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Footnotes from the Field: Intergenerational Soil Stewardship

in Current Issue/Fall 2018/Footnotes from the Field/Grow Organic/Land Stewardship/Organic Standards/Tools & Techniques
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Intergenerational Soil Stewardship: Our Only Hope?

Marjorie Harris BSc, IOIA V.O. P.Ag

Soil, specifically topsoil, is the foundation of life on this earth. Earth is the only planet with healthy fertile soil on it that we know of yet, in the whole of the universe. Fertile soil is a little-understood mixture of biology and geology whose potential only exists in the topsoil layer. The topsoil layer is composed of the topsoil itself and organic matter in various stages of mineralization and humus production. Degradation and erosion of the topsoil depletes soil fertility, restricting plant growth, vitality, and micronutrient content.

The theme for this month’s BC Organic Grower is: “Bioregionalism: building place based economies.” Agricultural philosopher Wendell Berry suggests that an agrarian economy is based on local adaptation of economic activity to the capacity of the land to sustain such activity.

This is a challenging idea because history shows us that farming as practised in the past and the present always causes topsoil degradation. Through the ages, soil degradation, or erosion, has steered the fate and course of human civilizations and ultimately caused the demise of those civilizations. This story has repeated itself throughout the world and in the history of every type of farming. In the words of Sir Winston Churchill, “Those who fail to learn from history are doomed to repeat it.” No greater historical comment can be made for agriculture: learn or be doomed. All farming societies exhausted their topsoils within 800 to 1700 years.

The Canadian Organic Standards speak to soil conservation and soil fertility specifically in the following sections:
The general principles of organic production in Annex 1:
1. Protect the environment, minimize soil degradation and erosion, decrease pollution, optimize biological productivity, and promote a sound state of health.
2. Maintain long-term soil fertility by optimizing conditions for biological activity within the soil.

Clause 5.4.3 Tillage and cultivation practices shall maintain or improve the physical, chemical and biological condition of soil, and minimize damage to the structure and tilth of soil, and soil erosion.

Principle of Health

Organic agriculture should sustain and enhance the health of soil, plants, animals, humans and the planet as one and indivisible.

We have run out of new lands to discover on planet Earth. In 1995, Dr. David Pimental of Cornell University calculated that we had already lost 30% of the arable land we were farming to soil erosion. With the advent of chemical and mechanical agriculture the soil erosion problem has increased a hundred-fold in areas. As an example, in the past 150 years, one-half the fertile topsoil of Iowa has been lost to erosion.

Topsoil is a strategic and underappreciated resource. Soil can be conserved, made, and lost and it is the balance of these factors that determines the soils fertility. How we manage the soil resource in our generation will affect generations to come. As long as soil erosion continues to exceed soil production, it is only a matter of time before agriculture fails to support Earths humanity.

What Can We Learn from the Trials and Errors of Our Ancestors?

Çatalhöyük, Anatolia (modern Turkey) was home to a Neolithic farming civilization that lasted around a thousand years starting about 7500 BC. Scientists have studied skeletal remains which have provided a highly informative record of human health. From the skeletal health record they have been able to divide this civilization into three distinct health time periods: Early, Middle and Late. During the Middle period the civilization reached its peak in population and health, and then as soil fertility was depleted the human skeletal health parameters demonstrated decline. By the end of the Late period 52% of human births resulted in infant mortality before the age of two months. Similar skeletal health studies have been conducted on the remains of other farming civilizations globally with outcome of human health declining in parallel with topsoil and soil fertility depletion, supporting the assumption that human health is interdependent on topsoil retention and soil fertility.

Dr. David R. Montgomery succinctly identifies the problem and a potential solution in his book Dirt: The Erosion of Civilizations: “Sustaining our collective well being requires prioritizing society’s long term interest in soil stewardship; it is an issue of fundamental importance to our civilization. We simply cannot afford to view agriculture as just another business because the economic benefits of soil conservation can be harvested only after decades of stewardship, and the cost of soil abuse is borne by all.”

What Does a New Sustainable Agriculture Ethic Require from Us?

In Dr. David Montgomery’s more recent publication “Growing a Revolution: Bringing Our Soil Back to Life,” he outlines solutions to soil conservation and topsoil rebuilding techniques he has witnessed applied in the field around the world. He identifies the main culprit of soil erosion in agriculture as the invention of the plow. The plow breaks the soil structure and exposes the underground community of biota to the surface. “The plow is the villain that set the seeds for soil degradation. Only deserts have bare earth and Nature tends to clothe herself in plants.”

Another challenge is that during one generation a farmer can seldom see the effects of topsoil erosion unless a dramatic natural weather event sweeps the soil away. During day to day farming it is difficult to ascertain the minimal yet additive effects of traditional tillage techniques. Fallow land tillage is a traditional technique that leads to desertification and needs to be abandoned and replaced with topsoil preserving methods. Topsoil conservation and rebuilding requires the focused consciousness of Intergenerational Soil Stewardship to guide agricultural sustainability.

Soil is in a Symbiotic Living Relationship with Plants

When plants are actively photosynthesizing they release 30% to 40% of the sugars, carbon compounds, and proteins they manufacture through their roots into the root rhizosphere. The root exudes these nutrients to feed the underground community of fungi and microbes in exchange for micronutrients from fungi and microbial metabolites that act as growth stimulators and plant health promoters.

When plants are fed synthetic N, P, K they grow big on top of the ground but do not invest in growing a big root system and do not deliver as much nutritious root exudates to feed the underground microbial and fungi communities. As a result the plant does not reap the benefits of vitality factors and micronutrients. The plants overall health is less and the plant tissue has demonstratively less micronutrient content to pass on up the food chain. Micronutrient studies demonstrate that under conventional agriculture the plants have lost between 25% to 50% of their micronutrient content in the past 50 years.

The solution to successful topsoil building Dr. Montgomery observed while touring farms around the world required three things to happen at once: no till planting techniques, cover cropping, and adding organic matter to the soil. Dr. Montgomery has coined the method Conservation Agriculture and the methods can be applied in both conventional and organic farms—because when it comes to soil conservation and restoration, everybody needs to get on board.

Principles of Conservation Agriculture:

1. Minimal or no disturbance/direct planting of seeds (e.g., no till)
2. Permanent ground cover: retain crop residues and include cover crop in rotations
3. Diverse crop rotations: to maintain soil fertility and break up pathogen carryover
4. Livestock assisting in topsoil building: mimic bison grazing, move cattle in a tight herd to intensive graze (high disturbance), and move frequently to produce low frequency grazing.

Benefits of Conservation Agriculture, after a short transition period of 2 to 3 years to allow soil organic matter to build fertility:

1. Comparable or increased yields
2. Greatly reduced fossil fuel and pesticide use
3. Increased soil carbon and crop resilience
4. Higher farmer profits

“This is not a question of low tech organic versus GMO & agro-tech….this is about ‘how to apply an understanding of soil ecology to the applied problem of increasing and sustaining crop yields in a post-oil environment’.”

“Agriculture has experienced several revolutions in historical times: the yeoman’s revolution based on relearning Roman soil husbandry and the agrochemical and green revolutions based on fertilizer and agrotechnology. Today, the growing adoption of no-till and organic methods is fostering a modern agrarian revolution based on soil conservation. Whereas past agricultural revolutions focused on increasing crop yields, the ongoing one needs to sustain them to ensure the continuity of our modern global civilization. The philosophical basis of the new agriculture lies in treating soil as a locally adapted biological system rather than a chemical system.”

Intergenerational Soil Stewardship: Society on a global scale based on an agrarian economy adapted to its bioregion dedicated to topsoil conservation and restoration and the development of soil fertility.


Marjorie Harris is an organophyte, agrologist, consultant, and verification officer in BC. She offers organic nutrient consulting and verification services supporting natural systems.

References:
1. Montgomery, D. (2007). Dirt: The Erosion of Civilizations. University of California Press. Montgomery, D. (2017). Growing a Revolution: Bringing Our Soil Back to Life. W. W. Norton & Company.
3. Pimental, D., Burgess, M. (2013). Soil Erosion Threatens Food Production. Agriculture, 3(3), 443-463; doi: 10.3390/agriculture3030443
4. Montgomery, D. (2014). Soil erosion and agricultural sustainability. PNAS. 104 (33) 13268-13272; https://doi.org/10.1073/pnas.0611508104

Ask an Expert: Fostering Resilient Soil Ecosystems

in 2018/Ask an Expert/Crop Production/Spring 2018

Emma Holmes, Organics Specialist, BC Ministry of Agriculture

Studies examining soil microbes are showing huge potential to improve growing practices. A number of soil microorganisms have abilities to increase soil fertility, aid in nutrient and water uptake by the root system, and protect crops against pests and disease.

Soil Bio-fertilizers

If you grow legumes, you are likely already familiar with Rhizobia, the family of soil bacteria that form symbiotic relationships with legumes to convert atmospheric nitrogen to a form of nitrogen that is plant available. Producers have been inoculating their legume seeds with rhizobium since the ‘50s and it is estimated that 70 million tonnes of N are fixed annually by Rhizobia (Zahran, 1999). There are significant potential gains to be had from reducing dependence on nitrogenous fertilizers by increasing biological nitrogen fixation including reduced input costs, pollution prevention, and improved yield and crop quantity (Kelly et al., 2016).

But it is not just legume crops that see big returns in partnering with soil organisms. Farmers around the world are using bio-fertilizers to cut back on expensive fertilizers, build their soil quality, and better protect their waterways and aquifers.

There are six main types of biofertilizers:

Symbiotic Nitrogen Fixers (e.g. Rhizobium) form nodules on the roots of legumes and can fix 50-200 kgs N/ha in one crop season.

Asymbiotic Free Nitrogen Fixers (e.g. Azobacter) live in the soil and fix significant levels of nitrogen without the direct interaction of other organisms.

Associative Symbiotic Nitrogen Fixers (e.g. Azospirillum) form close relationships with grasses and can fix 20-40 kgs N/ha.

Phosphate solubilizing bacteria (e.g. Fusarium) convert non available inorganic phosphorus into a plant available form.

Algae biofertilizers (e.g. Cyanobacteria) can provide plants with growth promoting substances (ex. Vitamin B 12) and fix 20-30 Kgs N/ha.

Mycorrhizal fungi refers to the symbiotic association between plant roots and soil fungus that enhances plant soil and nutrient uptake.

Growers in the Fraser Valley have reported that using a bio-fertilizer has allowed them to reduce their N fertilizer application by as much as 30-40% while seeing similar yields and higher product quality. The bio-fertilizer is called TwinN, a freeze dried microbial product that contains a group of asymbiotic free nitrogen fixing bacteria called diazotrophs. Along with N fixation, the diazotophs in TwinN have also been shown to increase root growth and root hair density and decrease root infection. It is thought that the colonization of the plant with beneficial bacteria protects the host plant from harmful bacteria (similar to the use of probiotics to promote human health).

Soil FoodWeb

Dr. Elaine Ingham, a soil microbiologist who previously worked with at Oregon State University and the Rodale Institute, is now the president of Soil FoodWeb. She has dedicated her career to help producers grow crops better by directly observing and promoting life in the soil.

Soil FoodWeb features comprehensive guides and online courses on making compost tea and analyzing soil samples using a microscope. Commercial growers using the Soil FoodWeb management programs report substantial savings in crop production input costs, reduced water usage, and increases in yield and quality.

Korean Natural Farming (KNF)

Koran Natural Farming looks very holistically at the entire farm system, including the people in it, and uses inputs that are generally close at hand and relatively inexpensive. Unlike bio-fertilizers, which involve bringing in microbes from another region or lab, KNF focuses on fostering beneficial Indigenous Micro-Organisms (IMO) within the ecosystem in which the crops are grown.

For more information, check out this link to a video on KNF Indigenous Micro-Organisms: https://vimeo.com/35078856

RootShoot in Vancouver provides 2-day workshops on KNF that includes a detailed explanation of the actual making of inputs including indigenous microorganisms, fermented plant juice, fish amino acid, and lactic acid bacteria.

Measuring Soil Diversity

The Plant Health Laboratory in Abbotsford can conduct a nematode assessment for $16-$32 (depending on turn around time). Nematodes are used as biological indicators of soil health because the number and types present in a soil reflect changes in the microbes they consume, and the soil’s physical and chemical environment.

Independent Soil FoodWeb consultants can analyze bacteria, nematodes, protozoa, and fungi using microscopes.

Managing for Soil Diversity

As the complexity of the food web increases, productivity of the soil tends to increase. Strategies for supporting robust soil biology include:

  • Supply organic matter, which acts as a home and food source for soil microbes. Composts and manures can also provide an input of beneficial soil microbes.
  • Leave crop residue to break down in place. Surface residue encourages decomposers and increases food web complexity.
  • Plant winter cover crops to act as a food source for bacteria in a time when food is otherwise scarce.
  • Create a diverse landscape that supports diverse niches of life.
  • Reduce tillage, which can disrupt sensitive organisms such as fungi. Over the long-term, tillage can deplete soil organic matter and thus reduce soil activity and complexity.
  • Minimize the use of fertilizers and pesticides. Even organic products can reduce the populations of fungi, nematodes, protozoa, and bacteria.
  • Minimize fallow periods, which can result in starvation for many creatures in the soil food web.
  • Minimize compaction and improve drainage to support aerobic microbial populations.
  • Cultivate beneficial indigenous micro-organisms
  • Apply compost teas and/or bio-fertilizers.

Emma Holmes has a B.SC in Sustainable Agriculture and M.Sc in Soil Science, both from UBC. She farmed on Orcas Island and Salt Spring Island and is now the Organics Industry Specialist at the BC Ministry of Agriculture.

Emma.Holmes@gov.bc.ca

References:

Kelly,  et al., (2016). Symbiotic Nitrogen Fixation and the Challenges to its Extension to Nonlegumes. Applied and Environmental Microbiology, 82(13). Retrieved from: http://aem.asm.org/content/82/13/3698.full

Zahran, H.H. (1999). Rhizobium-Legume Symbioses and Nitrogen Fixation under Severe Conditions and in an Arid Climate. Microbiology and Molecular Biology Reviews, 63(4). Retrieved from: https://www.ncbi.nlm.ih.gov/pmc/articles/PMC98982/

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