptake. Schnepf et al .…”

An Acceptance Analysis of Subsoil Amelioration Amongst Agricultural Actors in Two Regions in Germany

“…One opportunity for roots to overcome compacted soil layers is the use of large-sized biopores formed by tap-rooting plants or earthworms as preferential growth pathways (Kautz et al, 2014;Landl et al, 2019;Huang et al, 2020). Biopores are hotspots with particularly high organic matter, microbial activity and nutrient availability (Kautz et al, 2014;Kuzyakov and Blagodatskaya, 2015), which enhance water infiltration and have a proven beneficial impact on root water uptake in times of drought (Gaiser et al, 2012;Landl et al, 2019). These biopores can remain in the subsoil over years (Hagedorn and Bundt, 2002).…”

“…There are various mechanical and biological methods that help overcome such compacted soil layers, facilitate root growth into deeper layers (Schneider and Don, 2019b) and thus support the uptake of nutrients and water from the subsoil-and thereby increase yields (Gaiser et al, 2012;Cai et al, 2014;Landl et al, 2019;Sale et al, 2019;Seidel et al, 2019). Biological methods are based on the effect of the cultivation of deep-rooted precrops (e.g., alfalfa) and the formation of biopores down into the subsoil (bio-drilling) (Kautz et al, 2014;Landl et al, 2019;Seidel et al, 2019). Mechanical methods encompass for example deep loosening (subsoiling) to break up compacted layers (Frelih-Larsen et al, 2018).…”