Soil Fertility: 16 Methods to Understand

By Hugh Lovel

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.

Establishing a Self-Sufficient System
In nature, soil organisms cultivate the soil.

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.

Andre Leu, Soil Carbon, from the 2007 Eco-Ag Conference & Trade Show. (53 minutes, 44 seconds). Listen in as Leu, the director of Regeneration International, teaches how to store and repurpose carbon in your soil.

In both forests and grasslands,  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. Forest fires return most of the carbon 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.


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 processes. 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.

Earthworm in soil.

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 decline.

Even back in the 1920s, Rudolf Steiner saw these 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.

Author and Agronomist Neal Kinsey, Prioritizing Fertilizer Needs, from the 2008 Eco-Ag Conference & Trade Show. (1 hour, 17 minutes.) Listen in and Neal teaches a classroom about how to quantify your fertilizer needs and make a plan for your growing operation.

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.


High-density cell grazing is particularly effective. In this technique, 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.

Sarah Flack, Integrating Livestock into the Farm, from the 2006 Eo-Ag Conference & Trade Show. (1 hour, 32 minutes.) Listen to Sarah’s instructional workshop, as she teaches specific tactics for integrating livestock into your soil management program.

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 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.

Edwin Blosser: Composting Made Simple, from the 2017 Eco-Ag Conference & Trade Show. (1 hour, 58 minutes) Listen in as Blosser, the founder of Midwest Bio Systems, explains how to make compost, and how it can be used on a commercial scale.

Into the newly built pile, insert a small spoonful of each of the herbal “composting” preparations 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 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 humus-forming 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.

Soil expert and author William McKibben, The Art of Balancing Soil Nutrients, from the 2009 Eco-Ag Conference & Trade Show. (1 hour, 8 minutes). Listen in as McKibben talks about the steps you can take after you receive your soil test results to help balance your soil.

However, consider the economies of scale. On the one hand, Steiner indicated that 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, 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 manure 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 sprayed to minimize losses and keep smells in check.

Cover Crops & Green Manures

In general, cover crops and green manures 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.

Clover Field

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.

South Dakota farmer Gabe Brown, author of Dirt to Soil, speaks in 2016 at the Eco-Ag Conference and Trade Show. (1 hour, 18 minutes.) Listen in as Gabe Brown talks about how he uses cover crops to build soil health.

Broad-acre 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 in Australia. 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 that 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.

Neal Kinsey, Using Soil Analysis to Grow Crops, from the 2005 Eco-Ag Conference & Trade Show. (50 minutes, 12 seconds). Listen in as agronomist Neal Kinsey, the author of Hands-On Agronomy, teaches about how to test your soils, and use that data, to increase crop yield and decrease weed pressures.

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 in his agriculture course. Time passed, and Ehrenfried Pfeiffer, who worked closely with Steiner in his agricultural research, 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 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.

Neal Kinsey, Compost & Manure Analysis, from the 2005 Eco-Ag Conference & Trade Show. (50 minutes, 39 seconds.) Listen to Neal Kinsey’s helpful lecture on how to test compost and manure, to ensure those inputs are balancing your crops and soil.

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. This is modern agriculture.


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, which deplete their sulfur, boron, and silicon.

In addition to silicon rock powders, lime provides calcium; dolomite 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.

Gary Zimmer, Gaining a Working Knowledge of Calcium, from the 2002 Eco-Ag Conference & Trade Show. Listen to Gary Zimmer talk about how calcium drives the flow of other minerals and nutrients through the soil and plant, and how to measure and balance calcium levels in your fields.

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 that 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, feeding the fungi of the soil food web is essential. Fungi hold on to inputs that would otherwise 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. This delivers them to the soil’s fungi, which hold on to and deliver 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 starts releasing 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 produce a helpful response, and these rock powders also usually 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 caveat 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 titled Visual Soil Assessment Volume 1: Field Guide for Cropping & Pastoral Grazing on Flat to Rolling Country. 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, and potatoes indicate boron deficiency. Boron deficiency is also indicated by high Brix in the early morning, which shows that 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.

Soil consultant Noel Garcia, with Texas Plant & Soil Lab, speaks at the 2014 Eco-Ag Conference & Trade Show, on the Critical Growth Stages for Optimum Production. (1 hour, 15 minutes.) Listen in as he teaches a class on how to monitor plants for stress, and mineral and nutrition deficiencies.

The taste and smell of vegetation can be clues of 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.

The nitrogen fertilizer industry currently 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.

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 — unlike amino acid nitrogen, . 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 that 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. Biodynamic production can then 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

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

Keys to Composting for Increased Soil Health

By Bryan O’Hara

For many years we have been composting various agricultural and forest materials at Tobacco Road Farm to provide for the soil fertility in order to raise vegetable crops without the use of pesticides. This practice has been highly successful though it has required more refinement as the environment continues to deteriorate and the soil’s need for rebalancing becomes increasingly important.

The composting system is the mouth and stomach of the farm system and prepares the nutritive materials for absorption into the soil. How we choose the appropriate materials to feed into this system, along with an examination of mixing, piling and application of this material, is the focus of this article.

Let us set the stage of how and why this compost is utilized on our farm. At Tobacco Road Farm in Lebanon, Connecticut, we focus on intensive vegetable production with 3 acres in crops. The vegetable fields produce tremendous volumes of crops year-round. The soils are typical of the Northeast with a sandy acidic nature. The impact of pollution and climate manipulations on our soils is tremendous. The forest surrounding the farm is in a rapid state of decline. There are die-offs of trees and vastly reduced numbers of insects, bats, frogs, snakes and birds.

The variety of pest insects and diseases of vegetable crops moving into the region continues to increase and is a reflection of the environmental conditions. It has been very useful to re-examine compost and its utilization through a holistic eye that can see these changes and adjust the compost system accordingly. This is similar to the way humans have had to adjust their diets in this modern age of illness.

compost pile temperature gauge
Compost with undigested carbon materials still present has now cooled to about 80°F and is ready for application.

We utilize many techniques to deal with these difficulties, including no-till (Acres U.S.A., October 2016), Indigenous Microorganism cultures (Acres U.S.A., September 2017), foliar feeding, side dressings and cover crops as well as composting.

The no-till nature of the growing system influences compost production dramatically. Since the compost will only be applied to the surface of the soil and not turned into it, it simplifies its making greatly by allowing for more bulking with carbon-rich materials like wood chips. This allows for more air infiltration and thus less turning. The top-dressing of compost also allows for a less-decomposed compost to be applied, which is of great benefit to the hungry soil life. Let’s have a look at the materials and the process.

Compost Materials

For raw materials we blend relatively large amounts of carbonaceous wood chip, leaf and straw with nitrogen-rich cattle manure and vegetable wastes.

We maintain separate piles of all these ingredients on the farm and then blend them into compost windrows.

large compost pile
Large volumes of carbon-rich materials are incorporated into the compost at Tobacco Road Farm.

Wood Chips

The wood chips come from our surrounding forest and is primarily deciduous in nature. Often the chips are from roadside clearing and contain the small, more nutrient-rich branches and also possibly leaf.

The chips are available from various sources that manage to pile this material directly from roadside clearing trucks or land clearing companies. The material is generally free, but transportation adds cost.

Wood chips are considered one of the cleanest materials in commercial composting as the trees generally receive little to no pesticide applications, and there is little foreign matter mixed in. Wood chips are the primary ingredient in our compost.


Leaves are also incorporated into the compost at a relatively high volume. Leaves are generally collected in the fall so ample space is provided to bring in this harvest. Landscapers are our choice of providers here, where we have a personal relationship and can secure high quality. Again the material is essentially free, however we pay to have the materials delivered. Municipalities also collect large volumes of leaves and are often looking to give them away, however they contain a fair bit of plastic debris that must be picked out. Leaves also offer less risk of chemical contamination, however caution should be applied if lawn grasses are mixed in to any great degree.


Straw is another source of high-carbon material and provides a diversity of ingredient to our mix. The potential for herbicide contamination in straw is substantial so straw is secured from local producers whose practices are appropriate or from large commercial organic farms. The danger of “persistent” herbicide residues is said to be the most challenging problem in commercial composting. The chemicals do not readily break down during composting and can damage vegetable crops.

This group of herbicides is used in the production of small grains and hay.

When necessary, we purchase 1,000-pound square bales from organic farms in the grain growing regions of Maine. Since the straw is purchased and trucking is often paid for as well, it is our most expensive compost ingredient and thus is used to a lesser degree.

Straw is seldom totally free of the seed if the grain was harvested with a combine, however some rye straw is purchased from a local farmer who harvests before the seed heads are formed, yielding a seed-free straw. This rye straw is long-stemmed and is often run through a bale chopper for use as mulch (this helps with decomposition as well).

When used in composting, the straw, which has been run through a combine tends to be shorter in length and is generally not run through the chopper; instead the bales with grain seed in them are roughly laid out to allow rain to sprout the seed. Then the straw can be utilized either as mulch or put into the compost, as the process of moving the straw after grain germination effectively kills the sprouted grain.

Tobacco Road Compost Recipe

Base Ingredients
40% wood chip
20% leaf and/or straw
30% cattle manure mixture
10% vegetable scrap mixture

Mineral Additions at Assembly
(to about 30 yards-plus of base ingredients)
5-10% quarry dust or clay subsoil
100 lb gypsum
150 lb calcium silicate (wollastonite)
25 lb hydrated lime
250 lb talc (magnesium silicate)
100-200 lb soft rock phosphate

At Turning
(1-3 months later)
250 lb talc
100-200 lb soft rock phosphate
5-10 lb elemental sulfur (depending on pH of pile)
50 lb agricultural sea salt (Sea-90)
40 lb manganese sulfate
5-10 lb sodium molybdate
5 lb zinc sulfate
5 lb copper sulfate
1 lb sodium borate
2 oz. cobalt sulfate
And a splash of selenium feed supplement[/box]

Grass-Fed Cattle Manure

The primary nitrogen-rich material we utilize is grass-fed cattle manure. This material is from a nearby herd that is fed the farm’s hay on in-field concrete feed pads during the cooler months. This allows for easy collection of the manure and spent hay, especially with a few well-placed large concrete blocks for the loader to push against.

Since the hay is produced on the farm, the potential herbicide contamination is low, and the cattle eating grass in a natural environment are very healthy and require very little to no veterinarian intervention.

The mixed hay and cattle manure piles on the pads often are heating and composting at a high temperature (above 150°F) before we even begin to haul them for further composting at the farm. Cattle manure has a long tradition of being the manure of choice for vegetable crop production. It composts very well, adds an appropriate biology to the composting process and is the easiest manure to use for high-quality compost. We have also used manures from various other animals, including our own poultry flock as well as fish processing waste.

With all of these materials, contaminants always need to be seriously considered including de-wormers, antibiotics and feeds grown using persistent herbicides. That being said, nothing has produced as beneficial a compost for us as the cattle manure. The manure is piled on a wood chip base, when brought to the farm, and covered with a high-carbon material like leaf/wood chip/straw to await further assembly.

Food Waste

The other primary nitrogen-rich material utilized in the compost is vegetable scrap backhauled from our co-op grocer and restaurant accounts, combined with the farm and household wastes. This material provides a lot of feed for the poultry, but generally does need to be covered with the high-carbon materials to keep it from attracting flies and varmints and to begin the composting process.

It is surprising how much carbon materials need to be mixed with this vegetable scrap in order for it to properly compost. This pile is also preheating to a high temperature before being mixed into the fully assembled compost windrows.

It is much harder to make high-quality compost using just this material as the nitrogen source, but it works well when combined with cattle manure.


Minerals are the final raw ingredient. Often we utilize a ground rock from our local quarries such as traprock (basalt) or sometimes granite. This material is the end result of rock crushing and is very inexpensive at $3 to $5 a ton plus trucking. It is high in silica, a much-needed nutrient for us, and provides a clay-like material to provide a base for the compost to build aggregates upon and for clay-humic complexes to form.

Spraying minerals onto compost
Minerals are sprayed onto piles during assembly.

Clay subsoil from on-farm digging projects is also often incorporated. Other ground minerals of clay nature that are used in the compost are talc (magnesium silicate), wollastonite (calcium metasilicate) and rock phosphate (calcium phosphate).

Additional materials used include: gypsum (calcium sulfate), zinc sulfate, manganese sulfate, copper sulfate and cobalt sulfate along with sodium borate, sodium molybdate, sodium selenate and hydrated lime.

Seawater or liquified sea salt is also incorporated. Many of these materials and salts are utilized in very small quantities, and the formula is based upon tissue and soil laboratory testing, crop response in the field and other guidance. They are therefore somewhat unique to our fields’ conditions.

Although the formula on page 20 is specific to our farm, I’ve provided it to give you an idea of materials and amounts that have proven useful for our situation.

Composting Area, Method

The composting area is built up with a base of stone and processed gravel to allow for drainage and tractor traffic, though piles on top of topsoil may allow for even better soil microbe/compost pile interactions. The area has solid, easy access for truck deliveries of material. This always makes the truckers happy: an important component.

The raw materials are piled separately, except as noted when some carbon materials are premixed into the nitrogen-rich materials for preservation of quality. Generally all the materials described are present, however sometimes piles are assembled with more or less, or the complete absence, of a material.

Compost area at Tobacco Road Farm
Compost yard at Tobacco Road Farm with solid base, free of weeds.

The basic formula is something like 40 percent wood chip, 20 percent leaf and/or straw, 30 percent cattle manure and 10 percent vegetable scrap. On top of this is the quarry dust or subsoil and other minerals and clays up to a volume of about 10 percent, which of course gives 110 percent, but the point is that the loader takes four buckets of wood chip to two buckets of leaf to three buckets of cattle manure, etc.

The cattle manure and vegetable scrap also contain fair amounts of the more carbon-rich materials so overall the pile is quite high in carbon and moderate in nitrogen. This allows the pile to heat to a generally lower composting temperature of about 120°F, which favors a more fungal-rich compost, which is what we’re after due to our soil conditions.

The high volume of wood chip allows bulking of the pile that gives the ability of the pile to breathe and allows for adequate air infiltration, greatly reducing the need for turning, which is of benefit to fungal organisms.

The piles are built into windrows of about 15 feet wide and 6 feet high with varying lengths. Upon initial construction, wood chip is piled first at the base about a foot thick, then the other materials are piled atop this with as much mixing with the tractor bucket as can be done quickly and efficiently.

As the tractor is assembling, the minerals — talc, hydrated lime and wollastonite — are sprayed onto the pile. This liquefying and spraying requires two people as some of the minerals do not go into solution, and they must be constantly agitated in a large stock tank of water by hand.

A heavy-duty sump pump then moves the slurry to another person with a hose who is spraying down the pile.

This gives us a better mix into the pile and greatly cuts down on our exposure to the aggravating silica dusts and hydrated lime. The gypsum and rock phosphate are often applied dry as they are less dusty, and this helps cut down the amount of minerals that need to be agitated.

The pile is then covered with a bit of straw to provide a “skin,” and the biodynamic compost preparations are applied; they are a blessing for the pile. The pile is allowed to sit for a period of a month or more before it is turned. This is generally the only turning the pile receives and is an opportunity to further mix the materials as well as apply additional minerals.

The piles are turned using a loader tractor, and basically the windrows are moved sideways. At turning, additional talc and clay minerals are supplied, however a second stock tank is now mixed with the various salts that go into solution, and that is sprayed on as well.

The vast majority of mineral additions to our fields happen through the compost. This allows for digestion of these minerals into more accessible and biological forms and is very useful for the more difficult-to-access minerals like silicates.

It is also very useful for buffering the potential damage that the use of the soluble minerals could inflict upon the soil biology if applied directly.

The introduction of most of the materials, especially the soluble salts,later in the composting process seems best in terms of timing as it allows the process to be well underway before introduction of materials that could reduce biological activity. Also the piles are better prepared to buffer and hold these soluble nutrients at this time.

The addition of these mineral materials goes a long way toward increasing the soil’s fertility. Our soils have been damaged by past agricultural activities and the impact of various pollution sources. The pollution impact, combined with the use of various agricultural chemicals, has resulted in organic materials that are highly imbalanced, so as feedstocks for the composting system they are lacking in various mineral nutrients and excessive in others. In other words, it is difficult to take materials from a dying forest or from damaged agricultural soils and turn them into high-quality compost without some adjustment.

The knowledge of how to adjust the compost recipe comes from a variety of sources, including trialing various composts for their impact on soil and crop health, utilizing long-term soil and tissue testing to see mineral nutrient trends, biodynamic principles and spiritual guidance.

The temperature of the piles is monitored, and generally the hot cattle manure and vegetable scrap materials start to cool to about 120°F when they are incorporated in the windrows with such large volumes of carbon. This is the condition that we are seeking as our crops respond well to the more fungal-rich compost, which these lower temperatures encourage.

The compost is considered ready for use when the temperatures have dropped close to ambient and the nitrogen-rich manure and vegetable scrap has decomposed. Often there are still partially decomposed carbon materials left; this is ideal as with surface application these less-decomposed materials provide excellent food for in-field soil biology. So the compost at this stage resembles a mulch/compost mixture.

Moisture & Air

Other conditions to monitor as the piles progress include moisture and air. When there is more air there is less water, and vice versa. Generally in our environment in the Northeast there is sufficient rain for composting, so rarely do we have to add moisture, however the piles do need coverage during periods of excessive rain, often in the cooler months.

To cover these piles we use large, black plastic tarps, often silage-style tarps that have previously been used to cover straw or for field occultation. These used tarps have a few holes, which are helpful in allowing the piles to breathe while shedding the vast majority of rain.

Proper air penetration into the pile is provided by the coarse nature of the materials composted, along with moisture control and proper sizing of the piles.

Insufficient air will lead to anaerobic conditions which results in off-smelling compost with a black color similar to swamp muck. If this occurs we recycle this material into a new compost pile.


The compost is spread when the piles have significantly cooled using a loader tractor to fill various spreading equipment, such as a manure spreader, dump truck or a line of wheelbarrels. The dump truck and manure spreader fit to the bedding system.

Dump spreading compost onto beds.

The compost is spread on the surface of no-till soil, making it important to keep the material from drying out, so after the compost is spread the beds are seeded or planted, mulched and irrigated pretty much immediately. This preserves the biology present in the compost and provides an environment appropriate for plant feeder roots to penetrate the compost. Compost is spread before most, but not all crops, at a rate of about 30 tons per acre, or a wheelbarrel-full to 150 sq. feet.

The compost described here is utilized pre-plant and is meant for broadfield application to assist in soil remineralization and balance as well as to provide a food source for the very hungry soil biology in our fields. We also produce specific composts for other uses on the farm including specific blends for side-dressing vegetables at various growth periods, potting soil and vermicomposting.

Liquid compost extracts from the vermicomposting system are utilized in the liquid side-dress fertilization to help buffer salts. These specific compost recipes will have to await future articles.

Phosphorus Concerns

When discussing composting with other farmers, one recent concern has been phosphorus levels. Various laws and regulations have limited the application of phosphorus-containing materials including compost in the name of water quality. This kind of broad sweeping regulation defies common sense, agricultural tradition and experience; stands on weak science; and is unlikely to help water quality when the greater picture is considered.

However, phosphorus can be excessive in composts if they are not properly blended. Phosphorus levels are highly related to the grain ration in animal feeds, so usually the manures of these grain-fed animals are responsible for elevated phosphorus levels in compost.

Without manure from grain-fed animals we have seen the phosphorus levels on the Mehlich III soil test drop when applying 30-plus tons of compost per acre per year.

If you are interested in a more scientific evaluation of phosphorus level and plant availability, saturated paste soil tests and tissue analysis will probably give a more accurate assessment than the strong acid Mehlich III extract.

Spreading finished compost over potato hills at Tobacco Road Farm.

I have seen many lab results from various farms in the region showing what are now considered “high” levels of phosphorus on the Mehlich III that have low to very low levels of phosphorus on the weaker LaMotte and saturated paste soil tests as well as tissue analysis. These soils may well benefit greatly from phosphorus-containing compost application.

Compost is of course the very heart, backbone, and shall we say, digestive tract of the organic system of agriculture.

Most soils I’ve observed on vegetable fields in the Northeast region would most likely benefit to a great extent from the application of high-quality farm-made compost.

The benefits of the biological stimulant nature of compost are quite significant in terms of yield and quality, especially when combined with materials that aid in the mineral nutrient balance of the soil.

Compost can indeed imbalance a soil if the materials utilized are in severe imbalance, so guidance here may be appropriate. However, often the best way to learn these things is by doing: make the compost, trial it, evaluate and learn from error and success.

Editor’s Note: This article appeared in the October 2018 issue of Acres U.S.A. magazineBryan O’Hara can be contacted by mail, at 373 Tobacco St., Lebanon, CT, 06249.

Minerals: The Big 4 for Soil Health

By Gary Zimmer

Minerals and their respective roles in achieving healthy soil is a common topic of discussion among agriculture consultants and farmers. A long time ago, when I was going through my initial soil balance training, mineral balance was all that we talked about. Get the minerals right, address calcium and get it to 68 percent base saturation and all will be great.

The physical and biological aspects of soil weren’t even part of the discussion. Even alternate mineral sources were just touched on. Potassium chloride (KCl) was a no-no due to the high salt index and the chloride, as was dolomitic lime due to our already high magnesium soils. Also on this “not to be used” list was anhydrous ammonia because of its damaging effects on soils. The concept of soil correctives and crop fertilizers wasn’t talked about either, nor was the idea of different calcium sources for different soil conditions. The balance of nutrients on a soil test was the only goal.

Now, looking back, I can certainly see that wasn’t the whole picture. What about the biology and the physical structure? How about making a fertilizer that not only delivered soil minerals but did so more efficiently? Why not have fertilizer that can balance the soluble to the slow release, make sure carbon is added for the buffering effect and provides something for the minerals to attach to so that it is “soil biology food”? Soil health is the capacity to function without intervention; therefore minerals are certainly a part, but not the whole of soil health.

Gary Zimmer, Minerals for Healthy Soil, from the 2017 Eco-Ag Conference & Trade Show. (18 minutes, 56 seconds.) Listen in as agronomist Gary Zimmer, author of The Biological Farmer and Advanced Biological Farming, teaches why he puts these four minerals at the top of his priority list.

This article is about the minerals’ role in achieving the goal of soil health.

Minerals: The Big Four

healthy well-mineralized soil
Healthy, well-mineralized soils have good aggregation.

I always talk about my “Big Four” minerals: calcium, phosphorus, magnesium and boron. The Big Four relate to the plant, to the four minerals I like to get at real high levels in a plant compared to normal recommended levels.

Mineral 1: Calcium

Start by adding calcium. In most cases, just having the soil calcium level at some magic number, say 68 percent base saturation, does not guarantee the plant is able to take up sufficient levels of this mineral. The other cations in the soil, K and Mg, have an influence, and the soil’s physical properties also affect this. I know I was taught to get the calcium to magnesium ratio right and the physical structure of the soil will be great. It is true this helps, but it is not the whole picture. If the plant, let’s say it’s an alfalfa crop, on average is 1.5 percent calcium and your crop is 2 percent, something more is at work there. Generally, we have had to add some ‘soluble’ calcium along with boron to get more calcium into the plant.

Gary Zimmer, Gaining a Working Knowledge of Calcium, from the 2002 Eco-Ag Conference & Trade Show. Listen to Gary Zimmer talk about how calcium drives the flow of other minerals and nutrients through the soil and plant, and how to measure and balance calcium levels in your fields.

Remember, not all sources of calcium are the same. Using gypsum, mixing acid materials such as humates with fine ground limestone, burning limestone and hydrating it to make hydrated lime — all alter solubility, in effect making fertilizer out of lime.

After all, soil health is ideally measured as plant health, and plant health affects the health of whoever eats that plant. So it is fair to say that the real measure of a healthy soil is a healthy crop: a high yielding, disease- and insect-free crop. Remember, you can have soil that seems great (lots of earthworms, loose and crumbly texture with a great “root cellar” smell) and yet it doesn’t produce healthy crops.

So how do you get that healthy soil? Step one is to have enough available calcium.

Mineral 2: Phosphorus

Step two is to address phosphorus. Phosphorus is tied to energy production and cycling — get the P level high and you will have a higher yielding, healthier crop. I will use potatoes as an example.

Tomato leaves showing magnesium deficiency.
Tomato leaves showing magnesium deficiency. Healthy leaf is on the left, most affected leaf is on the right.

Potato growers know that the higher the petiole P level, the better the crop. Measuring the petiole and staying above 0.2 percent phosphorus is a challenge. You can apply all the soluble P the plants can tolerate and still not drive that number higher. Some growers have seen levels of 0.45 percent in the petiole on the same crop, same varieties, same locations. Why does that happen? Phosphorus is an indicator mineral because you can’t buy it in, there is a biological link required — soil life such as mycorrizhae need to be there and working in order to get more P into the plant. Just having a soil that tests high in phosphorus doesn’t guarantee high P uptake. I do like to see higher soil P levels, but there is more to getting it in the plant than just high soil test numbers.

Mineral 3: Magnesium

Step three, or mineral indicator number three, is magnesium. Many farmers and scientists already know that having soils with high magnesium levels does not guarantee high levels of the mineral in plants. If the plant takes up lots of magnesium, something ‘balanced’ is happening. Magnesium is another mark of healthy plants. It is needed for photosynthesis and is also a real indicator of proper potassium levels and distribution. (Don’t forget, sulfur is also required to achieve high magnesium exchangeability. Apply sulfate sulfur to make magnesium sulfate, a much more soluble, plant usable form than magnesium carbonate from lime.)

If extra soluble potassium is added, the plant magnesium level will drop. You can’t have both high or excess plant potassium and high magnesium. It just can’t happen! Magnesium and potassium are both cations, and compete with each other for uptake into the plant. It may be that the excess K level is more damaging than the shortage of Mg. And usually with high K, plant levels of calcium are also short.

Mineral 4: Boron

The fourth mineral as indicator is boron. Other trace minerals are also important, but boron being an anion is hard to build up and hold in the soil. It is also critical for calcium uptake and sugar translocation. Apply boron with your calcium source, and you’ll get more calcium uptake than if you apply calcium without any boron.

About Gary Zimmer

Gary Zimmer is the co-author of Advancing Biological Farming, a sequel to his earlier book, The Biological Farmer, both published by Acres U.S.A. He is also an organic dairy farmer, an accomplished speaker, a sought-after farm consultant and president of Midwestern BioAg, a biological farming products and services company.

Editor’s Note: This article was originally published in the October 2012 issue of Acres U.S.A.

Learn in the field with Gary Zimmer!

The Acres U.S.A. On-Farm Intensive is held in partnership with experienced farm consultants Gary Zimmer and Leilani Zimmer-Durand at their famous Otter Creek Farm near Lone Rock, Wisconsin. This two-day educational experience will help farmers, growers and land owners maximize their land’s potential. Learn more here!