Root‐dependent recovery of pore system functionality of compacted subsoil: A field case study with bio‐subsoilers in Denmark

Abstract

Cover crop effects on soil properties are site specific, and their use as an alternative management strategy to create macropores for subsoil compaction mitigation has not been widely investigated. This study aims to evaluate the effects of biosubsoilers on gas and water transport of a compacted sandy loam subsoil. A field screening trial was conducted for 2 yr with spring barley (Hordeum vulgare L.) as the control treatment and lupin (Lupinus luteus L.), chicory (Cichorium intybus L.), lucerne (Medicago sativa L.), tall fescue (Festuca arundinacea Schreb.), festulolium [×Festulolium braunii (K. Richt.) A. Camus], and cocksfoot (Dactylis glomerata L.) as bio-subsoiler treatments. Undisturbed samples of 100 cm 3 were taken at 0.3-and 0.5-m depth for measuring soil physical parameters. For chicory, lucerne, tall fescue, and spring barley, unsaturated hydraulic conductivity [K(h)] was measured at 0.3-m depth and root pattern distribution was evaluated from 0-to 0.6-m depth. Results showed a nonsignificant trend of larger air permeability (k a ), gas diffusivity (D s /D o ), and k a /ε a (where ε a is air-filled porosity) for lupin and lucerne, indicating enhanced pore continuity. Chicory and lucerne significantly increased the K(h) at −1-cm matric potential at 0.3-m depth in the second year of evaluation. Lucerne and tall fescue had a significantly larger root length and area than barley. We showed that under field conditions in a Danish sandy loam soil, lupin, chicory, and lucerne tended to increase gas and/or water transport on the compacted subsoil layer. The compaction mitigation potential of chicory and lucerne found in our previous soil column experiment with the same soil type was corroborated in our field screening trial.

Techniques for the recovery of compacted soils in Europe

“…Schneider et al, 2017), or by biological processes such as root penetration of compacted layers (e.g. Pulido-Moncada et al, 2021).…”