Going back to our roots with soilsFriday 05 June 2015
Soils – back to basics
Although we expected better weather for the first Lancashire Farmer Network summer farm walk this year 17 of our hard-core members turned up to Westhead Farm at Lathom to hear Neville Pearson talking about soil structure and how it can be managed. We braved the rain and gale force winds to gather round a soil pit kindly dug by our host Michael Rimmer whilst Neville showed us how and where to identify compaction, and then discussed (in the shelter of the barn) what we can do to remedy any issues caused by working soils in less than ideal conditions.
The main points are summarised below:
- Dig a hole to identify if there is compaction – and also where it is! Using a spade to dig a hole is most useful as you can easily identify where compacted layers are just by judging the resistance when you push the spade in. You need to know where the top of the compacted layer is and also the bottom – then set your sub-soiler legs to go 2 inches below this depth. There is no benefit to running the sub-soiler any deeper than this as it just wastes diesel!
- Use a sub-soiler with wings for greatest cracking effect. Also ensure that the legs aren’t set too far apart or the compacted layer won’t all be shattered.
- Ideally sub-soiling should be done in late summer / autumn when the soil at depth is at correct moisture level for optimum cracking – too wet and smearing will occur which makes the problem worse, too dry and the soil will be too solid to crack.
- If compaction is shallow an aerator can be used – this is best done in the spring, again when soil moisture is correct.
- Controlled Traffic Farming (CTF) is one methd which can be used to limit compaction to known areas in the field. As all machinery travels on the same tracks and headlands at all times these are the only areas which will be affected by compaction and can be treated accordingly after harvest. In comparison if machinery moves all over the field, as is often the case on grassland farms at silage time, there will be compaction everywhere and the whole field will need to be sub-soiled. This uses up much more time and fuel!
- As we all know worms are good news and will help to aerate soil – however they cannot cope with compacted layers.
- Deep-rooting cover crops are another method of alleviating compaction, however this will take a much longer period of time than using mechanical methods.
- Tramlines over winter are a high risk factor for soil erosion – especially on slopes. The soil in the tramlines is often compacted and forms a drainage channel to funnel the water downhill. Consider whether or not you can put tramlines in later in the spring, or scuff up the surface of the tramline to avoid compaction, or whether you need them at all! Could precision farming technology be used to do away with them altogether?
- Sandy soils are very easily capped during heavy rainfall and compacted. This then leads to run-off of sediment – which also carries valuable soil and nutrients away from the growing crop.
For more targeted advice for your own soils Neville recommended Think Soils - excellent informative publication produced by the Environment Agency which gives good practical advice on identifying the soils on your farm and how to deal with any issues.
Neville Pearson in the soil pit discussing soil texture and structure. We identified deep compaction at 18 inches below the surface - this may have been caused by using high pressure tyres with a heavy load on wet soils and could be remedied by deep sub-soiling.
This event was supported by the Campaign for the Farmed Environment – good soil management is key to farming in an environmentally sustainable way. If we manage our soils correctly to avoid (or minimise) compaction this will reduce run-off of sediment contacting nutrients and pesticides and minimise pollution of waterways. The new 2015 soil protection standards provide details of all the changes to cross compliance requirements for soil and are much more focussed on minimising soil erosion and subsequent pollution.