AcresUSA.com links

Tag Archives | carbon

Homemade Fertilizers

With the economy and farm finance more and more problematic, interest is growing in running farms with fewer, more accurate and less expensive inputs and homemade fertilizers can help cut costs and keep fertility on the farm.

homemade fertilizer

Vermiwash made in a small biodynamic apple orchard in the
Himalayan foothills of Uttaranchal in sight of Nanda Devi, India’s second highest
mountain.

Formerly we’ve overdosed with a plethora of harsh fertilizers — especially nitrogen. As a result we’ve burned up the better part of our soil carbon, and this has reduced our rainfall.

By burning off carbon, we have created droughts even as ocean warming has sent more evaporation into the atmosphere. We have ignored that few things have more affinity for hydrogen than carbon, and if we want rain to adhere to and permeate our soils we need to build soil carbon.

We thought salt fertilizers were cheap, and the stunning results encouraged us to wish away any hidden costs, no matter that earthworms disappeared simultaneously with the food chain that supported them. Our soils got hard and sticky as magnesium stayed behind while nitrates leached, carrying away silicon, calcium and trace minerals. The soil fused when wet, shed water when it rained, and we continued to get less for more.

As if this wasn’t enough, the mind-set we were sold was get big or get out. As our net margins dried up and our future prospects evaporated, our water dried up and our land became exhausted. Continue Reading →

Soil Restoration: 5 Core Principles

Soil restoration is the process of improving the structure, microbial life, nutrient density, and overall carbon levels of soil. Many human endeavors – conventional farming chief among them – have depleted the Earth to the extent that nutrient levels in almost every kind of food have fallen by between 10 and 100 percent in the past 70 years. Soil quality can improve dramatically, though, when farmers and gardeners maintain constant ground cover, increase microbe populations, encourage biological diversity, reduce the use of agricultural chemicals, and avoid tillage.

Soil restoration begins with photosynthesis.

The Power of Photosynthesis

Imagine there was a process that could remove carbon dioxide (CO2) from the atmosphere, replace it with life-giving oxygen, support a robust soil microbiome, regenerate topsoil, enhance the nutrient density of food, restore water balance to the landscape, and increase the profitability of agriculture. Fortunately, there is. It’s called photosynthesis.

The power of photosynthesis.

Without photosynthesis, the Earth’s surface would merely be weathered rocks and minerals.

In the miracle of photosynthesis, which takes place in the chloroplasts of green leaves, CO2 from the air and H2O from the soil are combined to capture light energy and transform it into biochemical energy in the form of simple sugars.

These simple sugars — commonly referred to as photosynthates — are the building blocks of life. Plants transform sugar into a great diversity of other carbon compounds, including starches, proteins, organic acids, cellulose, lignin, waxes, and oils.

Fruits, vegetables, nuts, seeds, and grains are packaged sunlight derived from photosynthesis. The oxygen our cells and the cells of other living things utilize during aerobic respiration is also derived from photosynthesis.

Significantly, many of the carbon compounds derived from the simple sugars formed during photosynthesis are also essential to the creation of well-structured topsoil. Without photosynthesis there would be no soil. Weathered rock minerals, yes… but no fertile topsoil.

The Plant-Microbe Bridge

It comes as a surprise to many that over 95 percent of life on land resides in soil, and that most of the energy for this amazing world beneath our feet is derived from plant carbon. Exudates from living roots are the most energy-rich of these carbon sources. In exchange for ‘liquid carbon,’ microbes in the vicinity of plant roots — and microbes linked to plants via networks of beneficial fungi — increase the availability of the minerals and trace elements required to maintain the health and vitality of their plant hosts (1,2).

Microbial activity in soil.

Exudates from plants feed microbes that live near plants’ roots. The microbes in turn bring nutrients to the root zone and make them bio-available to the plants.

Microbial activity also drives the process of aggregation, which enhances soil structural stability, aeration, infiltration, and water-holding capacity. All living things — above and below ground — benefit when the plant-microbe bridge is functioning effectively.

Sadly, many of today’s farming methods have severely compromised soil microbial communities, significantly reducing the amount of liquid carbon transferred to and stabilized in soil. This creates negative feedbacks all along the line. Over the last 150 years, many of the world’s prime agricultural soils have lost between 30 and 75 percent of their carbon, adding billions of tons of CO2 to the atmosphere (3).

The loss of soil carbon significantly reduces the productive potential of the land and the profitability of farming. Soil degradation has intensified in recent decades — around 30 percent of the world’s cropland has been abandoned in the last 40 years due to soil decline (4). With the global population predicted to peak at close to 10 billion by 2050, the need for soil restoration has never been more pressing. Soil dysfunction also impacts human and animal health.

Nutrient Depletion In Our Food

Over the last 70 years, the level of every nutrient in almost every kind of food has fallen between 10 and 100 percent. This is an incredibly sobering fact. An individual today would need to consume twice as much meat, three times as much fruit, and four to five times as many vegetables to obtain the same amount of minerals and trace elements available in those same foods in 1940.

Dr. David Thomas (5,6) has provided a comprehensive analysis of historical changes in food composition from tables published by the Australian Medical Research Council, the Ministry of Agriculture, the Ministry of Fisheries and Foods, and the Food Standards Agency. By comparing data available in 1940 with that in 1991, Thomas demonstrated a substantial loss in mineral and trace element content in every group of food he investigated.

The nutrient depletion summarized in Thomas’ review represents a weighted average of mineral and trace element changes in 27 kinds of vegetables and 10 kinds of meat:

Mineral Depletion in Vegetables (1940-1991; average of 27 kinds of vegetables):
Copper – declined by 76%
Calcium – declined by 46%
Iron – declined by 27%
Magnesium – declined by 24%
Potassium – declined by 16%

Mineral Depletion in Meat (1940-1991; average of 10 kinds of meat):
Copper – declined by 24%
Calcium – declined by 41%
Iron – declined by 54%
Magnesium – declined by 10%
Potassium – declined by 16%
Phosphorus – declined by 28%

Significant mineral and trace element depletion was also recorded in the 17 varieties of fruit and two dairy products tested over the same period (5). The mineral depletion in meat and dairy reflects the fact that animals are consuming plants and/or grains that are themselves minerally depleted.

In addition to the overall decline in nutrient density, Thomas found significant changes in the ratios of minerals to one another. Given that there are critical ratios of minerals and trace elements for optimum physiological function, it is highly likely that these distorted ratios have an impact on human health and well-being (5).

Restoring Nutrient Density to Our Food

It is commonly believed that the significant reduction in the nutrient density of today’s chemically-produced foods is due to the dilution effect. Dilution occurs when yields rise but mineral content falls. Significantly, though, vegetables, crops, and pastures grown in healthy, biologically active soils do not exhibit these compromised nutrient levels.

Nutrient density.

Most of the ‘deficiencies’ observed in today’s plants, animals, and people are due to soil conditions not being conducive to nutrient uptake.

Only in rare instances are minerals and trace elements completely absent from soil. Most of the ‘deficiencies’ observed in today’s plants, animals, and people are due to soil conditions not being conducive to nutrient uptake. The minerals are present in the soil but are simply not plant-available. Adding inorganic elements to correct these so-called deficiencies is an inefficient practice. Instead we need to address the biological causes of dysfunction.

Around 85 to 90 percent of plant nutrient acquisition is microbially-mediated. The soil’s ability to support nutrient-dense crops, pastures, fruits, and vegetables requires the presence of a diverse array of soil microbes from a range of functional groups.

The majority of microbes involved in nutrient acquisition are plant-dependent. That is, they respond to carbon compounds exuded by the roots of actively growing green plants. Many of these important groups of microbes are negatively impacted by the use of “cides” — herbicides, pesticides, insecticides, and fungicides.

In short, the functioning of the soil ecosystem is determined by the presence, diversity and photosynthetic rate of actively growing green plants — as well as the presence or absence of chemical toxins.

But who manages the plants and the chemicals? You guessed it… we do.

Fortunately, consumers are becoming increasingly aware that food is more than a commodity (7). It is up to us to restore soil integrity, fertility, structure, and water-holding capacity — not by applying Band-Aids to the symptoms, but by better managing our food production systems.

The Soil Carbon Sink

Soil can function as a carbon source — adding carbon to the atmosphere — or a carbon sink — removing CO2 from the atmosphere. The dynamics of the source/sink equation are largely determined by land management.

Over the millennia a highly effective carbon cycle has evolved, in which the capture, storage, transfer, release, and recapture of biochemical energy in the form of carbon compounds repeats itself over and over. The health of the soil and the vitality of plants, animals, and people depends on the effective functioning of this cycle.

Technological developments since the Industrial Revolution have produced machinery capable of extracting vast quantities of fossil fuels from beneath the Earth’s surface as well as machinery capable of laying bare large tracts of grasslands and forests. This has resulted in the release of increasing quantities of CO2 into the atmosphere while simultaneously destroying the largest natural sink over which we have control.

The decline in natural sink capacity has amplified the effects of anthropogenic emissions. Many agricultural, horticultural, forestry, and garden soils today are a net carbon source. That is, these soils are losing more carbon than they are sequestering.

The potential for reversing the net movement of CO2 to the atmosphere through improved plant and soil management is immense. Managing vegetative cover in ways that enhance the capacity of soil to sequester and store large volumes of atmospheric carbon in a stable form offers a practical and almost immediate solution to some of the most challenging issues currently facing humankind.

The key to successful soil restoration and carbon sequestration is to get the basics right.

Five Principles for Soil Restoration

  1. Green is good — and year-round green is even better

Photosynthesis draws hundreds of billions of tonnes of CO2 from the atmosphere every year. The impact of this reduction was dramatically illustrated in a stunning visualization released by NASA in 2014 (8). The movement of carbon from the atmosphere to soil — via green plants — represents the most powerful tool we have at our disposal for the restoration of soil function and reduction of atmospheric CO2.

While every green plant is a solar-powered carbon pump, it is the photosynthetic capacity and photosynthetic rate of living plants (rather than their biomass) that drive the biosequestration of stable soil carbon. Photosynthetic capacity is the amount of light intercepted by green leaves in a given area (determined by percentage of canopy cover, plant height, leaf area, leaf shape and seasonal growth patterns).

On agricultural land, photosynthetic capacity can be improved through the use of multi-species cover crops, animal integration, multispecies pastures, and strategic grazing. In parks and gardens, plant diversity and mowing height are important factors. Bare soil has no photosynthetic capacity. Bare soil is also a net carbon source and is vulnerable to erosion by wind and water.

Photosynthetic rate is the rate at which plants are able to convert light energy to sugars. It is determined by many factors, including light intensity, moisture, temperature, nutrient-availability and the demand placed on plants by microbial symbionts. The presence of mycorrhizal fungi, for example, can significantly increase photosynthetic rate. Plants photosynthesising at an elevated rate have a high sugar and mineral content, are less prone to pests and diseases, and contribute to improved weight gains in livestock.

Photosynthetic rate can be assessed by measuring Brix with a refractometer. An increase of around 5 percent in global photosynthetic capacity and/or photosynthetic rate would be sufficient to counter the CO2 flux from the burning of fossil fuels, provided the extra carbon was sequestered in soil in a stable form. This is feasible. On average, global cropland is bare for around half of every year (9). If you can see the soil, it is losing carbon!

Both photosynthetic capacity and photosynthetic rate are strongly impacted by management. Leading-edge light farmers are developing innovative and highly productive ways to keep soil covered and alive, while at the same time producing nutrient-dense food and high-quality fiber.

Grazing Management

Grazing management for microbial life.

Growth of both tops and roots is significantly impaired if more than 50 percent of the green leaf is removed in a single grazing event.

This topic requires far more space than is available here, but it is vitally important that less than 50 percent of the available green leaf be grazed (see figure on the right). Retaining adequate leaf area reduces the impact of grazing on photosynthetic capacity and enables the rapid restoration of biomass to pre-grazed levels. Over a 12-month period, significantly more forage will be produced — and more carbon sequestered in soil — if pastures are grazed tall rather than short.

In addition to leaf area, pasture height has a significant effect on soil building, moisture retention, nutrient cycling, and water quality. To maintain photosynthetic capacity (and to ensure rapid recovery) it is highly beneficial to remove livestock from a pasture before you can see their feet.

Regenerative grazing can be extremely effective in restoring soil carbon levels deep underground. The deeper the carbon, the more it is protected from oxidative and microbial decomposition. The sequestration of most significance is that which occurs below 30 cm.

Crop Production

Increasingly sophisticated machinery and a plethora of “cides” have provided the means for the planet’s rapidly expanding population to create bare ground over billions of acres, dramatically reducing global photosynthetic capacity. Reduced levels of photosynthesis have in turn resulted in reduced carbon flow to soil, significantly impacting soil and landscape function and farm productivity.

Organic carbon holds between four and 20 times its own weight in water. This means that when carbon levels are depleted, the water-holding capacity of the soil is significantly compromised. Low water-holding capacity results in poor structural stability when soils are wet and reduced plant growth when soils are dry.

One of the most significant findings in recent years has been the improvements to infiltration, water-holding capacity, and drought-resilience when bare fallows have been replaced with multi-species covers. This improvement has been particularly evident in lower rainfall regions and in dry years.

  1. Microbes matter

A healthy agricultural system is one that supports all forms of life. All too often, many of the life-forms in soil have been considered dispensable. Or, more correctly, they have not been considered at all.

The significance of the plant-microbe bridge in transferring and stabilizing carbon in soil is becoming increasingly recognized. The soil microbiome is now heralded as the next frontier in soil restoration research.

One of the most important groups of plant-dependent soil-building microbes are mycorrhizal fungi. These extraordinary ecosystem engineers access water, protect their hosts from pests and diseases, and transport nutrients such as organic nitrogen, phosphorus, sulfur, potassium, calcium, magnesium, iron, and essential trace elements including copper, cobalt, zinc, molybdenum, manganese and boron — all in exchange for liquid carbon. Many of these elements are essential for resistance to pests and diseases and climatic extremes such as drought, water-logging, and frost.

When mycorrhizal symbiosis is functioning effectively, 20-60 percent of the carbon fixed in green leaves can be channelled directly to soil mycelial networks, where a portion is combined with biologically-fixed nitrogen and converted to stable humic compounds. The deeper in the soil profile this occurs the better. Humic polymers formed by soil biota within the soil matrix improve soil structure, porosity, cation exchange capacity, and plant growth.

Soil function is also strongly influenced by its structure. In order for soil to be well-structured, it must be living. Life in the soil provides the glues and gums that enable soil particles to stick together into pea-sized lumps called aggregates. The spaces between the aggregates allow moisture to infiltrate more easily. Moisture absorbed into soil aggregates is protected from evaporation, enabling soil to remain moist for longer after rain or irrigation. This improves farm productivity and profit.

Well-structured soils are also less prone to erosion and compaction, and they function more effectively as bio-filters.

Sadly, many of the microbes important for soil function have gone missing in action. Can we get them back? Some producers have achieved large improvements in soil health in a relatively short time. What are these farmers doing differently? They diversify.

  1. Diversity is indispensable

Every plant exudes its own unique blend of sugars, enzymes, phenols, amino acids, nucleic acids, auxins, gibberellins, and other biological compounds, many of which act as signals to soil microbes. Root exudates vary continuously over time, depending on the plant’s immediate requirements. The greater the diversity of plants, the greater the diversity of microbes, and the more robust the soil ecosystem.

The belief that monocultures and intensively managed systems are more profitable than diverse biologically based systems does not hold up in practice. Monocultures need to be supported by high and often increasing levels of fertilizers, fungicides, insecticides, and other chemicals that inhibit soil biological activity. The result is even greater expenditure on agrochemicals in an attempt to control pests, weeds, diseases, and the fertility issues that ensue.

The natural grasslands that once covered vast tracts of the Australian, North American, South American, and sub-Saharan African continents — plus the ‘meadows’ of Europe — contained several hundred different kinds of grasses and forbs. These diverse grasslands and meadows were extremely productive prior to simplification through overgrazing and/or cultivation.

Diversity is indispensable.

A monoculture of triticale (left) is suffering severe water stress while triticale sown with other species (right) is healthy. The “cocktail crop” contains oats, tillage radish, sunflower, field peas, faba beans, chickpeas, proso millet, and foxtail millet in addition to triticale.

Innovative farmers are experimenting with up to 70 different plant species to see which combinations perform best for soil restoration. Some grain and vegetable producers are setting aside up to 50 percent of their cash crop area for multi-species diverse soil primers. They believe the benefits far outweigh the costs. It has been reported that two full seasons of a multispecies cover can perform miracles in terms of soil health. Mixtures of peas with canola, clover or lentils with wheat, soybean and/or vetch with corn, and buckwheat and/or peas with potatoes are becoming increasingly common.

The integration of animals into cropland can also be extremely beneficial. This doesn’t need to be complicated, though. Something as simple as including one or two companions with a cash crop can make a world of difference.

As well as improving soil function, companion plants provide habitat and food for insect predators. Recent research has shown that as the diversity of insects in crops and pastures increases, the incidence of insect pests declines, reducing the need for insecticides.

An aspect of plant community structure that is gaining increased research attention is the presence of ‘common mycorrhizal networks’ (CMNs) in diverse pastures, crops and vegetable gardens.

It has been found that plants in communities assist each other by linking together in vast underground super-highways through which they can exchange carbon, water and nutrients. CMNs increase plant resistance to pests and diseases, enhance plant vigor, and improve soil health.

In my travels I’ve seen many examples of monocultures suffering severe water stress while diverse multi-species crops beside them remained green (see photo above).

In mixed-species plantings, warm-season grasses (such as sorghum and maize) are the most generous ‘givers’ to soil carbon pools, while broadleaf plants benefit the most from the increased availability of nutrients. In livestock production systems, animal health issues linked to lack of plant diversity (and hence animal nutrition) can often mean the difference between profit and loss.

  1. Chemical use can be dangerous

Living soils can significantly improve the mineral cycle. Researchers have shown, for example, that mycorrhizal fungi can supply up to 90 percent of plants’ nitrogen (N) and phosphorous (P) requirements. In addition to including companions and multi-species covers in crop rotations, maintaining a living soil often requires reducing the application of high-analysis synthetic fertilizer and other chemicals.

Cover crops.

Applying inorganic fertilizers reduces plant exudates, which in turn reduces microbe populations in the soil.

Profit is the difference between expenditure and income. In years to come we will perhaps wonder why it took so long to realize the futility of attempting to grow crops in dysfunctional soils, relying solely on increasingly expensive synthetic inputs.

No amount of NPK fertilizer can compensate for compacted, lifeless soil with low wettability and low water-holding capacity. Indeed, adding more chemical fertilizer often makes things worse. This is particularly true for inorganic N and P.

An often-overlooked consequence of the application of high rates of N and P is that plants no longer need to channel liquid carbon to soil microbial communities in order to obtain these essential elements. Reduced carbon flow has a negative impact on soil aggregation and limits the energy available to the microbes involved in the acquisition of important minerals and trace elements. This increases the susceptibility of plants to pests and diseases.

Inorganic Nitrogen

The use of high-analysis N fertilizer poses a significant cost to both farmers and the environment. Only 10 to 40 percent is taken up by plants, which means that 60 to 90 percent of applied N is lost through a combination of volatilization and leaching.

It is often assumed that nitrogen only comes from fertilizer or legumes. But all green plants are capable of growing in association with nitrogen-fixing microbes. Even when N fertilizer is applied, plants obtain much of their N from microbial associations.

Farmers experimenting with yearlong green farming techniques are discovering that their soils develop the innate capacity to fix atmospheric nitrogen. If high rates of N fertilizer have been used for a long time, though, it is important to wean off N slowly, as free-living nitrogen-fixing bacteria require time to re-establish.

Another of the many unintended consequences of the use of nitrogen fertilizer is the production of nitrous oxide in water-logged and/or compacted soils. Nitrous oxide is a greenhouse gas with almost 300 times the global warming potential of carbon dioxide.

Inorganic Phosphorous

The application of large quantities of water-soluble P, which is found in fertilizers such as in MAP, DAP, and superphosphate, inhibits the production of strigolactone, an important plant hormone. Strigolactone increases root growth, root hair development, and colonization by mycorrhizal fungi, enabling plants to better access phosphorous that is already in the soil. The long-term consequences of the inhibition of strigolactone include destabilization of soil aggregates, increased soil compaction, and mineral-deficient (e.g. low selenium) plants and animals.

In addition to having adverse effects on soil structure and the nutrient density of food, the application of inorganic water-soluble phosphorus is highly inefficient. At least 80 percent of applied P rapidly adsorbs to aluminium and iron oxides and/or forms calcium, aluminum, or iron phosphates. In the absence of microbial activity, these forms of P are not plant-available.

It is widely recognized that only 10-15 percent of fertilizer P is taken up by crops and pastures in the year of application. If P fertilizer has been applied for the previous 10 years, there will be sufficient P for the next 100 years, irrespective of how much was in the soil beforehand. Rather than apply more P, it is more economical to activate soil microbes in order to access the P already there.

Mycorrhizal fungi are extremely important for increasing the availability of soil P. Their abundance can be significantly improved through cover crops, diversity, and appropriate grazing management.

  1. Avoid aggressive tillage

Tillage may provide an apparent quick-fix to soil problems created by lack of deep-rooted living cover. Repeated and/or aggressive tillage increases the susceptibility of the soil to erosion, though. It also depletes soil carbon and organic nitrogen, rapidly mineralizes soil nutrients (resulting in a short-term flush but long-term depletion), and is highly detrimental to beneficial soil-building microbes such as mycorrhizal fungi and keystone invertebrates such as earthworms.

The increased oxidation of organic matter in bare soil from tillage, coupled with reduced photosynthetic capacity, not only adds carbon dioxide to the atmosphere but may also contribute to falling levels of atmospheric oxygen.

Conclusion

All food and fiber producers — whether grain, beef, milk, lamb, wool, cotton, sugar, nuts, fruit, vegetables, flowers, hay, silage, or timber — are first and foremost light farmers.

Since the Industrial Revolution, human activities have sadly resulted in significantly less photosynthetic capacity due to the reduced area of green groundcover on the Earth’s surface. Human activity has also impacted the photosynthetic rate of the groundcover that remains.

Our role, in the community of living things of which we are part, is to ensure that the way we manage green plants results in as much light energy as possible being transferred to — and maintained in — the soil battery as stable soil carbon. Increasing the level of soil carbon improves farm productivity, restores landscape function, reduces the impact of anthropogenic emissions, and increases resilience to climatic variability.

It is not so much a matter of how much carbon can be sequestered by any particular method in any particular place, but rather how much soil is sequestering carbon. If all agricultural, garden, and public lands were a net sink for carbon, we could easily reduce enough CO2 to counter emissions from the burning of fossil fuels.

Everyone benefits when soils are a net carbon sink. Through our food choices and farming and gardening practices we all have the opportunity to influence how soil is managed. Profitable agriculture, nutrient-dense food, clean water, and vibrant communities can be ours… if that is what we choose.

The author extends special thanks to Sarah Troisi for expert technical assistance with the photographs used in this article.

Soil ecologist Dr. Christine Jones works with innovative farmers and ranchers to implement regenerative land management practices that enhance biodiversity, nutrient cycling, carbon sequestration, productivity, water quality, and community and catchment health. She launched Amazing Carbon (www.amazingcarbon.com) as a means to share her vision and inspire change. In 2005, Dr. Jones held the first of five “Managing the Carbon Cycle” forums to promote the benefits of soil carbon. Over the past decade she has gained international recognition as a speaker. She will be keynoting the 2017 Acres U.S.A. Eco-Ag Conference & Trade Show in Columbus, Ohio, as well as teaching a course on restoring diversity to agricultural soils during Eco-Ag University. For more information, visit acresusa.com/events or call 800-355-5313.

Literature cited:

1. Jones, C.E. (2008). Liquid carbon pathway. Australian Farm Journal, July 2008, pp. 15-17.

2. Kaiser, C., Kilburn, M. R., Clode, P. L., Fuchslueger, L., Koranda, M., Cliff, J. B., Solaiman, Z. M. and Murphy, D. V. (2015), Exploring the transfer of recent plant photosynthates to soil microbes: mycorrhizal pathway vs direct root exudation. New Phytologist, 205: 15371551. doi:10.1111/nph.13138.

3. Lal, R., Follett, R.F., Stewart, B.A. and Kimble, J.M. (2007). Soil carbon sequestration to mitigate climate change and advance food security . Soil Science, 172 (12), pp. 943-956. doi: 10.1097/ss.0b013e31815cc498

4. Pimentel, D. and Burgess, M. (2013). Soil erosion threatens food production. Agriculture 2013 , 3, 443-463; doi:10.3390/agriculture3030443

5. Thomas, D.E. (2003). A study of the mineral depletion of foods available to us as a nation over the period 1940 to 1991. Nutrition and Health, 17: 85115.

6. Thomas, D.E. (2007). The mineral depletion of foods available to us as a nation (1940-2002) a review of the 6th Edition of McCance and Widdowson. Nutrition and Health , 19: 21-55.

7. Latham, J. (2016). Why the food movement is unstoppable. Independent Science News. https://www.independentsciencenews.org/health/why-the-food-movement-is-unstoppable/

8. Miller, P. (2014). Stunning NASA visualization reveals secret swirlings of carbon dioxide. https://www.nasa.gov/press/goddard/2014/november/nasa-computer-model-provides-a-new-portrait-of-carbon-dioxide/

9. Siebert, S.; Portmann, F.T.; Döll, P. Global Patterns of Cropland Use Intensity. (2010). Remote Sensing, 2 (7), 1625-1643; doi:10.3390/rs2071625

10. Voth, K. (2015). Great “Grass Farmers” Grow Roots. National Grazing Lands Coalition.

11. Crider, F.J. (1955). Root growth stoppage resulting from defoliation of grass. U.S. Department of Agriculture Technical Bulletin 1102, 23 p. babel.hathitrust.org

12. Jones, C.E. (2011). Carbon that counts. New England and North West Landcare Adventure  16-17 March 2011. amazingcarbon.com

13. Weller, J. (2015). Testimony to House of Representatives Committee on Agriculture bipartisan subcommittee on Conservation, Energy and Forestry hearing on the Benefits of Promoting Soil Health in Agriculture and Rural America.

14. Natura, H. (undated). Illinois Native Plant Guide. Root systems of prairie plants. nrcs.usda.gov

15. Lundgren, J.G and Fausti S.W. (2015). Trading biodiversity for pest problems. Science Advances  1(6). doi: 10.1126/sciadv.1500558

16. The Plant Guy (2012). Plant Social Networks- is this why companion planting & inter-cropping work?

17. Walder, F., Niemann, H., Natarajan, M., Lehmann, M.F., Boller, T. and Wiemken, A. (2012). Mycorrhizal networks: Common goods of plants shared under unequal terms of trade. Plant Physiology , 159(2): 789797. doi: 10.1104/pp.112.195727

18. Johnson, D. and Gilbert, L. (2014). Interplant signalling through hyphal networks. New Phytologist, 205(4): 1448-1453. doi: 10.1111/nph.13115

19. Kelly (2014). Who knew? Cover crop cocktails are commune hippies.

20. Smith, S.E, Read, D.J. (2008). Mycorrhizal Symbiosis, 3rd Edition. Academic Press.

Carbon Cycling, Carbon Building

In this article I hope to provide some ideas concerning carbon cycling and how to effectively build soil carbonic organic matter. There seem to be three primary means by which we can increase a soil’s carbon content: carbon imports, carbon generation and carbon induction. Each of these possible methods can also offer other strengths to a soil-building program, compost can provide a biological inoculum, humates can provide a biological stimulant.

Adequate levels of functional organic matter and a robust soil digestive system are sorely lacking in most all agricultural soils. This lack of humic substances and biology significantly reduces a soil’s water-holding capacity and the ability to release nutrients, all of which leads to large losses in crop quality and yield.

Meanwhile, increasingly higher levels of atmospheric carbon or CO2 are being produced by the burning of fossil fuels and land desertification. Carbon sequestration — the term has been thrown around like a rubber ball. What does it really mean for agriculture? How can carbon be stabilized in soils most effectively?

Importing Carbon

There are three primary carbon imports: Humates or leonardite, and their derivatives such as fulvic and humic acids. The humic substances present in these materials generally provide very good nutrient exchange. Biochar is also a stable carbon import but not as active as leonardite seems to be. Compost can also be a viable carbon import with the added benefit of a strong biological component. Compost, however, tends to have a lower level of stable humic substances when compared with other materials. A fair proportion of compost can degrade over a period of a few years. Continue Reading →

Composting Tips and Strategies for Balanced Compost

Composting tips are common to find, but information to build a composting program is really what most people are seeking.

A wheelbarrow full of compost that is ready to apply.

Charles Walters, as quoted in Secrets of the Soil, by Peter Tompkins and Christopher Bird, says of microbial life: “There are more kinds and numbers of minute livestock hidden in the shallows and depths of an acre of soil than ever walk the surface of that field.”

As much as a cattle rancher’s livelihood depends on healthy livestock, he and his cattle’s very lives depend on armies of beneficial microbes for survival. Microbes are the foundation for all life on earth; without them the earth would be nothing more than a barren rock. There would be no fertile soils, no plants, no trees, no insects, no animals and no humans.

Soil bacteria secrete acids that break down rocks, and enzymes that break down dead plant and animal matter into rich, life-giving soil, while transforming minerals into forms that are usable to plants. Microbes help prevent soil erosion, combat disease organisms that attack plants, animals and humans, and are an important link our food chain.

Continue Reading →

Soil Carbon: Changing Dirt into Soil

Soil

Soil carbon’s role in creating healthy topsoil is becoming a global topic.

It’s a popular notion that humankind is contributing excessive amounts of carbon into the atmosphere in the form of greenhouse gas. There’s been debate on what can be done to correct this situation, going so far as to suggest methods of sequestering the carbon into places of long-term storage. Regardless of who’s right or wrong, it can’t be debated that the definition of a healthy topsoil is when the soil has a rich concentration of durable carbon compounds that change for the better the chemical, physical and biological nature of the soil.

I heard recently a Ph.D. horticulture specialist say that you cannot add too much compost to a soil and that compost was the key to building and preparing a soil. In fact, he published on his university’s letterhead a statement where he recommends adding as much as 6 cubic yards of compost to an area of 1,000 square feet while preparing the site for landscaping. I heard a similar statement was made at a Santa Fe nursery seminar by a guy who makes compost. Well, that statement may be true if the compost was still composed of extremely decay-resistant woody material that was also low in nutrients, but then it would not be compost.

Photo by the author.

Photo by the author.

The simple act of composting is where specialized fungi and bacteria called saprophytic microorganisms collaborate in the reduction (shrinkage) of organic matter by utilizing the calorie value of the fats, proteins and sugars contained in the organic matter. As the microbes eat, they are concentrating all the parts that cannot be eaten, such as the minerals and the humic substances (HS). If plentiful levels of oxygen are available, the microbes that need oxygen to function will do the composting. A bi-product of their work will be CO2 which the microbes liberated from the carbon that was part of the digestible (decomposable) organic matter — the proteins, the fats and the sugars (carbohydrates). We call this source of carbon “rapid cycling carbon,” as it simply will not persist in the soil as part of the long lasting carbon bank that defines a topsoil. The part of a topsoil that defines the very essence of the soil is the concentration of the carbon substance that is not rapid cycling, and which has a resonance time in the soil of thousands of years. These carbon molecules are powerful biologic chemicals of nature called humic acids (HA or HAs), which are contained within the whole material called humic substances. They are not food for microbes, fungi or bacteria, therefore, they are not decomposable and will persist for a long time. Compost is a poor source of these substances, which any commercial soil lab can verify by doing a humic acid extraction and assessment. Levels of 1 to 5 percent humic acid are typical of a high quality finished compost, which is insignificant and inadequate to expect compost to fulfill the objective of building soil carbon directly.

For this reason, you simply can’t add enough compost to make a difference without overdosing the soil with nutrients! This also makes the term humification in my opinion an obsolete term, since that term implies that composting (decomposition) of organic matter results in the formation and high concentration of humic substances, which it does not! If it did, we would see levels much higher than 5 or even 25 percent humic acid in commercial compost, which we rarely see unless the compost was salted (fortified) using humate/leonardite.

Soil Carbon and Compost

Carbon found within the molecular structures of proteins, fats and carbohydrates (sugars) is turned into CO2 when oxygen is plentiful and aerobic saprophytic microbes can do their work. If O2 is not plentiful, then only those microbes that can function anaerobically (without air) can do the decomposing. This is not good, because toxic chemical compounds are the byproduct of anaerobic organic matter decomposition.

Compounds such as lactic acid and alcohol are produced when oxygen is not available in adequate amounts and those chemicals are toxic to plants at even parts per million. Anaerobic metabolism can occur in our muscle tissue as well, when we are out of shape and have poor vascularity (blood flow) in the muscles. This causes poor gas exchange during exercise and the muscle cells will not have adequate levels of oxygen, resulting in the production and accumulation of lactic acid. The lactic acid is toxic and irritating to the cell walls of your muscles and nerve endings and you consequently will feel pain a day or two after you workout. So it doesn’t matter if we are talking about soil, or we are talking about our own bodies, we must have adequate amounts of oxygen at all times in order to have optimum health.

Soil Carbon and Compost Limits

So we don’t want compost that is produced without oxygen, but here’s the other side of the problem when we look back at the original statement “that you can’t add too much compost.”

Humic substances accumulatingYou can indeed add too much compost, and for many reasons, one of which is back to the problem of oxygen. Here’s how and why; the more decomposable organic material you have, the more microbes will want to get into the act therefore, the more oxygen will be needed to accommodate this feeding frenzy. We call this the “BOD” or the Biological Oxygen Demand. If you incorporate into the soil too much compost that still contains a lot of combustible organic matter, the resulting population explosion of saprophytic microorganisms will rapidly use up the oxygen and your soils will go anaerobic. This results in a whole slew of unhealthy conditions, including the production of lactic acid and alcohol, two chemicals that are toxic to plant roots.

The other problem with adding too much compost is that if it is really compost and if it is made from a source of nutrient-dense plant organic matter, it will contain a rich and concentrated source of plant nutrients. After all, who do you know that is intentionally looking for a poor nutrient source of organic matter in order to make their compost? That would be silly, plus you may not achieve the proper carbon to nitrogen ratio needed to actually instigate the composting process. If you made the compost using the proper carbon to nitrogen ratio, by default your finished product will contain a significant amount of nitrogen. The bulk density of compost can easily be 40 to 50 pounds per cubic foot, which is 1080 to 1350 pounds per cubic yard. If you add 6 cubic yards of compost, as suggested by the University Ph.D. for a total of 7,800 to 8,000 pounds of compost per 1,000 square feet, you have also added over 103 to 106 pounds of nitrogen, a toxic amount! On a per acre level, that’s approximately 4,600 pounds of nitrogen, an amount that no farmer on earth would dare apply. So yes indeed, you can add too much compost!

As I’ve already described, the carbon found in over 95 percent of the carbon-rich parts of a compost are easily and rapidly decomposed into CO2, which defends my claim that compost is the wrong tool in the tool box, needed to accumulate carbon into the soil. The purpose of this tool is that it could potentially be a source of plant available nutrients if the composter was actively utilizing nutrient dense sources of plant organic matter.

As a fertilizer, compost can nutritionally support vegetation and it is then that we see a more efficient and effective development of topsoil, only because the plant is better at photosynthesis! If the plant is better at photosynthesis it can convert more atmospheric carbon into biological carbon called glucose, which is then transported down into the roots and provided to the bacteria and the mycorrhizal fungus. “Root Exudates” are liquid glucose leaking into the soil from the roots of plants.

Soil Carbon and Humus

In the same article, May 2011 issue of Discover Magazine, my 30-year long opinion of where humus comes from is finally collaborated by another source. Humus does not come from humification of dead organic matter; rather, it’s a result of an efficient mutualism between plants and the terrestrial biosphere of soil microorganism, and most specifically the mycorrhizal fungi. The mycorrhizal plant fungi relationship is critical to the process of pedogenesis, because it’s the massive contribution this fungus makes to its host plant in the form of water and minerals that allows the plant to be healthier and to live longer. Science has demonstrated that when a plant is mycorrhizal, the uptake of minerals from the soil is dramatically better and the drought tolerance of the plant is also significantly better.

Once again, a healthier and longer living plant can contribute more carbon in the form of liquid glucose to the soils terrestrial biosphere and from there everybody gets fed. Be clear that almost without exception, farm soils worldwide are lacking a strong mycorrhizal component therefore, expecting humus to accumulate in those same farm soils is most likely not going to happen. Also, research has proven that plants must have the benefit of this amazing fungus in order to get those minerals out of the ground in a useful fashion and with the minerals comes water. This is how we grow a nutrient-dense crop and also grow soil. For farming, mine reclamation, landscaping, highway re-vegetation, and other venues where you hope to build soils, you must inoculate with a mycorrhizal product, if you expect to see these benefits.

In 1974 I described this relationship as the “Soil Food Web,” a process of soil formation and collaboration, where most terrestrial life benefits from the Bio-Geo-Chemical process of mineral nutrient sequestering and availability. The term humus is one used by the average person, but its technical description used in chemistry is humic substance! The term humic substance describes a whole bunch of carbon rich compounds that resist decay and which are products of soil chemistry. Within the whole substance is a chemical of nature called humic acid. While humic acids are powerful chemicals with many characteristics and benefits, it’s the whole substance of humic compounds that are the major bank of long lasting carbon in the soil, resulting in the formation and accumulation of a rich topsoil.

But What About Soil Compaction?

The large, air-filled spaces, or “macropores,” in untilled soil without compaction, often resemble the branching vessels of the human circulatory system. A team of Nordic researchers led combined computed tomography (CT) scanning with traditional measurements of air exchange to “diagnose” the long-term impacts of soil compaction on the hidden, but vital, soil pore network. When scientists examined cores of heavy clay subsoil suffering from compaction on a research site in Finland, they found the macropores were greatly affected compared with a non-compacted control soil. The compacted soil contained mostly long, vertical “arterial” pores, or pipes, with significantly fewer marginal pores branching from them.

Most troubling to the researchers was how lasting the impacts of compaction appear to be. In the study, the group examined soil cores taken from a depth of 0.9 to 1.2 feet in plots where 30 years earlier a heavy tractor-trailer drove over the ground four times to create compaction in an experimental treatment.

It’s where a lot of farmers end up at some point, with dirt. And turning it into soil starts with understanding carbon.

By Michael Martin Meléndrez. This report on soil compaction appears in the April 2014 issue of Acres U.S.A. magazine. This story originally published in October 2011 issue of Acres U.S.A. magazine. Michael Martin Meléndrez and his wife Kari, own Soil Secrets LLC, Soil Secrets Worldwide LLC, and the Trees That Please Nursery. Contact Soil Secrets and Michael by calling 505 550-3246, or email soilsecrets@aol.com.

Interview: Researcher, Author Eric Toensmeier Explores Practical, Effective Carbon Farming Strategies

Real-World Solutions

While this Eric Toensmeier_rgb (2)interview was being prepared a story surfaced on public radio about a couple of enterprising Americans who are taking advantage of changing policy to open a factory in Cuba. Their product? Tractors! The whole idea, the story helpfully explained, was to introduce “21st century farming” to the beleaguered island. By making it easier to tear up the soil. Clearly there is some distance to go before an accurate idea of 21st century farming penetrates the mainstream. It will take people like Eric Toensmeier. His new book, The Carbon Farming Solution, carries enough heft, range and detail to clear away forests of confusion. If the notion of leaving carbon in the soil is going to take its place next to that of leaving oil in the ground, this one-volume encyclopedia on the subject is exactly the kind of deeply informed work that’s required. Reached at his home in western Massachusetts, Toensmeier was exhilarated over finishing a project years in the making, and more than happy to talk about it.

This interview appears in the May 2016 issue of Acres U.S.A.

Continue Reading →