Avoid Soil Compaction When Grazing Cover Crops

By Sjoerd Willem Duiker

Cover crops are considered one of the most effective and economical ways to improve soil health. Grazing them can be a way to turn them into a profit center for your operation. It is important, however, to avoid causing excessive compaction that could negatively affect following crop yield and increase runoff and erosion. A few tips to avoid excessive compaction when grazing cover crops:

1. Use continuous no-till. A no-till soil resists compaction better than a tilled soil. Even two or three years after a tillage event, the soil will still be softer causing greater ‘pugging' by the grazing animal. The high organic matter content near the surface in continuous no-till is not easily compacted.
2. Make sure the cover crop stand is dense. A dense cover crop has a robust root system that will help resist compaction.
3. Rotate with perennials. Perennial crops such as orchard grass, fescue, bromegrass, alfalfa, or red clover improve soil beyond what is possible with an annual. The effect of the perennial lasts many years. Rotation with tap-rooted crops such as alfalfa, red clover, sweet clover, or chicory helps improve subsoil porosity.
4. Feed the ‘underground herd'. Stimulate fungal and bacterial activity and promote soil animals such as earthworms that create macro-pores in the soil. The practices previously mentioned will help improve soil health. Leave sufficient crop residue after grazing to feed the soil. Healthy soil with high biological activity will more quickly bounce back from any compaction that is caused.
5. Have a movable water source. Most compaction is typically caused near the water source. By moving it regularly you limit the potential for soil compaction around it.
6. Monitor soil moisture conditions and do not graze in areas that are too wet. You can use a ‘ball test' to determine if the soil is fit for the animals to be on it by grabbing a handful of surface soil and kneading it in your hand – if it forms a ball the soil is too wet to be on it. If soil conditions are marginal, you should consider if there are fields on your farm that drain more quickly than others – you might have sandy or shaly soil that drains quickly that might be ready sooner than limestone soil, or soil with seasonally high water table. Steeply sloping soils can also be problematic in wet times of the year. When you notice the animal, hoofs start skidding down the slope or create ridges it is time to move them to more level fields.
7. Move animals more frequently when soil is wet, to reduce the time of exposure. This means you pack the herd into a smaller area, but they are in there for a shorter period. Back-fencing is a good idea no matter what, so that the animals don’t go back over an area that has already been grazed.
8. Move animals to perennial pastures with tough root systems if conditions are wet. You will quickly notice the difference between tough rooted species like tall, chewing or red fescue pasture and annual cover crops that have a smaller root system. The perennial grass withstands compaction a lot better while you quickly bring up dirt when grazing the annuals when it is wet.
9. Pull the animals off if you expect them to cause severe compaction. This is a means of last resort, but it is preferred over mudding up your field.