Carbon Farming – Managing the Carbon Balancing Act

clrsystems
Jan 15
3 min read

Carbon Farming – Managing the Carbon Balancing Act for Crop and Soil Productivity

Note: The following will be purely agronomic. This is not an article about carbon credits.

Photosynthesis:

Carbon Dioxide + Water + Energy (light) → Oxygen + Sugar

Respiration:

Sugar + Oxygen → Carbon Dioxide + Water + Energy (heat)

Plant life is the mediator of carbon balance on the global, national, regional, local, and farm scales. With the exception of some microorganisms, plants are the only organisms capable of converting carbon dioxide to oxygen and sugars. In fact, soil and crop productivity are governed by the efficiency of this process.

Let’s look at the soil. How can we make an unproductive soil productive? How can we make a productive soil more productive? It all starts with improving microbial activity.

Improved biological activity

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Organic Matter Turnover (OM Cycling)

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Improved Nutrient Cycling

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Improved Soil Structure

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Improved Water Availability*

*Dr. Jerry Hatfield: Soil health, soil carbon, and the effects of tillage systems.

Like us, soil microbes need ample food (labile carbon and other nutrients) and drink, need fresh air to breathe, and need a place to rest their heads at night (soil aggregation, etc.).

Let’s take a step back. Plants serve as energy intermediaries between the sun and the soil. The currency of this intermediation is carbon, a molecule that forms the building blocks of life and governs energy balance through the creation and destruction of complex molecules. Let’s break this process down step by step:

1. Sunlight energy is intercepted by the plant and fuels the creation of complex carbon molecules (sugars, amino acids, etc.)

2. Some of these complex carbon molecules remain as structural/functional components of the plant, while some are exuded by the plant's root system (up to 40% of a plant’s photosynthates can be allocated as root exudates)

3. These carbon-rich exudates (composed of sugars, organic acids, amino acids, phenolics, etc.) fuel microbiology in the root zone

4. The root zone microbiology consumes and transforms soil organic matter, and liberates plant-available nutrients and carbon dioxide (respiration) in the process

5. These liberated plant-available nutrients are absorbed by the plant, fueling the photosynthetic process (back to step 1)

How can we manage this process for productivity and profitability?

1. Carbon gains and microorganisms must be protected.

- Minimize erosion of carbon gains by maintaining crop residue and living cover

- Soil microbes are sensitive, minimize disturbance (tillage, traffic compaction, etc.) to maintain a stable ecosystem

- Residue retention alone does not build carbon; nutrients such as nitrogen, phosphorus, and sulfur must be available to microbes to metabolize and stabilize this carbon.

2. Living roots are necessary to keep this process rolling.

- Maintains this plant-soil energy interface, fueling soil biological activity and its subsequent effects

- Crop diversity brings diverse functional biology:

o Crops differ in their root exudate composition, attracting different mixes of functional biology

o Crops differ in their root architecture (e.g., the taproot of radishes vs. the fibrous root systems of wheat), attracting different mixes of functional biology at different depths or in different areas of the soil

o Diverse functional biology = more resilient biology in diverse conditions

3. Carbon and nutrient inputs.

- Manures (green or brown) and carbon-rich nutrient inputs, which act as fertilizers as well as energy inputs for the microbiology present

o Form matters, as the carbon-to-nitrogen ratio dictates nitrogen availability, for example. Microbes need the right fuel mix, not just more carbon.

o More is not always better (overload can cause nutrient imbalances, salt accumulation, soil crusting, etc.)

- Fertilizers (used judiciously) to maximize and fulfill plant and microbiology metabolic needs

o Insufficient fertilization = insufficient plant and microbial metabolism

o Excess fertilization can create conditions that limit biological activity (e.g., root exudate limitations, osmotic stress, ionic toxicity, etc.)

- Organo-mineral strategy: likely best option for most farms

o Pairing mineral fertilizer inputs with a carbon source (hydrolysates, sugars, amino acids, humics, compost extracts, cover crops, etc.) can improve fertilizer use efficiency, reduce the shock to the microbiome, and improve plant root growth for better fertilizer interception

Overall, most of this comes back to good agronomy and a systems-based approach. Capturing carbon on-farm is of great agronomic value, as carbon lost or left uncaptured is money left on the table. Plants and microbiology have been working together for eons. If we can facilitate that relationship, we can move towards more efficient and profitable operations.

If I can assist in any way, please reach out.