Soils are a GHG sink. Soils are the greatest carbon sink after the oceans. There is a wide variability in the estimates of the amount of carbon stored in the soils globally. According to Professor Rattan Lal, there are over 2,700 gigatons (Gt) of carbon stored in soils. The soil holds more carbon than the atmosphere (848 Gt) and biomass (575 Gt) combined. There is already an excess of carbon in the oceans that is starting cause a range of problems. We cannot put any more CO2 in the atmosphere or the oceans. Soils are the logical sink for carbon.
Most agricultural systems lose soil carbon with estimates that agricultural soils have lost 50-70 percent of their original SOC (Soil Organic Carbon) pool, and the depletion is exacerbated by further soil degradation and desertification. Agricultural systems that recycle organic matter and use crop rotations can increase the levels of SOC. This is achieved through techniques such as longer rotations, ground covers, cover crops, green manures, legumes, compost, organic mulches, biochar, perennials, agro-forestry, agroecological biodiversity and livestock on pasture using sustainable grazing systems such as holistic grazing. These systems are starting to come under the heading of “regenerative agriculture” because they regenerate SOC.
Carbon sequestration in prairie grass roots.
The long roots of prairie grasses can store carbon. Only 4% of the tallgrass prairie is left in the USA. When the first settlers came to the rich grasslands and dug them up, billions of tons of carbon went into the atmosphere. We are just now figuring this out. HOW do we get the carbon back into the soil when most of that prairie system is gone? By managing pastures regeneratively.
Animal effects on soil
Grassfed animals drink 97% green water (rainwater) and increase soil health, spread seeds and nutrients, increase the bird and bee population, hinder wildfires, and a lot more.
Hooves on soil do not lead to erosion, tilling the soil does. Hooves pushing on soil actually helps the soil retain water. Hooves trample hay and seeds into the soil. The organic mater trampled into the soil helps build nutrients.
Topsoil
Soil retrogression and degradation are two regressive evolution processes associated with the loss of equilibrium of a stable soil. Retrogression is primarily due to soil erosion and corresponds to a phenomenon where succession reverts the land to its natural physical state. Degradation is an evolution, different from natural evolution, related to the local climate and vegetation. It is due to the replacement of primary plant communities (known as climax vegetation) by the secondary communities. This replacement modifies the humus composition and amount, and affects the formation of the soil. It is directly related to human activity. Soil degradation may also be viewed as any change or ecological disturbance to the soil perceived to be deleterious or undesirable.
Some major aspects identified as drivers of soil degradation are:
Biodiversity decline - induced by soil contamination, erosion, salinisation and sealing; Soil biodiversity reflects the mix of living organisms in the soil. These organisms interact with one another and with plants and small animals forming a web of biological activity.
Soil compaction - Induced by machinery use leads to a reduction in biological activity, porosity and permeability. It reduces water storage and conduct and make soil less permeable to plant roots, can affect water infiltration capacity and increase erosion risk by accelerating run‐off.
Poorly Managed Livestock - In this desertification of our soils we can target livestock and animal exploitation as the biggest actor in the changes that we know.
Cultural inappropriate practices - Practices in the agricultural world are one of the biggest threat for the soil. Farmers in the previous 50 years did not pay attention to the soil, animals or even people who used pesticides and fertilizers in big quantities. Now the biggest threat is from NOT using GMOs and instead using tons of synthetic fertilizers and pesticides to make up for it.
Soil salinization (irrigation) - Soil salinisation is, in some regions, is a huge problem for the agricultural world. It can lead to the reduction of soil productivity or even the impossibility to grow plants.
As rocks and soil are eroded by water, small amounts of the mineral salts they contain are carried to rivers and lakes. Thus, the latter seep into the irrigation water. If an insufficient amount of water is used in a field, the salts become encrusted in the soil. But the most serious danger for the soil is too much water. In fact, in these conditions, the soil is engorged and raises the level of the water under the first layer of soil. The soil then functions as a sponge and absorb water into the rhizosphere by capillarity. This effect can attract water to the surface for about 1.5 m, depending on soil types. Water evaporates and salt stays around the roots, impeding their ability to absorb water. A process encountered particularly in arid regions. Currently, only 17% of all agricultural land is irrigated. But they account for 40% of worldwide food production. This is why we should start thinking about soil salinization.
Regenerative Farming Practices
Conservation tillage: Plowing and tillage dramatically erode soil and release large amounts of carbon dioxide into the atmosphere. They also can result in the kind of bare or compacted soil that creates a hostile environment for important soil microbes. By adopting low- or no-till practices, farmers minimize physical disturbance of the soil, and over time increase levels of soil organic matter, creating healthier, more resilient environments for plants to thrive, as well as keeping more and more carbon where it belongs.
No till farming: also known as zero tilling or direct drilling. is an agricultural technique for growing crops or pasture without disturbing the soil through tillage. No-till farming decreases the amount of soil erosion tillage causes in certain soils, especially in sandy and dry soils on sloping terrain. Other possible benefits include an increase in the amount of water that infiltrates into the soil, soil retention of organic matter, and nutrient cycling. These methods may increase the amount and variety of life in and on the soil. While conventional no-tillage systems use herbicides to control weeds, organic systems use a combination of strategies, such as planting cover crops as mulch to suppress weeds.
Diversity: Different plants release different carbohydrates (sugars) through their roots, and various microbes feed on these carbs and return all sorts of different nutrients back to the plant and the soil. By increasing the plant diversity of their fields, farmers help create the rich, varied, and nutrient-dense soils that lead to more productive yields.
Rotation and cover crops: Left exposed to the elements, soil will erode and the nutrients necessary for successful plant growth will either dry out or quite literally wash away. At the same time, planting the same plants in the same location can lead to a buildup of some nutrients and a lack of others. But by rotating crops and deploying cover crops strategically, farms and gardens can infuse soils with more and more (and more diverse) soil organic matter, often while avoiding disease and pest problems naturally. Always remember, bare soil is bad soil.
Mess with it less: In addition to minimizing physical disturbance, regenerative agriculture practitioners also often seek to be cautious about chemical or biological activities that also can damage long-term soil health. Misapplication of fertilizers and other soil amendments can disrupt the natural relationship between microorganisms and plant roots.
Regenerative animal farming practices you take the same amount of land you’re already using, and rotate the animals around on the land.
Managed intensive grazing is a form of rotational grazing that emphasizes pounds of livestock per acre vs animal unit per acre. It can allow up to 1 million lbs per acre, depending on pasture quality, growth rate, etc. Livestock is moved frequently, as much as twice or three times a day. This method allows for much higher stocking densities, while still giving the land the opportunity to recover, reproduce and sequester carbon. Check out more recent work by Dr. Allen Williams and Jim Gerrish. This increased stocking density allows more beef to be produced per acre than following a more simplified rotational grazing program.
For instance on my acreage (I homestead in Iowa) we have 22 acres it has about 15 acres of woods, 2 creeks, and 3 ponds. Since we moved here we have made changes for the environment. Settling ponds along the creeks was the first thing to help protect the waterways. Native trees and bushes were planted last year. We are in a 2-3 year process of getting rid of plants that don’t belong in Iowa and replanting all the grasses to native prairie grasses. Their roots are sooooooo important for carbon sequestration.
- A.S., USA
References: Soils are a GHG sink https://regenerationinternational.org/.../reversing.../
Carbon sequestration in prairie grass roots Digging Deep Reveals the Intricate World of Roots http://proof.nationalgeographic.com/.../digging-deep.../
Animals effect on soil http://www.wildflowers-and-weeds.com/.../Trampling_Weeds.htm
Topsoil
Rotational grazing https://www.google.com/.../is-grassfed-good-enough...
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