Much soil damage repaired

Published 11 October 13

Much damage repaired but still some areas of concern for soils this autumn

Weather conditions this summer have given many soils the perfect opportunity to recover from last year’s monsoon conditions - but some soils will still need attention. Below, independent soils and grassland consultant Chris Duller outlines what he has seen on farms this season.

Most areas have had a decent warm, dry spell at some stage this summer, meaning soils with a significant clay content (30%+) have cracked and begun to repair themselves.

Good grass growth above ground has been mirrored by root growth below; roots produce chemical exudates which help soil structure to become more friable and less blocky. In soils which retained some moisture in the soil profile, worm activity has also been good this year, fed by surplus organic matter that didn’t breakdown during last year’s cold, wet conditions.  

The result of a decent summer and these natural processes is that compaction in many areas has been significantly reduced. For example, on a fairly heavy farm in Pembrokeshire, I monitored the effects of sward lifting this spring on subsequent silage production.  Although lifting did improve second cut yields by 15%, by the time we came to third cut in August, a control area which hadn’t been lifted was growing just as much grass.

This result was similar to the DairyCo/BGS demo farm in Cheshire, where benefits of soil aeration and sward lifting lasted around nine months. After this, the cracking we’ve seen this summer meant that the untreated plots had the chance to ‘repair’ themselves.  

However, there are exceptions to the recovery process– and it is worth digging and looking to see how your soils have coped. Many of the exceptions I have come across tend to be on soils with a low clay content. Some red sandstone soils, for example, are still suffering from plated structure and clear horizontal layers that have restricted root growth all summer. One farm I visited with such a problem was also suffering leatherjacket damage. With most of the root growth confined to the top couple of inches, leatherjackets were making a big dent in the total root mass.

Quite often the top few inches of soil have recovered well but compacted layers 4-8 inches deep, caused by machinery damage last year, are still very much in evidence. Particularly in drier areas where worm activity has been poor, many of these blocky structures haven’t broken up. When soils start to wet up again this autumn they are likely to hold water and be very prone to further poaching and machinery damage.

Soil conditions are still very good for taking action this autumn – especially for maize growers who didn’t get a chance to subsoil before drilling. Have a dig and assess how well soils have recovered and, if there are still large blocky structures intact after this good summer, then it makes sense to try breaking them up by lifting/subsoiling or aerating( if they are at the surface).  

The return on investment for soil management is massive – recent results from the DairyCo Grassland, Forage and Soils Research Partnership has shown that soil damage can reduce grass yields by almost 20% at first cut and increases the wetness of the soil.  Even slight soil damage could be costing you £200/acre each year in lost yields, quality and lost grazing days. Make the most of these good conditions; we may not see them again for a while!

For more information on the Grassland, Forage and Soils Research Partnership  as well as other R&D projects visit the DairyCo Research Day, Your levy, your future, 12 November at SRUC.