Soil Minerals and Soil Testing for Organic Gardeners

The Ideal Soil:
A Handbook for the New Agriculture

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Teaches all you need to know to become your own soil minerals expert!

(Yes, really) 

Sample Soil Mineral and Trace Mineral Reports
For Organic Gardens, Farms, and Landscapes

#1 The Nine-Year-Old "Problem" Garden

This first laboratory report and prescription is for an organic vegetable garden that had been in production for nine years but was just not doing what the gardeners expected.  As you look through the lab report and read the comments you will begin to see why: some important minerals are lacking and/or out of balance, especially that "king of nutrients", Calcium.

The recommendations made for this garden are quite extensive, but keep in mind that this needs to be done only once, at least in these quantities. Once the minerals are there and balanced only slight additions need to be made from year to year.

Here is an email we received from the owners of this "problem" garden, exactly two months later:

You did a soil test for us and "prescribed"  the missing minerals. I have
huge kale, and everything else is doing a great job of growing.
I'll take some photos one of these days, and bring them in for you.
Thanks! L.S.

Following the nine-year-old garden are the recommendations for a sheep pasture, and after that comes a landscaping problem from a high rainfall area of the Pacific Northwest.


S

Element

Results

Comments

Total Exchange Capacity 21.91 Good.
pH of soil sample    5.40 Too acid for garden soil. 6.0-6.5 is ideal.
Organic Matter % 12.67 High. Doesn’t need more.
Anions     
Sulfur S (parts per million) 27 Low. 50+ ppm is better.
Phosphorus (as P2O5) lbs/acre 1019 Low for the EC and recommended Potassium level.
Cations   Note: The figures below for “desired levels” are based on a theoretical ideal base saturation of 68% Calcium, 12% Magnesium, and 4% Potassium. Our recommendations may vary depending on soil type.
Calcium Ca   lbs/acre
Base Saturation
60 to 70%
Desired
Found
Deficit
Saturation%
5958
4202
-1756
47.95%
Low. Should be 68% of base saturation for this soil.
Magnesium Mg lbs/acre
Base Saturation
10 to 20%
Desired
Found
Deficit
Saturation%
630
537
-93
10.21%
A little low.
Potassium K
lbs/acre
Base Saturation
2 to 5 %
Desired
Found
Deficit
Saturation%
683
282
-401
1.65%
Much too low. Bringing this up to 4-5% saturation will make a big difference in plant vigor and production.
Sodium Na Lbs/Acre
Base Saturation .5 to 3%
59
0.59%
Too low. Plants need Sodium just like people and animals.
Other Bases (variable) 6.60% Iron, Manganese, Copper, Zinc etc.
Exchangeable Hydrogen (10-15%) 33.00% Will stabilize at around 10% as Ca, Mg, etc. are raised.
Minor Elements (ppm)    
Boron B 0.79 Low. Should be 1/1000 of Ca, around 3ppm for this soil.
Iron Fe+ 251 OK
Manganese Mn+ 53 OK
Copper Cu+ 1.56 Low. Should be ½ of Zinc.
Zinc Zn+ 8.51 A little low.
Aluminum Al+ 1922 Normal for this pH.

Notes and Recommendations
Nine Year Old Garden

Notes: Will make an excellent garden when the recommended nutrients are added. The extremely low Potassium levels and lack of Calcium will have been the main limiting factors before now. I think you will be amazed.

Soil organic matter is high, which is normal for this climate and the low pH. As the recommended minerals are incorporated into the soil, the organic matter will begin to break down and stabilize at a more normal 7-9%, releasing some nutrients as it does so.

Fish meal, liquid fish, or fish bone meal would be good Nitrogen boosters. The fish meal or fish bone meal should be mixed into the soil at the bottom of the planting furrow for sustained release during the growing season. Liquid fish fertilizer would be a good mid-season growth booster for Nitrogen loving crops like onions and corn.

Even though the organic matter is already high, I am recommending 1" of quality compost or chicken manure to boost Nitrogen and biological activity.

Nutrients Recommended:

Calcium: 40 lb/1000sqft

Magnesium: 2 lb/1000sqft

Potassium: 9 lb/1000sqft

Sodium: 3 lb/1000sqft

Sulfur: 2-3 lb/1000sqft

Phosphorus as P2O5: 12 lb/1000sqft

Boron: raise to 3ppm

Copper: add 4-5ppm

Zinc: add 3.5ppm

Azomite for trace minerals

Kelp meal for trace minerals, Iodine, and growth factors

Quality compost or chicken manure: 1"

Fish meal, fish bone meal, or liquid fish as needed for this years crops


Recommended organic approved soil amendments, per 1000sqft

Agricultural Lime, 39%Ca: 80 lb (32lb Ca)

Dolopril type Dolomite Lime: 15 lb (2lb Mg, 3.3lb Ca)

Potassium as sulfate of potash 50%K: 18 lb (9lb K, 3lb S)

Sodium, as sea salt: 6 lb (3lb Na plus Chlorine and trace minerals)

Montana rock phosphate: 60 lb (approx. 18lb total P2O5)

Boron as Solubor 20%B: 7 oz (2ppm B)

Copper as Copper sulfate 25% Cu: 13 oz (4.5ppm Cu)

Zinc as Zinc sulfate 35.5% Zn: 8 oz (3.5ppm Zn)

Azomite volcanic trace minerals: 10 lb

Kelp Meal: 10 lb

Quality compost or chicken manure: 1"

Fish meal, fish bone meal, or liquid fish as needed for this years crops

Application: The Zinc, Copper, and Boron should be mixed with the lime or potash to ensure even spreading. After all of the nutrients are applied they should be tilled into the top 4-6 inches of soil.

#2 The Sheep Pasture

The following report is for an existing pasture that has new owners.  They don't know the history of the pasture or  what may have been added in the past, but when submitting the soil sample they have told us that the area is very rocky.  The area is the Puget sound region of Western Washington, as far South as the glaciers went during the last ice age.  When the glaciers melted they left piles and swathes of stones sometimes hundreds of feet thick.  Stony, rocky ground there is very stony, basically a pile of rocks with the spaces in between filled with soil.  For that reason we have made the assumpton that only 1/2 of the pasture is actually soil and adjusted the amounts recommended accordingly.
S

Element

Results

Comments

Total Exchange Capacity 14.12 OK
pH of soil sample    5.30 Low.  6.0-6.5 is ideal.
Organic Matter % 9.71 OK
Anions     
Sulfur S (parts per million) 20 Low. 50+ppm is better. Needed for some proteins.
Phosphorus (as P2O5) lbs/acre 227 A bit low, but normal for this area.
Cations   Note: The figures below for “desired levels” are based on a theoretical ideal base saturation of 68% Calcium, 12% Magnesium, and 4% Potassium. Our recommendations may vary depending on soil type.
Calcium Ca   lbs/acre
Base Saturation
60 to 70%
Desired
Found
Deficit
Saturation%
3839
2666
-1173
47.21%
Low. Should be around 65% of base saturation.
Magnesium Mg lbs/acre
Base Saturation
10 to 20%
Desired
Found
Deficit
Saturation%
406
245
-161
7.23%
Low.
Potassium K
lbs/acre
Base Saturation
2 to 5 %
Desired
Found
Deficit
Saturation%
440
209
-161
1.90%
Low.
Sodium Na Lbs/Acre
Base Saturation .5 to 3%
56
0.87%
Too low.
Other Bases (variable) 6.80% Iron, Manganese, Copper, Zinc etc.
Exchangeable Hydrogen (10-15%) 36.00% High due to low pH.
Minor Elements (ppm)    
Boron B 0.93 A little l ow.
Iron Fe+ 265 OK
Manganese Mn+ 72 OK
Copper Cu+ 1.93 Low. Should be ½ of Zinc.
Zinc Zn+ 12.02 A little low.
Aluminum Al+ 2109 High, but normal for this pH.

Notes and Recommendations
Sheep Pasture

Notes: Sheep pasture; 37,800 sqft; rocky, stony soil.

This pasture is probably around 50% soil and 50% glacial till/rocks, so these recommended amounts are lower than they would be if it was all soil.  It does not appear to have had any mineral additions.  As usual in the Pacific Northwest, Phosphorus is a bit low, but probably sufficient.  The major cations Calcium, Magnesium, Potassium and Sodium are all low and should be amended.

Boron and Copper are also low.

In addition I am recommending Azomite and sea salt as trace mineral sources.

May is a bit late in the year to be adding these minerals.  In the fall or early spring would be better, but they are badly needed and will still help even without the spring rains to wash them in. None of the recommended nutrients pose any danger to animals in these amounts, although the Copper sulfate should be kept away from fish ponds.

Another soil test in early spring, January or February, is highly recommended.

Recommmended Organic approved soil amendments, per 1000sqft:

Calcitic Ag Lime (39%Ca, 1%Mg):  35lb

K-Mag (Langbeinite):  12.5lb      (Potash, Sulfur, Magnesium)

Boron  (as Solubor 20%B):  2 oz

Copper (as Copper sulfate 25%Cu):    6 oz

Azomite trace minerals:   5 lb

Sea salt:    5lb

Application:  The Copper and Boron should be mixed in with other amendments to assure even application. They may be mixed with any of the above.

#3 Native Pacific NW Landscape Planting

#3 is a landscaping problem.  A topsoil mix has been brought in from a local garden center and used to fill planters and curb areas that have then been planted with native species.   The native plants are not doing well.  The specific complaint is that their leaves are turning purple.
S

Element

Results

Comments

Total Exchange Capacity 35.33 Good.
pH of soil sample    7.70 Far too high for native NW plants.
Organic Matter % 9.02 OK
Anions     
Sulfur S (parts per million) 217 High.  Avoid adding more sulfates.
Phosphorus (as P2O5) lbs/acre 1841 High.  Doesn't need more.
Cations   Note: The figures below for “desired levels” are based on a theoretical ideal base saturation of 68% Calcium, 12% Magnesium, and 4% Potassium. Our recommendations may vary depending on soil type.
Calcium Ca   lbs/acre
Base Saturation
60 to 70%
Desired
Found
Deficit
Saturation%
9610
12221

86.47%
Here is the basic problem.  Calcium is far too high for native plants.
Magnesium Mg lbs/acre
Base Saturation
10 to 20%
Desired
Found
Deficit
Saturation%
1017
522
-495
6.16%
Low.  Most native plants like a high Magnesium soil.
Potassium K
lbs/acre
Base Saturation
2 to 5 %
Desired
Found
Deficit
Saturation%
1102
928
-174
3.37%
OK for now.
Sodium Na Lbs/Acre
Base Saturation .5 to 3%
51
0.31%
Low.
Other Bases (variable) 6.60% Iron, Manganese, Copper, Zinc etc.
Exchangeable Hydrogen (10-15%) 0.00% Due to over-abundance of Calcium.
Minor Elements (ppm)    
Boron B 1.28 OK
Iron Fe+ 258 OK
Manganese Mn+ 60 OK
Copper Cu+ 8,25 Perfect.
Zinc Zn+ 17,15 Perfect.
Aluminum Al+ 1380 Normal.

Notes and Recommendations
Northwest Native Plant Landscape

Notes:  "X" Street Bakery; Native NW plants; topsoil mix from "XX" Garden Supply.

This is a mounded landscape planting of native Pacific Northwest shrubs and flowers; varieties have not been named.  Report indicates the leaves are turning purple.

I am assuming that "native" would mean salal, Oregon grape, rhododendron, dogwood and the like for shrubs, perhaps camas and native lilies for flowers.  All of these are adapted to a soil with lower Calcium and higher Magnesium along with higher levels of exchangeable Hydrogen (lower pH). The topsoil mix in which they have been planted is very high in available nutrient minerals, and far too high in Calcium for these plants.

The challenge is to reduce the Calcium, raise the Magnesium, and lower the pH.  Usually this could be done with Epsom salts (Magnesium sulfate) but in this case Sulfur is already at maximum.

Although this test did not measure chloride, the extremely low Sodium level indicates that Chlorine is probably low also, so I am recommending using Magnesium chloride, which will (hopefully) complex some of the Calcium, lower the pH, and provide needed Magnesium as well as Chorine.  Chlorine is an essential nutrient for plants just as it is for animals, and is a good growth promoter as long as it is not overdone.

In addition, native NW shrubs are adapted to getting part of their food and water supplies through symbiotic relationships with fungi.  Salal, huckleberry, Oregon grape, bearberry (kinnikkinnik) etc. are all shallow rooted.  Their roots grow laterally along the forest floor and are provided with moisture and nutrients during dry spells by these symbiotic fungi. For that reason I would recommend gathering some "duff" of organic matter from an area where these plants are naturally thriving and applying it as a top dressing or mulch to inoculate the growing bed with beneficial fungi.


Recommended Organic approved soil amendments:

Magnesium chloride:  The easiest source for this would be Nigari, a natural Magnesium chloride derived from sea water.  Nigari is used for curdling soy milk in the making of tofu and is available at some health food stores and co-ops. In addition to Magnesium chloride Nigari also provides a small amount of Sodium chloride and trace minerals from sea water.

Application: 1 tablespoon Nigari per gallon of water.  The entire bed should be well watered with this solution once every other week for six weeks.  That should turn things around not only by adding Magnesium and Chlorine but also leaching out and complexing some of the Calcium into Calcium chloride.

Forest floor duff mulch: As noted above, taken from an area where these plants are naturally doing well.  It should be disturbed as little as possible when gathering; lift it in sheets and chunks so as not to break up the mycelium.  1 1/2" to 2" is sufficient.

Do not use other fertilizers at this time; there are plenty of nutrients available in the planting mix.

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