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.
Highlights
Biopores are voids in the soil created by soil organisms including earthworms and plant roots [1]
On the one hand, increased rooting depth via facilitated root growth through continuous vertical pores (CVPs) can be crucial for crop performance during dry spells: when high penetration resistance impedes root growth through the bulk soil, accelerated access to the subsoil via CVPs could enhance the ability of crops to explore water resources [10]
Total root length was generally higher throughout all soil depths when winter wheat was cultivated in topsoil containing high concentrations of P (Figure 2, Table 2)
Summary
Biopores are voids in the soil created by soil organisms including earthworms and plant roots [1]. On the one hand, increased rooting depth via facilitated root growth through CVPs can be crucial for crop performance during dry spells: when high penetration resistance impedes root growth through the bulk soil, accelerated access to the subsoil via CVPs could enhance the ability of crops to explore water resources [10]. This applies to spring crops, which depend on developing their root system in a comparatively short period of time. Since model predictions suggest severe drought conditions by the late half of this century over many areas such as Europe, the eastern USA, southeast Asia and Brazil [11], such processes will probably be of increased relevance in the future
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