A study held in São Paulo demonstrated that sustainable agricultural practices like the no-till farming system (NTFS) increase soil carbon stocks The research compared the physical attributes of soil samples from two irrigated areas cultivated with NTFS. Soil CO2 retainment reduces the release of the gas into the atmosphere, reducing the formation of greenhouse gases (GHGs). The soil is the biggest carbon deposit in nature, hence the study of its physical attributes is vital to understanding and mitigating climate change. An increase in food demand stimulates research on soil preservation and atmospheric carbon reduction. A study conducted in Itaí, SP, by scientists from Embrapa Environment and Embrapa Soils confirmed that sustainable agriculture practices such as the No-till Farming System (NTFS)are capable of increasing soil carbon stocks, reducing the release of the gas in the atmosphere. The conclusion is the result of comparisons and evaluations of physical and hydric attributes of soil samples from first-order watersheds (main water stream from springs) that are cultivated with NTFS and are irrigated by a central pivot. The study , authored by the researchers Heloisa Filizola, Alfredo Luiz, Aline Maia and Luís Carlos Hernani, from Embrapa, was published in the journal Revista de Estudos Ambientais. By pointing to increments to soil carbon stocks, which is one of the key indicators to evaluate agricultural practices, the research demonstrates that NTFS in the studied region directly impacts the reduction of the formation of greenhouse gases (GHGs) due to CO2 retainment in the soil. “The increase in the demand for food, associated with the scarcity of areas for agriculture expansion, makes studies related to soil conservation and atmospheric carbon reduction even more necessary,” Filizola declares. The evaluated areas present the Participative Quality Index (IQP, in Portuguese) – a methodology that evaluates the quality of this production system based on an assortment of indicators relating to efficiency, profitability and environmental conservation – and similar physical-hydric conditions. In the parts where management was better done, there was higher water retention and at least 50% less clay dispersion. The establishment of management systems like No-till farming helps to preserve the physical quality of soil, once species diversification and associations increase root quantity and distribution. In addition, the soil surface remains covered with plants in development or with harvest residue, moderating evaporation and minimising losses by erosion. Carbon sequestration: more than a key indicator, it is vital for GHG reduction There is a scientific consensus that terrestrial ecosystems have much importance on the carbon cycle and on soil, which is its biggest reservoir. Carbon sequestration depends on factors such as plant cover, management practices and soil classes. According to Filizola, soil carbon stocks are the main indicators of environmental services promoted by good agricultural practices. This explains a strong correlation between this element and chemical, physical and biological attributes, serving, thus, as a sustainability evaluator. According to the Intergovernmental Panel on Climate Change (IPCC),the soil stores approximately four times more carbon than plant biomass and three times more than the atmosphere, thus having bigger importance on the biogeochemical cycle of carbon. The importance of keeping the carbon in the soil exceeds the role of key indicator for the determination of soil quality, as once it is released, it will contribute to increasing the greenhouse effect. Changes in land use are among the main sources of anthropogenic carbon emissions to the atmosphere. When the soil is cultivated and managed, there are alterations in the efflux and influx of CO2 in the soil-atmosphere interface, especially through tilling and harrowing, since they take the bigger oxidation of organic material when in contact with air. These carbon emissions also occur through the alteration of water regimen, erosion and wildfires. Mitigation of climate change Among many solutions to mitigate climate change, one important option is carbon sequestration in agroecosystems, especially in agricultural soils. In addition, the soil carbon stock could compensate for anthropic emissions, benefiting agriculture productivity and mitigating temperature increases. For such carbon sequestration to happen, the management systems have to keep high quantities of biomass, cause minimal disturbance to the structure, and promote soil and water conservation. These practices also increase the activity and diversity of edaphic fauna – an expressive parcel of organisms that live in soil -, strengthening mechanisms of element cycling. Maintaining soil organic matter influences flocculation, i.e. reducing clay removal from the soil, either by forming bridges between particles, or by favouring their union and raising the structural stability in soils, especially electropositive ones. Furthermore, after the death and decomposition of the radicular system, there remain the canaliculi or bio-spores, which are associated with the orifices built by soil mesoorganisms and microorganisms and amplify soil drainage and water infiltration. What is the No-till Farming System? It is considered the most efficient and conservationist tool for sustainable exploration of agricultural production systems. It is based on species diversification, through crop rotation and intercropping, with the absence or a minimum of soil revolving and soil covered with mulch. It is vital to maintain physical, chemical and biological characteristics, granting the soil sustainability. Distinct from other management systems, in NTFS there is a recommended use of integrated agricultural practices that verbalise technics and economically the continuous dissemination or planting without preparing the soil, crop after crop, by undetermined time. The production systems conducted with no-till farming demand less infrastructure and human labour, consume less fossil energy, reduce erosion, demand less corrective chemicals and fertilizers, and favour the integrated management of pests, diseases and weeds. Therefore, at the same time in which they provide improvements to soil, water and air, they also increase the income generated by agriculture.