Soils are a farmer’s most valuable resource so every effort should be made to keep them in good physical and biological health. Moist and wet soils are less able to support the weight of grazing stock than dry soils, so treading on moist soils can lead to compaction and, on wet soils, animal hooves cause pugging damage.
Pugging reduces a soil’s performance because its structure has changed. Pugging damage increases the soil density but decreases its porosity, drainage and aeration. Damaged soils stay wetter much longer, and because wet soils are more easily pugged, this compounds the pugging problem. A pugged surface can result in a compacted layer about 5-10 cm down, impeding plant growth and drainage.
The best way to avoid this is to prevent pugging, and this can be achieved by moving stock to a hard pad or sacrifice area when pugging damage is likely to occur, or by draining any wet areas. A pugged soil may need cultivation to aid its recovery and may even need a fallow period without any crop or pasture on it. Damaged and resown sacrifice paddocks will produce less than their potential even after cultivation, until the soil structure fully recovers.
When a paddock becomes pugged during a wet spell then it needs to be nursed back into good health. Soils are not just dirt – they are a growing medium for plant roots, a source of essential nutrients for plants and animals and are home to a myriad of small animals, microbes and seeds. Earthworms are great for aerating soil, which enables plant roots to develop, and they turn over the soil continuously – essential long-term cultivation.
So when a soil becomes damaged then avoid more use. A pugged soil should not be subjected to intensive grazing, especially with heavyweight livestock on damage-prone soils. Furthermore, keep heavy vehicles off these soils when they are becoming wet. In the longer term, plan to drain any noticeably wet areas, but remember that recently developed pumice or peat soils often have few (if any) earthworms.
Good quality soils under pasture will normally contain more than 500 earthworms per square metre, which is equivalent to more than 30 in two spades of soil. Earthworm populations may be boosted by:
- Reducing stocking on compacted areas.
- Improving drainage on soils prone to waterlogging.
- Using irrigation on soils prone to extreme drying.
- Improving pasture growth by applying fertiliser and lime.