Subsoiling to remediate compacted grassland soils

Soil compaction has become a serious threat to the well-functioning of intensively cultivated grasslands. Finding sustainable remediation strategies has therefore become a pressing concern to ensure yield stability. We assessed the effectiveness of a subsoiler, to alleviate moderately compacted grassland loamy sand and silt loam soils in Flanders. We also studied the ideal timing of subsoiling (spring vs. autumn) and the combination with oversowing. Overall, the effect of subsoiling on grassland yield proved negligible. On the silt loam soil, subsoiling even led to a significant reduction in yield in the subsequent growing season. The long-term penetration resistance (PR) reducing effect of subsoiling was only observed in the upper-subsoil (20–40 cm), and only if the subsoiling was done at optimal soil conditions. Especially in silt-rich soils, it is important to avoid wet soil conditions during subsoiling. Oversowing marginally improved the long-term effect on PR, but this was only observed in the loamy sand soil.