Summary
At Orup in Skåne, Sweden, SoilCare tested whether loosening a naturally compacted subsoil could improve rooting and yields. The site is a silty sand with high subsoil bulk density and roots seldom below 30 cm. The trial compared three treatments implemented once in autumn 2018: standard practice, subsoiling to the upper subsoil, and subsoiling with straw pellets injected into the 24 to 35 cm layer. A randomized block design with four replicates and 6 × 20 m plots was used. Winter wheat grew in 2019 and sugar beet in 2020. Measurements covered the volume of subsoil affected, root counts by depth, penetration resistance with a 2.5 MPa root-limiting threshold, bulk density and coarse fragments, soil C, N and pH in top- and subsoil, and yields.
Mechanical loosening created distinct subsoil rows. Only 38 to 45 percent of the upper subsoil volume was affected. Straw pellets settled at the bottom of loosened rows rather than mixing. Even so, rooting improved. Maximum rooting depth reached about 35 cm with subsoiling plus straw, compared to about 27 cm in the control. Penetration into the compacted layer increased from roughly 4 cm in the control to about 11 cm with loosening treatments. Despite better rooting, grain and beet yields did not differ significantly at whole-plot scale over two seasons. When results were adjusted for the fraction of subsoil actually affected by the strips, relative yields increased compared to the control.
Stakeholders judged the approach plausible and were interested in learning more, but highlighted barriers. Injecting large amounts of organic material is technically demanding and costly. Advisory capacity and subsidy flexibility matter for adoption. The short-term conclusion is pragmatic. Subsoiling, with or without straw pellets, improved rooting in a naturally compacted subsoil but did not deliver short-term yield gains. Longer-term, repeated treatments, alternative organic materials and multi-site testing are needed to understand agronomic and hydrological benefits.
Photo gallery
Overview
Increase rooting depth and reduce penetration resistance
Enable better water and nutrient uptake and potentially improve yields
| Authority type | Authority name | Authority role | Comments | Authority responsibility |
|---|---|---|---|---|
| Research institute / University | Swedish University of Agricultural Sciences (SLU) | Initiation of the measure | Study site leadership, experiment design and monitoring. | Responsible |
| Farmers | Rural Economy and Agricultural Society | Implementation | Help in site management. | Supporting |
| Farmers | T. Ingelsson (farmer/consultant) | Determination of design details of the measure | Adaptation of subsoiling equipment. Responsibility: supporting. | Supporting |
Site Information
Design and Implementation
Financing
Policy and Governance
| Wider plan focus | Name | Comments |
|---|---|---|
| Agriculture | SoilCare | Horizon Europe project on agricultural soils |
| Activity stage | Activity type | Key issues |
|---|---|---|
| Implementation phase | Implementation and results discussion with stakeholders | Unchanged yields, technical difficulty and cost of injecting large organic inputs, need for longer-term and multi-site testing, subsidy flexibility and advisory capacity. |
Impacts and Monitoring
Monitoring System
Impact Assessment Methodology
Socio-economic Impacts
Subsoil moved irregularly into topsoil
Straw pellets tended to settle at the bottom of the loosened rows rather than mix through the subsoil
Only 38–45% of the upper subsoil volume was actually affected by subsoiling passes
Biophysical impacts: Hydrology
Biophysical impacts: Water & Soil Quality
Lessons Learned
| Comments |
|---|
| Research need to address natural subsoil compaction limiting root growth and yield. |
| Success factor type | Success factor role | Comments |
|---|---|---|
| Attitude of relevant stakeholders | Main factor | Functional advisory system and farmer interest in learning about subsoiling with organic amendments. |