Carbon farming is a set of agricultural methods that aim to store carbon in the soil, crop roots, wood and leaves. The technical term for this is carbon sequestration. The overall goal of carbon farming is to create a net loss of carbon from the atmosphere. [1] This is done by increasing the rate at which carbon is sequestered into soil and plant material. One option is to increase the soil's organic matter content. This can also aid plant growth, improve soil water retention capacity [2] and reduce fertilizer use. [3] Sustainable forest management is another tool that is used in carbon farming. [4] Carbon farming is one component of climate-smart agriculture. It is also one way to remove carbon dioxide from the atmisphere.
Agricultural methods for carbon farming include adjusting how tillage and livestock grazing is done, using organic mulch or compost, working with biochar and terra preta, and changing the crop types. Methods used in forestry include reforestation and bamboo farming.
Carbon farming methods might have additional costs. Some countries have government policies that give financial incentives to farmers to use carbon farming methods. [5] As of 2016, variants of carbon farming reached hundreds of millions of hectares globally, of the nearly 5 billion hectares (1.2×1010 acres) of world farmland. [6] Carbon farming is not without its challenges or disadvantages. This is because some of its methods can affect ecosystem services. For example, carbon farming could cause an increase of land clearing, monocultures and biodiversity loss. [7] It is important to maximize environmental benefits of carbon farming by keeping in mind ecosystem services at the same time. [7]
Modification of agricultural practices is a recognized method of carbon sequestration as soil can act as an effective carbon sink and thus offset carbon dioxide emissions. [8]
Agricultural sequestration practices may have positive effects on soil, air, and water quality, be beneficial to wildlife, and expand food production. On degraded croplands, an increase of one ton of soil carbon pool may increase crop yield by 20 to 40 kilograms per hectare of wheat, 10 to 20 kg/ha for maize, and 0.5 to 1 kg/ha for cowpeas. [9]
Compared to natural vegetation, cropland soils are depleted in soil organic carbon (SOC). When a soil is converted from natural land or semi natural land, such as forests, woodlands, grasslands, steppes and savannas, the SOC content in the soil reduces by about 30–40%. [10] The loss of carbon through agricultural practices can eventually lead to the loss of soil suitable for agriculture. [11] The carbon loss from the soil is due to the removal of plant material containing carbon, via harvesting. When land use changes, soil carbon either increases or decreases. This change continues until the soil reaches a new equilibrium. Deviations from this equilibrium can also be affected by varying climate. [12] The decrease can be counteracted by increasing carbon input. This can be done via several strategies, e.g. leaving harvest residues on the field, using manure or rotating perennial crops. [13] Perennial crops have a larger below ground biomass fraction, which increases the SOC content. [10] Globally, soils are estimated to contain >8,580 gigatons of organic carbon, about ten times the amount in the atmosphere and much more than in vegetation. [14]
In part, soil carbon is thought to accumulate when decaying organic matter was physically mixed with soil. [15] Small roots die and decay while the plant is alive, depositing carbon below the surface. [16] More recently, the role of living plants has been emphasized where carbon is released as plants grow. [17] Soils can contain up to 5% carbon by weight, including decomposing plant and animal matter and biochar.
About half of soil carbon is found within deep soils. [18] About 90% of this is stabilized by mineral–organic associations. [19]
Carbon farming can offset as much as 20% of 2010 carbon dioxide emissions annually. [8] Organic farming and earthworms may be able to more than offset the annual carbon excess of 4 Gt/year. [20]
As of 2016, variants of carbon farming reached hundreds of millions of hectares globally, of the nearly 5 billion hectares (1.2×1010 acres) of world farmland. [6]
However, the effects of soil sequestration can be reversed. If the soil is disrupted or intensive tillage practices are used, the soil becomes a net source of greenhouse gases. Typically after several decades of sequestration, the soil becomes saturated and ceases to absorb carbon. This implies that there is a global limit to the amount of carbon that soil can hold. [21]
All crops absorb CO
2 during growth and release it after harvest. The goal of agricultural carbon removal is to use the crop and its relation to the carbon cycle to permanently sequester carbon within the soil. This is done by selecting farming methods that return biomass to the soil and enhance the conditions in which the carbon within the plants will be reduced to its elemental nature and stored in a stable state. Methods for accomplishing this include:
Livestock, like all animals, are net producers of carbon. Ruminants like cows and sheep produce not only CO2, but also methane due to the microbes residing in their digestive system. A small amount of carbon may be sequestered in grassland soils through root exudates and manure. By regularly rotating the herd through multiple paddocks (as often as daily) the paddocks can rest/recover between grazing periods. This pattern produces stable grasslands with significant fodder. [26] Annual grasses have shallower roots and die once they are grazed. Rotational grazing leads to the replacement of annuals by perennials with deeper roots, which can recover after grazing. By contrast, allowing animals to range over a large area for an extended period can destroy the grassland. [27]
Silvopasture involves grazing livestock under tree cover, with trees separated enough to allow adequate sunlight to nourish the grass. [26] For example, a farm in Mexico planted native trees on a paddock spanning 22 hectares (54 acres). This evolved into a successful organic dairy. The operation became a subsistence farm, earning income from consulting/training others rather than from crop production. [28]
Carbon farming minimizes disruption to soils over the planting/growing/harvest cycle. Tillage is avoided using seed drills or similar techniques. [29] Livestock can trample and/or eat the remains of a harvested field. [26] The reduction or complete halt of tilling will create an increase in the soil carbon concentrations of topsoil. [11] Plowing splits soil aggregates and allows microorganisms to consume their organic compounds. The increased microbial activity releases nutrients, initially boosting yield. Thereafter the loss of structure reduces soil's ability to hold water and resist erosion, thereby reducing yield. [6]
Mulching covers the soil around plants with a mulch of wood chips or straw. Alternatively, crop residue can be left in place to enter the soil as it decomposes. [26]
Compost sequesters carbon in a stable (not easily accessed) form. Carbon farmers spread it over the soil surface without tilling. [26] A 2013 study found that a single compost application significantly and durably increased grassland carbon storage by 25–70%. The continuation sequestration likely came from increased water-holding and "fertilization" by compost decomposition. Both factors support increased productivity. Both tested sites showed large increases in grassland productivity: a forage increase of 78% in a drier valley site, while a wetter coastal site averaged an increase of 42%. CH
4 and N
2O and emissions did not increase significantly. Methane fluxes were negligible. Soil N
2O emissions from temperate grasslands amended with chemical fertilizers and manures were orders of magnitude higher. [30] Another study found that grasslands treated with .5" of commercial compost began absorbing carbon at an annual rate of nearly 1.5 tons/acre and continued to do so in subsequent years. As of 2018, this study had not been replicated. [27]
Mixing anaerobically burned biochar into soil sequesters approximately 50% of the carbon in the biomass. Globally up to 12% of the anthropogenic carbon emissions from land use change (0.21 gigatonnes) can be off-set annually in soil, if slash-and-burn is replaced by slash-and-char. Agriculture and forestry wastes could add some 0.16 gigatonnes/year. Biofuel production using modern biomass can produce a bio-char by-product through pyrolysis sequestering 30.6 kg for each gigajoule of energy produced. Soil-sequestered carbon is easily and verifiably measured. [31]
Cover crops are fast-growing species planted to protect soils from wind and water erosion during the off-growing season. The cover crop may be incorporated into the soil to increase soil organic matter. Legume cover crops can also produce a small amount of nitrogen. The carbon content of a soil should not be increased without also ensuring that the relative amount of nitrogen also increases to maintain a healthy soil ecosystem.
Perennial crops offer potential to sequester carbon when grown in multilayered systems. One system uses perennial staple crops that grow on trees that are analogs to maize and beans, or vines, palms and herbaceous perennials. [32]
Forestry and agriculture are both land-based human activities that add up to contribute approximately a third of the world's greenhouse gas emissions. [33] There is a large interest in reforestation, but in regards to carbon farming most of that reforestation opportunity will be in small patches with trees being planted by individual land owners in exchange for benefits provided by carbon farming programs. [34] Forestry in carbon farming can be both reforestation, which is restoring forests to areas that were deforested, and afforestation which would be planting forests in areas that were not historically forested. [4] Not all forests will sequester the same amount of carbon. Carbon sequestration is dependent on several factors which can include forest age, forest type, amount of biodiversity, the management practices the forest is experiences and climate. [35] [36] Biodiversity is often thought to be a side benefit of carbon farming, but in forest ecosystems increased biodiversity can increase the rate of carbon sequestration and can be a tool in carbon farming and not just a side benefit. [36]
A bamboo forest will store less total carbon than most types of mature forest. However, it can store a similar total amount of carbon as rubber plantations and tree orchards, and can surpass the total carbon stored in agroforests, palm oil plantations, grasslands and shrublands. [37] A bamboo plantation sequesters carbon at a faster rate than a mature forest or a tree plantation. [38] However it has been found that only new plantations or plantations with active management will be sequestering carbon at a faster rate than mature forests. [39] Compared with other fast-growing tree species, bamboo is only superior in its ability to sequester carbon if selectively harvested. [40] Bamboo forests are especially high in potential for carbon sequestration if the cultivated plant material is turned into durable products that keep the carbon in the plant material for a long period because bamboo is both fast growing and regrows strongly following an annual harvest. [37] [41]
While bamboo has the ability to store carbon as biomass in cultivated material, more than half of the carbon sequestration from bamboo will be stored as carbon in the soil. [41] Carbon that is sequestered into the soil by bamboo is stored by the rhizomes and roots which is biomass that will remain in the soil after plant material above the soil is harvested and stored long-term. [38] Bamboo can be planted in sub-optimal land unsuitable for cultivating other crops and the benefits would include not only carbon sequestration but improving the quality of the land for future crops and reducing the amount of land subject to deforestation. [38] The use of carbon emission trading is also available to farmers who use bamboo to gain carbon credit in otherwise uncultivated land. [38] Therefore, the farming of bamboo timber may have significant carbon sequestration potential. [42] [43] [44]
Many factors affect the costs of carbon sequestration including soil quality, transaction costs and various externalities such as leakage and unforeseen environmental damage. Because reduction of atmospheric CO
2 is a long-term concern, farmers can be reluctant to adopt more expensive agricultural techniques when there is not a clear crop, soil, or economic benefit.
Carbon farming methods might have additional costs. Individual land owners are sometimes given incentives to use carbon farming methods through government policies. [5] Governments in Australia and New Zealand are considering allowing farmers to sell carbon credits once they document that they have sufficiently increased soil carbon content. [22] [45] [46] [47] [48] [49]
Approved practices may make farmers eligible for federal funds. Not all carbon farming techniques have been recommended. [27]
Carbon farming is not without its challenges or disadvantages. When ecosystem restoration is used as a form of carbon farming, there can be a lack of knowledge that is disadvantageous in project planning. [7] Ecosystem services are often a side benefit of restoring ecosystems along with carbon farming, but often ecosystem services are ignored in project planning because, unlike carbon sequestration, is not a global commodity that can be traded. [7] If and how carbon farming's additional sequestration methods can affect ecosystem services should be researched to determine how different methods and strategies will impact the value an ecosystem service in particular areas. [7] One concern to note is that if policy and incentives are only aimed towards carbon sequestration, then carbon farming could actually be harmful to ecosystems. [7] Carbon farming could inadvertently cause an increase of land clearing and monocultures when species diversity is not a goal of the landscapes project, so there should be attempts to balance the goals of carbon farming and biodiversity should be attempted. [7]
Critics say that the related regenerative agriculture cannot be adopted enough to matter or that it could lower commodity prices. The impact of increased soil carbon on yield has yet to be settled.[ citation needed ]
Another criticism says that no-till practices may increase herbicide use, diminishing or eliminating carbon benefits. [27]
Composting is not an NRCS-approved technique and its impacts on native species and greenhouse emissions during production have not been fully resolved. Further, commercial compost supplies are too limited to cover large amounts of land. [27]
Carbon farming may consider related issues such as groundwater and surface water degradation. [2]
In 2011 Australia started a cap-and-trade program. Farmers who sequester carbon can sell carbon credits to companies in need of carbon offsets. [26] The country's Direct Action Plan states "The single largest opportunity for CO
2 emissions reduction in Australia is through bio-sequestration in general, and in particular, the replenishment of our soil carbons." In studies of test plots over 20 years showed increased microbial activity when farmers incorporated organic matter or reduced tillage. Soil carbon levels from 1990 to 2006 declined by 30% on average under continuous cropping. Incorporating organic matter alone was not enough to build soil carbon. Nitrogen, phosphorus and sulphur had to be added as well to do so. [44]
The largest international effort to promote carbon farming is "four per 1,000", led by France. Its goal is to increase soil carbon by 0.4% per year through agricultural and forestry changes. [27]
By 2014 more than 75% of Canadian Prairies' cropland had adopted "conservation tillage" and more than 50% had adopted no-till. [53] Twenty-five countries pledged to adopt the practice at the December 2015 Paris climate talks. [26] In California multiple Resource Conservation Districts (RCDs) support local partnerships to develop and implement carbon farming, [2] In 2015 the agency that administers California's carbon-credit exchange began granting credits to farmers who compost grazing lands. [26] In 2016 Chevrolet partnered with the US Department of Agriculture (USDA) to purchase 40,000 carbon credits from ranchers on 11,000 no-till acres. The transaction equates to removing 5,000 cars from the road and was the largest to date in the US. [26] In 2017 multiple US states passed legislation in support of carbon farming and soil health. [54]
Other states are considering similar programs. [54]
A carbon sink is a natural or artificial process that "removes a greenhouse gas, an aerosol or a precursor of a greenhouse gas from the atmosphere". These sinks form an important part of the natural carbon cycle. An overarching term is carbon pool, which is all the places where carbon on Earth can be, i.e. the atmosphere, oceans, soil, plants, and so forth. A carbon sink is a type of carbon pool that has the capability to take up more carbon from the atmosphere than it releases.
Crop rotation is the practice of growing a series of different types of crops in the same area across a sequence of growing seasons. This practice reduces the reliance of crops on one set of nutrients, pest and weed pressure, along with the probability of developing resistant pests and weeds.
Organic farming, also known as ecological farming or biological farming, is an agricultural system that uses fertilizers of organic origin such as compost manure, green manure, and bone meal and places emphasis on techniques such as crop rotation and companion planting. It originated early in the 20th century in reaction to rapidly changing farming practices. Certified organic agriculture accounts for 70 million hectares globally, with over half of that total in Australia. Biological pest control, mixed cropping, and the fostering of insect predators are encouraged. Organic standards are designed to allow the use of naturally-occurring substances while prohibiting or strictly limiting synthetic substances. For instance, naturally-occurring pesticides such as pyrethrin are permitted, while synthetic fertilizers and pesticides are generally prohibited. Synthetic substances that are allowed include, for example, copper sulfate, elemental sulfur, and veterinary drugs. Genetically modified organisms, nanomaterials, human sewage sludge, plant growth regulators, hormones, and antibiotic use in livestock husbandry are prohibited. Organic farming advocates claim advantages in sustainability, openness, self-sufficiency, autonomy and independence, health, food security, and food safety.
Sustainable agriculture is farming in sustainable ways meeting society's present food and textile needs, without compromising the ability for current or future generations to meet their needs. It can be based on an understanding of ecosystem services. There are many methods to increase the sustainability of agriculture. When developing agriculture within sustainable food systems, it is important to develop flexible business processes and farming practices. Agriculture has an enormous environmental footprint, playing a significant role in causing climate change, water scarcity, water pollution, land degradation, deforestation and other processes; it is simultaneously causing environmental changes and being impacted by these changes. Sustainable agriculture consists of environment friendly methods of farming that allow the production of crops or livestock without causing damage to human or natural systems. It involves preventing adverse effects on soil, water, biodiversity, and surrounding or downstream resources, as well as to those working or living on the farm or in neighboring areas. Elements of sustainable agriculture can include permaculture, agroforestry, mixed farming, multiple cropping, and crop rotation.
No-till farming 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.
Afforestation is the establishment of a forest or stand of trees (forestation) in an area where there was no recent tree cover. In comparison, reforestation means re-establishing forest that have either been cut down or lost due to natural causes, such as fire, storm, etc. There are three types of afforestation: Natural regeneration, agroforestry and tree plantations. Afforestation has many benefits. In the context of climate change, afforestation can be helpful for climate change mitigation through the route of carbon sequestration. Afforestation can also improve the local climate through increased rainfall and by being a barrier against high winds. The additional trees can also prevent or reduce topsoil erosion, floods and landslides. Finally, additional trees can be a habitat for wildlife, and provide employment and wood products.
Carbon sequestration is the process of storing carbon in a carbon pool. It plays a crucial role in limiting climate change by reducing the amount of carbon dioxide in the atmosphere. There are two main types of carbon sequestration: biologic and geologic.
Energy crops are low-cost and low-maintenance crops grown solely for renewable bioenergy production. The crops are processed into solid, liquid or gaseous fuels, such as pellets, bioethanol or biogas. The fuels are burned to generate electrical power or heat.
Biochar is the lightweight black residue, consisting of carbon and ashes, remaining after the pyrolysis of biomass, and is a form of charcoal. Biochar is defined by the International Biochar Initiative as the "solid material obtained from the thermochemical conversion of biomass in an oxygen-limited environment".
Soil carbon is the solid carbon stored in global soils. This includes both soil organic matter and inorganic carbon as carbonate minerals. It is vital to the soil capacity in our ecosystem. Soil carbon is a carbon sink in regard to the global carbon cycle, playing a role in biogeochemistry, climate change mitigation, and constructing global climate models. Natural variation such as organisms and time has affected the management of carbon in the soils. The major influence has been that of human activities which has caused a massive loss of soil organic carbon. An example of human activity includes fire which destroys the top layer of the soil and the soil therefore get exposed to excessive oxidation.
Rodale Institute is a non-profit organization that supports research into organic farming. It was founded in Emmaus, Pennsylvania in 1947 by J. I. Rodale, an organic living entrepreneur. After J.I. Rodale died in 1971, his son Robert Rodale purchased 333 acres and moved the farm to Kutztown, Pennsylvania.
Carbon dioxide removal (CDR) is a process in which carbon dioxide is removed from the atmosphere by deliberate human activities and durably stored in geological, terrestrial, or ocean reservoirs, or in products. This process is also known as carbon removal, greenhouse gas removal or negative emissions. CDR is more and more often integrated into climate policy, as an element of climate change mitigation strategies. Achieving net zero emissions will require first and foremost deep and sustained cuts in emissions, and then—in addition—the use of CDR. In the future, CDR may be able to counterbalance emissions that are technically difficult to eliminate, such as some agricultural and industrial emissions.
The environmental impact of agriculture is the effect that different farming practices have on the ecosystems around them, and how those effects can be traced back to those practices. The environmental impact of agriculture varies widely based on practices employed by farmers and by the scale of practice. Farming communities that try to reduce environmental impacts through modifying their practices will adopt sustainable agriculture practices. The negative impact of agriculture is an old issue that remains a concern even as experts design innovative means to reduce destruction and enhance eco-efficiency. Though some pastoralism is environmentally positive, modern animal agriculture practices tend to be more environmentally destructive than agricultural practices focused on fruits, vegetables and other biomass. The emissions of ammonia from cattle waste continue to raise concerns over environmental pollution.
The term cropping system refers to the crops, crop sequences and management techniques used on a particular agricultural field over a period of years. It includes all spatial and temporal aspects of managing an agricultural system. Historically, cropping systems have been designed to maximise yield, but modern agriculture is increasingly concerned with promoting environmental sustainability in cropping systems.
Soil management is the application of operations, practices, and treatments to protect soil and enhance its performance. It includes soil conservation, soil amendment, and optimal soil health. In agriculture, some amount of soil management is needed both in nonorganic and organic types to prevent agricultural land from becoming poorly productive over decades. Organic farming in particular emphasizes optimal soil management, because it uses soil health as the exclusive or nearly exclusive source of its fertilization and pest control.
A peatland is a type of wetland whose soils consist of organic matter from decaying plants, forming layers of peat. Peatlands arise because of incomplete decomposition of organic matter, usually litter from vegetation, due to water-logging and subsequent anoxia. Like coral reefs, peatlands are unusual landforms that derive mostly from biological rather than physical processes, and can take on characteristic shapes and surface patterning.
Regenerative agriculture is a conservation and rehabilitation approach to food and farming systems. It focuses on topsoil regeneration, increasing biodiversity, improving the water cycle, enhancing ecosystem services, supporting biosequestration, increasing resilience to climate change, and strengthening the health and vitality of farm soil.
Soil regeneration, as a particular form of ecological regeneration within the field of restoration ecology, is creating new soil and rejuvenating soil health by: minimizing the loss of topsoil, retaining more carbon than is depleted, boosting biodiversity, and maintaining proper water and nutrient cycling. This has many benefits, such as: soil sequestration of carbon in response to a growing threat of climate change, a reduced risk of soil erosion, and increased overall soil resilience.
Climate-smart agriculture (CSA) is a set of farming methods that has three main objectives with regards to climate change. Firstly, they use adaptation methods to respond to the effects of climate change on agriculture. Secondly, they aim to increase agricultural productivity and to ensure food security for a growing world population. Thirdly, they try to reduce greenhouse gas emissions from agriculture as much as possible. Climate-smart agriculture works as an integrated approach to managing land. This approach helps farmers to adapt their agricultural methods to the effects of climate change.
Fruit production is a major driver of deforestation around the world. In tropical countries, forests are often cleared to plant fruit trees, such as bananas, pineapples, and mangos. This deforestation is having a number of negative environmental impacts, including biodiversity loss, ecosystem disruption, and land degradation.