Manure - how much is too much?

[newspud9]

For the first time since I've had a plot, a local farmer has kindly dumped a mountain of horse manure for everyone.  It looks excellent consistency...not too fresh but certainly not like the bagged stuff from garden centres.  Parts of my plot has a high % of clay in the soil and this looks like a good opportunity to really improve matters.  But how much to use?  Some plotters have a thin layer others have put down an 8-10" covering.  Can you over do it?  Also, does it need digging in or can you leave it to break down and just use the beds next season.  Also, best to cover it or leave open?

Many thanks for all the guidance.   

[newspud9]

[Tee Gee]

Can you over do it? 

In my opinion... No!

Also, does it need digging in or can you leave it to break down and just use the beds next season.  Also, best to cover it or leave open?

My beds were approximately  1.5 m wide x 10 m long and I used 4-5 builders barrelful for each bed and I did it like this:







and this is how I describe the task in my website:

http://www.thegardenersalmanac.co.uk/Content/S/Soil-Preparation/Soil%20Cultivation.htm

[BarriedaleNick]

You'll get a dozen different answers to that question!
Personally I think anything more than about 4" is overdoing it or at least a waste of resources.
Some people like to trench it like above, others will leave it on top of the soil (no dig) and others will just sort of fork it in.
I have a solid clay soil so I choose to pile manure and compost on top of the soil because any nutrients will leech down and it also acts as a mulch which can reduce watering. Eventually it gets drawn into the clay by general action of worms and weathering.
As long as it isn't to hot and fresh you are fine whatever you choose to do with it. 
I let it rot down over winter and then use it where and when I want it - plenty on the spuds to earth them up, none on carrots/parsnips, loads for squash both in a hole and as a mulch..

[newspud9]

Many thanks for all the helpful advice.

[Obelixx]

If it's spread as a thick layer in autumn you can just leave it for the worms and other organisms to work into the soil but if it's for spreading now I'd do some trenching and some mulching to get the best of both worlds but not where root crops like carrots are going to be grown cos they'll get excited and grow funny shapes.