Effects of Continuous Vertical Soil Pores on Root and Shoot Growth of Winter Wheat: A Microcosm Study

Abstract

Round shaped, continuous vertical pores (CVPs) in the soil are typically created by roots and earthworms. CVPs with diameters > 2 mm are abundant in many agricultural soils. We hypothesized that potential effects of CVPs on shoot growth of winter wheat (Triticum aestivum L.) increase with: 1) decreasing availability of water and 2) decreasing availability of nutrients in the topsoil. We conducted a microcosm experiment with different irrigation regimes (Irr+/Irr−) and P concentrations (P+/P−), with or without artificially created continuous vertical pores (CVP+/CVP−). Winter wheat was cultivated for 16 weeks. In the bulk soil, presence of CVPs resulted in decreased root length in 20 -40 cm but increased root length in 40 -60 cm soil depth. In general, total root length of winter wheat in 20 -60 cm soil depth was higher when CVPs were present or when P concentrations in the topsoil were elevated. Presence of CVPs generally had a positive effect on shoot dry matter and N uptake of wheat. In columns with high phosphorous concentrations but low soil moisture in the topsoil, presence of CVPs increased shoot dry matter by 66%; in contrast, the beneficial effect of CVPs on shoot dry matter was only 39% in columns with high nutrient concentrations and high soil moisture in the topsoil. In total numbers, however, the effect of CVPs on P uptake into the shoot was more pronounced when P concentrations in the topsoil were elevated. We conclude that CVPs can promote the exploration of the solid soil phase by high root-length densities, but adequate nutrient supply in the topsoil is essential.

Root and shoot growth of spring wheat (Triticum aestivum L.) are differently affected by increasing subsoil biopore density when grown under different subsoil moisture

“…Therefore, the superior supply of the plant with water might also have led to a superior plant nutrient status. Similar to our findings, Volkmar (1996) indicated a positive relationship between a higher soil moisture level and shoot N uptake, and Dresemann et al (2018) between a higher soil moisture level and shoot N and P uptake.…”

“…In the present study there was no effect of an increasing biopore density on the aboveground biomass under comparatively dry subsoil conditions (WHC 10% ). However, in a microcosm study using soil columns with or without artificial continuous vertical macropores and varying soil moisture, presence of macropores generally had a positive effect on shoot dry matter and N uptake of wheat, which was especially pronounced under dry conditions (Dresemann et al 2018). Beside, in a simulation approach based on data from field experiments, the impact of different taprooted and fibrous rooted precrops on spring wheat growth, water and nutrient uptake and grain yield under varying weather conditions was investigated (Seidel et al 2019).…”

“…After filling the subsoil into the columns, artificial vertical pores with a diameter of 5.3 mm were created with help of an iron rod in the subsoil part. Previous studies have shown that this diameter is large enough to allow incubation with adult individuals of L. terrestris (Dresemann et al 2018). Five different pore densities were set in each soil moisture regime: 0, 1, 2, 3, and 4 pores column −1 (Fig.…”

Comparing Macropore Exploration by Faba Bean, Wheat, Barley and Oilseed Rape Roots Using In Situ Endoscopy

“…There are conflicting results regarding the implications of this preferential root growth in macropores for crop performance, both from pot and field experiments: Plain additional artificial macropores in pots with tightly packed soil resulted in smaller leaf area of barley (Passioura 2002). A similar experimental arrangement, but with earthworm incubation into macropores preceding crop cultivation and with a water source in the 70-cm soil depth, resulted in higher shoot dry matter and N uptake of winter wheat (Dresemann et al 2018). In the field on a Red Kandosol in Australia, White and Kirkegaard (2010) found 85-100% of wheat roots in the subsoil clumping in biopores, establishing contact only via root hairs, without access to the surrounding bulk soil.…”

New tools for dead roots: Radioisotope labelling and compound‐specific analysis reveal how subsoil hotspots work

“…How these contribute to plant growth is not yet known. The establishment of roots in subsoil biopores early in the growth season may act as an insurance for crops in case the topsoils run dry by an early drought or nutrient demands cannot be met from topsoils (Cresswell & Kirkegaard, 1995; Dresemann et al., 2018). More frequent droughts and rising fertiliser costs are two challenges which agriculture will be facing in future (Cordell & White, 2011).…”