Lo-till has caused grass weed and ergot problems
I have been using min cultivations for 20 years on heavy land. I have now got to the point that grass weed control is getting impossible and ergot is also a serious problem. So now I am having to go back to ploughing certain fields.
Is there any way I can avoid having to do this on the whole farm? This may not be what you want to hear, but on the bit of lighter soil I have, Ive found the plough and drill method is the most reliable and cheaper option!
Your last point first. I quite agree that on light land a fast, shallow plough can be just as cost effective a carry on!
Ergot can be encouraged by grass weeds, especially black-grass and annual meadow grass as they are also a host plant for the strain of fungus that infects wheat.
The answer is to plough to bury the sclerotia (the black bits you see in the ears) to a minimum depth of 10 cm.
I am assuming that you have a rotation which includes a break crop when I suggest that this is probably the place where you can still min till, but you MUST ensure that you control the grass weeds in this break crop.
For example, in oilseed rape use Kerb (propyzamide) plus a specific graminicide such as Laser (cycloxydim).
Ploughing down black-grass seed results in 70% control of the weed.
Our experience has shown that wherever we fail to get a decent stale seed bed (when using lo-till) the weed problems can increase. It can be for a number of reasons, many often out of your control.
1) Insufficient time between harvesting one crop and establishing the next. This theoretically can be overcome by drilling later – not always an option on heavy land.
2) Trying to cultivate too deep whilst forming a stale seed bed. Shallow surface cultivations (50mm) do not bury weed seeds so deep, fewer clods are formed, moisture is retained, and it is easier to re-consolidate thus improving the effectiveness of the stale seed bed.
3) Always spray off prior to drilling even if the weeds are very small and would appear to be destroyed by the drilling process.
I fully sympathise with you – weed control IF IT GOES WRONG using a lo-till system can be more costly in herbicides and lost yield than is saved in cultivation costs.
We have concluded after our limited experience that if there is insufficient time to create an effective stale seed bed, dont even try. Plough and cultivate conventionally, or do as we do under these circumstances: direct drill.
Using a disc drill we move very little soil and as a result fewer weed seeds germinate (especially when drilling OSR).
We are seeing farmers in our part of the world investing very heavily, in expensive lo-till kit and big tractors in an attempt to get a stale seed bed.
In my opinion this defeats the object of going down the lo-till route. One should be REDUCING THE AMOUNT OF ENERGY you are putting into your system. This can sometimes be done by ploughing just a bit shallower and pressing.
This autumn we are going to look at a number of ways of improving and speeding up the stale seed bed process, including harrowing, applying nitrogen to the stubble to aid straw breakdown and grass weed emergence and finally by using cover crops.
So far as the ergot part of the question is concerned, it was a real problem for us last year (2000), but has equally been a problem in the past when everything was ploughed.
I am told effective autumn grass weed control helps to reduce their numbers…..