Counting the cost of compaction

Published 5 June 15

With feed and forage costs remaining the largest driver to unlock profit on dairy farms, optimising grassland production has never been more important. That was the message at the recent AHDB Dairy Research Day held on the farm of Aeron and Carys Owens, St Clears, Carmarthen.  

“Efficient grassland production is key to reducing feed costs and improving farm profitability,” comments AHDB Dairy Technical Extension Officer, Piers Badnell, speaking at the event. Piers continues, “Start from the ground up by ensuring soil fertility and structure are correct to provide a good growing medium for a highly productive grass sward.  With 58% of grasslands soil in GB lower than pH 6, improving soil pH is a quick win for many farmers but dealing with soil compaction is moving high up the agenda as well.”

A recent survey has highlighted as much as 70% of grassland soils in England and Wales are showing signs of compaction and the latest AHDB Dairy-funded research has highlighted the costs of this compaction. “Compaction, either by animals or tractors, can cause yield losses of as much as 2 tonnes per hectare,” explains AHDB Dairy R&D Manager, Dr Debbie McConnell. “Coupled with poor nitrogen recovery (up to 40% can be lost) and high water retention delaying turnout, compaction can easily cost in excess of £250/hectare in lost sward productivity and utilisation,” she continues.

Soil Compaction DM

Image 1 Dr Debbie McConnel talks about soil compaction at the AHDB Dairy Research Day

The three-year AHDB Dairy compaction project, which is taking place at SRUC and HAU, has also been trialling different aeration equipment to improve soil structure. In the trials, both spike and sward lifting aeration had a positive effect on soil structure, encouraging oxygenation and improving water infiltration. “However, there can be a short-term yield penalty associated with aeration, resulting from root damage,” warns Debbie. “As a consequence, it’s important to identify why aeration is necessary, with any aeration being completed in the autumn to minimise yield loss.”

The research also showed little benefit to using aeration equipment on uncompacted soils. At a cost of £35–70/ha for spiking and lifting, the importance of examining the soil with the DairyCo-EBLEX Healthy Grassland Soils scoring system* to identify compaction was emphasised to make the most of this investment. 

*The DairyCo-EBLEX Healthy Grassland Soils scoring system helps identify which fields have compaction and outlines the management options available to alleviate compaction. The resources can be downloaded from the website at www.healthygrasslandsoils.org.uk