A cover crop that dramatically improved soil structure for me was daikon radish. I saw changes fast because the roots punched through compacted layers. After one season, infiltration improved and standing water disappeared sooner after rain. I measured progress by using a simple soil probe and timing how long water soaked in after irrigation. Organic matter increased too once the roots decomposed. The biggest benefit was how easily the next crop rooted. The soil felt looser by hand, not just on paper.
Hairy vetch (Vicia villosa) is a cover crop recognized for enhancing soil structure quickly. Its robust root system improves aeration and water infiltration by breaking up compacted layers. Additionally, when incorporated into the soil, its biomass adds organic matter, increasing nutrient-holding capacity and promoting biodiversity and nutrient cycling.