Over the past 80 or more years, the pressures applied to subsoils (0.4 m depth) by machinery has increased by a factor of about 15. While some subsoils have already experienced this pressure through glaciation in the ice age or high pressure tyres working in the bottom of furrows, many have never experienced pressures of this magnitude. What happens to them? Logically, the porosity (air space) gradually gets squashed out of them with the result that roots can no longer find as much air and there is less space for water. Trials prior to 1994 conducted in seven countries, including ones with deep freezing of soils each winter, showed that several passes of wheels on one occasion at the surface with loads of just 5 t was enough to permanently depress yields by 2.5%. We now have loads of 12 t under a single harvester wheel! Are we getting a similar effect and would we actually notice this drop in yield in the short term? Improvements in varieties and better chemical agronomy might mask it, but we are almost losing out on yield potential.
Some might argue that we can go to low ground pressure, but two problems become apparent. First, unless we put all very heavy vehicles on rubber tracks, getting low enough pressures with tyres is impractical – they would be too wide and too costly. Secondly, the unfortunate fact is that it is load not pressure that determines the depth to which compaction travels in the soil. Repetitive loading also builds up compaction – you only have to look at the ruts formed on motorways, or even those on your driveway where your relatively light car runs! OK, I know what you are going to say now, “what about the controlled traffic wheel tracks, aren’t they going to get rutted?” The answer is yes, of course they will, but we need to manage them, either by infilling or a combination of infilling and light cultivation. This is no reason to throw out the system, it’s up to us to design and implement the correct management strategy for permanent wheel tracks, taking account of soils, traffic and moisture regimes.
So, can anyone think of a better way than CTF for managing soil compaction? It’s not perfect and we don’t have the right machinery yet to make it easy, but doesn’t putting all your compaction in as small an area as possible make sense? At least we know where it is and if desperate, can repair it without massive cost.
Your thoughts and ideas would be much appreciated in what I’m sure will be an ongoing debate.
In many controlled traffic systems the permanent wheel tracks not used for chemical applications are often sown with crop and it is in our interests to maximise the yield from these wheelways that may only be tracked a few times each year. The first essential is to achieve just as good crop establishment as in the adjacent beds. People direct drilling often recommend setting coulters deeper in the wheel tracks to ensure good cover, others suggest a shallow cultivation such as duck foot tines.
Obviously crop in the wheel tracks will not generally perform as well as on the beds (otherwise why would we be using CTF?!) but the first essential is to get crop established. So what do you do? Anyone’s thoughts and experiences on this subject would be greatly appreciated.
I recently made the comment that CTF is purely a traffic management system and I was castigated by our Australian colleagues who said it was a whole lot more than that – it’s the start of a completely new way of thinking which delivers a more precise way of farming. Precision that opens up a whole range of new opportunities from accurate mapping, inter-row operations, massive reductions in fuel use and input conservation to name but a few – overall a much more efficient and environmentally sensitive way of farming.
I do of course agree but my aim was to make it simple so that people aren’t put off giving it some thought and even trying some things, as is our host farmer who we plan to visit in November. His simple approach will allow him to see what is happening under one pass of a machine, two passes and however many may occur in one place during the several seasons he is going to monitor them. As our Australian “cousins” often say – “know where you are farming” and this is made easy by RTK GPS. I know this isn’t cheap, but the returns can be calculated reasonably easily using data from your own farming operations. Becoming a member of CTF Europe makes this easier still – we have the tools ready and waiting for you to use!
Anybody have any comments on this?
What could be more appropriate than 2010 for CTF? 20% less in and 10% more out
Come to our RTK workshop on 9 Feb to learn about the essential guidance technology that you need. Visit www.controlledtrafficfarming.com to find out more and register for this open event.
Controlled traffic farming needs a lot of thought and planning and being able to “talk” to others about how to do it can be extremely valuable. We’ve created this blog so that all the aspects of CTF can be discussed. For example, what drill would be best for you, what sat nav do you need and a host of other things.
Are there any things you want to know about?