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Sourcing Fertility in the Soil

By Charles Walters and Esper K. Chandler

The book Ask The Plant is based on the agronomy of Esper “K.” Chandler, and offers farmers and growers a better way to grow plants that involves reading the unique language of plants, utilizing leaf and petiole testing, and in turn knowing how to produce a better crop using only the fertilizers and soil-building ingredients that are truly needed, when they are most needed.


Instead of following the decades-old conventional model where plants are given copious amounts of soluble nitrogen fertilizers aimed to force-feed the landscape green, Ask the Plant addresses how to build a healthy soil without excessive inputs. After more than seven decades of soils being mined not replenished, especially of organic matter and minerals — it is time to “ask the plant” and find out what our crops and soils are really telling us so we can produce a better crop using only what is truly needed.

The excerpt below discusses soil minerals, including issues, ideal levels and requirements.

From Chapter 6: Sourcing Fertility

There may be many troublesome words in modern agriculture, but none glows in the dark as much as “conventional.” How a recently minted term such as “conventional” came to label practices less than 60 years old in agriculture, a practice that goes back 10,000 years, surely must puzzle etymologists. Nevertheless, we appear to be stuck with the word, and might as well examine it in the context of modernity.

Calcium (Ca)

“On any soil on any continent,” says Chandler, “we are required to look at the available calcium level, which is possibly the most variable of the elements required for crop growth.” The needs of the soil dictate the kind of lime to be applied. Some soils have fairly good magnesium. Therefore, calcareous sources of lime ask for evaluation. There are many such sources, Chandler cautions. He cites oyster shells, even caliche, and if magnesium is deficient, then high-magnesium limestones are needed.

What, then, is dolomitic lime and what is high-magnesium lime? In Texas, dolomitic lime is notoriously absent, but there are natural lime deposits of 8, 10, and 11% magnesium. “Get to know your highway department because they know where the deposits are,” farmers are often told, and it’s valid advice. “In Texas,” Chandler explains, “most of the local limestone is used in roadbed construction. The Texas-Louisiana Aglime and Fertilizer Association, supported largely by the Sneed family of Georgetown, Texas pioneered the agricultural lime business, supporting research, education, and quality programs for gen­erations. But then when we go to agricultural lime, an overriding factor is the fineness of the grind.” Specifically, it must be ground as finely as talcum powder if it is to be reactive.

This is a basic problem. Chandler learned back in his experimental station days that Arkansas dolomite lime ground only to the fineness of beach sand would have little to no effect on pH. This meant more fine­ness was needed. Such a grind takes a generation of weathering to be use­ful. But lime with the consistency of talcum powder goes to work quickly as microbes break it down to help neutralize the soil’s natural acidity.

The classes and sources of limestone are too numerous to catalog in one sitting. Just the same, mere consideration of the subject makes it necessary to determine what is available to the plant. Or, as Chandler recites, “You have to ask the plant whether indeed it is getting the cal­cium.”

The Rio Grande Valley has soils with 4,000 to 10,000 ppm cation exchange capacity calcium, based on conventional testing. Still, calcium- deficient crops grow on that soil. The lesson is clear. Without the required amount of calcium available, how can such an overload be released? The problem is staggering in its dimensions. Soils well endowed with cal­cium often produce hungry plants because that prince of nutrients is not available. Conventional agriculture asks for water solubility, and yet the natural product often is not water-soluble. In any case, conventional testing does not look at water solubility (available H2O/Ca).

That’s the why and wherefore of calcium, the major building block of all life. Many soils are not well endowed with calcium. Even if mea­sured, the calcium is often not available. The one lesson commercial farming has to face tells us more than a lot of farmers want to know about those microbes. The microbes alone can slowly regenerate the fertility of the minerals. The business of extracting the minerals is one of nature’s finest accomplishments.

Humus and calcium have an intractable partnership in good soil tilth. Calcium is often called the VIP of minerals. Calcium takes top billing in some lab recommendations after humus.

Here, gypsum enters the fray. Chandler puts it this way, “The over­riding factor in getting calcium available is converting it to an available form of calcium-sulfate as gypsum. Enter the sulfur content coming from the natural degradation of organic matter, which contains the sul­fur nutrient, or it has to come from elemental sulfur itself.”

Magnesium (Mg)

The process of loading the soil colloid with an available form of calcium is crucial to cell life. Soil biology is a major factor. From there, the equation progresses to the magnesium factor. Magnesium is not as major an element, but it commands a ratio and has an essential func­tion. Thus, the hunt for sources of magnesium calls up Epsom salts. Magnesium sulfate is a primary source, as is the mined naturally occur­ring mineral called Sul-Po-Mag and K-Mag, which is sulphate of potash magnesium. When conventional agriculture made its case, the rush was on to buy up either magnesium deposits or vulnerable competitors. Magnesium is a finite resource. This reality had smaller companies finding and exploiting smaller veins, now dominated by the marketing name of K-Mag.

Potassium (K)

The next major fertility requirement is potash, often available as K2O. Most sugar crops require more potash than nitrogen. Potash is a natural, mined mineral. It is not a rare earth, but it calls for entrepre­neurial skill and dedication to wrest it from the earth. Deep-vein, hot- water mining in Canada has placed high-cost extraction in the United States onto the back burner. “I’m told that we have some deep deposits of potash in the Rocky Mountains. It can be mined using Canadian tech­nology,” Chandler points out, citing the method that has been proved.

Chandler is more than a little concerned about the future of fertil­izer inputs, not because of technology that powders, prills, and other­wise refines the materials for field distribution, but because sources are finite and use is often wasteful. “We have natural deposits of potash,” Chandler reminds, “from the desert and Dead Sea areas where it has accumulated due to a natural distillation process. These materials have ample amounts of other minerals as well. So, there are many sources of potash, but it is the economic considerations that usually prevail.”

As an aside, Chandler explains the range of the subject to natural/organic folks who often want to prohibit the use of potassium chloride because of the chlorine. This, in excess, is a problem. Unfortunately, “you run the cost up to the natural/organic grower when he or she has to turn to more costly sources of potash,” reminds Chandler, “and potash is one of the largest quantity elements necessary for production of all crops.”

Some soils are well endowed with potash as measured by almost any laboratory inventory, but is it available? And even more important, how can it be made available? To ask these questions is to suggest the availability of an answer. Here is where natural/organic insight comes to the rescue. These denizens of the academic underworld forced down the throats of academia the come-lately consideration of humus, the food for microbial balance in the soil for release of minerals and plant nutrients.

A natural mineral that once figured in the research of William A. Albrecht is langbenite, more commonly known as Sul-Po-Mag, and now as K-Mag. Chandler has extensive experience with this mined product. Langbenite is the basis for both chemical and organic agriculture. It is, as the secondary name implies, a balance of sulfur, potash and magne­sium. Unfortunately, many of the owners of such mines have relegated K-Mag to the back burner of company economics. This means little or no investment in production facilities. Cargill controls both ends of major production. As it stands, fertilizer fabricators literally synthe­size the natural product much as they do all salt fertilizers. The label misleads farmers who often burn crops because they believe the label, thinking their purchase is the real thing.

Most of the firms that control mineral resources are busily consoli­dating, as the saying goes, “into a few strong hands.” The process erases competition, establishes administered prices, and relies on the old iron law of “What will the traffic bear?” Chandler sharply defines secondary minerals as absolutely essential, the primaries being NPK.

  1. (“Potash”) Chandler seldom drops the fertilizer subject or the laboratory equivalent thereof without a word on potassium. Potassium is the largest cation in almost any plant. It usually accounts for more pickup than nitrogen. This appears to be a strange statement since nitrogen has the reputation as a dominant element. There seems to be a natural antagonism between potash and phosphorus. The two are constantly trying to tie each other up, and nature loves balance as much as fecundity.

Now the sequence becomes clear. That overload of phosphorus sup­plied at the beginning of the year tends to run out. Electrical charges figure, most notably the penchant of potassium to tie it up. As phospho­rus uptake falters, so does yield. Small amounts of phosphorus in the drip line along with humic acid doubles the phosphate uptake. Moreover, merely using humic acid can deliver as much phosphate to the petiole as a smaller amount of phosphate alone. The two together seem to double the P uptake. This achievement, faced off against the usual research-proven 5-15 percent P uptake, confers an efficiency on precision agricul­ture only wished for by staid conventional farmers.

Chandler asserts that the above procedure with seaweed hormones and soil inoculants, all together, have quadrupled the effects of available phosphorus. When phosphorus is taken up, so too climbs the uptake reading of nitrogen and all other nutrients. Now Albrecht’s sage obser­vation kicks in. Plants in touch with exchangeable nutrients have the capacity for manufacturing their own hormone and enzyme systems, which are needed to challenge insect predators and crop diseases.

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About Charles Walters

Charles Walters
Charles Walters

Charles Walters was the founder and executive editor of Acres U.S.A. He penned thousands of articles on the technologies of organic and sustainable agriculture and authored many books on the subject, including Weeds: Control Without Poisons, Dung Beetles, Grass, the Forgiveness of Nature, A Farmer’s Guide to the Bottom Line, Fertility from the Ocean Deep, as well as many others. A leading proponent of raw material economics, he served as president of the National Organization for Raw Materials (NORM) and authored several books on economics, including Unforgiven: The American Economic System Sold for Debt and War.

About Esper K. Chandler

Esper K. Chandler
Esper K. Chandler

Esper K. Chandler was a professional agronomist and soil scientist who traveled the country consulting with growers in a quest to improve yields, quality, and profits. He was the owner of TPS Lab for more than 27 years. K. Chandler was a founding member of the National Oraganic Standards Board and a Certified Professional Agronomist (CPAg) by the American Society of Agronomy. He has been proclaimed as a leader in the soil fertility and plant nutrition field. Chandler passed away in 2008.