Did you know? In the 19th century, when the land-hungry pioneers steered wagon trains westward through the United States, they encountered a huge landscape of grasses that nurtured fertile soils. Presently, only 3% of North America’s tallgrass prairie remains. The disappearance of such grasses had a significant impact on the landscape and ecology of the US. However, a major consequence of the transformation has been overlooked-the massive loss of soil carbon in the atmosphere. Carbon in soil organic matter in the USA is crucial for agricultural yield.
The world’s cultivated soils have lost 50-70% of it’s original carbon stock, most of which has oxidized upon exposure to air to become CO2. With the quickly expanding knowledge of carbon sequestration in the soils, researchers are studying how land restoration programs can help put carbon back into the soil. With the absence of carbon and critical microbes, the soil becomes nothing but dirt. The process of this deterioration is rampant around the globe.
A lot of scientists are of the opinion that regenerative agricultural practices can turn back the carbon clock while also reducing atmospheric CO2, boosting soil productivity, and increasing resilience to floods and droughts. Regenerative techniques include planting fields throughout the year in crops or other cover and agroforestry combining trees, crops, and animal husbandry.
Recognizing the Crucial Role Played by Carbon in Soil Organic Matter in the USA:
Organic carbon influences soil characteristics, including nutrient and water-holding capacity, nutrient cycling, stability, better water infiltration, and aeration. Soils preserve organic carbon which is the primary component of organic matter. Soil forms aggregates and mineral-organic complexes. The clay particles are much more effective than sand and silt in preserving the soil’s organic matter. Soil carbon is the food source for soil micro-organisms and an important bacteria metabolite.
Microbial activity plays a vital role in improving soil structure. The soil microflora creates macroaggregates in the soil by binding the soil particles together with the secretions. These are like the building blocks to improve soil structure. Better soil structure improves water filtration and increases the water-holding capacity of the soil. A lot of bacteria create a layer of polysaccharides or glycoproteins that cover the surface of the soil particles. These substances play a crucial role to keep the sand, silt, and clay particles together into stable microaggregates that will improve soil structure.
Building soil carbon also requires the nutrients to be present in the soil. The transformation of organic residues into humus by the soil organisms needs nitrogen, sulfur, phosphorus, and other elements in smaller quantities. Higher levels of organic carbon help maintain agricultural production through the positive role of maintaining soil health, reducing erosion, raising fertility, and encouraging soil biota. Higher soil organic matter levels can cause better soil nitrogen retention and better microbial biodiversity and promote the presence and growth of the arbuscular mycorrhizal fungi that colonize the roots of the crops and facilitate the movement of plant nutrients from the soil into the plants that improve growth and yield.
Appropriate Crop Residue Management to Maintain Carbon in Soil Organic Matter in the USA:
Soil carbon levels increase when the carbon-based inputs are higher than the losses. The primary carbon losses from soil happen through organic matter decomposition, biomass burning, soil erosion, and biomass burning.
Proper crop residue management is crucial to maintain or increase the soil carbon levels in the cultivated soils, especially when the organic carbon is not offered from any external source. The higher amount of crop residue that can be returned to the soil, the better it is. Recycling as much residues as possible from different kinds of harvested crops is crucial to maintaining or increasing soil carbon.
Productive perennial pastures incorporate grass species with extensive root zones. They are popular for improving the soil carbon levels. Dry matter from the pastures will decay in the soil, and when the pasture is grazed or harvested for hay or silage, the plants will shed the roots that decay into organic carbon. The pasture phase in every crop rotation is a great way to develop soil carbon.
Humus is vital to rehabilitate soils, increase soil cation exchange capacity, improve tilth and porosity, water retention and availability. Humic compounds play a pivotal role in soil aggregation, making clay much more soft, porous, aerobic, and with better drainage, which results in deeper root growth in all plants. Humic substances are stable and long-lasting biomolecules.
Is Reducing Emission Enough?
Recognizing the role played by soil carbon marks a crucial shift in the discussion of global warming. It is heavily focused on reducing the emission on fossil fuels. However, if you take a closer look at soil in general, it is crucial to focus on potential carbon sinks. Reducing emissions is critical, but soil carbon sequestration also needs to be part of the picture.
The priority must be restoring the eroded and degraded lands, along with avoiding deforestation and the farming of peatlands. These are the primary reservoirs of carbon, and they can easily decompose upon cultivation and drainage. Bringing carbon back into the soil must be done not only to offset the fossil fuels but also to ensure that we get to feed the expanding global population. Food insecurity will increase immensely if the soil is degraded.
It is not possible to reduce CO2 to safe levels in time to avoid any serious long-term impacts unless the other side of the atmospheric CO2 balance is added. More carbon resides in the soil than in the atmosphere and all plant life combined. There are 2500 billion tons of carbon in soil compared to the 800 billion tons in the atmosphere and 560 billion tons in animal and plant life. Also, compared to multiple proposed geoengineering fixes, it is easy to store carbon in soil. Thus, it is simply a matter of returning carbon where it belongs.
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