It will Pay to Assess Sward Quality this Spring

With many grazing fields showing signs of severe poaching and machinery damage due to the wet summer last year, NWF’s Commercial Manager Rupert Stafford urges farmers to get out and decide what needs to be done to maximising grassland productivity this spring.

2007 was a difficult grass growing year with the wet weather making both grazing and silaging a real challenge. With higher milk prices, all dairy farmers will be keen to make the most of grass again this season and faced with record fertiliser prices must focus must on maximising both yields and quality.

One of the main consequences of last year will be a lower proportion of ryegrasses and a higher proportion of weed grasses which will have been quick to colonise any space within the sward. Weed grasses will reap havoc with both grazing quality and quantity.

A good quality grazed ryegrass sward will produce around 12tDM/ha which will supply enough energy for 24,000 litres of milk over the season. A sward with only 50% perennial ryegrass, with the remainder being weed grasses will yield upto 2tDM/ha less which is equivalent to enough grass to produce nearly 4000 litres of milk.

If that is not enough, weed grasses are less effective converters of fertiliser into plant material. A 50:50 ryegrass: weed grass sward will use nitrogen fertiliser 35% less efficiently than a pure ryegrass ley and at today’s prices this will cost around £45/ha in lost potential.

Taking the time to walk fields early this season to assess the quality of the grasses present will be well worthwhile. A reasonable judgement can be made by walking in a ‘W’ shape across the field. By walking the fields you will get a good idea of the proportion of ryegrass in the leys and you can decide on what action to take to get the most from your grass.

Perennial ryegrass is easily identified as it has a crimson red base. Grasses without this will tend to be less desirable species.

If there is more ryegrass than weed species then the pasture will probably respond to harrowing or rolling to remove ruts, followed by usual fertiliser applications.

If the sward is somewhere around 50% ryegrass then consider looking to rejuvenate the sward by slot seeding or overseeding.  A reduced seed rate of around 13kg/ha can be used and at less than £15/ha the cost of the operation is considerably less than a full reseed.

Rejuvenation is also worthwhile where there are open spaces due to rutting etc. As ryegrass grows with a tufted habit, it will not spread significantly and these areas will soon be colonised by weed grasses.

If the sward is less than 50% ryegrass, and certainly if it below 25%, then reseeding is really the best option. Despite the higher costs associated with a full reseed, there is usually a short pay back period. A vigorous new ley can produce 25% more DM/ha than a tired mixed species ley allowing the establishment costs to be recovered in the first year.

Whether rejuvenating or reseeding it is essential to consider the seed mixture to use. Select a mix designed for the use for which the field is primarily used and look to use the new high sugar varieties to maximise the kgDM produced per kgN applied.

It is certainly worth considering using a high proportion of clover in any reseeding mixtures. Fertiliser prices are likely to remain high for the foreseeable future so the benefits of nitrogen-fixing legumes will be even more important.

Look to use a blend of clovers. Some varieties have a more erect habit and will compete well with the existing sward while other have a more prone habit and will happily fill gaps in the sward and provide competition with weed grasses.

Despite higher fertiliser prices, grazed grass is still a very cost-effective feed but the objective must be to maximise the yield and response to nitrogen through the maintenance of an optimum sward composition. The starting point for this should be a slow walk round all the grassland this spring.