Plant Nutrition, The Driver of Soil Regeneration
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. This factor is 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, and 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 (AEA), we understand that plant nutrition and microbiome management are the foundational drivers of plant immunity and crop yields. 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.
Greater than 95% of the sap analysis results we see when we begin working with a farm for the first time show manganese and iron deficiencies. Over 60% show low magnesium. Shortfalls of zinc, copper, boron, cobalt, sulfur, and silicon are so common, we expect to see several of these showing up at inadequate levels in practically all the initial samples when we begin working with a farm to transition to regenerative nutrition management. 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 also a key oversight in most carbon sequestration literature. It is not safe 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.
A version of this article was first published at AgFunderNews.