Catch crops are a sustainable practice that improves nutrient management and soil structure. Sown after the main crop, they absorb residual nitrogen in autumn. Over winter, this nitrogen is mineralized and becomes available to spring crops. Some species also accumulate phosphorus and potassium. Deep-rooted species like radish improve soil porosity and nutrient mobility. Sowing time is critical: early sowing boosts biomass and nitrogen uptake but may expose young plants to drought stress. In 2022, LAAS on-farm trials showed that sowing between harvest and early August led to higher soil nitrogen levels in spring than later sowing. However, sowing too early can reduce emergence due to summer dryness. The first half of August appears optimal—balancing biomass growth and water availability. Proper timing ensures effective nutrient capture and supports soil structure improvement.