#SoilMatters - Organic Acids: Foliar Feeding and Plant Benefits





Organic Acids: Foliar Feeding and Plant Benefits

In 1947, Dr. William Albrecht wrote, “To be well fed is to be healthy.” This was as true then as it is today. For crops to be healthy, requires energy and nutrients, but crops can be no better (nutritionally) than the nutrient-template supplied them during the growing season. The supply depends on how available nutrient sources are for plant and crop use. Available means “plant-ready” or immediately ready for use. Applying “plant-ready” forms of nutrition helps your crop to be well fed.

 

 

One way to feed your crop well, is by increasing the uptake efficiency of foliar nutrient applications. Uptake efficiency refers to the velocity of nutrient translocation from “source” to “sink”. A rapid plant and crop response is needed, at key stages of growth, to avoid crop and monetary losses. A foliar application that merely coats the canopy and isn’t absorbed is not efficient. Unless needed nutrients get into the plant and then into the fruit (sink), nutrient needs go unmet and complete benefit isn’t achieved. During the growing season, timing is a critical factor in crop development. For example, applying the right nutrition, at the right time, yields the right response, but the right nutrition applied late reduces the benefit or doesn’t help at all. Application timing is driven by temperature and nutrient availability (or unavailability) limits the efficiency of the growth process. Therefore a foliar spray application, with “plant-ready” nutrients, at the right timing, is a good option to ensure proper crop response.

 

 

Organic acids (O.A.) are not new to agriculture. In fact, they have been used for multiple decades because of the benefits they provide. While Humic acid (HA) and Fulvic Acid (FA) are classified as O.A., there are many more O.A. forms that are useful to growers; i.e. lactic, citric, gluconic, malic, etc. In Neoteric Agriculture, these are referred to as True Organic Acids (TOA), because of their high purity levels. Higher purity equals higher efficiency or “bio-availability”. TOA efficiency is due to their low molecular weight (small size). This makes them very effective natural chelators for more efficient nutrient translocation and growth response into plant and fruit tissue. Because TOA are in a “plant-ready” form, when combined with foliar nutrients, like calcium, magnesium, zinc, boron, etc., become “bio-available” as well. True Organic Acids also contain carbon rings, in their composition. Carbon buffers phytotoxicity risks in foliar nutrient applications and supplies a concentrated food (carbon-energy) source for plants and microbiology. On a pound for pound basis, True Organic Acids provide 2.25x more energy than sucrose.

Every stage of crop development is important and demands energy. This energy could come from stored carbohydrate reserves, foliar nutrient sprays, fertigations, etc. But, regardless of the source, if the energy runs short (energy deficit), it becomes the limiting factor to yield potential. All development stages are temperature driven; warmer temperatures speed stages up and cooler temperatures slow stages down. This makes early season nutrient decisions very time sensitive. Using “plant-ready” nutrient sources allows you to meet those nutrient demands in a timely manner more successfully and lessen the risks of energy deficiencies.

 

 

Foliar feeding is a proven way to supplement nutrition, especially when soil conditions cannot meet the demands of the plant development. For example, calcium is vital for good development, but in its elemental form it can’t supply plant energy unless combined with a carbon source like TOA. Calcium chloride (CaCl₂) is a widely used and accepted calcium foliar-feeding source. It is water-soluble and proven effective, but the chloride must be factored into application rates to avoid plant tissue damage. When combined with TOA, the CaCl₂ compound is split and the O.A. bond with both the calcium and chloride ions. This makes “bio-available” calcium as calcium lactate, -citrate or -gluconate and the chloride is carbon-buffered reducing phytotoxicity risk. Additionally foliar calcium is difficult to get absorbed into fruit versus leaves, as leaves are a much stronger calcium “sink” than fruit. This is why multiple foliar applications are needed, with fruit-surface contact through the growing season, for best efficacy. By incorporating a TOA, with your calcium foliar sprays, complete nutrient absorption is rapid for better plant health and fruit quality.

Plant leaves are an additional limiting factor to efficient plant uptake. You 

Cross Section of Leaf - P. Wojcik

know that foliar nutrient absorption rates are higher in young leaves versus old leaves. As leaves mature, a waxy cuticle develops, that layer serves to protect the plant. It helps to regulate evapotranspiration (ET) rates but also limits the amount of nutrient ion penetration. In many cases, the amount of epicuticular wax is greater with higher levels of environmental stress. This varies by species, but regardless, the waxy protective coating limits efficient foliar-nutrient uptake. Foliar nutrients combined with TOA are able to permeate the mature leaf cuticle because of their “bio-available” form and small molecular size. Their size is small enough to be absorbed through the ectodesmata (plant pores) for a positive plant growth response. The ectodesmata are located on surface of leaves. The pore size is less than 1nm. These are much smaller than stomata and serve a different purpose. Because TOA are smaller than 1nm, this makes them an ideal nutrient chelator for higher absorption rates by plants and fruit. Synthetic chelating agents (EDTA, DTPA, EDDHA, etc.), are much larger molecules (higher molecular weight) and therefore not readily permeable into plant ectodesmata (pores), thus limiting nutrient uptake efficacy.

 

 

Ninety-five percent of plant mass is carbon, hydrogen and oxygen based

material (roots, wood, leaves, buds, fruit, etc.) and merely 5% is from other nutrients (fertilizer applications). Therefore nutrient focus should be on growing the healthiest canopy possible to take advantage of every daylight hour. Nutrient deficiencies limit photosynthetic efficiency and therefore plant and crop health. That’s lost opportunity. Applying foliar nutrients in “plant-ready” and “bio-available” forms supplements the crop when soil nutrient release is limited and supplies a rapid absorption response in order to maintain maximum yield potential. Both quantity and quality are a reality, when you foliar apply “plant-ready” nutrients with TOA, in your fertility plan.

Here’s to your crops’ success!

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Soil Management by Nature or Man? - Natural Food and Farming: 1965

In our studies of how Mother Nature was growing crops which were able to protect themselves against pests and disease to survive the ages, and to be available for domestication by man when he took over the soil and crop management, we find that two basic requirements had always been met or fulfilled.

In the first place, rock minerals were weathering in the soil to remind us of the poetic claim that "The Mills of God must grind.” In the second place, the organic matter grown on the soil was naturally put back in place on top or within the soil for its decay there. That served to put microbial life into the soil. It generated the carbonic acid there (and other acids of decay) to break some of the nutrient elements out of the rock more rapidly for them to be caught up and held, or adsorbed, by some of the more stable, weathered, non-nutrient elements like the silicon of the clay. That adsorption holds them for plants services when the plant uses the same kind of carbonic acid to take those nutrients off by trading the hydrogen, or acid, for them.
 

By means of grinding fresh rock regularly as natural mineral fertilizers in the soil, and by conserving the organic matter to go back to maintain the soil’s humus at higher levels, nature had protected her crops so they grew annually from their own seeds. By a unique self protection they were doing well when man came along to take over what we call “scientific” crop management and “scientific” soil management. Certainly we are not now duplicating those practices in which nature was more successful than we appreciate.

According to our knowledge to date, the soil’s total capacity to hold electrically positive nutrients in available form should have about 60-75% for calcium, 6-12% for magnesium, 3-5% for potassium, and not more than that much of sodium and also all the needed trace elements and non-nutrient hydrogen, or acidity.

Those figures represent the soil’s content of positively charged elements in what, to date, we may consider a balanced plant ration… In our preceding remarks, we have not spoken about the soil’s organic supplies of nitrogen, sulfur and phosphorus in the required plant’s ration. We have not mentioned some of the trace elements also connected more actively with the supply of organic matter than with the reserve minerals.

We need to look to the organic matter of the soil to make these last three more essential major nutrient elements available to the crops. We need to remind ourselves that it is the organic matter that makes the surface layer the “living soil” and the “handful of dust” with its power for creating life.

We must not forget that microbes are what make a living soil “alive.” And far more important, we must remember that soil microbes, like all other microbes, eat at the first sitting, or first table. Plants eat at the second. Microbes go first for energy food, since they cannot use the sunshine’s energy directly. Plants go first for “grow” food, since they can use sunshine energy that way.

A sprouting seed “roots” for a living, or for “grow” food first. It puts up its advertising of growth by showing its leaves above the soil in the sunshine second.

 

Microbes are the decomposers of the organic matter and the conservers of the inorganic fertility, of the nitrogen, of the sulphur and of the phosphorus. Those three elements do not escape so much from a soil which has plenty of organic matter and growing crops to conserve those elements. We need to consider organic matter to conserve, to mobilize and to increase the nitrogen, the sulfur and the phosphorus of the soils, if those are to be fully productive.

Soil microbes oxidize carbon, nitrogen, sulfur and phosphorus to get energy thereby. It is in their oxidized forms that those elements are taken into the plant. Carbon is taken into the leaves. The others are taken into the plant root and, thus, all are in cycles of re-use.

It was by that more complete recycling for conservation that nature built up the soil in organic matter which we are compelling our microbes to burn out so rapidly when we return primarily chemical salts and little carbon of organic matter by which in this combination for microbial service, these fertility elements must be held in the soil. Plants and microbes must be in symbiotic activity and not in competition for fertility if our productive soils are to be maintained.

Carbon, nitrogen, sulphur and phosphorus are the negatively charged elements with which the positively charged hydrogen, calcium, magnesium, potassium and sodium combine to make the readily soluble inorganic salts. But in those combined forms they are not held by the soil as such. They are ionically injurious to plant roots. They are leached out by percolating rainwater. It is the clay-humus part of the soil which filters the positively charged ions, or elements, out of those salts; much like the household water softener takes the calcium, or lime, hardness out of the water supply. The clay-humus holds them as insoluble, yet available, to plant roots which are trading acid, or hydrogen, for them.

 

The negatively charged, soluble nitrates, sulfates, phosphates, so oxidized by the microbes, serve as nutrition for them and for the plants to be reduced into the organo-molecular states of living tissue where they are insoluble but functional in large organic molecules and not as salts. On death, they are oxidized again for microbial energy and repeat the cycle.

It is in this natural plan of soil management where we must recognize the real service by the fertility elements of soil, air and water playing their roles in creation before we can take over for wiser management of nature’s part in crop production. Her two phases of management stand out. Nature returned the organic matter as completely as possible, in that she held many of the fertility elements and kept them available. She grew crops where she also added unweathered mineral salts and dusts through winds with their storms of such and by overflowing waters with their inwash of deposited minerals.

By that simple, two-phase procedure of fertility management, nature had many different crops of healthy plants here for man when he arrived. But each crop was on its own particularly suitable soil in its specific climatic, geo-chemical and balanced fertility setting with man and warm-blooded animals on the high-calcium soils. We have not yet included calcium as the foremost fertility element when we list the contents of commercial fertilizers, for the inspector, even though we lime the soil to combat its acidity and, thereby, work against the very mechanism by which the plant roots feed our crops.

Feed the soil and it will feed you.

- Excerpts from: Natural Food and Farming: 1965—The Albrecht Papers Vol. 1

 

 

 

 

 

 

 

 

 

Soil Microbes Get Their Food First

 

It was less than three generations ago that Pasteur’s work in France suggested the bacterial causation of disease. Even though we are coming to see that the bacterial entry into the body may be encouraged by weakness induced by deficiencies of many kinds, yet the fear of microbes, germs and bacteria is almost universal. Everybody is afraid of getting germs. Pasteur told us that heat is the best weapon for fighting these microscopic life forms and we have been heating, boiling, steaming and sterilizing in the fight against microbes.

Now that the science of microbiology has brought us penicillin, streptomycin and other similar microbial products as protection for our bodies against the microbes, particularly since we are learning to live with them more for our benefit than for our harm. We are coming to see that microbes are a foundational part of the pyramid of life forms, of which we are the topmost. If we are to live complacently with them, we must remember that they are next to the soil in that pyramidal structure. They are between the soil and the plants. They either cooperate with, or compete with, the plants for the creative power in the form of nutrients in the soil. Hence, they are a part of the biotic foundation on which animal and human life depend. Microbes are now recognized as important because they eat more simply than all other life. They also eat first of the fertility of the soil.

1.      struggle for calories

Microbes are less complex in their anatomy and in many respects are less highly developed than plants. Unlike plants, the microbes cannot make their own energy-food compounds by the help of sunlight. On the contrary, sunlight kills microbes. By the process of photosynthesis, plants build their own carbohydrates for body energy from carbon dioxide in the air and from hydrogen and oxygen in water from the soil. Plants make many carbonaceous complexes from these three simple elements which they build into intricate energy-giving compounds of high fuel value and as deposits above the soil or as additions within its surface layer. Plants work in the light. Microbes work in the dark. Unable to derive energy directly from the sun, they must get it from these chemical compounds passed on to them by the death of the plants.

As a means of getting energy for heat and work, the microbes burn or oxidize organic compounds, just as we do in our bodies. Microbial life depends on just such compounds as make up dead plant and animal bodies. It simplifies them. It tears them apart. It is the wrecking crew taking over dead plant and animal tissues or return the separate elemental parts back to the air, water, soil or other points of origin. It is working in the dark and sending back to simplicity all that the plants built up to complexity.

This microbial struggle is what we call decay. The process of rotting organic matter is the result of microbial processes of digestion and metabolism of the organic matter, by which the energy initially put into chemical combination through plant photosynthesis, is released again for microbial life service.

As humans, we too use organic compounds such as sugars, starches, proteins, fat and other food components to provide our energy. This occurs as part of the process by which we break down these compounds into carbon dioxide, water, urea and other simple substances eventually thrown off as body excretions. Humans, like the microbes, are struggling for calories. In humans we call it digestion and metabolism. For the microbes, it means decay, or the simplification process which the different substances are undergoing when we commonly say “They are rotting.”

2.      competition with crops

Plowing under some organic matter in the garden or field is a good way of disposing of crop residues because the microbes “burn” or oxidize them. They do it slowly, however. Yet the process of microbial combustion of such materials may have disastrous effects on a crop planted soon after plowing, when we say we “burned out” the crop.

Microbes need more than energy “go” foods. They need the “grow” foods, too, just as we do. They do not demand that their nitrogen be given them in the complete proteins or the more complex compounds of this element as we do. Nevertheless, they are just as exacting in their needs for nitrogen, at least in its simpler forms. This is a “grow” food necessary to balance their energy foods in the proper ratio just as we demand the balance in speaking of our own nutritive ratio, or the balance of carbohydrates against proteins in our own diets or in the ration of feeds for our domestic animals.

So when we plow under any woody residue of stalks, leaves or other parts of plants that have given up their protein contents for seed making, these residues are an unbalanced microbial diet. They do not permit the microbes to grow rapidly on them. They are too much carbohydrate. As a diet they are deficient in “grow” foods. They are short in proteins, or nitrogen, and in minerals, hence decay very slowly.

Woody crop residues, like straws, have long been used for roof covers in the Old World. They last well but need to be replaced more often at the ridge top than over the entire roof. It is at the ridge tops that birds sit more often to leave their droppings, which are rich in urea nitrogen. When this soluble nitrogen – along with the mineral salts of the bird droppings – is added to the straw, the first rain hastens its decay. This decay, however, is limited to the ridge of the roof, or to the area in which these supplements of nitrogen balance the microbial diet originally consisting of straw. Until this balance was brought about the straw was too carbonaceous to decay, and was good thatch. Microbes require little of the “grow” foods but without it they do not carry out their decay processes.

When strawy crop residues or sawdust, for example, are plowed into the soil, the soil microbes are offered a diet that is high in carbon, or energy, and low in bodybuilding foods. Since the microbes are well distributed throughout this plowed soil, they are in such intimate contact with the clay that they make colloidal exchanges with it for its available nutrients. They can take ammonia nitrogen, potassium, phosphorus, calcium and other nutrients for their own growth from the clay to balance the sawdust as a more adequate diet.

It is unfortunate for the plants when woody residues are plowed under. When the microbes are more intimately in contact with the soil than are the plant roots, the microbes eat first of the available fertility elements. While the microbes are balancing their sawdust diet by taking the fertility of the soil into their own body compounds, we do not appreciate the production of the microbial crop, nor the proportion of the available fertility which they appropriate for their own needs. Instead we see how poorly the corn crop or other plants grow when planted soon after straw, heavy weeds or sawdust are plowed under. We say “The crop is burned out,” when it is extra fertility and not water that is needed. Yes, the microbes eat first. This disaster follows inevitably when the soil is too low in fertility to feed both the microbial crop within and the farm crop above the soil.

But unfortunately the disaster is only temporary. While the energy compounds are being consumed, the excessive carbon is escaping to the atmosphere as carbon dioxide. The nitrogen and inorganic nutrient elements are kept within the soil. Thus while the carbon supply in the soil is being lessened by volatilization, the ratios of the carbon to the nitrogen and to the inorganic elements are made more narrow. These ratios approach that of the microbial body composition – more nearly that of protein.

Thus by decay the straw with a carbon-nitrogen ration of 80 to 1 leaves microbially manipulated residues going toward what we call “humus” and toward a carbon-nitrogen ratio of nearly 12 to 1. This resulting substance is then more nearly like the chemical composition of the microbes themselves. So when no large, new supplies of carbonaceous organic matter are added to the soil, new microbes can grow only by consuming their predecessors or the humus residues of their creation.

Humus residues, used as food by the microbes, comprise a diet low in energy values, but high in body-building values. Humus is also unbalanced, but unlike straw, it is unbalanced in the opposite respect. It is not badly unbalanced, because “grow” foods, like proteins, can be “burned” for energy. Man can live by meat (protein) alone, as Steffanson and other Arctic explorers have demonstrated. It is a bit costly, however, so we use carbohydrates to balance the protein. In that case the proteins are going for tissue building rather than to provide energy. The microbes also can use protein-like compounds for energy and very effectively. We encourage them to do this when we plow under legumes. Here again they balance their own diets but with benefit to the crop above the soil, rather than with disaster which follows the plowing under of straw.

When we plow under proteinaceous organic matter, such as legumes, with not only a high content of nitrogen but also a high content of calcium, phosphorus, magnesium, potassium and all the other inorganic nutrient elements, the microbes are placed on a diet of narrow carbon-nitrogen ratio. The ratio of carbon to the inorganic nutrients is also narrow. It is like an exclusively meat diet would be for us, or like a tankage diet would be for a pig. The energy foods in such a ration are low in supply. Conversely, the nitrogen and minerals are a surplus. This surplus is not built into microbial bodies. Instead, it is liberated in simpler forms which are left in the soil as fertilizers for farm crops.

What we plow under determines what we have as left-overs for the crops. The microbes always eat first. The crops we grow “eat at the second table.” In wise management of the soil we must consider whether the composition of the organic matter we plow under is a good or poor diet for the microbes. If the soil is so low in fertility that it grows only a woody crop to be plowed under, then there can be little soil improvement for the following crop. It gives the microbes only energy foods. They must exhaust still further the last fertility supply in the soil to balance their diet and consequently the crops starve.

But if the soil is high in fertility so that it grows legumes, and if we then plow these protein-rich, mineral-rich forages under, the microbes receive more than energy foods. Given the nitrogenous, fertility-laden green manures plowed under, they pass this fertility back to the soil. Here their struggle is for energy, a struggle by which they are not in competition with the crop, the energy for which comes not from the soil but from the sunshine instead.

Microbes eat first. On poor soil with little humus and inorganic fertility, this spells disaster to the farm crop if we plow under only the poor vegetation which such soils produce. Growing merely any kind of organic matter to let it go back to the soil is not lifting the soil to higher fertility; any more than one lifts himself by pulling on his bootstraps. On soils that are more fertile in mineral nutrients, the idea in plowing cover crops to turn under is to help the farm crop. It helps them if we plow under the more proteinaceous and leguminous cover vegetation which fertile soils produce.

While we have been mining our soils to push them to a lower level of fertility, the microbes that originally were working for us are now working against us. They are eating first, not only so far as the plants are concerned, but indirectly so far as even we and our animals are concerned.

It is in this competition with the microbes that inorganic fertilizers and mineral additions to the soil can play their role by balancing the microbial diet. Such minerals are taken by both the plants and the microbes. But if the fertilizers are put deeper into the soil, they may be below the layer where they affect the microbes, either favorably or unfavorably. They will serve the plants, which send their roots down there, under the power coming from the sunshine. They will not affect the microbes unless they are mixed into the humus-bearing surface soil. Putting the fertilizers down deeper puts their nutrient contents where the plants, rather than the microbes, eat first. This is fertilizing, by means of inorganics, the fertilizing crop that combines them with organics to serve the microbes when this fertilizing crop is turned under for true soil improvement. This is a way of composting the inorganics within the body of the soil itself.

-          Excerpt from The Albrecht Papers Vol.1 - 1948

Phosphorus - There is a chemistry

 

When phosphate loads are rapidly complexed or not made available, fundamental sugar formation continues to function. Symptoms wave a warning flag that can be seen from great distances. Leaves often become reddish and purplish – a lack of chlorophyll – and tips die off. Seeds, tubers, grains, all suffer since all require phosphorus for adequate metabolism. Growth is slowed accordingly. The corn plant has a sign all its own. When there is a phosphorus deficiency, the kernels drop off about an inch or two from the cob’s end, or they may fail to develop in the first place.

In short, there is a chemistry involved whenever anything is put into the soil, inorganic, organic, salt form, whatever. Rock phosphate is called tricalcium phosphate, and this means it has three calciums, or three negative charges for bonding. This makes it more difficult to disattach from fixation than would be the case with dicalcium phosphate, which has only two charges – thus tri, di! Last, there is the water soluble monocalcium phosphate, which means that as a consequence of acid treatment this form has only one remaining bond.

So if you’re over 6.5 pH, and you want to farm organically for good and obvious reasons, you’re in trouble. You probably shouldn’t be using nonwater soluble phosphorus because the soil does not have enough acid to free it up. If a soil system has a pH of 7.5 the farmer probably shouldn’t be using the di forms. He should go to strictly mono forms of phosphate. Any farmer who doesn’t take into consideration the importance of the active hydrogen ion as being the most important thing to work with thereby authors his own failure.

Acid treatment merely means rock phosphate is being converted from tricalcium phosphate to monocalcium phosphate, and that this highly unstable form is subject to natural reversion back to the stable tricalcium form. The rate of reversion differs. The pH, the free calcium in the soil, the organic matter – all figure in this rate of reversion. But it is safe to say that 75% of the monocalcium phosphate reverts back to stable tricalcium phosphate within 90 days. In some soils the reversion takes place within hours. As soil conditions worsen, release of nutrients from rock phosphate worsens, and the chemical amateur becomes married to buying salt fertilizers, each go-round worsening still further the structure of that soil.

The water soluble phosphates are simply water soluble, not acid. But they are a poor substitute for having the proper pH with calcium, potassium, magnesium and sodium in equilibrium, and form an economic point of view they take on ripoff dimensions.

First, the soluble phosphates come from rock phosphate in any case. By treating, say, 1,400 pounds of rock phosphate with 1,200 pounds of sulfuric acid, the fertilizer industry gets 20% superphosphate – the tricalcium phosphate form being converted into water soluble monocalcium form. This chemical reaction causes 20% superphosphate to be represented by about 45% monocalcium phosphate, and 55% calcium sulfate, or gypsum. This means the bag of 0-20-0 contains about 45 pounds of water soluble monocalcium phosphate, which is presumably desired, and about 55 pounds of calcium sulfate, which may or may not be desired, but which farmers are frequently not aware of.

The fertilizer rating 0-45-0 is quite different material. Farmers who see symptoms of phosphorus deficiency sometimes think a higher rating is the answer, and this one comes styled triple superphosphate. Here the acid used to do the etching is phosphoric. This eliminates the calcium sulfate in the bag, calcium frequently needed to kick up to calcium reserve, sulfate needed to complex an excess of magnesium. By invoking the hotdog concept of plant nutrition a much needed nutrient might be eliminated exactly when it is needed.

Ammonium phosphate such as 8-32-0, 11-48-0, and 80 on, also involve concentrated phosphoric acid in the processing, and this provides a handy outlet for otherwise unsalable fossil fuel company byproducts.

- Excerpted from Eco-Farm An Acres U.S.A. Primer

Calcium - 4. Delayed Appreciation

 

The delayed appreciation of the significance of calcium in plant nutrition may be laid at the doorstep of a confused thinking about liming and soil acidity. The absence of lime in many soils of the non-temperate zone has long been known. Lime in different forms such as chalk, marl, gypsum or land plaster, has been a soil treatment for centuries. Lime was used in Rome in times B.C., and the Romans used it in England in the first century A.D. Chalking the land is an old practice in the British Isles. The calcareous deposits like “The White Cliffs of Dover” were appreciated in soil improvement for centuries before they were commemorated in song. Liming the soil is a very ancient art, but a very recent science of agriculture. It was when Liebig, Lawes and Gilbert and other scientists began to focus attention on the soil as source of chemical elements for plant nutrition that nitrogen, soluble phosphate, and potassium became our first fertilizers. It was then that the element calcium and the practice of liming were put into the background. Unfortunately for the wider appreciation of calcium, this element in the form of gypsum was regularly a large part of the acid phosphate that was applied extensively in fertilizer to deliver phosphorus. Strange as it may seem, superphosphate fertilizer carries more calcium than it does phosphorus, and consequently calcium has been used so anonymously or incidentally that its services have not been appreciated. Fertilizers have held our thought. Calcium was an unnoticed concomitant. It has been doing much for which the other parts of the fertilizers were getting credit. Appreciation of the true significance of calcium in plant nutrition was therefore long delayed.

More recently soil acidity has held attention. This again has kept calcium out of the picture. Credit for the service of liming has been going to the carbonates with which calcium is associated in limestone. It was a case of the common fallacy in reasoning, namely the ascribing of causal significance to contemporaneous behaviors. Here is the line of reasoning: “Limestone put on the soil lessens the acidity, and limestone put on the soil grows clover. Therefore the change in acidity must be the cause of the growing clover.” Therefore the change in acidity must be the cause of the growing clover. At the same time, there was disregarded the other possible deduction, namely: “Limestone put on the soil applies the plant nutrient calcium. Therefore the applied calcium must be the cause of the growth of clover.”

The labeling of calcium as fertilizer element of first importance was delayed because scientists, like other boys, enjoyed playing with their toys. The advent of electrical instruments inducement to measure soil acidity everywhere. The pH values were determined on slight provocations and causal significance widely ascribed to them, when as a matter of fact the degree of acidity like temperature is a condition and not a cause of many soil chemical reactions.  Because this blind alley of soil acidity was accepted as a thoroughfare so long and because no simple instrument for measuring calcium ionization was available, it has taken extensive plant studies to demonstrate the hidden calcium hungers in plants responsible in turn for hidden but more extensive hungers in animals. Fortunately, a truce has recently been declared in the fight on soil acidity. What was once considered a malady is now considered a beneficial condition of the soil. Instead of a bane, soil acidity is a blessing in that many plant nutrients applied to such soil are made more serviceable by its presence, and soil acidity is an index of how seriously our attention must go to the declining soil fertility.

Now we face new concepts of the mechanisms of plant nutrition. By means of studies using only the colloidal, or finer, clay fraction of the soil, it was learned that this soil portion is really an acid. It is also highly buffered or takes on hydrogen, calcium, magnesium, and any other cations in relatively large quantities to put them out of solution and out of extensive ionic activities. It demonstrated that because of its insolubility, it can hide away many plant nutrients so that pure water will not remove them, yet salt solutions will exchange with them. This absorption and exchange activity of clay is the basic principle that serves in the plant nutrition. This concept comes as a by-product of the studies of calcium in relation to soil acidity.

Imagine that a soil consists of some calcium-bearing minerals of silt size mixed with acid clays. The calcium-bearing mineral interacts with the hydrogen of the acid clay. The hydrogen goes to the mineral in exchange for the calcium going to the clay. Imagine further that the plant root enters into this clay and mineral mixture. It does so more readily because of the presence of the clay. It excretes carbon dioxide (possibly other compounds) into this moist mixture to give carbonic acid with its ionized hydrogen to carry on between the root acid and the clay particle and the mineral. The hydrogen from the root exchanges with the calcium absorbed on the clay in close contact.

Thus plant nutrition is a trading business between root and mineral with the clay serving as the jobber, or the “go-between”. The clay takes the hydrogen offered by the root, trades it to the silt minerals for the calcium and then passes the calcium to the root. Thus nutrients, like calcium, and other positive ions as well, pass from the minerals to the clay and to the root, while hydrogen or acidity, is passing in the opposite direction to weather out of the soil its nutrients mineral reserve and leave finally the acid clay mixed with unweatherable quartz sand. Acid soils are, then, merely the indication of nutrient depletion.

 

- Excerpt from Albrecht's Foundation Concepts - The Albrecht Papers Vol. 1 - pgs. 149-150