Soil compaction limits soil water dynamics and reduces canola yield components

Background and Aims Soil compaction may alter soil water dynamics, potentially limiting yield in oilseed crops such as canola ( Brassica napus L.). Although canola exhibits moderate drought tolerance, responses to soil compaction in this species have not been well documented. Methods This study evaluated the effects of increasing soil compaction levels (1.0, 1.1, 1.2, 1.3, 1.4, and 1.5 Mg m⁻³) on canola yield components and spatial soil water distribution. The experiment employed PVC tubes under controlled conditions, with a compacted subsoil layer (10–30 cm) overlain by non-compacted topsoil. Soil water was monitored using capacitive sensors. Results Soil water sensors revealed that compaction increased water retention in the compacted zone, but this water remained unavailable to plants. Increasing soil density from 1.0 to 1.5 Mg m⁻³ reduced all yield components, with grain yield decreasing by approximately 76% and vegetative growth parameters declining by 45–65%. Canola yield components improved only when water was accessible in the topsoil layer. Principal Component Analysis confirmed clear segregation, associating high compaction with trapped subsoil water and low compaction with better yield and topsoil water use. Conclusion These findings demonstrate that soil compaction induces physical hydric stress in canola by restricting water availability, rendering canola sensitive to compaction due to critical changes in soil water dynamics.