As agricultural practices intensify, soils are becoming more prone to compaction. Recent work carried out by AHDB Dairy has shown that compaction caused by machinery can reduce grass dry matter (DM) yields by 22% and by as much as 14% when compaction is caused by grazing animals. Producers must ensure that grass yields are not being compromised by a limiting layer of compaction in the soil. If problems with soil structure are not corrected, then soils are unable to sustain good productivity. This will lead to reduced efficiencies and increased costs.
To combat soil compaction, it is essential to routinely assess soil structure and September is a good time of year to do that, as soil is starting to wet up. A spade should be used to remove a ‘plug’ of topsoil and producers can then assess the overall quality of the surface layer of soil. This technique also allows producers to decide what type of remedial action is required, if any. By digging a plug, it is possible to tell at which level any limiting layers of compaction are located.
The Healthy Grassland Soils assessment tool should be used to identify the severity of the compaction. If the soil scores four or five, it is essential to choose the correct type of machine when carrying out any remedial work. If the problem lies at the surface layer (0 –10 cm), an aerator can be used. AHDB Beef & Lamb is currently investigating the role that cover crops may have as a method of improving soil surface aeration.
If the limiting layer is found to be at a deeper level, a sward lifter or subsoiler may be used to break up any layers of compaction. It is crucial that soil conditions are good when performing any remedial work and producers are advised to carry out the work on the shoulders of the season, when the impact on sward production levels will be reduced.
The AHDB Healthy Grassland Soils pocketbook is available online .