The increase of organic matter in the soil contributes to mitigate the emission of greenhouse gases by animal farming. The research showed that agroforestry systems may increase the organic carbon stock in the soil in up to 50% more than in a natural vegetation area. Nitrogen content in the soil also may increase about 60% compared to the Caatinga forest. Reduced erosion and degradation of the Caatinga soil is another benefit of increasing organic matter in the soil. The biggest organic carbon reservoir is the soil, not the forest. A study carried out by Embrapa Goats and Sheep and Embrapa Mid-North demonstrated that agroforestry systems increase the organic carbon stock in the soil in 50% or more than in a natural vegetation area. In the intercropping system of corn or sorghum with 'Massai' grass, the nitrogen content in the soil was 60% superior if compared to the Caatinga forest. Data indicate that the use of integrated production systems can sequestrate carbon and compensate the emission of greenhouse gasses by livestock farming. The results of the study were published in Revista Brasileira de Ciências do Solo and they indicate that it is possible, in integrated systems, to adopt a Caatinga sustainable management that mixes natural vegetation with agricultural areas, providing benefits like land and pasture recovery. This is an important alternative since the agricultural activities in the biome have not been characterized by fire and overgrazing yet, which results in soil fertility reduction. In the Brazilian Semiarid, the organic carbon stock might be reduced between 12% to 27%, due to climate conditions and inadequate management. According to Rafael Tonucci, a researcher at Embrapa, these results occur because integrated production systems favor the so-called net primary production [ increased production of forage and herbaceous vegetation] and the decomposition of organic matter of crops and trees, providing both soil cover soil carbon increases. “This carbon basically comes from the decomposition of roots and falling leaves (also known as litter) of the grass and the crop in the area cultivated with the system. High-quality organic matter”, he highlights. Tonucci adds that, in the specific case of the intercropping systems, the increase of nitrogen is mainly due to the mix of legumes with the fertilizer used. “There was a great contribution of nitrogen due to the input from pigeon pea plants and to fertilizers in conventional farming”, the researcher explains. The research In the tests carried out in the Embrapa experimental field in Sobral, Ceará, soil samples of four different areas were evaluated: natural Caatinga vegetation; intercropping system of corn or sorghum mixed with 'Massai' grass; two agroforestry systems (AFS 10 e AFS 20), with different rates of preserved natural forest areas and crop areas, composed of removal of commercial interest wood and agricultural area with crops of sorghum (or millet), beans and 'Massai' grass. Photo: Adilson Nóbrega Both agroforestry systems presented the best performance regarding organic carbon stocks in the soil: AFS 20 analysis showed an indicator 50% higher than the one of the natural vegetation, while the AFS 10 analysis showed an indicator 26% superior compared with the Caatinga natural area. The intercropping system presented good indicators for nitrogen, 60% proportionally better than the one of the Caatinga natural area. The research team considered these data interesting, since the conversion of natural Caatinga in crop and pasture areas, in general, reduce the carbon and nitrogen stocks in the soil. However, implementing crops producing high amounts of biomass can promote the increase of these elements content, providing a favorable environment for microorganism development in the soil. The study highlights that, with adequate management practices, it is possible to restore pastures and soil fertility, as well as to develop crops and pastures of forages, resulting in more autonomy for animal feed. All these factors favor carbon sequestration in the soil in enough quantities to restore losses by greenhouse gas emissions by livestock production systems, including the emission of enteric methane by ruminants (such as cattle, goats, sheep) and of nitrous oxide by the use of fertilizers “Every time we talk about gas mitigation, we refer to the logic of a balance of emissions and reductions. The soil is part of this balance as the main component: trees are important for carbon sequestration, but the biggest organic carbon stock is the soil, not the forest”, Tonucci emphasizes. Reduced land degradation The researchers point to other benefit of the organic matter increase in the soil through integrated production systems, which is the possibility of reducing erosion and land degradation processes in the Caatinga biome. Tonucci highlights that organic matter works as a “cement” to give cohesion to the particles that form the soil. In Caatinga, besides the soil being naturally poor in organic matter, it is common to occur strong rainfalls in a short period of time, which might cause land degradation processes. “The main benefit of integrated systems is that there is a soil coverage almost all year long. This minimizes erosion a lot, as if there were a stronger ‘cement’ in which particles got closer to each other, reducing the rain impact: water would slowly infiltrate, and the soil would have more time to absorb it”, Tonucci explains and adds that the vegetal coverage also reduces the soil temperature, favoring microorganisms and essential nutrients for the vegetation Henrique Antunes, a researcher at Embrapa Mid-North, explains that the main measure to minimize land degradation is conservation agriculture, as intercropping of corn mixed with forage. “It helps, for example, to increase, in long-term, the organic matter in the soil and even to stifle weeds that could appear during corn cultivation”, he comments. These strategies are accessible to farmers, who can also grow forest species, contributing to animal welfare, in case there are any in the area. Antunes highlights that nutrient cycling generated by forest litter is also important to improve organic matter. The researcher recommends that farmers use vegetal coverage and straw to protect the soil, besides implanting either any integrated or agrosilvopastoral system. “The idea is that, whenever possible, the farmer can adopt any system that provides or enables increasing or, at least, maintaining the levels of organic matter in extreme fragile environments, as in degraded lands, for instance”. Improving sustainability By reconciling agricultural and livestock activities with the sustainable use of Caatinga vegetation resources, including conservation areas in the rural properties, the integrated systems of production contribute to the biome sustainability. These systems are alternatives to enable agriculture to farmers, minimizing environmental impacts caused by either natural conditions or human action. In agroforestry systems, the combination of different vegetable species on the farm (trees, grasses, legumes) increases organic matter and soil quality, as well as improves land use: farmers can combinate food production activities, forage, and wood, which generates more income. In animal farming, the systems benefit animal nutrition and welfare. “The system allows a rational use of the environment, resulting in a higher nutrient supply for the animals, which eat litter and vegetation in the areas. The shadow of the trees also creates natural shelter, providing higher comfort”, Tonucci highlights. Benefits of organic matter increase in the soil Nutrients and biological activity are among the benefits provided by the increase of organic matter in the soil. The researcher Henrique Antunes explains that, in the Caatinga biome, the use of intercropping provides root heterogeneity of the different crops in most conservative systems, as agroforestry. “It is quite important, not only for the generation of mulch, but also for the quantity of roots that remain in the soil and ends up contributing to organic matter increase. Consequently, the biological activity in the soil increases and it also contributes to a higher nutrient cycling. Thus, in less resilient environments, it is important to insert organic matter. The strategy to be used to increase organic matter must be diversified and especially more accessible for farmers”, Antunes clarifies. The use of mulch, of cover crops, the adoption of agroforestry systems, or integrated crop-livestock-forestry systems (ICLFS - pictured below) or even intercropping with mulching, this is, well-managed pasture, are ways to increase organic matter. “The importance of increasing organic matter in the medium to long run translates into system stability, which contributes to more productive crops. However, it does not refer only to yield, but to an improvement of the edaphic [soil health] environment, developing the chemistry, physics, and biology of the area, and, consequently, higher resilience to abiotic stresses such as water stress”, he adds. Photo: Rafael Tonucci The increase of organic matter in the soil also contributes to mitigate the greenhouse gas emissions by agriculture; however, according to the researcher, this reduction does not occur fast: it is a process that depends on the farmer’s dedication, the adoption of conservationist practices, and use of biodiverse systems with the presence of forest components, forage grasses, and different crops with varied types of roots. “Agrosilvopastoral systems help minimize the greenhouse gas emission, but they especially help to increase the quality and the quantity of organic matter, impacting directly the mitigation of those gases. Thus, if one is stocking more, one is emitting less. If it is not possible to increase organic matter, it is important to maintain it with an increase perspective, which is extremally important to agriculture in the Caatinga biome”, says Henrique, adding that Caatinga naturally has low organic matter due to the characteristics of the biome, hence the need to adopt systems that maintain or increase organic matter concentration or even the carbon stock. Guidelines on integrated production systems For further information on integrated systems in the Caatinga biome, including recommended types of production systems, benefits, and guidance on how to implement an integrated crop-livestock-forestry system (ICLFS) in the biome, click here to download a primer on the topic (file in Portuguese).