Root growth dynamics inside and outside of soil biopores as affected by crop sequence determined with the profile wall method

Abstract

Taprooting crop species are capable of creating soil biopores (>2 mm in diameter) in the subsoil due to their large root size and deep-rooting habit. The aim of this study was to quantify root growth dynamics of wheat in the subsoil during its complete growth season as affected by crop sequence. Temporal observation on root length (km m −2 ) of wheat inside and outside of biopores at four growth stages (tillering, booting, anthesis, and milk) was conducted by using the profile wall method under the two crop sequence treatments involving two precrops, viz., chicory and tall fescue. Frequency of biopore presence measured on vertical profile walls depended on the choice of precrops in which chicory precrop resulted in higher frequency (2.3 %) compared with tall fescue (1.5 %). Root length of wheat measured inside biopores was significantly higher when grown after chicory (0.024 km m −2 ) in comparison to tall fescue (0.006 km m −2 ). On average, root length outside biopores after growing chicory was 45.9 % higher than tall fescue until the stage of anthesis. We conclude that at the site under study biopores as pathways for rapid root growth into deeper soil layers allow roots to re-enter and explore the subsoil. Thus, cereals cultivated in rotation with taprooted crops can draw benefit from enhanced uptake of water and nutrients from deeper soil layers during early growth stages. Model simulations with various abiotic and biotic factors will be helpful to reveal the direct evidence of biopore-root-shoot relationship in the future.

Bacteria utilizing plant‐derived carbon in the rhizosphere of Triticum aestivum change in different depths of an arable soil

“…However, although previous studies have investigated the nature and composition of rhizosphere microbes in detail, the transferability of findings to natural plantmicrobe-soil systems may not always be straightforward due to the following considerations: (i) experiments are often conducted with disturbed or sieved soils, where the soil structure and compartments have been homogenized, thus, neglecting the influence of small-scale soil heterogeneity on root development (Luster et al, 2009;Han et al, 2015), (ii) studies are often limited to nutrient rich topsoil, although roots of agricultural crops can easily grow down to 2 m (Kautz et al, 2013;Perkons et al, 2014) and soil depth is recognized as a further important driver of soil microbial community composition (Berg and Smalla, 2009;Scharroba et al, 2012) and (iii) rhizosphere microbiomes are often investigated at the level of presence or the relative abundance of taxa, but not their direct involvement in rhizosphere carbon flows.…”

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

“…Biopores are generally vertically oriented, tubular-shaped cavities in the soil formed by decayed plant roots or earthworm burrowing (Kautz, 2015;Naveed et al, 2016). Their abundance depends on soil management and cropping sequence (Han et al, 2015;Kautz et al, 2010), and they can persist for 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.…”

Uptake of subsoil water below 2 m fails to alleviate drought response in deep-rooted Chicory (Cichorium intybus L.)

“…Studies covering a longer growing season have found extensive root growth in chicory down to 2.5 m, where equipment limitations prevented observations deeper down (Thorup-Kristensen 2006; Thorup-Kristensen and Rasmussen 2015). In the field, factors such as high soil strength (Stirzaker et al 1996;Gao et al 2016), biopores (Han et al 2015), and hypoxia might restrict deep root growth, which is less likely in our facility with drained repacked soil. However, we did use field soil with a soil bulk density comparable to field soils.…”