Archive: Soil MOT

Published 12 September 14

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September is MOT time for soils

September is the ideal period to MOT your soils, says independent soil and grassland consultant, Chris Duller.  It’s time to check the soil health and, with current weather conditions, it’s also a good time to take any remedial action, with aerators or lifters, if needed.  

This year has been good for many soils, with spells of dry weather to promote natural cracking and with enough soil moisture to keep earthworm activity going right through the summer. This means that a lot of ‘damaged’ soils have sorted themselves out, but there are still plenty of soils which need a helping hand to recover.

Any soils which now show signs of compaction will be far more prone to further damage as we go into winter. In compacted ground, ryegrass plants may well be hanging on at the moment, but give them another winter with poor living conditions and they could disappear altogether. Timely intervention now could cost you £30 or £40/acre to set things right. If you leave it until next spring, you could be faced with more serious compaction and a sward full of meadow grass which needs reseeding. This repair bill will be closer to £200/acre.

There are often clear visual signs of soil damage in late summer/autumn, urine scorch marks and sod pulling being two of the most obvious. As the grazing round extends out towards 30 days you should expect to see all dung pats broken down by the time the cows come back to graze, if not, then it’s a good sign that soil conditions aren’t encouraging biological activity. Another sign this autumn can be the increase in disease levels (mainly crown rust) where soils are damaged and the grass plant is under stress.

Digging a quick inspection pit where you have concerns shouldn’t take long. You are looking for roots that extend well down the soil profile and that there aren’t any large tight soil blocks or layers which limit water movement and root growth. Take out an intact block and pull it apart gently – any lump bigger than a 50p piece which doesn’t break easily between your fingers is a good signal of some damage.

If you decide to use a machine to alleviate compaction, the soils need to be dry enough so that the machine doesn’t smear and compact the soil even further but, if conditions are too dry, there is a danger that the slots stay open and grass will be damaged. The results of using these machines are highly variable depending on soil type, ground conditions and weather following treatment.

Don’t forget that your farm is one big experiment – so make sure you leave an untreated area so you can be clear in your mind that it was a worthwhile investment of time and money.

More information on assessing and alleviating soil compaction as well as outwintering cattle can be found on the DairyCo-BGS Demo Farm on 16 September in St Ives, Cornwall. Where you can also hear about DairyCo’s latest research findings from a four-year programme of research on optimum strategies for assessing and alleviating soil compaction.

If you are not in the position to attend the Demo Farm, you can watch the DairyCo video on soil compaction which demonstrates how to recognise signs of compaction as well as possible actions to take. What’s important at this stage is that you identify where the damage is – anything in the top 10cm can probably be helped with slit aerator, anything deeper is more suited to a sward lifter-type machine.