[Juli]

Good evening everyone,

I have today ordered a cubic metre of horse manure (mushroom compost) to dig into all my new garden beds as they are completely lacking in organic material, having been covered up for at least 4 years.

My questions is, it's obviously well rotted manure, so once I've dug it in can I plant things straight away (like strawberries, rhubarb, raspberries), or do I have to wait until spring?

Also, in one garden bed I have field beans growing as green manure. Can I mulch with the manure to provide some more organic matter in addition to the green manure? Or will that be bad for the field beans?

We've also ordered quite a few fruit trees. Will the horse manure be good to mix in with the soil when we plant the fruit trees?

Thank you 

[mumofstig]

mushroom compost is very alkaline because of the chalk content, so don't put it where you will grow potatoes next year, or they'll be scabby

Other than that it makes a good mulch/soil conditioner and shouldn't hurt the beans at all, just don't bank it up around their stems

RHS advice is here
http://apps.rhs.org.uk/advicesearch/profile.aspx?pid=294

and suggests that fruit won't like it.

[Juli]

Thanks Lesley.

I've written to them to ask about the chalk content, because if I can only use it on the vegetable beds I probably don't need a cubic metre.

[gremlin]

I always assume fruit trees and bushes are hungry blighters and you have a one-off chance to get some food as deep underground as possible to tempt the roots to grow deep.  The tree can grow horizontal feeding roots in it's own time during the next 10 or 20 years.

I put as much manure and bone meal as I can get at the bottom of the hole, but then cover it with maybe 3 inches of ordinary soil so that the roots that have grown in the pot aren't shocked by touching the manure or bone meal when first planted.

I'm not saying this is right or wrong.  It just the way I do it. 

[Juli]

Just to update, they wrote back and said they had just tested the pH and it was 6.0. I then searched for "mushroom compost pH" and found this: http://www.turfandstuff.com/page.php?xPage=spentmushroomcompostpharticle.html  which was interesting. So given that, I'm going to go ahead and dig it into all the new garden beds including the ones for the fruit trees. And I'll follow gremlin's advice when it comes to actually planting the fruit trees.

[JayG]

I suppose it's perfectly possible that different mushroom growers use different recipes for their compost - although gypsum is a source of calcium, unlike limestone or slaked lime it is not alkaline.
I would want to check the pH of any I got hold of before using it, and it has to be said that the RHS is one of the majority who rightly or wrongly still consider SPC to be quite strongly alkaline, and even one of the suppliers who quotes a slightly acid pH of 6.6 doesn't recommend it for already chalky soils, "growing fruit" or ericaceous plants......

From Juli's linked website:

The other great piece of information for gardeners from this study is that we now have some quantities for the nutrients supplied in spent mushroom compost. The numbers, expressed in % fresh/wet weight are as follows:

Nitrogen (N) 1.1%
Phosphate (P) 0.7%
Potash (K) 1.3%
This gives an equivalent NPK ratio of 11:7:13

There is no such thing as an "equivalent NPK ratio" - NPK values are always quoted as the % by weight of NPK in the product, so multiplying by 10 to get rid of the decimal points makes it appear to be a very much richer product than it is - the nutrients are actually of similar values found in most composted materials, hence the sentence in bold italics is rather misleading.