slugs and direct drilling

[mikep]

The point is that slug populations seem to come and go and no one has any idea why, talk to any farmer about their experiences and they cannot predict when they will get a problem, or when they don't need to worry. I have had epidemics after beans and even linseed. I've also had loads eating rape volunteers in emerging wheat, then when the rape is all gone, so have the slugs. I would also agree that the longer I have been no-tilling, the less of a problem they have become.

It just seems to me that there is something else going on here that hasn't been worked out yet and I would bet that it is to do with soil biology and plant health.

You are correct in the difficulty of predicting attacks or level of damage. There can be slugs knee deep with little damage or conversely difficult to find but much damage.
Slugs we are told like cleaning up, true maybe but why do you never get many near or in a muck heap but lots of worms when it starts to rot?
Put this with some of the observations that there seem to be less of a problem when the OM level is higher or after manuring and there is possibly a tie. It may be a product of breakdown or perhaps conditions are better for free living nematodes that predate the slugs.
So maybe there is a relationship between the breakdown of OM and slug activity lets take a bit of a stab at something. I have found that pre harvest glypho keeps the straw clean for a long time after cutting so obviously there is some fungicidal action taking place. Worms don't eat directly they extract the bacterial residue from OM breakdown from the soil (they do not eat slugs eggs nail that one on the head).
If we have slowed down the first fungal actions perhaps we have changed the worms feeding patterns or amount of feeding. In conditions that does not suit a worm we may find that this suits the slugs as the inhibitor (from the muck heap) is not present.
It may be worth noting glypho applications and subsequent slug problems to see if there is any correlation but this would explain why long term no-till that increases soil activity and worms may produce a habitat that is disadvantageous to the slug.

 

[Richard III]

I still think the level of damage has a lot to do with consolidation and the clue is that the headlands normally have less problem than the rest of the field. One of the problems with heavy land is it cracks open and gives them somewhere to hide, also the drill can create clods or smear a trench in anything other than ideal conditions. The more years of No Till you have done then the less the above things are a problem.

 

[mikep]

I still think the level of damage has a lot to do with consolidation and the clue is that the headlands normally have less problem than the rest of the field. One of the problems with heavy land is it cracks open and gives them somewhere to hide, also the drill can create clods or smear a trench in anything other than ideal conditions. The more years of No Till you have done then the less the above things are a problem.

I am sure it is a whole host of contributory factors, are headlands less prone to attack because of greater consolidation or more cultivation? could be both.

 

[Richard III]

I am sure it is a whole host of contributory factors, are headlands less prone to attack because of greater consolidation or more cultivation? could be both.

I would agree that there are many factors at play, not least the weather. However my headlands get as little cultivation as possible, just the same as the middle of the field. I would think the same would be true for most No Tillers?

 

[britt]

Surley one of the factors reducing the slug population on headlands is predators, such as beetles coming out from the field edge. Isn't that one opf the theories behind putting "beetlebanks" across big fields ?

 

[martian]

Surley one of the factors reducing the slug population on headlands is predators, such as beetles coming out from the field edge. Isn't that one opf the theories behind putting "beetlebanks" across big fields ?

Absolutely. This is certainly one of the factors. I think maybe some of our beetles are working to rule, or at least carrying tape measures, as the 24 metre line from the headland is quite clear on one or two cover crops, with the headlands thriving and the land work shall we say, a little behind

 

[mikep]

I would agree that there are many factors at play, not least the weather. However my headlands get as little cultivation as possible, just the same as the middle of the field. I would think the same would be true for most No Tillers?

I take cultivation in its broadest sense as rolling to my mind is a cultivation, the turning on headlands is what I refer to by extra cultivating. the act of turning moves more soil than you would believe but only by a small distance so you only notice a slight scuff. True a tight seedbed makes it harder for sluggy to find the seed but I reckon a lot of turning in confined areas does more to kill the slugs and their eggs.

 

[Richard III]

Absolutely. This is certainly one of the factors. I think maybe some of our beetles are working to rule, or at least carrying tape measures, as the 24 metre line from the headland is quite clear on one or two cover crops, with the headlands thriving and the land work shall we say, a little behind

I see the same work to rule effect here sometimes, seems they must belong to the same union as yours because mine stop at 24 metres too.

Do you use liquid fertilizer? Frederic Thomas reckons the size of an autumn cover has a lot to do with the amount of N available in the soil. Any extra residual N from a double overlap would show up as a nice line in a cover crop.

I'm seeing quite a clear effect this year, the worse the previous crop, the better the following cover. I'm putting this down to more residual N after a poorer crop.

 

[martian]

I see the same work to rule effect here sometimes, seems they must belong to the same union as yours because mine stop at 24 metres too.

Do you use liquid fertilizer?

No, but it looks just like we do. Broadcast urea, so wouldn't expect such a clear cut line. I suspect that there's a bit of cover crop seed overlap as well as extra disturbance where double drilled, but it looks like the centre of the field was sprayed with something that was still a bit toxic when we drilled the cover and we left a conservation headland. But we didn't. All a bit mysterious...