Sustainable Soil: Four Rules for Controlling Organic Inputs

By John B. Marler

Sustainable soil requires profitability. No matter how desirable a sustainable program might be, it must be tempered by the realities of making a total commercial agriculture program work economically. Growers attempting to deal with this reality often focus on sustainability in a piecemeal manner, as they do not always understand the basic rules or guidelines that are required of a sustainable soil program. In this article, we will review the guidelines on achieving sustainability and also report on new developments in sustainable soil nutrition products.

Commercial agriculture programs are often unable to profitably approach sustainability due to economic pressures. Time-honored practices that require land to lay fallow and the use of cover crops along with manure or compost applications are expensive when compared to the rapid prepare-fertilize-plant harvest cycle that has come to dominate commercial practice. Sustainability struggles within such a marketplace, as growers rarely receive a premium for crops grown on sustainable soil versus crops grown conventionally. When a grower is faced with the hard choice of feeding his soil or feeding his family, the family will win.

farmers talking in field

A relatively new concept in fertilizer manufacturing is the attempt to accelerate the realization of sustainable soil. With these new products, known in the trade as CNEF — Complex Nutrition Enabling Fertilizers — growers will be able to build and maintain sustainable soils at an annual cost per acre of applied nutrients and amendments that is equivalent or less than today’s conventional nutrient programs.

Together, in a single-application interactive form, fertilizer and soil amendment components engender a synergistic action of the soil that accelerates microbial action, resulting in increased nutrition for plants. Manufactured with a stable, slow-release organic base, CNEF can actually grow crops in sand by adding critical organic content to the soils along with primary, secondary and trace nutrients in a single application. Repeated applications actually decrease the need for the use of these products. Once a grower nears sustainability, the amounts of CNEF required drop as the soil is again alive and productive and able to sustain itself with only the replacement of extracted nutrients.

Developing CNEF has provided insights that have allowed us to develop rules for sustainability, rules which may be universally applied with or without the new fertilizers. We quickly realized that many growers do not fully understand the mechanisms involved in mineral and organic restoration. Given adequate soil moisture along with temperate soil and atmosphere temperatures, almost any soil can be rendered sustainable. Sustainability requires that two simple components be added to moist soil. One of the components is the restoration of complete mineral nutritional values to the soil. The other component is the restoration of carbon forms of soil acid gels, in the form of humic and fulvic acids to the soil.

Rule 1: Complete soil minerals + humic soil acids + moisture = sustainable soil.

The first rule of sustainable soil is straightforward. While all growers are aware of the need for nutrients in order to grow crops, many only focus on NPK, as these are primary growth nutrients. However, in order to achieve sustainable soils a grower must, in addition to the primary NPK minerals, restore complete secondary nutrients, including sulfur, calcium and magnesium, as well as a full complement of trace minerals. In addition, a grower must systematically build organic matter in the form of soil acids in order to put these minerals to work.

While developing CNEF, we learned that combined mineral components in a balanced blend along with a slow release organic base provides a superior means of delivering mineral values to the soil. Molecular structures containing chelated minerals in the soil acid gels are determined by the minerals available at the time of acid structure formation.

The basic goal of any grower should be to build nutritionally balanced soil acid gels, as these gels offer a long-term, slow-release source of nutrition for soil ecosystems.

Complete mineral restoration is essential to all sustainably farmed soils. Farming is essentially a form of mineral mining. A tomato grower who removes a crop from a piece of land has essentially mined that land of the minerals contained within that crop. While the mineral value in the tomatoes produced by a single plant is only a fraction of an ounce, by the time the aggregate of the field is weighed, the total amount of minerals mined becomes substantial. Over years and decades, the amounts add to hundredweights and then tons of minerals. Monoculture is thus the most destructive approach, as it concentrates the removal of the same minerals over and over in a repetitive manner.

Without mineral replacements, soils are slowly stripped, and plants are unable to sustain their health and will fail from mineral/nutritional deficiency diseases that are the result of disproportionate mineral contents. Molds will increasingly appear on crops, as systemic copper and zinc are simply no longer available from the soil to protect plants.

Land is often labeled as “diseased” or “poor” simply due to the lack of a few nutrients. Without the ability to grow profitable and nutritious crops, farmland is more easily abandoned or turned into pasture. After the loss of their topsoil structures, weakened or destroyed soils are frequently subject to erosion.

In a similar manner, humic substances in the form of fulvic and humic soil acids are essential to all farmed soils. Any organic matter that decomposes creates a leachate that is used by soil-dwelling bacteria and fungi to create soil acids. Soil acid gels are created when the soil acids collect moisture to their structure. As much as 98 percent of a soil acid gel can be contained moisture.

Soil acid gels are vital to the soil as they perform multiple functions, all of which are critical to the sustainability of soils and the growth of plants. According to literature from the International Humic Substances Society and our own observations and research, some of the functions of soil acids include:

  • Acting as a source of nutrition to soil microbes;
  • Acting to transform soil minerals into an ionic form that can be taken up by plants through chelation;
  • Transfer of the minerals in the soil directly into the roots of plants through transcellular penetration;
  • Formation of minerals into chemical substances;
  • Detoxifying pesticides and herbicides in the soil by rendering them into elemental forms;
  • Dissolving silica to transmute vegetal silica and magnesium into a form of plant-contained calcium;
  • Dissolving minerals to eliminate molds and disease through higher systemic levels of copper and zinc;
  • Holding very large amounts of water in the gel matrix.

Without soil acids, microorganisms — the engines of the soil — shut down along with a wide range of critical soil operations. Nutrient building stops and crops decline.

Humic substances in the form of soil acids are the principal holding elements of moisture and nitrogen in the soil. That statement refutes much of the available water capacity science and Nitrogen

Cycle beliefs of the last 50 years. New soil science, along with an understanding of the role of humic substances, has refuted much of the earlier theory about how the soil works.

When soil acids are present in a soil they act like a sponge that has been buried in the soil, which absorbs and retains moisture. These acids hold moisture in a gel-like form that does not migrate into ground water structures or is easily subject to wind, sun, or other drought conditions. Soil acids are usually only lost from soils by plant utilization or by out-of-balance carbon to nitrogen ratios that are the result of over application of nitrogen fertilizers. A failure to replace these acids results in the soil losing its resistance to rain. Soil acids act to give soils waterproof permeability in much the same way that high-technology rainwear can repel water but still breathe. Given the moisture retention ability of soil acids much of the ability of the soil to hold water is lost when soil acids are not present. Without the carbon-based soil organic matter form of soil acids, soil becomes sand and subject to the erosion of wind and rain.

Rule 2: In order for plants to efficiently intake nutrients, the minerals must be subjected to the transfer and storage mechanism of soil acids. Without soil acid there is decreased transfer of minerals into plants.

The second rule of sustainable soils is intriguing yet elegantly simple. A chelating agent is required for the transfer of soil minerals from an elemental form, or an elemental form already bound to another element, into an ionic form that is usable by plants. Soil acids act as chelating agents to react with minerals and transform them from a solid elemental form that is unusable by a plant into an organic molecular structure that is usable. Soil acid gels, formed when soil acids attract and hold moisture, act as storage facilities for ionic mineral forms. Soil acids play a dual role of adopting mineral elements into a form that a plant can use and then storing those elemental forms until the plant is ready to use them. Soil acid gels are the critical transfer agent of minerals within a soil. Only soil-contained, organic-based, bacterially processed and formed soil acids can perform this work.

Synthetic fertilizer blends, based primarily on NPK formulations, have no such transfer mechanism, nor do mined humic acid, reconstituted fulvic acid or manmade fulvic acid. Only living, soil produced humic and fulvic acids that result from organic deterioration have the ability to efficiently effect elemental transfers within the soil. Born from natural processes, soil acids are unique in molecular composition. They are specifically tailored by soil bacteria and fungi to the climate and soils in which they originate. Man, despite millions of dollars of research, is currently unable to duplicate these extremely complex carbon structures. The only way soil acids are manufactured is by the addition of organic materials to the soil and the reduction of these materials by soil microorganisms.

Soil acids provide the transfer and storage mechanism to change the minerals into usable forms. These usable mineral forms are vital to the health and well-being of plants and to sustainable agriculture.

Rule 3: Any organic material applied to the soil will eventually dissolve into the earth and become a form of soil acids.

The third rule is the empowering rule that will change the way a grower views soil elements. The fresher the organic material, the greater the likelihood that the material will convey valued nutrients to a soil. For this reason, green cover crops plowed under are a high-quality method of developing soil acids. Fresh, green leaves and plants have more nutritional value than dried, dead leaves.

Fresh manure has more value than dried or sunbaked manure.

The complexity of nutrition is another factor. Some organics simply have greater mineral values than others. A mineral-rich organic material will convey greater nutritional value to the soil than a mineral-poor organic mixture. Applied organics with nutritionally complex ingredients will form soil acids with complex molecular structures. Nutritionally complex soil acids are of greater value to crops than simple nutrients.

That being said, growers must be knowledgeable as to the nature of the organics and the efficiency of transformation from a solid into a soil acid. Improperly applied organic methods can be dangerous or destructive to the soil. Little has to be said as to the unpredictability and unreliability of manure as a fertilizer, as many growers who have used it indiscriminately have suffered losses as a result. Manure with a high pH, manure with high arsenic-V content (in the case of poultry manure) and manure with active colonies of harmful bacteria can actually damage or ruin fields. Conversely, many growers have successfully mastered the use of manure and learned the secrets of successful applications.

Learning how to apply organics effectively is critical to the grower who is working for sustainable soils.

Rule 4: Organic materials do not transform from an organic material into soil acids in an equally efficient manner.

The fourth rule is a little more complex and requires understanding and application, and is only truly understood with experience. This rule acts to clarify the third rule, and is actually a set of sub rules, as described below. Often these sub-rules are only established after trial and error.

Manures. Raw or dehydrated manures are unstable substances that do not always efficiently transform nutrient content into soil acids. The labile nature of manure means that raw or moisture exposed dehydrated manure will quickly lose its nutrients into the atmosphere, ground or surface waters. As a result, untreated manure usually transforms poorly into soil acids when compared to better processed materials.

Raw or dehydrated manures often carry putrefying bacteria that can seriously damage soils and fail altogether to transform into soil acids. Manure incorporated into the soil will more effectively transmit its nutrients into soil acids. However, such manure is also prone to putrefaction, as its pathogen content may overcome the existing soil bacteria responsible for transformation into soil acids. When this occurs, manure can produce potentially harmful, putrefactive, soluble metabolites that can actually harm plant growth. Given such an event, there is little or no transformation into soil acids. Application of raw manures that putrefy can kill the aerobic organisms that form beneficial soil aggregates, including soil acids. Should this occur the soil structure can collapse. Soil clays can de-flocculate. In the worst circumstances of collapse, the soil may seal completely. The result is that the soil becomes subject to a high degree of erosion.

Compost. Compost does not always efficiently transform contained nutrients into soil acids, either. Commercially composted organics are typically processed at temperatures of between 135°F to 155°F (57° C to 68° C) for four to six weeks to get rid of weed seeds, spores and pathogens. During this time the majority of nutrients are destroyed by the heat process and turn into CO2, methane and ammonia, which are released into the atmosphere or lost by leaching into ground or surface water. The balance of most well-processed composts is essentially humin, a type of soil organic matter that is almost inert. The transformation of this material into soil acids is slow and inefficient, in that the majority of nutrients have already been lost through processing.

Cover crops. As for cover crops, whereas they are an excellent way of building soil acids, a grower must also be aware of the time lag caused by the dual problems of conversion and nitrogen immobilization. Conversion from a cover crop into usable soil acids is a factor of soil temperature and moisture. Higher temperatures and higher moisture accelerate the conversion. Low temperatures and dry soils slow down the process. Nitrogen immobilization may be a factor if the carbon:nitrogen ratios of the cover crop are out of balance. The availability of nitrogen from the soil acids may be temporarily blocked by soil microbes that use it for the digestion of the carbon remnants of the cover crop.

Other materials. While space constraints do not allow extensive instruction in this area, it is easy to observe that for every soil input there is an accompanying rule. An example is feather meal. This organic nutrient is high in nitrogen but is sometimes slow in transformation into soil acids, especially in drier regions.

Feathers, from which feather meal is made, are made up largely of keratin, the same material that makes up hooves and fingernails. Surface-applied feather meal can still be seen on the surface a year after application in some circumstances. Growers who focus solely on what they perceive to be units of N (a synthetic concept, in that synthetic N units are easily measured) may find themselves short-changed when attempting to buy or correlate N units from organic sources.

In organic nutrition, the degree of efficiency of transformation is the most important aspect of the nutrient source.

To sum up, while any organic material can be transformed into soil acids, the ideal organic materials for this task are typically low-cost, processed organic fertilizers that have been rendered into stable, slow-release forms specifically for soil microbes. Such fertilizers are not commonly produced at this time. Growers who are looking for sustainable soils should take the time to learn about new organic fertilizers and understand their natures, advantages and limitations. Within the next decade, facilities for manufacturing these fertilizers will gain an even greater foothold in the nutrient marketplace. Within the next few years, high-speed manufacturing processes and new larger facilities for these fertilizers will lower CNEF prices to a point below that of synthetic nutrient programs.

Crops grown with the new products are nutritionally superior to those grown with synthetic nutrient programs due to the organic mineral transfer mechanism inherent in these fertilizers. Crops grown with these fertilizers are typically less susceptible to fungus due to the plant’s high systemic levels of copper, zinc and magnesium. Additionally, growers have observed higher brix levels in their produce grown with these fertilizers.

Editor’s Note: This article was originally published in the August 2006 issue of Acres U.S.A.

Increasing Soil Organic Matter Through Organic Agriculture

By André Leu

Numerous scientific studies show that soil organic matter provides many benefits for building soil health such as improv­ing the number and biodiversity of beneficial microorganisms that pro­vide nutrients for plants, including fixing nitrogen, as well as controlling soilborne plant diseases. The decom­position of plant and animal residues into SOM can provide all the nutri­ents needed by plants and negate the need for synthetic chemical fertilizers, especially nitrogen fertilizers that are responsible for numerous environ­mental problems.

The year 2015 was declared the International Year of Soils by the 68th UN General Assembly with the theme “Healthy Soils for a Healthy Life.” I was particularly pleased with the theme because this is a message that we in the organic sector have been spreading for more than 70 years, and at first we were ridiculed. Now there is a huge body of science showing that what we observed in our farming systems is indeed correct.

“Organic farming” became the dominant name in English-speaking countries for farming systems that eschew toxic, synthetic pesticides and fertilizers through J.I. Rodale’s global magazine Organic Farming and Gar­dening, first published in the United States in the 1940s. Rodale promot­ed this term based on building soil health by the recycling of organic matter through composts, green ma­nures, mulches and cover crops to increase the levels of soil organic matter as one of the primary management techniques.

organic field
Organic vs. Conventional. The higher levels of organic matter allow the soil in the organic field to resist erosion in heavy rain events and capture more water.
Water run-off

Soil organic matter improves soil structure so that it is more resistant to erosion and is easier to till, resulting in lower energy use and less greenhouse gas output. Soils with good SOM levels are more efficient at absorbing rain­water and storing it for plants to use in dry periods. Studies show that organic systems get around 30 percent higher yields in periods of drought than con­ventional systems due to the increase of SOM and its ability to capture and store water for crops.

SOM is composed largely of car­bon that is captured as CO2 from the air by plants through photosynthe­sis. Published, peer-reviewed meta-studies show that organic farming systems are superior to conventional systems in capturing CO2 from the atmosphere (the primary greenhouse gas responsible for climate change) and sequestering it into the ground as SOM.

Soil Organic Matter & Climate Change

Worldwide, agriculture is respon­sible for between 11 and 30 percent of greenhouse gas emissions, depending on the boundaries and methodolo­gies used to determine its emissions. According to the United Nations En­vironment Programme, the estimates of global greenhouse gas emissions in 2010 were 50.1 gigatons of carbon di­oxide equivalent (Gt CO2e) per year. To keep global mean temperature increases below 2°C compared to pre-industrial levels, GHG emissions will have to be reduced to a median level of 44 Gt CO2e in 2020.

This means that the world will have to reduce the current level of emissions by 6.1 Gt CO2e by 2020 and reduce it every subsequent year. According to the latest World Me­teorological Organization figures, the levels of GHG pollution in the atmosphere and the oceans are the highest in history and are still increasing.

Keeping the rise in temperature below 2°C will not only involve re­ducing emissions through energy effi­ciency, renewable energy and cleaner energy sources; sequestering GHGs already present in the atmosphere will also be necessary to reduce the current levels. Currently most seques­tration is based on growing biomass as carbon sinks and capturing it as wood-based products.

Soils are the greatest carbon sink after the oceans. According to Profes­sor Rattan Lal of Ohio State Univer­sity, there are over 2,700 Gt of carbon stored in soils worldwide. This is considerably more than the combined total of 780 Gt in the atmosphere and the 575 Gt in biomass.

The amount of CO2 in the oceans is already causing problems, particu­larly for species with calcium exo­skeletons such as coral. Scientists are concerned that the increase in acid­ity caused by higher levels of CO2 is damaging these species and threatens the future of marine ecosystems such as the Great Barrier Reef.

Mitigation Through Aboveground Biomass

Currently the major push for car­bon sequestration is through above-ground biomass, despite that fact that its potential as a carbon sink is signifi­cantly less than that of soil. The other issue is the need to take land out of food production to grow trees. There is some potential with agroforestry and trees as shade cover for some cash crops like coffee and cacao, however this will deliver considerably less than research has shown can be sequestered into soils with good agri­cultural practices.

Sequestration Through Agriculture 

The ability of soils to absorb enough CO2 in order to stabilize cur­rent atmospheric CO2 levels is a criti­cal issue, and there is a major debate over whether this can be achieved through farming practices. Reviews of conventional farming systems have found that most are losing soil car­bon and at best they can only slow the rate of loss. On the other hand, farming systems that recycle organic matter and use crop rotations can increase the levels of soil organic car­bon (SOC).

A preliminary study by the Re­search Institute of Organic Agricul­ture, Switzerland, published by FAO, collated 45 comparison trials between organic and conventional systems that included 280 data sets. These studies included data from grasslands, arable crops and permanent crops in several continents. A simple analysis of the data shows that on average the or­ganic systems had higher levels of soil carbon sequestration.

Dr. Andreas Gattinger and col­leagues wrote, “In soils under organic management, the SOC stocks aver­aged 37.4 tons C ha-1, in comparison to 26.7 tons C ha-1 under non-organic management.”

This means that the average differ­ence between the two management systems (organic and conventional) was 10.7 tons of C. Using the accepted formula that SOC x 3.67 = CO2, this means an average of more than 39.269 tons of CO2 was sequestered in the organic system than in the con­ventional system.

The average duration of manage­ment of all included studies was 16.7 years. This means that an average of 2,351 kg of CO2 was sequestered per hectare every year in the organic sys­tems compared to the conventional systems.

In a later peer-reviewed meta-anal­ysis, published in PNAS, that used 41 comparison trials and removed the outliers in the data sets in order not to overestimate the data and to obtain a conservative estimate, researchers reported that organic systems seques­tered 550 kg C per hectare per year. This equates to 2018.5 kg CO2 per hectare per year.

Based on these figures, the wide­spread adoption of current organic practices has the potential to sequester around 10 Gt of CO2, which is the range of the emissions gap in 2020 of 8-12 Gt CO2e per year.

The potential exists for higher lev­els of CO2 sequestration. All data sets that use averaging have outlying data. These are examples that are sig­nificantly higher or significantly lower than the average.

There are several examples of higher levels of carbon sequestra­tion than the averages quoted in the studies above. The Rodale Institute in Pennsylvania has been conducting long-running comparisons of organic and conventional cropping systems for more than 30 years that confirm organic methods are effective at re­moving CO2 from the atmosphere and fixing it as organic matter in the soil. Tim LaSalle and Paul Hepperly wrote, “In the FST [Rodale Institute farm systems trial] organic plots, car­bon was sequestered into the soil at the rate of 875 lbs/ac/year in a crop rotation utilizing raw manure, and at a rate of about 500 lbs/ac/year in a rota­tion using legume cover crops.

During the 1990s, results from the Compost Utilization Trial (CUT) at Rodale Institute — a 10-year study comparing the use of composts, ma­nures and synthetic chemical fertil­izer — show that the use of composted manure with crop rotations in organic systems can result in carbon seques­tration of up to 2,000 lbs/ac/year. By contrast, fields under standard tillage relying on chemical fertilizers lost almost 300 pounds of carbon per acre per year.”

Converting these figures into kilo­grams of CO2 sequestered per hectare using the accepted conversion rate of 1 pound per acre = 1.12085116 kg/ ha and SOC x 3.67= CO2, gives the following results: The FST legume-based organic plots showed that car­bon was sequestered into the soil at the rate of about 500 lbs/ac/year. This is equivalent to a sequestration rate of 2,055.2kg of CO2/ha/yr, which is close to the average found in the Gat­tinger meta-study.

However, other organic systems produced much higher rates of se­questration. The FST manured or­ganic plots showed that carbon was sequestered into the soil at the rate of 875 lbs/ac/year. This is equivalent to a sequestration rate of 3,596.6 kg of CO2/ha/year and if extrapolated globally would sequester 17.5 Gt of CO2.

The CUT showed that carbon was sequestered into the soil at the rate of 2,000 lbs/ac/year. This is equivalent to a sequestration rate of 8,220.8 kg of CO2/ha/year and if extrapolated globally, would sequester 40 Gt of CO2.

A meta-analysis by Eduardo Agu­ilera et al. published in the peer-re­viewed journal, Agriculture, Ecosystems and Environment, of 24 comparison trials in Mediterranean climates be­tween organic systems and non-or­ganic systems without organic supple­ments found that the organic systems sequestered 970 kg of C/ha/year more than the non-organic systems. This equates to 3559.9 kg of CO2/ha/year. The data came from comparison trials from Mediterranean climates in Eu­rope, the United States and Australia, and if extrapolated globally, would sequester 17.4 Gt of CO2.

The Louis Bolk Institute conducted a study to calculate soil carbon seques­tration at SEKEM, the oldest organic farm in Egypt. Their results show that on average SEKEM’s management practices resulted in 900 kg of carbon being stored in the soil per hectare per year in the fields that were 30 years old. Using the accepted formula of SOC x 3.67 = CO2, this means that SEKEM has sequestered 3,303 kg of CO2 per hectare per year for 30 years.

Based on these figures, the adop­tion of SEKEM’s practices globally has the potential to sequester 16 Gt of CO2, which is around 30 percent of the world’s current GHG emission into soils.

It is not the intention of this paper to use the above types of generic exercises of globally extrapolating data as scientific proof of what can be achieved by scaling up organic systems. These types of very simple analyses are useful for providing a conceptual idea of the considerable potential of organic farming to reduce GHG emissions on a landscape scale. The critical issue here is that urgent peer-reviewed research is needed to understand how and why — and for the skeptics, if — these systems seques­ter significant levels of CO2 and then look at how to apply the findings for scaling up on a global level in order to achieve GHG mitigation.

Greater Resilience in Adverse Conditions 

According to research by the UN­FCCC IPCC Fourth Assessment Re­port (IPCC 2007) and others, the world is seeing increases in the fre­quency of extreme weather events such as droughts and heavy rainfall. Even if the world stopped polluting the planet with greenhouse gases to­morrow, it would take many decades to reverse climate change. This means that farmers have to adapt to the increasing intensity and frequency of adverse and extreme weather events.

organic vs conventional fields
From The Rodale Institute: Organic vs. Conventional fields side by side.

Published studies show that organic farming systems are more resilient to predicted weather extremes and can produce higher yields than conven­tional farming systems in such con­ditions. For instance, the Wisconsin Integrated Cropping Systems Trials found that organic yields were higher in drought years and the same as con­ventional in normal weather years.

Improved Water Use Efficiency 

Research shows that organic sys­tems use water more efficiently due to better soil structure and higher levels of humus and other organic matter compounds. D.W. Lotter and col­leagues collected data over 10 years during the Rodale Farm Systems Trial. Their research showed that the organ­ic manure system and organic legume system (LEG) treatments improve the soils’ water-holding capacity, infiltra­tion rate and water capture efficiency. The LEG maize soils averaged 13 percent higher water content than conventional system (CNV) soils at the same crop stage and 7 percent higher than CNV soils in soybean plots. The more porous structure of organically treated soil allows rain­water to quickly penetrate the soil, resulting in less water loss from runoff and higher levels of water capture. This was particularly evident during the two days of torrential downpours from hurricane Floyd in September 1999, when the organic systems cap­tured around double the water as the conventional systems.

Long-term scientific trials con­ducted by the Research Institute of Organic Agriculture in Switzerland comparing organic, biodynamic and conventional systems had similar re­sults showing that organic systems were more resistant to erosion and better at capturing water.

“We compare the long-term effects (since 1948) of organic and conven­tional farming on selected properties of the same soil. The organically farmed soil had significantly higher organic matter content, thicker topsoil depth, higher polysaccharide content, lower modulus of rupture and less soil erosion than the conventionally-farmed soil. This study indicates that, in the long term, the organic farming system was more effective than the conventional farming system in re­ducing soil erosion and, therefore, in maintaining soil productivity (Regan­old et al. 1987).”

Humus, a key component of SOM, allows for the ability of organic soils to be more stable and to hold more water. This is due to its ability to hold up to 30 times its own weight in water, and being a ‘sticky’ polymer, glues the soil particles together, giving greater resistance to water and wind erosion.

There is a strong relationship be­tween SOM levels and the amount of water that can be stored in the root zone. The table below should be taken as a rule of thumb, rather than as a precise set of measurements. Different soil types will hold different volumes of water when they have the same levels of organic matter due to pore spaces, specific soil density and a range of other variables. Sandy soils generally hold less water than clay soils.

The table above gives an under­standing of the potential amount of water that can be captured from rain and stored at the root zone in relation to the percentage of SOM.

There is a large difference in the amount of rainfall that can be captured and stored between the current SOM level in most traditional farms in Asia and Africa and a good organic farm with reasonable SOM levels. This is one of the reasons why organic farms do better in times of low rainfall and drought.

The Rodale Farming Systems Trial showed that the organic systems produced more corn than the conventional system in drought years. The average corn yields during the drought years were 28 to 34 percent higher in the two organic systems. The yields were 6,938 and 7,235 kg per ha in the organic animal and organic legume systems, respectively, compared with 5,333 kg per ha in the conventional system. The researchers attributed the higher yields in the dry years to the ability of the soils on organic farms to better absorb rainfall. This is due to the higher levels of organic carbon in those soils, which makes them more friable and better able to capture and store rainwater which can then be used for crops.

This is very significant information as the majority of the world’s farming systems are rain-fed. The world does not have the resources to irrigate all of the agricultural lands, nor should such a project be undertaken. Improving the efficiency of rain-fed agricultural systems through organic practices is the most efficient, cost-effective, environmentally sustainable and practical solution to ensure reliable food production in the face of increasing weather extremes.

Synthetic Nitrogen Fertilizers 

One of the main reasons for the differences in soil carbon between organic and conventional systems is that synthetic nitrogen fertilizers de­grade soil carbon. Research shows a direct link between the application of synthetic nitrogenous fertilizers and decline in soil carbon.

Scientists from the University of Il­linois analyzed the results of a 50-year agricultural trial and found that syn­thetic nitrogen fertilizer resulted in all the carbon residues from the crop disappearing as well as an average loss of around 10,000 kg of carbon per hectare per year. This is around 36,700 kg of CO2 per hectare on top of the many thousands of kilograms of crop residue that is converted into CO2 every year.

Researchers found that the higher the application of synthetic nitrogen fertilizer the greater the amount of soil carbon lost as CO2. This is one of the major reasons why most conventional agricultural systems have a decline in soil carbon while most organic sys­tems increase soil carbon.

Plant-Available Nitrogen Levels

One of the main concerns about organic agriculture is how to get suf­ficient plant-available nitrogen with­out using synthetic nitrogen fertilizers such as urea.

SOM, particularly the humus frac­tions, tend to have a carbon nitrogen ratio of 9:1 to 11:1. As the carbon levels increase, the amount of soil ni­trogen increases in order to maintain the carbon-nitrogen ratios. Adding organic matter into the soil to increase carbon, results in the nitrogen levels increasing.

organic nitrogen in soil amounts
Table: amount of organic nitrogen held in soil.

Much of this soil nitrogen is fixed by free-living soil microorganisms such as azobacters and cyanobacte­rias. The use of DNA sequencing is revealing that cohorts of numerous thousands of species of free-living microorganisms are involved in fix­ing nitrogen from the air into plant available forms. There are many stud­ies that show that there is a strong relationship between higher levels of SOM and higher levels of soil biologi­cal activity.

This biological activity includes free-living nitrogen-fixers, and they turn the atmospheric nitrogen, the gas that makes up 78 percent of the air, into the forms that are needed by plants. They do this at no cost and are a major source of plant-available nitrogen that is continuously over­looked in most agronomy texts.

New research has found a new group of nitrogen-fixing organisms called endophytic microorganisms. These microbes can colonize the roots of numerous plant species including rice, grain crops and sugar cane.

Soil Carbon, Nitrogen Ratios 

It is important to get an understanding of the potential for how much nitrogen can be stored in SOM for the crop to use. SOM contains nitrogen expressed in a Carbon to Nitrogen Ratio. This is usually in ratios from 11:1 to 9:1; however, there can be further variations. The only way to firmly establish the ratio for any soil is to do a soil test and measure the amounts.

For the sake of explaining the amount of organic nitrogen in the soil we will use a ratio of 10:1 to make the calculations easier.

The amount of carbon in SOM is expressed as SOC and is usually measured as the number of grams of carbon per kilogram of soil. Most texts will express this as a percentage of the soil to a certain depth. There is an accepted approximation ratio for the amount of soil organic carbon in soil organic matter: SOC × 1.72 = SOM.

The issue of working out the amount of SOC as a percentage of the soil by weight is complex as the specific density of the soil has to be factored in because some types of soils are denser and therefore heavier than other soils. This will change the weight of carbon as a percentage of the soil.

To make these concepts readily understandable we will use an average estimation developed by Dr. Christine Jones, one of Australia’s leading soil scientists and soil carbon specialists. According to Dr. Jones: “… a 1 percent increase in organic carbon in the top 20 cm of soil represents a 24 t/ha [24,000 kg] increase in SOC …”

This means that a soil with 1 percent SOC would contain 24,000 kg of carbon per hectare. With a 10:1 carbon to nitrogen ratio this soil would contain 2,400 kg of organic nitrogen per hectare in the top 20 centimeters, the primary root zone.

The conventional dogma around nitrogen is that it can only be used by plants if it is in the form of nitrate or ammonium and that organic nitrogen is mostly not available to the crop until it has been converted into these two forms of N.

There are hundreds of peer-reviewed scientific studies that show that this assumption is incorrect and that in natural systems plants take up nitrogen in numerous organic forms such as amino acids, amino acid precursors and DNA.

The fact is that the significant proportion of the organic nitrogen in the soil is readily available to the crop. The key to get an adequate level of N is to increase SOM levels rather than adding synthetic nitrogen fertilizers.

Given that synthetic nitrogen destroys organic matter, the use of these fertilizers should be avoided as they lock farmers into a perpetual dependence on these costly inputs once the organic matter levels have been run down and most of the organic nitrogen forms in the soil have been depleted. Farmers should be encouraged to obtain all their nitrogen from organic sources such as composts, manures, green manures and legumes and build up their organic matter levels.

By André Leu. This article appeared in the July 2015 issue of Acres U.S.A.

André Leu is the author of Poisoning our Children and The Myths of Safe Pesticides. He is the International Director of Regeneration International.

True Soil Health: Create the Capacity to Function Without Intervention

By Gary Zimmer and Leilani Zimmer Durand
From the October 2018 issue of Acres U.S.A. magazine

My philosophy is that whatever you do on your farm should improve soil health. But how do you know what that is? The USDA defines soil health as, “The continued capacity of soil to function as a vital living ecosystem that sustains plants, animals and humans.” I would add to that definition and say that soil health isn’t just the capacity to function, it’s the capacity of soils to function without intervention.

Soil management creates healthy corn

What counts as “intervention?” Does intervention mean biotechnology, insecticides, fungicides and tillage? Is fertilizer an intervention? Do these interventions make your farm better for future years? I believe money spent on interventions needs to be shifted to inputs that yield soil health.

Appropriate intervention when absolutely needed is wise, but the goal is minimum intervention — in other words do everything you can to get the soils healthy and mineralized. Mineralize your soils using exchangeable nutrient sources that come from the carbon biological system. You have to create an ideal home for soil life and feed them in order to build soil health.

Remove the negatives, which include monoculture crops and excessive tillage. Reduce the use of other possible negatives added through harsh soluble fertilizers and excessive nitrogen, not to mention chemicals and biotechnology.

Farming for soil health means treating your farm like a system. For years we have been promoting the “rules” of biological farming (Six Principles of Biological Farming). Following these rules will lead to healthy soils that produce good yields. The soil health guidelines you now see published in many places focus on minimum disturbance with an emphasis on no-till. In my opinion not all soils are capable of being farmed no-till.

The Six Principles of Biological Farming

  1. Test and balance your soils, and in addition, feed the crop a balanced supplemented diet.
  1. Use fertilizers that do the least damage to soil life and plant roots. Watch salt and ammonia levels. Use a balance of soluble and slow-release nutrients for a controlled pH. Use homogenized micronutrients — add carbon — and place them properly to enhance performance.
  1. Use pesticides, herbicides, biotechnology and nitrogen in minimum amounts and only when absolutely necessary.
  1. Create maximum plant diversity by using green manure crops and tight rotations.
  1. Use tillage to control the decay of organic materials and to control soil air and water. Zone tillage, shallow incorporation of residues and deep tillage work great on many farms.
  2. Feed the soil life, using carbon from compost, green manures, livestock manures and crop residues. Apply calcium from a quality source in order to feed your crop and soil life.

I believe strip-till has its place on many farms as the strips create an ideal area where you can concentrate needed nutrient inputs and warm up our northern soils in order to grow large root systems. Some farms may also need to run deep rippers as compaction is a problem on many farms, and tight waterlogged soils are not healthy.

On-Farm Intensive with Zimmer Ag

Learn about soil health in person with Gary Zimmer

The Acres U.S.A. On-Farm Intensive – July 19-20, 2021 – 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 biological farming from Gary Zimmer himself!

Learn more here!

Regenerative Farming

Regenerative farming is another philosophy of farming with a focus on soil health. Not just sustaining your soils but regenerating them makes sense, but this method of farming generally calls for cattle on every farm. Just like no-till doesn’t fit every farm, having cattle is not possible on every farm.


Cattle are desired for digestion — they eat the cover crops and digest them into plant nutrients in the form of manure. While this system can work well in northern climates where there is low rainfall and snow and frozen soils to minimize soil damage, how do you deal with waist-high cover crops in cold, wet, black soils? And what about all the compaction caused by those large animals stomping around, often in wet conditions?

I am a believer in growing cover crops and shallow incorporating the residues, using strip-till to get the right nutrients in the right place, with deep ripping to break up compaction. I believe on most farms some tillage is needed, but it’s the middle zone from 3-8 inches down with earthworm channels and old, dying roots that needs to be left alone. You don’t want to break up all your soil aggregates, fungal networks and homes for soil life, but you do want to till in order to digest residues and keep the soil loose and crumbly for air and water to infiltrate.

Plant Diversity

The more diversity of plants that you grow, the more types of root exudates to feed the soil life, and therefore the more diverse the soil biology and the less likely potential for large populations of trouble-causing insects and diseases. The plants determine the soil life so the more types of plants, the more diverse the biological life pool, and no one population takes control. Planting a diversity of crops and cover crops leads to healthy soils and healthy plants.


Minerals are also key for soil health and crop yields. There are at least 20 minerals known to grow healthy crops, and balance and ratio between those minerals is important, as is having a soil sufficiency level.

Trace elements are often overlooked, but are a key to plant health. Farmers often look for the direct yield increase for any added inputs on their farm, but what about the benefits gained from healthier plants that are able to resist pests and diseases?

Healthier plants lead to fewer interventions, which saves money and increases profits.

When applying fertilizer I like adding minerals in a carbon biological matrix. This is the way it’s done in nature. Plants, animals and soil biology all die with minerals tied to carbon in their bodies, and as they decompose they give those minerals up in a timed-release process.

For liquid carbon-based fertilizers I like to mix molasses or humic acids with the minerals. With dry fertilizers I like compost or digested manures. We use the manures from dairy farms that have gone through an anaerobic digester and then have minerals added to make blends that fit the farm’s needs. This anaerobic digestate and mineral blend has a large number of biological properties and dead bugs from the digester process that feed soil life and give up minerals in a plant-available form.

It’s also important to keep your soil life fed with the right kinds of food to maintain balance in the soil. I think of it as feeding the soil life like we feed our dairy cows. Any high-producing healthy dairy cow not only has a diversity of food in her diet but also has added minerals to maintain her health.

Her feed is a balance of soluble and slowly digestible food sources. You don’t get high production from feeding all mature, lignified plants because even though the cow may be healthy, production will be low as her rumen is spending a lot of time and energy doing the digesting. The same is true for soils.

alfalfa crop
Working in a young alfalfa crop in May helps provide nutrients for the corn about to be planted on this field. This practice provides readily available food for microbes and cycles a lot of nitrogen for this year’s crop.

Mature cover crops are slow to digest, which means they tie up nutrients and starve the crop while they’re breaking down. Young, green, knee-high diverse plant mixes will rapidly break down after they’re shallowly incorporated, providing soluble nutrients that feed soil bacteria and your crops for high yields.

As an organic farmer I have no choice but to take advantage of the nutrients released by working in a young cover crop if I want to grow high-yielding, nutrient-demanding crops like corn. Supplying nutrients for a good organic corn crop is like feeding a milk cow to get 100 pounds of milk per day — you need a lot of grain and other quickly digestible nutrients.

Growing legumes like soybeans is more like feeding your dry cow. You don’t need as many quickly available soluble nutrients, so you can use more mature plants that are slower-release nutrient sources.

When farming organically you have to get this system working perfectly or you need to do some interventions. Smaller amounts of high-quality fertilizers and nitrogen properly placed and timed provide extra quickly available nutrients to feed your crop.

Even though you can have really healthy soils by growing only mature cover crops and doing no-till and compost, you won’t get great yields following this practice.

Mature cover crops will build soil organic matter, but they do it by breaking down slowly and scavenging nitrogen, sulfur and other key nutrients from the soil.

Those nutrients will eventually be released back into the soil, but it can take a long time, and in the meantime your crops will be starved of those nutrients. Yield is minerals, sunshine and water, and when you limit minerals, you limit yields.

The Soil Health Mineral

In my opinion the final key to soil health is managing calcium because calcium is king. For soil health you need to maintain a certain sufficiency level of calcium in the soil, but it’s also important to add smaller amounts of a soluble calcium source that fits your soil and crops and provides minerals above and beyond what the soil can dish out. Calcium is the soil health mineral — it builds good soil structure, is a key nutrient for earthworms and interacts with soil aggregates to provide homes for other forms of soil life.

All of these management practices may sound difficult and complex, but at the end of the day achieving soil health on your farm is really simple. For healthy, high-yielding soils you need to deal with the physical (soil structure and tillage), chemical (nutrients) and biological (plant diversity and soil life) soil properties.

It’s a system. When you balance all of the components of the soil the system works and farming is a joy.

By Gary F. Zimmer & Leilani Zimmer Durand. This article appeared in the October 2018 issue of Acres U.S.A. magazine.

Gary Zimmer and Leilani Zimmer Durand are the authors of Advancing Biological Farming, a sequel to Gary’s earlier book, The Biological Farmer, both published by Acres U.S.A. Gary 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. Leilani has written extensively about biological farming and runs training courses for farmers and farming consultants on the principles of biological farming at Midwestern BioAg where she serves as vice president of education initiatives.

Both are regular speakers at the annual Acres U.S.A. Eco-Ag Conference, and other related events.

Learn in the field with Gary Zimmer!

Learn biological farming this summer with Gary Zimmer. The On-Farm Intensive with Zimmer Ag is a two-day educational event. Join a small group of fellow farmers and growers on Gary Zimmer’s Otter Creek Organic Farm in Lone Rock, Wisconsin. Walk away with practical information you can apply to your operation right away! Event lasts from July 19-20 so don’t wait to sign up! Learn more about it here.

How to Read a Soil Test

By Charles Walters

The first step on the road to achieving healthy soils able to sustain productive plants is the soil or plant analysis test. For optimum results, the initial test relies heavily on proper sampling.

Quality samples submitted to the laboratory and excellent testing methods can produce the most accurate results possible but without an interpretation of the nutrient recommen­dations that speaks to the grower — all may be for naught.

Graphs and charts filled with color-coded lists of numbers speak volumes to those that know how to read them. But the uninitiated may glean just a fraction of the total message.

A soil or plant analysis test from a quality laboratory contains much more than just the raw data. Using an integration of field and cropping history with the test results, interpretations and recommen­dations are formulated to tell the grower the meaning behind the num­bers. It is these soil and plant test interpretations and recommendations that matter most and have the greatest benefit for many people.

Agronomist Esper K. Chandler, author of Ask the Plant and founder of TPS Lab, was asked to look at several plant and soil analysis tests from different crops and give his expert interpretation of the results. The results are below. For each example, Chandler’s com­ments offer new insight and enlightenment about what the results said to him. The soil and plant test samples presented in this chapter are actual real-life examples included here with Chandler’s dictated interpretation and recommendations — presented so others can gain a deeper insight into the important messages held within. For each example, the most important messages have been highlighted and explained by Chandler.

Above: A Guide from TPS Lab on Compost STA Test Reports. 

Source: Ask the Plant;

What’s Wrong with the N-P-K Approach to Farming?

By Gary Zimmer and Leilani Zimmer Durand
Excerpt from The Biological Farmer, 2nd Edition

Does it make sense to use high levels of only highly concentrated water-soluble nutrients? The N-P-K-pH chemical approach to farming is both incomplete and wasteful.


Managing nitrogen should not be just mathemati­cal. Crop rotation, the nitrogen source used, and when and where the nitrogen is applied all have a bearing on how much nitrogen we need, as does soil air, soil life, organic matter, and the presence and balance of other elements (such as sulfur and calcium).

Biological farmers do not want to use any more nitrogen than absolutely necessary, not only because of cost and possible environ­mental pollution, but also because excess nitrogen suppresses long-term stable biological processes in the soil.

Research from the University of Minnesota has found that corn yields are highest when legumes are added to the rotation (O’Leary, Rehm, and Schmitt, 2008). By including soybeans, alfalfa, or other nitrogen-fixing plants, it is possible to grow your own plant-avail­able nitrogen and reduce fertilizer requirements. Now consider how conventional thinking advocates applying more nitrogen to increase yield. Is yield always increasing as much as the nitrogen applied? Are your added fertilizer dollars getting you results? If not, what happens to the extra nitrogen you apply? Does it benefit the soil, the environment — or your water? What are the overall costs?

Two very real examples of the costs of applying more fertilizer than plants can use are the water quality issues in Iowa and the “dead zone” in the Gulf of Mexico (NOAA, 2014). In Iowa, drinking and surface waters are being polluted with nitrates from heavily fertilized agriculture fields (Herring, 2013). Nitrate levels are so high that the city of Des Moines operates the largest nitrate removal drinking water system in the country. The runoff nutri­ents are so great in the tributaries feeding the Mississippi River that a dead zone, or hypoxic zone (an area depleted of oxygen), exists at the northern edge of the Gulf of Mexico (NOAA, 2014).

Nitrates that have run off from farm fields are carried down the Mississippi River to the Gulf of Mexico, where they feed algae blooms. When the algae decomposes, it uses up all the deep-water oxygen, which then kills a lot of the plants and animals living in gulf waters. All that runoff begs the question: Did the farmers really need all that nitrogen they applied? Their crops certainly didn’t use the nitrogen that ran off their fields.

soil inputs


Only a small amount of the total fertilizer phos­phorus is available to the growing crop because most of it changes back into the insoluble rock phosphate form. However, research has shown that phosphorus availability increases where there are high levels of soil organic carbon and phosphatases (Oberson et al., 1992). Soil phosphatases are enzymes that catalyze processes that make phosphorus available for plant uptake (Nannipieri et al., 2011).

Having higher levels of available soil phosphorus can help to increase plant health and feed quality. These higher levels can be reached by using a combination of naturally mined rock phos­phate, some high-quality manufactured phosphorus, green manure crops, livestock manure, and biological activity.


The most common commercial source of potassi­um is muriate of potash, also called potassium chloride, a strong salt containing 47 percent chloride. Research has found that chlo­ride causes calcium to leach out of the root zone and inhibits soil microbial nitrification and root nodulation (Khan, Mulvaney, and Ellsworth, 2013). While chloride is in the upper layers of soil, high levels of it can also kill beneficial soil life and injure roots.

Conventional specialists often recommend potassium applications at rates that are far too high, leading to soil imbalance and lower quality crops, in part due to the excess chloride and high solubility of the K source. Although conventional wisdom (and the fertilizer industry) links high potassium levels to big piles of crops (yield), plants are good at tapping into soil potassium reserves, and we can often obtain higher yields along with better quality by instead applying more calcium and less potassium.

On-Farm Intensive with Zimmer Ag

Learn about soil health in person with Gary Zimmer

The Acres U.S.A. On-Farm Intensive – starting in summer 2021 – 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!

Examining the N-P-K approach

Synthetic N-P-K fertilizers have few or no secondary and trace elements, yet all 20 elements are necessary for plant growth, not just the “big three” — N, P, and K. Continued use of N-P-K alone can result in calcium, sulfur, magnesium, and trace ele­ment deficiencies.

Does the N-P-K farming approach seem to be balanced with nature? Does it seem to be beneficial for soil life and crop health? How would your livestock perform if you only fed them carbohy­drates and ignored protein, fats and minerals? It’s the same thing. Look around: the soil gets harder and erodes, water quality dete­riorates, animal and human health problems increase, pests and weeds proliferate, and more fertilizers, chemicals, and biotechnol­ogy are continually needed.

In addition to the environmental problems of the N-P-K approach, research shows that yields are no longer responding to applying more nutrients, and in some cases yields are declining (Ciampitti and Vyn, 2014). It’s all related to how we treat “Mother Nature’s” soil. Balance is the key, just as it is with livestock and human nutrition. We need a farming method that produces “quality” — healthy, mineralized, balanced crops.

My introduction to biological farming came from teaching and working as a consultant. After growing up on a dairy farm, I spent eight years in college studying agriculture and earned a master’s degree in dairy nutrition. Then I taught agriculture for five years before finally returning to farming and working with farmers as a soils and nutrition consultant. That’s when I came to the conclu­sion that management, balance, and efficiency are what make farm­ing profitable. Over the ensuing years, I have continued to learn from my own farm, from other farms, and from the many farmers I have talked to across the U.S. and around the world. …

Biological farming will improve your farm. Don’t just accept the farm situation the way it is. It can change and become profitable. Many farmers are doing it right now. There are many books and printed materials that provide useful information. Visit the farms, read the books, and check it out for yourself.

Biological farming is a program, not just adding a single product and hoping for a miracle. It takes time to change things, and there is no one single way to do anything. But there are techniques that make sense. To be successful in the long run, you must use an approach that has you working with and properly utilizing nature’s biological systems.

When the original edition of this book came out more than 15 years ago, not many people involved in agriculture were focusing on soil biology. We called our approach “biological farming” to change that view (and we also named our company Midwestern BioAg). If you farmed by taking measures to care for the soil biology, not only in balance but also in abundance, your farm would really improve.

Back in the nineties, “biotechnology” — or plant manipulation—was just starting to appear on the farm scene. It has now taken over conventional agriculture, but it hasn’t solved the problems it promised. I don’t believe you can manipulate plants to fix today’s problems. Maybe the attempt had to be made and fail before we could develop the right attitude: “Let’s fix the problem, not dodge it.” We have the know-how, we have the products, and we have the successful farmers who have already made it a reality. The farmers with the most resilience to deal with bad years weatherwise, prevent most disease and insect problems, and have the highest yield with reduced cost and increased profits, are what we call “Biological Farmers.”

It’s never too late to start.

Want more? Buy this book here.

The book, The Biological Farmer, Second Edition, by Gary Zimmer with Leilani Zimmer Durand, is a practical, how-to guide on biological farming. In this greatly expanded, revised edition of a modern farming classic, Gary Zimmer draws on a lifetime of farming experience and adds in the latest science and experience on modern issues facing farmers including the impact of GMOs, herbicide-resistant weeds, and more.

About Gary Zimmer and Leilani Zimmer Durand

Gary Zimmer stands in a field

Gary Zimmer is president and co-founder of Midwestern BioAg, which preaches Better Farming Through Better Soil. Together with his son, Nicholas, and his daughter, Sadie, he runs the renowned Otter Creek Organic Farm, and he speaks frequently to audiences around the world.

Gary Zimmer presented at the 2019 Acres U.S.A. Eco-Ag Conference & Trade Show  in December 2019 on Soil Health: The Foundation of Farm Success.

Leilani Zimmer Durand is an executive at Midwestern BioAg and leads the company’s education efforts. She focuses much of her work on helping conventional farmers make the shift to biological and/or organic farming.

Leilani Zimmer Durand

Leilani has also spoken at past Eco-Ag Conferences.

Learn in the field with Gary Zimmer!

Learn from Gary Zimmer this summer on the ground at his organic Otter Creek Farm in Lone Rock, Wisconsin. This two-day educational experience will provide key tactics to improving soil health and your operation through biological farming. July 19-20, 2021. Learn more here!

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!

Setting the Table to Optimize Fertilizers, Soil Amendments

By Neal Kinsey

By using detailed measurements and specifically formulated procedures for controlling nutrient excesses and deficiencies in soils, it is possible to define, measure and manage soil fertility to help grow crops of the highest quality.

Whether trees, vines or cane crops, when it comes down to fertility, there are three very specific considerations that woody plants need to perform at their very best. The same is true for vegetables, grasses, legumes and small grain crops. Those needs are adequate water infiltration, proper environment for soil life and the correct amount of nutrients to supply that life and the crop via plant root uptake.

It is a big mistake to consider that just adding enough fertilizer to grow the crop is what determines soil fertility. There is far more to it than that, and if not correctly understood this can be very costly to those trying to survive and profit from such land. On the other hand, once these principles are understood and put into practice, it is like finding the road map to building up land for achieving its top performance.

Top fertility begins with soils that “drink in the water” — not those that are so hard that water is unable to penetrate and runs off as a source of erosion instead. Even on “flat” fields, whichever way the water moves, soil nutrients move with it. This is because soil colloids, the tiniest and yet most fertile clay particles, and the soil humus are so small that they will be picked up and eroded away first.

Corn leaves
Soil fertility directly affects the quality and yield of your crops.

Is there anything growers can do about poor soils? Are you just stuck with that soil if a general fertility program will not suffice to solve the problem? Though much of agriculture seems to imply that this is the only real choice (because the farmer or grower is told it is too expensive to correct the soil) that does not have to be the case.

Adding carbonaceous materials, growing cover crops, using composts and manures and other conservation methods can help, but if any of these are considered as the initial key to lasting success, that is like the old saying about “getting the cart before the horse.”

The place to start is to consider and deal with the “science” of the soil as quickly as possible. That means providing exactly the right environment for the soil organisms, from microbes to earthworms, and all the other organisms that work to feed the plant. Soil scientists say this soil life is equivalent to the weight of an average sized cow in the soil under each acre of ground. This life in the soil eats first and the plants we are growing then get to choose from what is left.

In other words, the plants eat at the second table. When there is not a sufficient amount to supply the needs of both the soil and the plant, it is the plant that suffers. A good example is how soil organisms confiscate nitrogen needed to break down crop residues. They get first choice and if there is too little there, the plant will suffer a nitrogen deficiency.

Still, when soil organisms are placed into a hostile environment, they have trouble thriving and possibly even surviving. This is where the science of the soil again takes precedence. It now has to do with the proper amount of air and water the soil contains, as compared to the content of minerals and organic matter. This relates to the physical structure of the soil — or soil physics.

The soil needs plenty of room for supplying the needs of the living organisms that must survive there, including plant roots. That room or space must provide the needed air and water as well as sufficient soil and plant nutrient sources. To provide the most beneficial environment for the life of the soil requires 25 percent as air space, 25 percent for water, 45 percent for soil nutrients and 5 percent for organic matter.

But there is another aspect of soil science that has to be considered in order to provide this ideal physical structure. It has to do with the chemistry of the soil. The lack of proper emphasis on this aspect of soil science is why most of agriculture does not accomplish building the proper environment for soil life, including the plant roots that should be correctly feeding our crops.

The makeup of soil fertility should be based on the chemistry of the soil because only with the correct soil chemistry can the optimum physical structure (which determines the environment for life in the soil) be achieved.

Without a proper relationship between the soil minerals, which determines how they will react with one another, the physical structure will be lacking in a soil. There will not be the proper amount of air and water in relation to the mineral and organic matter content. Hence, the “house” or proper living conditions for all of the soil organisms will be lacking. That soil is not the “living soil” it needs to be. Now whatever we try to grow there suffers as a result. This is the real life-giving aspect of soil fertility.

Once the science is right, then you can consider and stress the differences that fertilizers and soil amendments can provide to keep the life in the soil functioning as it should, including the nuances of fertility needs for wine grapes or table grapes, versus raspberries or blackberries, versus almonds or walnuts, or whatever else is to be produced there.

Until this point is reached, the basics of topsoil performance to grow whatever crop you have in mind are still limiting. The sooner these can be corrected, the sooner each soil will be able to achieve its absolute top potential in terms of both yield and quality. Even though many other soil-building programs can help make improvements, the greatest limitations to top performance of all productive land is the lack of the right chemistry, which determines the right physical structure, which will then provide the ideal environment for the life in the soil and consequently what the producer wants to grow.

Utilizing a detailed soil analysis, combined with available GPS technology, now makes it possible to accurately determine exact requirements for each specific nutrient as required for significant variations in the soils of every vineyard, orchard or field. This technology is used to accurately measure, map for sampling and correctly fertilize for specific soil differences.

By understanding the subtleties of each different soil and the consequences that nutrient deficiencies or excesses will cause for walnuts, wine grapes, vegetables or any other crop to be grown on that land, potential problems can be identified and prioritized and appropriate solutions proposed.

On-site consultations should also be considered from time to time as they can prove useful to help ensure that growers are correctly using the best proven methods to achieve and maintain established needs.

By Neal Kinsey. This article appeared in the December 2017 issue of Acres U.S.A. magazine.

About Neal Kinsey

Neal Kinsey
Neal Kinsey

Neal Kinsey has worked as a soil fertility specialist in his home state of Missouri since 1973, with clients in all 50 states and at least 70 other countries. He also conducts training courses for interested farmers and growers each year as well as on-farm consultations. He is a contributor to Acres U.S.A. magazine and author of Hands-On Agronomy.