AcresUSA.com links

Soil Fertility: 16 Methods to Understand

Establishing a Self-Sufficient System

In nature, soil organisms cultivate the soil.

Soil fertility and sustainable agriculture practitioners know that most soils today need their health and vitality rebuilt. In times past, nature built healthy, vital soils, and there is value in copying nature in rebuilding soil health. However, we cannot afford to take millions of years to do so as nature did — we need intelligent intervention. Cultivation, grazing, composting, soil conservation, green manuring, soil testing, soil remineralization, fertilizer priorities, fossil humates and visual soil assessment all play a role in establishing self-regenerative, self-sufficient fertile soils.

The biological activities at the basis of self-regenerative soil fertility occur at the surfaces of soil particles where minerals come into contact with water, air and warmth. It is at these surfaces that biological activities provide nitrogen fixation and silicon release.

Building Soil Fertility

Nature, with minimal human intervention, developed biologically diverse, richly fertile soils and ecosystems with little by way of inputs other than the accumulation of dust, periodic rainfall, fresh air and sunlight. Rainforests are fertile ecosystems with rich diversity of microbial, plant and animal species.

While rainforests can be quite fertile, the world’s deepest, richest topsoils evolved as grazing lands — prairies, steppes, plains, savannahs, veldt and meadows that grew grasses, legumes and herbaceous plants and supported herds of herbivores along with the predators they attracted.

Check out Acres U.S.A. magazine

In both forests and grasslands, the vegetation draws in carbon. Forests store most of their carbon above the surface of the soil where it cools the earth and helps precipitate rain. Grasslands store more of their carbon in the soil as humus complexes. With forest fires most of the carbon returns to the atmosphere, but with grassland fires most of the carbon remains in the soil.

Nature’s way of building soil fertility involves awesome diversity and intense cooperation. Every ecological niche is filled, every need is satisfied, and everything is gathered, recycled and conserved. No area is left bare, and no opportunity lost. And nature is patient. If something is missing or deficient it may take eons upon eons for it to accumulate from dust and rainfall or cosmic ray bombardment. Nature can also use our help.

Cultivation

In nature, soil organisms cultivate the soil — from the smallest protozoa, arthropods, nematodes, mites and collembolans to beetle grubs, earthworms, ants and even larger burrowing animals. Plants and their fungal symbiotes spread rocks and soil particles apart by growing into pores, cracks and crevasses. They secrete substances that etch the surfaces of rocks and soil particles and feed micro-organisms that free up minerals. Inevitably at some point animals will consume the plant roots and open up passages where air and water are absorbed by the soil. Some, like earthworms, grind soil particles up in their digestion. They also recycle plant matter as manures, building soil fertility and feeding further growth. This softens the soil and builds crumb structure, tilth and retention of moisture and nutrients while allowing water, air and root penetration. Conversely, continuous grazing — to say nothing of human and machinery impact — compresses the soil and reverses these gains.

Mechanical cultivation softens the soil and prepares a clean seedbed for planting. For the most part, cultivation destroys soil life and is highly digestive and oxidative. In an age of machinery and power equipment with excessive cultivation and monocropping as the norm, this provides more and faster nutrient release as it collapses the soil biology. More importantly, it depletes nutrient reserves. This leads to higher and higher fertilizer inputs while biodiversity and soil fertility declines.

Even back in the 1920s, Steiner saw the trends and introduced horn manure [500], horn silica [501], horn clay and biodynamic compost made with the herbal preparations [502-507] as remedies. But we also need to reverse the trends outlined above. Too much cultivation burns up organic matter, impoverishes soil life, breaks down soil structure and releases nutrients that then may be lost. Wind and water erosion may also occur, and the result all too often is loss of soil fertility. The biodynamic preparations are no universal remedy for all mistakes. We must farm sensitively and intelligently as well.

Various strategies are used for minimizing cultivation damage while still enjoying cultivation’s benefits. Some crops, such as potatoes, require cultivation. But with a mixed operation, crop rotations can take this into account and soil building can still proceed. Strip cropping, composting and rotations in pasture and hay can help restore diversity so that soil biology recovers. Controlled traffic, where machinery strictly follows predetermined lanes, reduces compaction. No-till and minimum till planting methods help, especially when used with biological fertilizers and biodynamic preparations to feed the soil food web and take the place of harsh chemicals. Inter-cropping, multi-cropping and succession cropping increase diversity and reduce machinery impact. Instead of herbicides, managing mixed vegetative cover on roads, access strips, headlands, fence rows, laneways, waterways and ditches provides biological reservoirs that interact with cultivated areas.

Grazing

High-density cell grazing is particularly effective, where large numbers of livestock graze and trample small blocks for a few hours and then are moved on, not to return until plants have regrown. Based on what a pasture needs rather than on a calendar, this could be two weeks, two months or more than a year. With high-density cell grazing the impact is minimal, and what is not grazed is trampled so the more sought-after plants that get grazed hard have a chance at regrowth.

Soil animals recycle what is trampled, feeding it back to the regrowth.

Composting

Composting is more than a simple process of digestion and decay. Nature breaks down every sort of organic material into simple carbohydrates and amino acids, but in many cases these would oxidize and leach if there weren’t ways of storing and conserving them in easy-to-use forms.

Bees gather nectar, digest it, concentrate it and store it in their honeycomb. Similarly there are microorganisms in the soil that gather up loose nutrients, store them in large, carbon molecules called humic acids and complex them with clay particles in the soil. As with bees, the organisms that gather and complex these nutrients have access to them when needed, and these microorganisms are mainly the actinomycetes and mycorrhizal fungi that form close relationships with plants to the benefit of both. To favor these microbes and their activities, manures and organic wastes can be composted by building stacks, piles or windrows with a favorable mix of carbon and nitrogen rich materials, soil, moisture and air. A ratio of 30 to 1 carbon to nitrogen materials along with 10 percent soil and at least 50 percent water is a good starting mix.

Into the newly built pile, insert a small spoonful of each of the herbal ‘composting’ preparations [502–507] described in Steiner’s agriculture course. In the case of the valerian flower juice tincture the liquid is diluted in water, stirred intensively and sprinkled over the pile. Sprinkling the horsetail herb [508] over the pile before covering can also help.

These preparations impart a balanced range of activities that assist and improve the breakdown and humification process. A covering of some sort will be very helpful in providing an outer skin or membrane that holds in the life and vitality of the compost heap as it matures. Once it is stable with most of its nutrients bound up in humic complexes its microbial activity should be rich with nitrogen-fixing, phosphorus-solubilizing and humusforming species.

Using the composting preparations is equally important in large-scale composting operations, whether piles are frequently turned or left static.

Biochemical Sequence of Nutrition in Plants

Plant biochemical sequences begin with: 1. Boron, which activates 2. Silicon which carries all other nutrients starting with 3. Calcium which binds 4. Nitrogen to form amino acids, DNA and cell division. Amino acids form proteins such as chlorophyll and tag trace elements, especially 5. Magnesium which transfers energy via 6. Phosphorus to 7. Carbon to form sugars which go where 8. Potassium carries them. This is the basis of plant growth.

However, consider the economies of scale. On the one hand, Steiner indicated each preparation need only be inserted in a single place — even in a pile as large as a house — and its effects would radiate throughout the pile. On the other hand, since Steiner’s death special composts known as manure concentrate, Cow Pat Pit (CPP) and barrel compost contain all the herbal preparations in one easy-to-use formula that can be stirred intensively for 20 minutes and sprayed throughout the pile as it is assembled or added to the water used to moisten the compost. This can bring the benefits of the preparations into a large-scale operation economically.

Some composters prefer to use the horn preparations with the herbal preparations, and a biodynamic agriculture Australia formula called Soil Activator combines all the preparations in one compound that is stirred and applied like CPP. According to John Priestley, one of Australia’s most experienced and innovative biodynamic farmers, “The only way the biodynamic preparations don’t work is if you don’t use them.”

Volatilization & Leaching

A criticism identified by organic farm research is volatilization and leaching from raw animal or plant wastes. These losses can be pollutants in the atmosphere, in waterways or in the water table. Biodynamic management of plant and animal wastes prior to application on soils involves composting of solid wastes and fermentation of liquids, such as effluents, with the herbal preparations. All materials need to be broken down into stable humus or stable liquid brews before use. Proper application of the full range of biodynamic preparations ties up loose nutrients and minimizes run-off or leaching. Rank, manurey smells are a sure sign of nitrogen loss and are also an invitation for weeds, pests and diseases. This is neither a plus for soil fertility nor a plus for the environment. Wherever animal wastes collect or nitrogenous materials break down, soil or rock powders can be scattered and CPP or Soil Activator can be sprayed to minimize losses and keep smells in check.

Cover Crops & Green Manures

In general these are quick-growing annual plantings of grasses, legumes and herbaceous species intended to rebuild soil biology, restore nitrogen fixation and provide material for grazing, composting, mulching or ploughing back into the soil. In some cases seed is harvested off of these mixes before they are grazed, composted, used for mulch or ploughed down. Applications of barrel compost, CPP or Soil Activator can assist in rapid breakdown, re-incorporation and humification of these green manures.

Ideally, cover crop mixtures should include at least 15 to 20 species of annual grasses, legumes and herbs. These can restore diversity, rebuild soil biota, conserve loose nutrients, help with pest, weed and disease control, increase soil carbon, conserve moisture, reduce run-off and prevent erosion — while protecting what might otherwise be bare soil.

Broadacre cover crops may be under-sown with succession species to take over after harvest. Or cover crops may be planted as catch crops at the end of growing seasons. They may also follow short season crops depending on region and climate, and they can provide handy ways to feed rock powders and composts to the soil biology. Vegetation is almost always a plus, while bare soil ensures the opportunity is lost.

For example, a winter crop of oats, lupines, rape, clovers and corn salad could be taken to the point the grain and other seeds are harvested and separated. Alternatively, mixes of winter cereals, legumes and broadleaf plants might include wheat, barley, rye, triticale, vetches, clovers, medics, turnips, mustards, rape and radishes. If the area in question is to be used as pasture, perennial grasses, legumes and other species such as dandelions, plantains, chicories and yarrow may be sown along with the annuals as succession species. For summer covers, a mix may include different kinds of sorghums, millets, cowpeas, lablab, maize, soybeans and buckwheat, harvested either green or at seed to be milled for animal feed. Experiments along these lines were pioneered by Colin Seis of Winona Farms. Direct seeding (minimum or no-till) of a diversified mixture of compatible annual species into existing vegetation, such as pastures and hayfields, shows considerable promise for soil improvement and increased forage yields, and at the same time reduces risks where droughts can be followed by floods which would devastate cultivated soils.

Soil Testing

Before bringing in manures or mineral inputs it is important to have reliable information about what is already there. Soil testing can be helpful, but it also can be misleading. Since the birth of chemical agriculture, most soils have been tested for soluble nutrients using dilute solutions of mild acids in an attempt to mimic the weak acids plants give off at plant roots. This ignores the wider range of soil biology and assumes plants only access those elements in the soluble form as shown by the testing method.

In his retirement, Justus von Liebig, the father of chemical agriculture, realized he was wrong in thinking plants depended on solubility.

Rudolf Steiner took up the challenge of correcting Liebig’s errors by teaching his agriculture course. Time passed, and Ehrenfried Pfeiffer, who worked closely with Rudolf Steiner in his agricultural researches, immigrated to the United States after World War II and set up testing laboratories in Spring Valley, New York. He conducted extensive total testing of soils and found that most soils contained large quantities of nitrogen, phosphorus and potassium that didn’t show up on soluble tests. These were the very elements being applied in large quantities to agricultural crops, though soils continued to decline in fertility.

In many cases, soil biology, given encouragement and sufficient trace elements, would provide access to the insoluble but available nutrients stored in the humic fraction of the soil. However, fertilizer industries using soluble testing as a sales tool and selling farmers minerals they already had in abundance, were unstoppable. They perpetuated Liebig’s errors and financed ongoing research into solubility based agriculture, building a momentum that relegated Liebig’s final wish to obscurity.

Today in Australia, Environmental Analysis Laboratories at Southern Cross University in Lismore, New South Wales, offers both the soluble Albrecht test and a hot aqua regia total digest test similar to the one Pfeiffer used. EAL accepts samples from anywhere in Australia or the world.

The Albrecht test measures the ratios of calcium, magnesium, potassium and sodium, which are the major cations or metallic elements in the exchangeable portion of the soil. The ratio of calcium to magnesium is particularly important for soil mechanics. Heavy soils may need as high as a 7-to-1 ratio of calcium to magnesium to crumble and expose particle surfaces. By the same token, light soils may need more like a 2- or 3-to-1 ratio to hold them together. Other soluble analysis targets of importance for robust, vigorous growth include 50 ppm sulfur, 2 ppm boron, 100 ppm silicon, 70 ppm phosphorus, 80 ppm manganese, 7 to 10 ppm zinc, 5 to 7 ppm copper, 1 ppm molybdenum, 2 ppm cobalt and 0.8 ppm selenium.

In total tests, the targets for nitrogen, phosphorus and potassium depend on the carbon content of the soil, since most soil reserves are stored in humus or accessed by humus-based organisms. Most importantly, total testing addresses what is contained in the soil reserves despite what may seem like deficiencies in soluble tests. As Pfeifer discovered, it is common to find huge reserves of phosphorus, potassium and other elements that are deficient in soluble tests, which indicates something else is going on.

The Biochemical Sequence

There is a hierarchy or biochemical sequence of what must function first before the next thing and the next thing works. The elements early in this sequence must be remedied before later elements have much effect. Nitrogen, phosphorus and potassium occur late in this sequence, while sulfur, boron, silicon and calcium start things off.

Since everything going on in the biology of the soil occurs at the surfaces of soil particles where minerals combine with water, air and warmth, sulfur is the essential key-in-the-ignition for activating the soil biochemistry.

Sulfur works at the surfaces, boundaries and edges of things to bring life and organization into being. It is the classic catalyst of carbon-based chemistry. Regardless of the other soluble elements in the soil test, there should be 50 ppm sulfur [Morgan test] for biological soil fertility to function properly and a 60 to 1 carbon to sulfur ratio in the total test.

Silicon & Boron

Silicon forms the basis for the capillary action that transports nutrients from the soil up. Fortunately for agriculture, the activity of silicon is to defy gravity, but this silica activity relies on boron, a component of clay, to do so. Boron is the accelerator while silicon is the highway. If either boron or silicon is deficient the soil biology will function below its potential. Ironically, the most effective way to make sure boron and silicon are deficient is clean cultivation and heavy use of soluble nitrogen fertilizers. Hello, this is modern agriculture.

Calcium

Calcium, which comes next in the biochemical sequence, is the truck that travels on the highway. It collects and carries with it the nutrients that follow in the biochemical sequence. As the opposite polarity from the aloof silicon, calcium is hungry, even greedy. Calcium engages nitrogen to make amino acids, the basis of DNA, RNA and proteins. These in turn are responsible for the complex enzyme and hormone chemistry of life that utilize magnesium, iron and various trace elements as well as depending on chlorophyll and photosynthesis for energy.

Photosynthesis is where magnesium, phosphorus, potassium and a wide range of micronutrients follow nitrogen in the biochemical sequence. Unfortunately, NPK fertilizers stimulate this latter portion of the sequence without addressing the priorities of sulfur, boron, silicon and calcium. The NPK approach usually grows crops that are highly susceptible to pests and diseases.

Minerals & Rock Powders

Even though biodynamics is primarily about organization and biological activities, soil mineralization must be considered. It is pretty hard to organize something if it isn’t there. Many soils need gypsum or elemental sulfur. Many soils also need boron, especially after nitrogen fertilization, but also following overgrazing or clean cultivation. Silicon may also be needed to get the soil biology up and running so it can release more silicon from the surfaces of soil particles. It too is depleted by overgrazing, clean cultivation or nitrogen fertilization. Many ‘organic’ farms using raw manure — especially chicken manure — as a nitrogen source deplete their sulfur, boron and silicon.

In addition to silicon rock powders, lime will provide calcium, dolomite also provides magnesium, and rock phosphorus provides silicon, calcium and phosphorus. There are also natural potassium sulphates, and many rock powders provide trace elements. For high pH soils with large excesses of sodium and potassium, the remedy may be humates and zeolite to buffer pH and build additional storage capacity.

Most importantly, the biochemical sequence shows us we need to start with a full correction for sulfur to expose the surfaces of soil particles to biological activity before the biochemistry can kick in. Other methods may not recognize sulfur’s key importance, but in biodynamics this should be clear. Liebig’s ‘law of the minimum’ rightly says plants only perform as well as their most deficient nutrient.

Calculating Inputs

A soil test can show how many parts per million (ppm) of each element are present and whether target levels are being met. The question is, how can we calculate the right adjustment and add no more and no less? Fortunately there is a rule of thumb.

Two-hundred and fifty kg/ha (250 lbs/ac) of any input supplies that input’s percent analysis as parts per million. Note: This is based on the average weight of the top 17 centimeters of soil in 1 hectare, which is approximately 2,500,000 kilograms (to calculate, 2,500,000/250=10,000 which is 1 percent of 1 million parts per million). Since a hectare is 2.5 acres and a kilo is 2.2 pounds we can approximate this rule fairly closely using 250 pounds per acre in the place of kilos and hectares. For example, if the soluble test for sulfur (Morgan test) shows 5 ppm when the target is 50 ppm, then 45 ppm sulfur is needed. If gypsum is 15 percent sulphur then 750 kilograms per hectare (750 pounds per acre) gypsum will deliver 45 ppm sulfur. If gypsum is 20 percent S then 565 kilograms per hectare (565 pounds per acre) will be required. If the gypsum is 12 percent S then nearly a metric ton per hectare (or 1,000 pounds per acre) is needed.

Since gypsum is calcium sulphate, it provides both calcium and sulfur, which is usually desirable. However, in the event the soil is already rich in calcium and has a pH of 6.3 or higher, elemental sulfur may be a better choice. In contact with moist soil, sulfur will oxidize to sulphate and lower the pH slightly, but it will open up the surfaces in the soil, stimulate soil biology and release some mineral reserves. For practical purposes elemental sulfur may be combined with 10 percent bentonite for ease of handling. Ninety percent elemental sulfur would require 125 kilograms per hectare (125 pounds per acre) to deliver 45 ppm S.

As a different example, sodium molybdate is 42 percent molybdenum. To add 0.5 ppm Mo to the soil requires 42 divided by 0.5 which equals 84. If we divide 250 kilograms by 84 we get 2.976 kilograms sodium molybdate. However, to add this much in one go would be expensive and unwise. With most inputs, especially the traces, the soil has trouble adjusting to a full correction of anything other than sulfur. In the case of sodium molybdate 0.5 kilograms per hectare (0.5 pounds per acre) is the usual correction and 1 kilogram per hectare (1 pound per acre) is considered the limit. The maximum manganese or zinc sulphate per application per hectare is 25 kilograms per hectare (25 pounds per acre), and copper sulphate rarely is applied at any rate higher than 15 kilograms per hectare (15 pounds per acre).

Boron, Humates and Trace Minerals

When adding trace elements, especially boron, food for the fungal activity of the soil food web is essential. Fungi hold on to inputs that otherwise would leach. If available, well-humified compost produced on the farm is highly desirable. If this is not available then other humic inputs must be considered. Humic acids are extracted commercially from carbon-rich deposits such as leonardite, soft brown coal and peat. While raw leonardite or brown coal may be processed and sold as raw humates, the extracts, sold as soluble humates, are a handy food concentrate for actinomycetes and mycorrhizal fungi, which are amongst the most important microorganisms for nutrient retention and delivery in the soil. Soluble humates and raw humates are excellent for buffering boron and trace elements such as copper, zinc, manganese or sea minerals. They also are helpful when adding bulk minerals such as gypsum, silica rock powders, lime, rock phosphate or potassium sulphate. Trace elements may be combined with 250 kilograms per hectare (250 pounds per acre) of raw humates or 25 kilograms per hectare (25 pounds per acre) soluble humate extracts in dry blends, or they may be dissolved in liquid soil drenches with soluble humates and water. Feeding them in this fashion to the soil biology delivers them to the soil’s fungi which holds on to them and delivers them to plants.

Crusher Dusts

Siliceous rock powders such as granite or basalt crusher dusts only provide silicon from the surfaces of their particles, but they can be helpful in repairing silicon deficiencies while the soil biology gets going to release the soil’s silicon reserves. Siliceous rock powders can be fed to the soil biology along with humates as a food source and the actinomycetes and mycorrhizae will gradually weather the particle surfaces and release silicon. Crusher dusts are especially effective when fed to pigs and their manure is composted. They also can be added to composts or spread along with composts. Generally 2 or 3 tons per hectare will get a helpful response, and usually these rock powders also release boron, which is especially essential for legumes.

Lime, Rock Phosphate, Potassium Sulphate, etc.

Each of these has its own story, and, as Pfeiffer discovered, the soil total test is a better indication of whether these are needed than the soluble test. If deficient, any of these can be built into soils by inputs, with the exception that it is not a good idea to add bulk lime to composts. Lime should not be added to compost at more than 0.1 percent of the total mass, as it tends to drive off nitrogen as ammonia. It can be spread along with composts, but when added to composts at more than 1 kilo per ton it tends to waste valuable nitrogen.

Visual Soil & Crop Assessment

Visual soil assessment is helpful in order to evaluate soil biology. New Zealand soil scientist Graham Shepherd has published a book on this Visual Soil Assessment Volume 1: Field guide for cropping & pastoral grazing on flat to rolling country, and while it may not be the last word on the subject, it is a surprisingly good start toward evaluating soils, their conditions and their biological activity. This system assesses texture, structure, porosity, mottling, soil color, earthworm activity, aroma, root depth, drainage and vegetative cover.

There also are many visual clues to mineral deficiencies. For example, hollow stem clover, lucerne, beans, potatoes, etc. indicate boron deficiency. Boron deficiency is also indicated by high Brix in the early morning which shows plants are holding their sugars in the foliage, and the cycle of root exudation is not occurring at night.

Dwarf leaves in clover indicate zinc deficiency. Purpling of grass and clover in winter indicates copper deficiency, and so on. Poor chlorophyll development and pale, yellowish green vegetation often indicate magnesium deficiency on a magnesium-rich soil. This is common where the soil is too sulfur deficient to release magnesium properly. Under these conditions foliar analysis usually shows high sulfur because what little sulphate is present is soluble and plants take it up even though there is not enough in the soil for magnesium release. This slows growth and sulfur builds up in the plant because it is not being used. Adding magnesium to a high mag soil will only make matters worse, while the real cause of magnesium deficiency is the first priority of all soil amendment programs — sulfur.
Taste and smell of vegetation can be clues to excess nitrate uptake and poor photosynthesis, while complex, delicious flavors and aromas indicate high Brix and nutritional density. Biodynamic growers should be aware that their own senses can be the best guide to determining what is going on with pastures and crops. Sending soil and plant specimens to laboratories for analysis is a useful tool for learning what the senses reveal, but firsthand observation is quicker as well as less expensive, and it can be far more informative.

Nitrogen Fixation and Silicon Release

Nitrogen and silicon are present in enormous abundance, though this usually goes ignored. Nitrogen fixation and silicon release should be the highest priority in agricultural research. If growers knew how to access nitrogen and silicon in abundance, it would eliminate the larger part of their fertilizer costs, to say nothing of most of the rescue remedies for weeds, pests and diseases. Unfortunately, little funding is available for such research since industrial concerns would suffer if this knowledge became widespread.

Currently the nitrogen fertilizer industry uses 10 units of methane to manufacture 1 unit of ammonia. With a little more energy, this can then be converted into urea and applied as fertilizer. With straight urea applications to the soil, losses of 50 percent and more are normal, since large amounts of nitrogen evaporate as nitrous oxide (N2O) when the urea oxidizes.

The same 10 to 1 carbon to nitrogen ratio holds true for biological nitrogen fixation since it takes 10 units of sugar from photosynthesis to fix 1 amino acid. However, the losses are nowhere near as great. The grower’s challenge is making photosynthesis as efficient as possible so that biological nitrogen fixation is abundant.

Nitrogen fixation is more robust when plants have steady access to all the necessary requirements for efficient photosynthesis. This feeds a steady abundance of carbohydrates to their microbial nitrogen-fixing partners in return for amino acid nitrogen. Biodynamic farms attain this level of mineral balance and photosynthetic efficiency when everything is working near optimum. This deserves replicated scientific trials, but it hardly makes sense to wait for funding when there isn’t any money to be made from the research. Farmers must simply try their hand at it. Some will undoubtedly succeed with relative ease while others will find it difficult for a variety of reasons.

Silicon, Nitrogen and the Soil Food Web

The previous subheading on soil testing indicates optimum levels of minerals for plant efficiency and nitrogen fixation. Though these guidelines are generally higher than those considered adequate in chemical agriculture, these levels are desirable for efficient photosynthesis, especially at lower temperatures. This is particularly true for silicon, which is almost always deficient in conventionally farmed soils. Silicon, and its co-factor, boron, are the principal keys to transport speed, which is the key to abundant photosynthesis in plants. Energy must be transferred from the chloroplasts in the leaf panel to the leaf ribs where sugars are made. Silicon is basic to fluid transport, and this transport determines how fast sunlight is converted into sugar.

Unlike amino acid nitrogen, nitrates, nitrites and other nonorganic forms of nitrogen impair the silicon chemistry of the plant as well as the symbiosis between plants and their microbial partners in the soil. Raw manures and poorly composted manures, especially raw poultry manure, are extremely detrimental because of the nitrate burden they impose on the soil biology. Nitrates flush silicon out of both plants and soils. How well a plant picks up silicon from the soil depends, at least in part, on the level of actinomycete activity at its roots. This in turn depends on the extent to which the soil opens up and is aerated, which in turn depends on sulfur levels and soil microbes such as Archaea which digest siliceous rocks. The sensitive biochemistry of these activities, in both soils and plants, is impaired by high levels of nitrates.

Animal activity in the soil around plant roots provides freshly digested amino acid nitrogen, which encourages the release of silicon from the surfaces of soil particles. Living in partnership with plant roots, actinomycetes form fine fuzz along the root exudate zone of young roots, and nitrogen-fixing microbes make this their home. In the process the actinomycetes utilize the silicon and boron in forming their fine, fuzzy hairs. As roots age and mature, these microbes are consumed by soil animals ranging from single-celled protozoa upward. The nutrients they excrete are taken up as nourishment by plants, often providing a high proportion of amino acid nitrogen and amorphous fluid silicon.

Soil microbial life can only access silicon at the surfaces of soil particles where moisture, air and warmth interact. The rest is locked up. Nitrogen fertilizers, particularly nitrates, suppress actinomycete development and the nitrogen-fixing microbial activity they host. On the other hand, if actinomycete activity is robust, the soil food web freely provides a luxury supply of both amino acids and amorphous fluid silicon.

Biodynamic practices promote this activity as a way to achieve quality production that sustainably and efficiently rivals the yields of chemical agriculture. The bonus comes when environmental conditions are less than ideal. Then biodynamic production can easily surpass chemical yields.

Hugh Lovel is an agricultural consultant serving clients in both the United States and Australia. He consults, speaks and teaches on all aspects of agriculture. For more information visit www.quan tumagriculture.com.

This article is in the July 2014 issue of Acres U.S.A.

 

,