Compaction is when the soil is compressed or squeezed by animal treading although vehicles and farm machinery also contribute to this problem.
However, aerating the compacted soil at the correct depth and time can increase the amount of dry matter by about 30% within six months and about 50% after eight months.
Other problems caused by compaction (and pugging) include more frequent and persistent surface ponding, increased sediment, and nutrient and effluent losses through surface run-off.
It also means it takes longer for pasture to recover after grazing, and weed invasion often occurs in the bare sites pugging and compaction creates.
Problems like these can be minimised by:
Reducing stock density, especially on sensitive, e.g. wet, paddocks.
Not feeding out on sensitive paddocks.
Constantly monitoring pugging and compaction during at-risk periods and moving stock off before damage occurs.
Having multiple exits from paddocks.
Grazing the back of the paddock first.
It is important to cultivate soil at the right time - when the moisture content isn't too high or too low.
To assess soil's moisture content, take a piece of soil (half the volume of an index finger), press it firmly and roll it into a 'worm' on the palm of the hand until it's about 50mm long and 4mm thick.
It's the right time to cultivate if the soil cracks before the worm is made.
If the worm can be made the soil is too wet. Clods that are too dry won't break down when cultivated and won't provide a good seedbed.
An easy way to keep up to date with soil condition is to carry out a visual soil assessment (VSA) at least once a year.
Excessive nutrients and fertiliser use can contribute to nitrogen leaching and phosphorus run off, degrading surface and groundwater quality.
So wise use of fertiliser in these systems can increase agricultural yields, maintain soil health, nutrient balance and protect the environment.
Farmers can reduce the amount of nutrients leaching or running off pasture by ensuring they prepare a nutrient budget.
Farmers should:
Apply fertiliser when the grass is in an active growing phase.
Make sure fertiliser isn't applied near waterways.
Leave a grassed buffer strip between paddocks and waterways – the strip filters the nutrients before the run-off reaches the water.
Control run-off from tracks, races, feed and stand-off pads.
Another important issue for soil health management is how the animals are wintered.
Several studies indicated that degradation of soil and most of the nitrogen losses to water from grazed winter forage crops occur in a nitrate (N) form and are transported via leaching rather than overland flow.
Losses appear to be exacerbated by the high density of urine patches that are deposited at times of the year when plant growth rates are low and drainage is high.
Consequently, on a per hectare basis N leaching losses from grazed winter forage crops are high relative to losses measured under pasture.
The effectiveness of the nitrification inhibitor Dicyandiamide (DCD) in reducing nitrogen leaching from urine patches deposited during grazing was evaluated in several trials in New Zealand the last few years.
Results from these studies show the treatment of the soil with DCD, at recommended doses, was effective in reducing nitrate leaching from the urine patches in a grazed pasture soil.
In addition to the environmental benefits of decreased nitrate leaching, the treatment of the soil with DCD also provided good agronomic benefits with increased herbage dry matter yield from increased nitrogen retention in the soil and improved nitrogen utilisation by the plant.
Bala Tikkisetty is a sustainable agriculture coordinator at Waikato Regional Council in New Zealand.
