Hello,

I want to thank Al again for the information he has posted on these forums. Since I am want to start making my own soil and lessen the amount of organics, I used Al's soil suggestion as my main basis for soil components. After spending some time reading up on the different characteristics of the items used in soil I wanted to see if I am getting the basics. Let's begin :)

1. Conifer Bark - Both Fir and Pine have pH around 4.5 and lower. used to increase the porosity of the soil. Breaks down slowly. Retains nutrients with positive charged ions;

calcium, magnesium and potassium. Repels negative charged ions; phosphate.

2. Sphag/Peat - Seems to be most common ingredient in commercial soils. High organic content, large water holding capacity, breaks down very fast

3. Turface - Excellent water and nutrient holding capacity, also helps improve aeration of the soil

4. Crushed Granite/Grit - improves draining and aeration. Breaks down very slow so will not add any worthwhile minerals

5. Perlite - Used to improve aeration and drainage. Breaks down much faster then above inorganics.

6. Vermiculite - Same as above, except has good water retention

7. Lime - Used to decrease acidity of the soil, adds Calcium and Magnesium to the soil

8. Gypsum - Used instead of lime when pH does not have to be raised. Only provides calcium, need to used epsom salt to add magnesium

So, most of the above information is from various posts from here. If the above is mainly true, then my questions would be as follows:

1. Bark - Above I mentioned about retaining and repeling certain kinds of ions. This causes leeching of nutrients. Does this affect the amounts of nutrients that need to be added? One site says only the phosphate is leached out quickly since it has a negative charge


NC Dept. of Agri.

Another site says that it leeches all three; nitrogen, phosphate and potassium


NC Dept. of Agri. 2

I also read a good bit of information on the properties of bark at


Cornell Dept. of Hort.

2. Will Turface, sand, perlite and/or vermiculite add any nutrients/minerals as they break down? Am I correct in thinking that even if Turface did add something, it would be worthless because of how long it takes to breakdown and does the same go for the sand?

3. A couple of sites state that the optimal pH range for the solubility of certain minerals is between 5.0-5.5. I am just curious if this is only for very specific kinds of plants? And if not, why is a pH of 6.5-7.0 most recommended.

"Solubility of mineral nutrients are affected by substrate pH. Iron, manganes, boron, copper, and zinc are most soluble when pH is above 5.0 and below 5.5. On the contrary, as pH increases greater than 6.5, the availability of iron, manganese, boron, copper, and zinc decrease and micronutrient deficiencies symptoms begin to appear." Quoted from
Univ. of Kentucky Agri.

There is another article about the relation between nutrient uptake and pH at:
USDA-ARS Agri. Researh

4. This question is mainly for Al, if you are reading this. I am in no way questioning your suggestions or advice, just wanted to understand a little better :)

Your soil suggestion was the following:

3 parts Turface

3 parts crushed granite (farm feed store)

3 parts pine or fir bark (see photo for size)

1 part coarse silica sand (masonry supply company)

1 part vermiculite

Dolomitic lime or gypsum

Micronutrient granules

I asked why the soil was acidic, which I now know is from the bark. You said that the above mixture would have a pH of about 6.5 without adding either the lime or gypsum. That would mean the main ingredients would be bark, turface, granite and vermiculite. Which of those ingredients is raising the natural acidity of the bark up to 6.5. Or is the bark that we are using treated in some way that the pH is raised?

5. Another question for Al :) On your "A Soil Discussion" (link below) you have a picture of three kinds of bark. You suggest to find the bark at the top in the bottom picture, the left is more coarse and the right is fine fir bark. Is the top bark already composted somewhat and is that why it looks wet? Where as the other two look more, "raw", in that nothing has been breaking it down yet. If I am correct, does the decomp of the top bark help provide nitrogen where the "raw" bark would not? They talk a bit about composted bark at the Cornell link above.


A Soil Discussion

I want to thank anyone who reads thru this mess. I want to understand how the main soil ingredients interact with one another before working my way to understanding fertilizers.

Thanks in advance,

Ross :)