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An illustration of John Kempf

Why plant nutrition is the driver of soil regeneration

March 27, 2023

Editor’s Note: John Kempf is founder and chief vision officer of Advancing Eco Agriculture (AEA), and one of the leading thinkers in regenerative agriculture. AEA recently announced the expansion of its crop nutrition manufacturing capabilities in Aurora, Colorado to supply an extra 20 million acres of farmland. Here Kempf writes in-depth about why crop nutrition is so important in regenerative agriculture but is often left out of the conversation.

An illustration of John Kempf

Regenerative agriculture is commonly defined as a regeneration of soil health. A set of soil management practices that includes non-disturbance (no-till), keeping soil covered, incorporating livestock, utilizing cover crops, increasing species diversity, and maintaining continuous living roots in the soil are generally agreed upon as the drivers of a regenerative farm management system.

However, these management practices all miss a fundamental driver of soil health, which can supersede the impact of all the practices above: plant nutritional integrity.

The nutritional integrity of a crop determines its capacity for photosynthesis and carbon sequestration. Photosynthetic activity can vary as much as 3-4x based on a plant’s nutritional status. Manganese, magnesium, phosphorus, nitrogen, iron, and other minerals are directly involved in the photosynthesis process. Inadequate levels of any of these nutrients will directly bottleneck photosynthesis and limit the quantity of carbon that is fixed and converted into sugars over each 24-hour photoperiod cycle.

The foundational requirements of photosynthesis are adequate water, carbon dioxide, sunlight, a green leaf containing chlorophyll and balanced mineral nutrition. Farmers intimately understand the critical requirement for water. Sunlight is considered a given. Carbon dioxide supply and mineral nutrition are commonly misunderstood or ignored entirely in outdoor production agriculture. Because of this misunderstanding, most crops being grown in an outdoor agricultural setting are photosynthesizing at only a fraction of their inherent genetic potential.

In our consulting work at Advancing Eco Agriculture, we understand that plant nutrition and microbiome management are the foundational drivers of plant immunity and crop yields, which are brought together in the Plant Health Pyramid. We collect plant sap analysis data through the entire crop life cycle to manage nutritional integrity and increase disease and insect resistance. Our team has collected tens of thousands of samples over the last fifteen years on dozens of crop species. Almost universally, crops experience significant nutritional imbalances that limit their capacity for photosynthesis. Once we correct these nutritional imbalances, yields and pest resistance increase immediately as a result of the increased photosynthetic activity.

This misunderstanding of the primal importance of photosynthetic efficiency underscores the misconception around the slogan “healthy soils create healthy plants”. While it is true that healthy soils produce healthy plants, the question is: “What creates healthy soils?” At the most fundamental level, what creates healthy soils is plants photosynthesizing, sequestering carbon, and transferring that carbon through root exudates into the soil profile to feed the symbiotic microbial community in the rhizosphere.

Without photosynthesis and carbon induction, there is no soil. Soil without the contribution of plants is nothing more than decomposed rock particles. The generally accepted ‘regenerative management practices’ all point to the necessity of maintaining living plants constantly photosynthesizing but miss addressing the fundamentals of photosynthetic effectiveness. Thus, it is healthy plants that create healthy soil. Plant photosynthesis is the engine that drives the generation (and regeneration) of soil health, not the other way around.

It is commonly assumed that growing crops is somehow inherently extractive, that we deplete soil carbon when growing a crop, and to regenerate, we need to grow ‘cover’ crops to place carbon back into the soil. In the agronomic literature, it was historically understood that the fastest way to build soil carbon was to grow corn. Today, growing corn is considered one of the fastest ways to deplete soil carbon. This is a result of the nutritional mismanagement of contemporary agronomy, focusing exclusively on a few nutrients (and applying them in excess), while not maintaining nutritional balance to manage photosynthesis. We can build soil carbon levels while we are growing a crop. Any crop. It only requires managing plant nutrition differently and optimizing for photosynthesis and immune function.

Not considering photosynthetic variability is a foundational oversight in almost all of the carbon sequestration literature. It is not accurate to assume that the rate of photosynthesis is a constant and remains consistent across different research settings. For example, researchers report wildly varying percentages of plant photosynthates being transferred to the soil as root exudates, some as low as 5%, and some as high as 95%. This extremely high variability depends on many factors, including plant species, stage of growth, microbiome, and soil environment. But the biggest driver of variability remains the rate of photosynthetic efficiency. Imagine how our agriculture might look different if every crop transferred 95% of its total carbon to the soil, as compared to 5%? Our contemporary agronomy management practices ensure that most crops remain on the bottom end of the spectrum.

The best news is, when you increase photosynthesis, you cannot prevent yields from increasing. Healthy plants with abundant energy levels will produce more fruit, seeds, and vegetative biomass. A model of regenerative agriculture based on sound nutrition management has the capacity to increase the yields of many crops significantly, while simultaneously reducing the need for fertilizers and pesticides.

Managing plant nutritional integrity is a fundamental driver of regenerating soils, and the one driver with an immediate economic impact for farmers. Because of the rapid economic response, the demand for nutritional products designed to fit a regenerative management system is growing quickly.

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