Friday, 11 October 2013

The Blind Leading the Blind

The greatest thing about the Horsch CO8 seed drill is the amount of air between the tines. It's rather like looking under the bonnet of my old farm mechanic's Morris van: lots of space to work and it all looks so simple. 

If you get a blocked coulter on the Horsch, there is enough room for a well built man to thread himself through the tines to the middle section and do his work without too much discomfort. As far as simplicity is concerned, the Horsch makes an egg whisk look complicated. There is no dallying with closely packed discs, all independently sprung and leaving a gnats breath between them, not a bit of it. The Horsch is essentially a sparsely shod cultivator with some tubes loosely attached to the back of it's tines spaced generously at twenty five centimeters with a boot at the bottom out of which the seed Is liberally sprayed. 

Aside from the thousands of tyres at the back of the drill used for consolidation, if a young leveret managed to avoid the Case Quadtrac's thunderous tracks, he could easily wander through the working machine without parting a hair, whereas any other drill on the market would see him sliced and diced. This life saving ability also allows the drill to cope with any amount of trash that we farmers can throw at it. When a little bit over overnight rain has kept other drills in the farm yard, the Horsch has been working since six o'clock in the morning with another hundred acres under its belt.

So why haven't we all got one?

Two words: seed placement. Another two words: It's crap.

With many of our tractors steering themselves these days we all have a huge amount of time to look out of the rear window of our metal horse to get a proper look at what we are actually doing. In the good old days of steering wheel caressing you normally saw what had happened during your last bout when you turned around at the end of the field, but with RTK steering our tractor, I have spent many long autumn afternoons looking at the leading tines of the Horsch diving in and out of the seedbed with alarming imprecision. Unless you have achieved a seedbed that would satisfy an onion grower, the Horsch's construction will never enable it to place seeds at an even depth, but what is the problem if an acceptable percentage of the seed comes up in the end?

This is the argument that I have always applied. You might have had to put your seed rates up to compensate for the seeds that the drill had put beyond Hades, but what it costs in extra seed is outweighed in the sheer hectares per hour you can achieve in all weather conditions and in any amounts of trash saving time and sowing costs. That was all fine until this year when we tried blind weeding.

Although blind weeding is common practice on organic farms in many countries, we have never tried it here as historically we have relied on post emergence methods of weed control. It wasn't until an introduction to a young Swede, Joel Massön, who came to see me last summer and extolled the virtues of the technique, that I considered attempting the method. Joel rightly likened our weeding programme to dealing with the problem after the horse had bolted, and he had a point.

Essentially blind weeding relies on weeds emerging before the crop, and this year due to dry weather when my bête noire black-grass was flowering, mean’t that the shed seed would not be dormant and so a good kill might be possible at sowing time. Black-grass generally germinates at one to two centimeters depth and should emerge quickly in a warm seedbed, while wheat sown at one and a half inches should emerge a few days later  leaving you a small window to harrow, or blind weed the back-grass at it’s most vulnerable without damaging the crop.

Timing is everything and so an extra tactic has to be employed. Using a cloche placed on the seedbed straight after you have sown your crop you can predict a day or so before the weeds will emerge, making it easier to kill them before they have a chance to put down proper roots or even see the light of day. 

It was exactly a week after we started sowing our wheat when it all started to kick off. I had been keenly inspecting the cloche on a daily basis which was strategically placed as soon as the field had been sown, when on the seventh day I saw the first blades of black-grass emerging through the artificially heated soil. Scrabbling down into the dirt I found that the wheat had just germinated and had a shoot on it about one centimeter long. Perfect. 

The harrow comb weeder was immediately summoned and after a few adjustments to the rake of the tines we were bravely weeding at twelve kilometers an hour. I hung around in the field nervously for a few minutes feeling slightly under confident about my decision, seeing my beautifully rolled fields being pulled up again. The theory was right, but it looked so wrong, never mind the fact that at that speed with a twelve meter machine you can do an awful amount of damage in a morning.

That night was sleepless. I had visions of thousands of wheat shoots lying mangled in the dry soil with the exhausted seed disgustedly withdrawing it's roots in protest and submitting itself to the inevitable slug. I could hear my seed merchant sniggering into his coffee at the end of the phone as I placed a new seed order to repair my foolish mistake. 

The next morning I sheepishly ventured into the fields that we had decimated the previous day and to my huge relief I discovered that my nightmare had not been realised. The wheat was still growing strongly and I could easily find evidence of weed seedlings lying lifeless in the soil or drying out in the September sun. Joy of joys, it had been a huge success!

However, on closer examination I noticed something else. I could also find wheat seeds that the Horsch had sown at one to two centimeters that although had not yet germinated had been upheaved by the harrow comb and were now too close to the soil surface for comfort. The weakness of the Horsch was laid bare for all to see: horribly inaccurate seed placement. 

In my experience the Horsch places around fifty percent of the seed at the required inch and a half, but the remainder is spread shallowly above the moisture needed for germination, or buried to such a depth that not even the most vigorous seed could ever produce a shoot to see the light of day. All fine if accurate seed placement is not the be all and end all, but as far as this weeding technique is concerned, accurate seed placement is essential.

So, where do I go from here? The plan is to do some plant and weed counts on the fields that we have blind weeded and compare those results with the occasional strips we left unweeded in the fields as a comparison. A further test of the blind weeding will be performed later this month when we sow our winter beans which could be more interesting as the beans are sown at a depth which should, weather permitting, allow a much bigger window for the practice. 

Blind weeding makes complete sense to any farming system where black-grass is a problem, and if it is the success that I think that it could be we may be looking at a new drill. 

For the National Farmers Union Website - October 2013

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