DairyCo at Grassland & Muck event

Published 9 May 14

Looking to the Future

‘Looking to the future’ is the theme of the DairyCo-EBLEX- BGS stand at this year’s Grassland & Muck event where grassland and soil experts will be on hand to discuss the latest research and technical developments in the areas of grassland management, alternative protein crops and grass varieties.

Researchers will also be on stand to offer advice on soil nutrition, structure and health. Dr Debbie McConnell DairyCo research & development manager says, ‘it is important that farmers regularly monitor the nutrient status and structure of their soils. With incorrect pH resulting in drops of crop yield of up to 30%, the wrong pH level can have large financial ramifications for dairy businesses through reduced soil quality, lower uptake of nutrients in slurry, manures and purchased fertilisers, and poorer competition of grass and clover species against weed species.’

Farmers are encouraged to bring along soil samples (quantity of a small spade) to the stand to discuss aspects of soil management with the experts.  Soil texture and structure will be inspected and tests conducted looking at pH, Nitrogen, Phosphorus and Potassium levels will be carried out.

It is also important that farmers understand their soil structure. Good soil structure is vital for maintaining productive pastures however a recent survey across England and Wales has shown that over 70% of grassland soils are exhibiting signs of soil compaction.

Compaction, whether caused by cattle trampling or tractor traffic can significantly reduce first cut yields by as much as 30%. Compaction is the primary focus of a three year, DairyCo funded research project which is being undertaken at Scotland’s Rural College and Harper Adams University, as part of the DairyCo Grassland, Forage and Soils Research Partnership.

In general, soil comprises half soil particles, 25% air and 25% water (by volume), explains Dr Debbie McConnell. “Soil structure is important because it determines the ability of a soil to hold and conduct water, nutrients, and air necessary for plant root activity. Compaction arises when soil particles are compressed reducing both the air and water space between particles – and the effects of this is what we’ve been studying through our research partnership.”

Dr McConnell continues, “The impacts of soil compaction include displaced earthworm populations and nutrient efficiency and the restriction of plant root growth, which limits the plant’s access to nutrients further down the soil profile.”

Compacted land may also show a reduction in water infiltration to and drainage from the compaction layer, increasing the risk of flooding. This reduction in water movement can also create anoxic conditions in the soil, restricting gas exchange killing healthy soil biota and restricting the breakdown of organic matter into nutrients.

Dr McConnell says, “From the first two years of the DairyCo soil compaction experiment, it’s clear these effects have had a cumulative impact on grass sward performance. Trampling compaction reduced first cut yields by an average of 14% compared with uncompacted areas, and tractor compaction reduced first cut yields by an average of 22%.  What’s more, tractor compaction became more severe in the second year as compaction extended further down the soil profile, as shown by the yield reduction of 13.5% in the first year and 30.2% in the second.”

What can farmers do about soil compaction?

DairyCo research is currently investigating the effectiveness of sward lifting and slit aeration techniques at alleviating compaction. There are a number of options for dealing with soil compaction however little independent research to date has been completed on any of these and so the outcomes of the DairyCo research will be of great value.

Dr McConnell says, “In some cases of soil compaction, doing nothing is actually an option. Some soils will recover with time, particularly if compaction is not severe. The rate of recovery will depend on a number of variables including the extent of the compaction, climate, soil type and so on.

“Ploughing is a course of action, but is only likely to be viable on old, poor performing leys. Remember to have a look at the percentage sown species in the sward – if this is over 50%, it’s unlikely to be economical to plough out the ley.”

Aeration techniques such as sward lifting and spike aeration can also be used.  Spike aeration is best used for shallow compaction in the top 10 cm – usually associated with compaction from grazing animals as opposed to tractor compaction which tends to be deeper in the soil profile.  Sward lifters can be used for deeper compaction at 25-30 cm.

A video is available on the DairyCo website (www.dairyco.org.uk) covering the basics of soil compaction.

For the very latest up to date information and for a working demonstration of the new Recommended Grass and Clover database visit stand 329 and speak to forage experts from DairyCo, EBLEX and BGS.