Manure question

[clive fMember]

By adding manure year after year will it reduce the fertility of the soil by making it to acid so the nutrients are locked up and the plants can not access them

[charlesModerator]

 Clive, thanks for your comment. But I disagree, if you mean animal manure…
There is some muddled use of language happening here, for instance after googling "lime and manure" I found this:

"To raise the pH and lower acidity or sweeten the soil, we add lime. To lower pH and increase acidity you can add sulphate of ammonia or urea which are high nitrogen fertilizers.

 

From this you can see that adding manure will also lower pH and make the soil more acid."

 

So the writer is using the word ‘manure’ for BOTH animal manure and chemical fertiliser!! This is confusing, and it happens a lot.

I never use or recommend chemical fertilisers from packets and all my writing is about composts, and animal manures which have been composted. So perhaps that confuses any people who in their minds think of "manure = nutrients", whether

1 man-made, mostly water soluble as in sulphate of ammonia above, or

2 held in organic matter, when nutrients are more stable and mostly water insoluble, as long as a composting process has happened, as in a garden heap (it could be cool composting over a period of many months or hot composting in a few weeks) or as when animal manure is stacked and heats up.

Many of the nutrients in cases 1 and 2 above are similar but how they are held in the soil, or sometimes not in the case of no.1 above (as in ‘leaching’), affects plant growth. You can see the difference in wheat fields which are almost blue in spring after artificial nitrogen is applied, compared to organic fields of paler green colour.

An important difference is that ‘manures’ (synthetic fertilisers) of type no. 1 need careful application when plants are about to grow or are growing. They are plant food.
Whereas manures of type no. 2 (composts) can be applied at any time of year because their nutrients are held until plants need them. They are soil food. As well as having nutrients for plant growth, their organic matter feeds soil organisms and improves soil structure.

From this and replying specifically to your two questions, I find that repeated use of compost and composted animal manure does not increase acidity. If other writers are using "chemical manures", there may be an increase in acidity!

Applying lime then composted animal manure on top may cause a slight reaction but most of the nitrogen in composted manure is not water soluble and is not washed out or reacting with the lime. So I would add them at the same time.
Here I do not add lime because my soil is not becoming acid.

[clive fMember]

Thanks for the prompt reply Charles that made very interesting reading.

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