Indispensable to life on Earth, the soil (lithospere) is an element that influences and is influenced by the two other main compartments of the biosphere, water (hydrosphere) and air (atmosphere), interacting with them in all the processes that determine quality of life in the Planet. Soil degradation and inadequate management have caused imbalance in water flows, in greenhouse gas emissions and in the attenuation of the effects of pollutants, directly influencing the regulation of water and air quality.
It is no wonder that there is consensus in Academia regarding the need for technical-scientific advances for soil protection, with the aim of balancing several of its roles, such as production of food, fibers and fuels; nutrients and carbon storage; water filtration, purification and stocks; oxidation and reduction of organic and inorganic pollutants; and waste storage and degradation.
An important interference from the soils came to light with the recent Brazilian water crisis, which advanced beyond the borders of Northeastern backlands (where dry spells are a natural occurrence) and made it clear that the reasons for the lack of water go much beyond the scarcity of rains, and is closely related to soil management. Problems like erosion and impermeability not only reduce the amount of soil nutrients but also hinder water permeabilization for the recharge of rivers and aquifers. As opposed to droughts, floods are also related to soils. A common problem in many Brazilian cities, the phenomenon especially occurs because water does not have where to infiltrate, especially due to the soils being covered with asphalt, flowing off to where there is less energy and accumulating somewhere.
Soils are also directly related to climate issues. Agricultural research is engaged in developing technological solutions that prevent soils from degrading from the standpoint of production capacity and that reduce greenhouse gas (GHG) emissions to the least possible, a process that is aggravated by the use of nitrogen fertilizers. In that sense, existing soil carbon has gained special attention. Besides preventing GHG emissions, research has sought to remove such gases from the atmosphere through agricultural activity, a process known as carbon sequestration, since the soil is one of the best places to deposit excess carbon from the atmosphere. In a well-managed cultivation, where it is possible to store up to a ton of carbon in the soil in one year, 3.7 tons of carbon dioxide (CO2) are removed from the atmosphere. However, for a given production system, every year the amounts of carbon that can be sequestered into the soil have been reducing to the point of not obtaining more gains. After 20 years, on average, the soil no longer sequesters any more carbon, unless the system is modified to be more efficient.
The Brazilian Government's Low Carbon Agriculture Program, which aims at to the reduction of carbon emissions in agriculture through the adoption of sustainable technological solutions, was an advance towards the establishment of national knowledge bases on the subject. Through the survey and monitoring of areas with different management levels, it will be possible to learn the amount of carbon being sequestered from the atmosphere with more precision. It is known that the no-till farming system significantly contributes to carbon sequestration, as well as reforestation in areas without vegetation.
History of soil classification in Brazil
In-depth knowledge about soils and their roles is fundamental for their correct management and to map land suitability. The knowledge and identification of soil horizons and component layers and the improvement of the diagnostic criteria used in their identification are the result of the experience accumulated throughout the years in several countries. From the concept established by the Russian geographer Vasily Dokuchaev, it was possible to individually classify soils.
In Brazil, soil classification started at the end of the 19th century. But the first soil surveys systematically conducted in the domestic territory began in 1947, with the establishment of the Soils Commission of the Ministry of Agriculture's National Agricultural Research Service (SNPA). The efforts continued in the 1950s and 1960s, respectively, with the Brazilian Soil Recognition Survey Program, presented by the Commission, and with the foundation, in 1962, of the Division of Pedology and Soil Fertility, under the the National Department of Agricultural Research (DNPEA). In 1969, the Manual of Soil Analysis Methods was authored by Leandro Vettori, responsible for the beginning of the automation of Brazilian soil analyses, which is used in laboratories throughout the country to date.
With the Foundation of Embrapa, in 1973, the Division of Pedology and Soil Fertility was transformed, two years later, in the National Soil Survey and Conservation Service (SNLCS), current Embrapa Soils, giving continuity to the recognition work initiated in 1947. The information generated by the SNLCS provided the technical base for several applications, following the example of the reclaiming of the Brazilian Cerrados for agricultural production. The accumulation of such knowledge, developed in partnership with universities and with the Brazilian Institute of Geography and Statistics (IBGE), ended up generating, in the 1970s, the Brazilian Soil Classification System, which has evolved into its 4th printed edition this year, to be launched during the World Congress of Soil Science, in Rio de Janeiro, in August.
The conquest of the Cerrado
The Brazilian Cerrado is currently one of the largest agricultural frontiers of the world and an international reference in productivity. But it was not always like this. To reach its records in food production, it was necessary to correct the soils of the region, which are naturally acid and poor in nutrients.
Historically, agriculture in Brazil has always been developed in fertile soil regions, which would be cultivated to exhaustion and later abandoned. Hence the Cerrado region was seen as unsuitable to produce foods. But, in the mid-1970s, with the government's decision to expand agriculture to this region, it was necessary to especially invest in research to try to change such reality.
In this context, Embrapa Cerrados was established in 1975, and has led research related to determining indicators to evaluate the quality of soils in the region, both with regard to soil chemistry and with regard to their biology − which is especially connected to organic matter. With intensive field experimentation, throughout the last 40 years it has generated criteria to interpret soil analysis and adequately recommend fertilizers and correctives in suitable doses, which provided crops in the Cerrado with good productivity and economic returns.
The challenges of agricultural research for this region are currently related to perfecting conservationist systems such as the no-till farming system, and the development of integrated systems.
Megaproject with 20 institutions will map Brazilian soils
In a country with continental proportions like Brazil, there is still a large lack of data on its soils. There is, for example, a generalized idea that in the Amazon region, the soil are poor and with a lot of iron oxide. But researchers have discovered that there areareas that totally differ from this pattern, as they are influenced by the Andes. There is even a dark, fertile and anthropogenic type of soil, also found in this region, known as Terra Preta de Índio, with really high levels of fertility. Just to mention examples from the Northern region of the country alone.
To solve the problem of the lack of suitable knowledge about a good portion of the soils in the domestic territory, Brazil is structuring the National Soils Program (PronaSolos), the largest Brazilian technical-scientific enterprise in the area of soils. An undertaking to be performed throughout the next 30 years and estimated at about R$740 millions in the first ten years.
The program, which is coordinated by Embrapa Soils, will gather activities like the investigation, documentation, inventory and interpretation of Brazilian soil data for the management and conservation of this resource. The information is fundamental for countless areas that range from climate change and water resources to rural insurance and telecommunications.
The work will provide the basis for land use planning in Brazil, combining economic development in the fields with the conservation of natural resources and the management of water resources.