Plant diversity leads to microbe diversity, which leads to ecosystem functionality
Editor’s note: This is the third in a series of five explanations of the principles of soil health, as described by Jay Fuhrer, who was one of the first to define these principles as a whole. Each article will include a description of the principle along with a profile of a farm that is successfully implementing it.
Diversity is the elusive “holy grail” of ecosystem function. It is always easier to discuss than to achieve.
The definition of a plant includes more than just plant tissue — it’s plant tissue plus the multitude of microbes both inside and outside the plant, from the tallest growing point to the last root tip in the soil.
We know that plants contain thousands of metabolites, functioning through both a primary and a specialized metabolism, as referenced by van Dam and Bouwmeester in Metabolomics in the Rhizosphere: Tapping into Belowground Chemical Communication: “Indeed, plants secrete a large array of primary and secondary plant metabolites into the rhizosphere to facilitate interactions with their biotic and abiotic environment.”
Ecosystem processes worked well when highly diverse grasslands, forests, animals and microbes were building our soils over geological time. Energy flowed, with sunlight always shining on a green plant; water cycled with both quality and quantity; mineral cycles were managed by the plants and microbes; community dynamics connected and benefited all life. However, agriculture has replaced this polyculture, perennial environment with limited crop diversity with an annual landscape.
Civilization Critical by Darrin Qualman describes early agriculture as a recycling circular symbol and today’s amendment-driven agriculture with a linear symbol. We have long limited crop diversity in the U.S. as humans have striven for efficiency. In addition, we are typically better at extracting old-sunshine carbon and nutrients from soil than we are at rebuilding it with new-sunshine carbon and nutrients.
But combining no-till planting with crop diversity and cover crops moves the carbon needle. Reversing the status quo is never easy and does not guarantee instant success, but if our goal is to “farm forever,” it is necessary to achieve a healthy landscape with nutrient-rich crops instead of short-term economic gains at the soil’s expense.
How do we start to bend today’s linear symbol into a more circular symbol? Expanding our crop rotations would more closely mimic the original plant communities. In addition, this would create windows of opportunity for cover crop integration, which in turn creates windows of opportunity for diverse livestock integration. This sets the stage for longer photosynthetic periods and ultimately more carbon available to the microbes.
As a society, we need to fully understand and value soil health, clean and plentiful water and air, animals in the landscape, nutrient-rich food, and thriving rural communities. Diverse crop rotations mimic our original perennial landscapes. They are important to the long-term sustainability of our soil resource and our food security.
Healthy soils are both a source and a sink for the carbon cycle. We’ve utilized the source part; now let’s add the sink.
| Featured Farm: Bacon Heights Farms Regan, North Dakota Steve and David Bauer Bacon Heights Farms has become synonymous with soil health – specifically the principle of plant diversity. Now managed by brothers Steve and David Bauer, the farm evolved over time from dairy, then to hogs, and eventually to cow/calf pairs. “Our dad, Glenn, grew up with both plant and animal diversity,” David says. “He was an early adapter of sunflowers and grain corn, while working closely with the local banker to construct one of the first hog confinement operations in North Dakota.” In addition to adopting the soil health principle of plant diversity, Glenn was an early adopter of the other four soil health principles (armor, minimizing soil disturbance, continual living plants, and livestock integration). The farm grew several crops in 2024, including pea, buckwheat, spring wheat, durham, adzuki bean, pinto bean, soybean and corn. Additional crops in other years are oat, malting barley, and sunflower; in any given year, there are six to eight crops growing. Steve and David are quick to mention that while there are many benefits to a more diverse rotation, there are significant factors to consider. These include bin space requirements, avoiding conflicting planting and harvesting windows, allowing additional marketing time, season length considerations, and allowing time for cleaning trucks, augers, and combines between crops. What are some of the benefits of expanding plant diversity, though? Optimal use of labor and equipment, more marketing options, longer periods of sunlight harvest with improved soil health, and more. As Steve says, “It looks like nature at work with the plants healing the land, cycling deep nutrients, and developing at their own rate. ”Diversity has allowed the Bauers to remove insecticides, to use fungicides only as needed and used sparingly, and to lower herbicide and fertilizer levels. The farm eliminated tillage 40-plus years ago, first by moving into direct seeding and the last 20 years with a no-till planting system. Multi-species cover crops were added to the crop rotation in 2007. Some of their commonly used covers include camelina, buckwheat, oat, radish, pea, cereal rye and turnip. Cover crops have also allowed the brother to plant green, a practice that supplies additional soil carbon to low-carbon crops such as soybean, pinto bean, and buckwheat, while also extending photosynthesis prior to corn. Plant diversity also benefits the livestock side of Bacon Heights Farm. David, who serves on the board of the Burleigh County Soil Conservation District, says, “We use a multi-paddock system with high rest and recovery time. This enhances the native rangeland wildflowers, vetches, and numerous grasses such as Big Bluestem. Large cattle numbers for short time periods encourages grassland plant diversity and overall plant biomass. It allows grass banking for late-fall/early-winter grazing when weather permits.” The conservation ethic transferred from Glenn to his sons, Steve and David, will continue. The brothers agree about the need to work toward keeping desiccants out of the food chain, finding an acceptable amount of weed pressure, and treating all crops as food crops, whether they go directly or indirectly into the food system. |
