The Ideal Soil Chart [version 1.7] October, 2008
Everything on the chart is related to everything else based on the Cation Exchange Capacity (CEC) of the soil you are working with.This chart reflects the current level of knowledge. It has been put together over a period of years from many sources, including a lot of personal experience. It is meant to represent an ideal soil for growing food for people and animals, not necessarily the ideal soil for pine trees or rhododendron flowers. It is fine for lawns, though.
In high doses, many mineral elements can be toxic to people, animals, plants and soil organisms. This is true regardless of whether they are in a naturally occurring or purified, concentrated form. Keep them out of ponds and streams. Any of them, if used in excess, can screw everything up, so take it easy. It is much easier to put them in than to get them back out of the soil.High levels of some minerals in the soil may inhibit sprouting of seeds. Boron is definitely known to do this. High levels of free minerals (not biologically assimilated) can also “plug up” the vascular systems of young plants, stunting their growth. Seeds may sprout fine but stall out after the first set of true leaves. This seems to be particularly true after adding high amounts of Calcium. For these reasons it is best to wait until the minerals are chemically and biologically a part of the soil before starting seeds in it. Transplants usually do fine if you wait a week or so after adding large quantities of minerals before replanting them, and we have seen no problems with established plantings, trees, or pastures. Adding minerals in the fall or in the very early spring works best.
If minerals are added directly to potting mixes the mix should be moistened after mixing in the minerals, and it is best to give it a little time, a week or so, to “settle in” before the potting mix is used. Adding a biological activator such as beneficial bacteria or fungi to the soil will greatly speed up the process.The mineral concentrations shown on this chart are perfectly safe for plants once they are assimilated into the living soil. If the chart’s guidelines are followed you won’t end up with too much of anything–many soils naturally contain higher levels of available minerals than the chart calls for.
First of all, primarily, and before anything else, please get a professional soil test. Soil testing is not expensive and most testing labs pride themselves on getting your results back to you quickly, usually within a few days of receiving the soil sample. You must have a soil test before you add any minerals at all. This is not to make us happy, but to ensure your happiness in the long run. You will want to know what you started with. If you insist on adding minerals without a soil test, don’t say we didn’t warn you!A good soil test will give readings for most of the minerals on this chart and will also tell you the CEC (cation exchange capacity) and the base saturation percent of Calcium, Magnesium, Potassium, Sodium and Hydrogen in your soil sample. The soil test should also tell you the amount of Boron, Iron, Manganese, Copper, and Zinc. These are minerals whose function we understand well and it is essential that they all be in your soil in sufficient quantities. You do not need to know the amounts of the minor trace elements to start with (those at the very bottom of Agricola’s chart), and ordinary soil tests don’t measure them anyway.
If you are a very cautious or doubtful person, or the expense seems too great, you may choose not to balance the minerals on the whole farm or the whole garden or pasture at once. Start with maybe one-half of the area and see how things go, or divide it into two or more parts and treat them slightly differently, for instance putting the whole amount called for on one part and only half that amount on the other. It is always a good idea to leave a small representative area untouched as a control. After a year or so you will enjoy pointing out that area and saying “See, that’s what I started with!”Don’t expect immediate and fantastic results from adding some minerals to your soil. It takes time for them to work their way into the living systems of the soil. As the minerals settle into the soil ecology, some will become available to the plants and soil microorganisms and others may get tied up for a while. Adding a little bit of a badly needed mineral nutrient to the soil may greatly increase microorganism and fungal activity, and may catalyze the release of other previously bound-up minerals. Adding a little Copper may make more Zinc available (or less Zinc available). You won’t know until the next soil test.
If you are serious about gardening or farming and having the healthiest soil and plants possible you will want to get a soil test at least once a year. Twice a year, in the spring and in the fall is even better. The spring test will show you what you should apply for this years crop, and the fall test will tell you what to add to settle in over the winter. Calcium and Magnesium, for example, become much more bio-available if they are spread on top of the soil in the fall and allowed to leach into the soil with the winter’s rain or snow.Ignore the pH. If you bring the mineral balance into line with the chart, the pH will self-correct to what is perfect for your soil and climate.
Mother Nature and the soil are very forgiving and you do not have to be exact in these proportions. It would be unlikely to find two soil samples taken one foot apart that were identical. The soil test will give you the general idea, and as long as you go slow and take it easy everything will be fine.Start with the major and most important cation minerals, Calcium and Magnesium. They are fully as important in the soil as they are in the human body and the least expensive to buy. In a very loose and sandy soil with a low exchange capacity you will want about 60% Ca saturation and 20% Mg saturation. In a heavy clay soil with a high exchange capacity, about 70% Ca to 10% Mg. This is because the higher the ratio of Calcium to Magnesium, the looser the soil gets, and as the Magnesium portion gets higher, the soil gets tighter. Once these two are balanced and in the right saturation they will bring many other things into line and you may want a new soil test to guide you to your next step.
Calcium sources: Sweet lime (Calcium carbonate) and gypsum (Calcium sulfate) are the preferred sources of calcium. Gypsum will not make your soil more acid, supplies readily available Calcium, and is also a good source of Sulfur, an element that is seriously lacking in many soils. Sweet lime supplies Carbon as well as Calcium. Carbon helps make a soil less sticky. If you already have plenty of Carbon in your soil as organic matter, but are low on Sulfur, gypsum is a better bet. The various rock phosphates and regular superphosphate are also significant Calcium sources. *Note: regular superphosphate, a concentrated form of natural rock phosphate, is not approved for certified organic use under the USDA’s National Organic Program (NOP).
As a rule, don’t use Dolomite lime, regardless of what you may have read in various gardening books, unless you are sure that you need Magnesium. Dolomite is a high Magnesium limestone. Using dolomite will tighten the soil, reducing air in the soil and inducing anaerobic alcohol fermentation or even formaldehyde preservation of organic matter rather than aerobic decomposition. If the soil test calls for more Magnesium, Magnesium sulfate (Epsom salts) or K-Mag (also known as Sul-Po-Mag, sulfate of potash magnesia, or Langbeinite), are generally safer and quicker acting sources of Magnesium than dolomite. Magnesium oxide is the purest and quickest acting Magnesium additive, but is not presently allowed under USDA NOP organic rules, for some reason. About the only time dolomite lime might be called for would be if the soil already had too high a level of Sulfur to use Magnesium sulfate (Epsom salts) or K-Mag, or if other sources of Magnesium weren’t available. If one is not concerned with being “certified” organic under USDA rules, Magnesium oxide is the best bet. MgO (Magnesium Oxide)is around 50% Mg, a much higher percentage than dolomite lime (13% Mg) or Epsom salts (10% Mg) so it is also a much cheaper source of Mg. If you are not concerned about being certified by the government, we would recommend using MgO.
.Although this chart emphasizes minerals, you would not have much luck trying to grow food in a soil that wasn’t bio-active even if it contained the perfect mineral balance. The goal is to get these minerals into the soil in a biological or at least bio-available form. We add them and let the soil life assimilate them over time.
In some cases minerals may be added to the compost pile to start the bio-availability process, but it’s a good idea to keep good records of how much of what is in which pile. For example, one could mix a 50# bag of rock phosphate into a good sized compost pile , but it would be nice to know just how much Phosphorus, Calcium etc was in the bag to start with, and that it was all in that pile and could be spread over X amount of area.
Know all the ingredients of anything you add to the soil if at all possible. How much Cadmium (a toxic heavy metal) does that phosphate rock have in it? And how much Calcium? Montana rock phosphate contains around 30% total phosphate (13% actual P) but it also has around 30% Calcium. The Calcium is chemically attached to the Phosphorus in the form of Calcium phosphate. As the Phosphorus is made available by the soil microorganisms, so is the Calcium.
Glacial rock dust, granite dust etc. are great sources of fresh trace minerals, but they can’t be relied on for the major minerals. Most of them have low enough numbers of the major nutrients that they won’t throw things out of balance, though, and because they are freshly ground up and sharp grains of rock, they will increase the energy level in the soil. Both heat and electrical charge concentrate at sharp points.
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