SOIL, WATER & GRAZING
The connection between grazing, soil health, and healthy food has never been clearer. Human health ultimately depends on healthy soil. Now soil scientists have documented that multi-paddock, regenerative grazing, sequesters carbon, and improves soil fertility and water retention.
So how do Big Picture Beef's methods reflect the latest findings from soil science? Our basic pasture management goals are simple: (1) to maintain deep-rooted pasture plants, and (2) to foster abundant life in the soil food web. Here is why and how we do both.
INCREASING FERTILITY BY GRAZING
Soil microorganisms are critical to plant health—and to human health, through our diet. By fostering beneficial soil fungi and bacteria in our pastures, we also increase the depth of fertile topsoil. Mycorrhizal fungi, which are in and on and around the deep pasture roots, have hyphae that can extend several yards into the soil.
These long filaments allow for a two-way flow that (1) takes a portion of the carbon from pasture plants and stores it deep in the ground as humus, and (2) transports soil nutrients and water to the pasture plants. These nutrients benefit the plants, the cattle, and the people who eat the meat.
The fungi are a critical source of nutrients for the plants: phosphorous, organic nitrogen, and calcium, as well as trace elements such as zinc, boron, and copper, and plant growth-stimulating substances.
In fact, if poor management causes the carbon supply to become limited by the loss of this two-way transfer system, soil loses its physical, chemical, and biological functions, which in turn causes mineral depletion in food. Scientists have noted that the loss of soil microbes in recent decades has caused a decline in nutrients in both crops and meat.
The following conventional agricultural practices have contributed to the destruction of natural systems that we rely on for nutritious food:
soil disturbance, such as plowing,
application of nitrogen or water-soluble phosphorus, and
application of herbicides and pesticides that kill essential soil microbes.
Plowing, or any activity that exposes soil to the air, causes carbon to oxidize so that it becomes carbon dioxide, a greenhouse gas that is released to the atmosphere.
What can replace the environmentally destructive practices that have become the norm? Big Picture Beef uses regenerative approaches that have been pioneered by progressive agriculturalists in the United States and overseas. Multi-paddock, rotational grazing is an important method for fostering the soil food web on which our health depends.
We move our cattle in a rotation from paddock to paddock, with new paddocks being created simply by moving flexible fencing.
Eventually the cattle are cycled back to the original paddock after that area has had sufficient rest to rejuvenate, so that the grass grows tall again. This repeated rest and regrowth of the paddock fosters deep roots, which are important for creating humus and making soil minerals available to the cattle via fungi and associated bacteria.
Studies show that regenerative grazing produces more herbage than conventional grazing or ungrazed land, and that this translates into greater weight gain of livestock that are grazed in a rotation rather than conventional grazing.
GRAZING INCREASES FERTILITY IN SEVERAL WAYS
(1) When a cow takes a bite of grass, the plant send a chemical signal to the roots to shed carbon compounds, called exudates into the soil. (2) Short grazing periods and long recovery periods allow soil microbes time to transfer nutrients from the soil to the plant roots. (3) Trampling of green residues by the cattle hooves, aid decomposition of that material. (4) Manure , which the cattle spread evenly over the land, supplies microorganisms as well as soil nutrients. (5) The remains of dead mycorrhizal fungi, bacteria, and other soil life, dead roots, and green manures that decompose, add to fertility.
Dung beetles have a unique role in the soil food web. Found on every continent except Antarctica, they quickly remove large animal manure from the surface and bury it, using it subsequently for food and for incubating their eggs.
INCREASING WATER RETENTION BY GRAZING
Regenerative grazing is a critical protection against drought and flooding because it increases soil carbon by fostering the microbes that store carbon in the soil. Without a carbon “sponge,” rain will not penetrate soil; instead the water runs off, causing the soil to erode. While the Northeast generally has adequate rainfall on a yearly basis, soil carbon is necessary to keep grass green and growing during dry spells. Carbon allows rainwater to infiltrate soil and remain to protect against drought and erosion. Sequestering carbon in the ground is also an essential strategy for stabilizing the climate.
Just as soil microbes are key to fertility, they are also key to water retention. The Glomerales fungi colonize plant roots and make a protective waxy coat called glomalin that stores both water and carbon.
Glomalin improves water infiltration and water retention in the soil and keeps soil carbon from escaping to the atmosphere. A 2013 study of three cropland scenarios and three grazing scenarios found that the highest concentration of glomalin is in native grassland pastures managed by rotational grazing.
Glomalin glues together silt, sand, or clay soil particles, forming large granules or aggregates that improve soil condition, providing what is commonly known as “tilth.” Aggregates protect soils from eroding winds and water. Previously plowing was thought to increase tilth, but now it is understood that soil disruption contributes to soil compaction, whereas no-till seeding protects soil structure and allows glomalin to increase, which provides protection against both drought and flooding.
Read more on how glomalin combats climate change.
The critical thing to know about rainfall is not how much there is but how much of it infiltrates the soil and remains there until it is needed. The NRCS (Natural Resources Conservation Service) made this 6-minute video below about water infiltration to demonstrate the dramatic difference between fields that are managed with rotational grazing and minimum soil disturbance and fields grazed all season or planted with crops:
Once a piece of land has become healthy and fertile from good grazing and pasture managment, it can be used for cropland in rotation with pasture for livestock; crop yields will be more abundant than could be expected on land that has not been managed by rotational grazing.