Hello all,
We've done a fairy elaborate soil test on our new
land. We thought it was good to test the base level extensively, then we can test again after 10 years of
permaculture. Yet any expert advice on how to interpret the results is greatly appreciated, it's a bit beyond us.
The land had been used as a vegetable plot by an old farmer, who probably did not shy away from tilling, fertilizing and chemicals, but luckily the land has been fallow for 7 years and is overgrown with brambles. In general, I think we can be quite happy with these results such as organic matter levels and mineral availability. But perhaps I am missing something.
Information:
- 1800m2. South of France, Mediterranean climate (on northern edge, max frost last winter -4 Celsius), right at the southern feet of the Massive Central, so loads of rain (I think 1500mm), mostly in autumn/winter, but still 2 to 3 very dry rainless months in June/July/August. 250m altitude.
- Riparian zone, clay, next to small river and including 2 little sources.
In particular, my questions are:
- Is it possible to lower the pH (it's 7.7) slightly by adding conifer mulch or sulfur? There seems to be some
answer to this in the Ph water/ pH KCI results, whether you can sustainably change the pH or whether you can only do it temporarily (see note 1). I don't understand.
- Can we grow certain
trees to acidify the soil a bit? Interplanting with trees such as Stone Pine (pinus pinea)? In general we would not be a big fan of growing just any fruitless shade creating evergreen conifer such as Douglas pine.
- How to improve the potassium? We have access to loads of
wood ash from stoves in the area, isn't that good for potassium? Is there a danger that would make the pH even more basic? [edit: Paul Wheaton says: "if your soil is already over 7.0, you probably don't want to use ash"]. or perhaps growing a lot of comfrey?
We will have a family sized bio-intensive vegetable garden and the rest will become food forest. We will plant Robinia Pseaudoacacia everywhere for nitrogen fixing, controllable shade and mulch.
(The test is attached. it's is in French but I've mostly added English translation.)
Best regards
Note 1. (google translate) Ph water/ pH KCI= measures the acidity of the soil.
water pH is the acidity of the soil solution. the pH KCL is the acidity integrating the pH of the clay-humic complex. the difference between water pH and KCI pH gives a good idea of ​​potential acidity. in calcareous soil the risk of acidification is zero. the pH is closely related to the carbonates of the limestone. the assimilation of elements by the plant is optimal at a water pH of 6 to 7.
1) To increase the pH, liming (addition of carbonate) is mandatory. the dose is related to the buffering capacity of the soil. (CEC size).
2) To lower the pH, the supply of acidic such as flower sulfur is possible at a dose of 3g / m2 three times a year. the purpose of sulfur is to break down carbonates. if the soil is calcareous, only the soil solution will be temporarily acidified. if the soil is not calcareous despite a basic pH, it is possible to gradually and sustainably buffer the water pH
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