Compaction & pugging
Compaction & pugging
As soil resources are finite and only slowly renewable, their sustainable management is of prime importance. Pugged soils are highly compacted and have lost their natural soil structure. Continuous ‘treading’ behaviour (for example, fence-line pacing or feed site trampling), by any stock group, on susceptible soils, increases the risks of compaction of moist soils and pugging of wet soils. ‘Treading’ reduces the number and size of soil pores important for water and air movement. Free-draining soils are less likely to compact and pug than heavy soils.
Photograph copyright Graham Shepherd
Consequences of continuous treading
The consequences of continuous treading include:
- reduced rainwater absorption coupled with muddied exposure of soil results in higher levels of phosphate loss during rain storm events
- wetter & less free draining soil, inhibiting root penetration
- cooler soil temperature, slowing grass growth rates in spring
- low aeration, reducing root vigour, density and growth of pasture and increase of weeds
- long term affects on organic decomposition, nutrient cycling and soil structure development and resilience
- ‘pugged soil’ when it dries out, becomes brittle and with further treading turns it to dust and is then prone to wind erosion.
As part of your Land and Environment Plan (LEP), classify your vulnerable soils into an appropriate Land Management Unit (LMU) and manage these differently during wet weather. LMUs are explained in Level 2 LEP.
Practices to minimize compaction and pugging
To minimise compaction and pugging, take the following measures:
- where possible avoid stock concentrations on heavy soils that are at higher risk during wet weather
- develop a planned contingency for wet periods, with a runoff block or paddocks that are well sheltered with good draining soils.
- reduce stock densities and limit grazing time during high risk periods on high risk paddocks
- Feed supplements off pasture; and
- wean in fine weather on well drained pasture.
For other measures and further infomraiton on soil management refer to the NZDFA Landcare Manual 2012
Further specialist advice
- Some soils compact and pug more easily than others. A Land Management Officer at your Regional Council can assist you with soil mapping or refer you to the appropriate expertise for soil mapping your farm.
- Landcare Research’s Visual Soil Assessment (VSA) Field Guides contain advice to limit pugging. This advice includes the “worm test”, a practical field tool to help you assess if your soil is pugging on any particular day.
- Take a walnut sized piece of soil, roll between palms of the hands to 50mms long and 2mm diameter. The soil is suitable for grazing if it cracks before it is made and too wet to graze if you can make the worm.