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Introduction
Good soil management is vital for the production of high yielding, good quality grass and forage crops which are the basis for economic milk production.  How the soil is managed largely governs crop growth.  Dairy enterprises are commonly located on heavy soils in wetter areas of the country and these factors increase the risk of soil damage.  Livestock may damage the soil surface structure if grazing is allowed in wet conditions, which may sometimes be unavoidable when extending the grazing season in spring and autumn.  Furthermore, manure spreading by tankers and spreaders can cause serious compaction to depth when the soil is wet.  Poor soil condition can reduce sward growth and markedly increases the risk of soil erosion on sloping ground.

Poaching
Poaching when accessing pasture at either end of the grazing season and during wet weather periods is a serious problem for dairy herds. Poaching damages the soil structure, reduces grass yields and in severe circumstances farmers have to resort to costly re-seeds to rectify the damage. With ever tightening margins, farmers are encouraged to reduce winter housing and feeding costs by turning cows out earlier in the spring and housing later in the autumn. Grazed grass, in the majority of cases, is the cheapest feed on the farm, the biggest barrier for utilising grazed grass is field access without poaching. There has been considerable investment in cow tracks on many farms to reduce poaching by providing a secure surface for cows to walk on while moving to and from milking.

Compaction
Maize is extremely susceptible to compaction with crops grown on compacted soils unable to develop a deep root structure. A yellow stunted crop with poor yields is evidence that compaction is likely to be a problem. Subsoiling  is carried out as part of routine cultivations on some farms especially where continuous maize is grown on heavier soil types. Secondary cultivations should be carried out using the minimum number of passes possible to avoid re compacting the soil after subsoiling and ploughing. Compaction and soil pans also produce similar problems in grass although they are less visual.  Poaching causes compaction at around 5-10cm (2-4") with plough pans and heavy machinery pans occurring at 10-15cm (4-6"). To identify compaction dig holes with a spade and examine the vertical profile of the soil for consolidation and poor root penetration.

Water erosion
Forage maize production is the major cause of runoff and erosion on dairy farms, with water channelled along maize drill rows after planting and wheel marks left by harvesting machinery.  Farmers should consider using early maturing maize varieties to allow earlier harvesting and the chance of sowing winter cereals or a cover crop following the harvesting of the maize.  Poaching is also a problem with damaged grass cover allowing soil erosion with soil particles washing off, especially during periods of heavy rainfall.

MDC Grass⁺ Chapter 10

Maximising Sward Productivity    (266kb)

For more information visit the Milk Development Council's website at http://www.mdc.org.uk/