Author: Leonor Assad
Given the importance of livestock in Brazil's agricultural economy - the world's second largest beef producer and largest global exporter - it is important to consider the quality of our pastures, since the Brazilian cattle herd is raised mainly on pasture, which gives it the classification of green cattle (or grass feed beef), considered healthier.
But the mapping of pastures in Brazil, released by MapBiomas in October 2021, points out that in 2020 the total pasture area of1 54.7 million hectares, more than half was in some stage of degradation, of which 14.3% was severely degraded. Pasture degradation is the result of several factors (overgrazing, lack of management or inadequate management of cultural treatments such as fertilization, control of weeds, pests and diseases and type of forage plant, mainly). Once degradation has been verified, one of the major problems that the rural producer faces is the cost of recovery, which is higher the more advanced the degree of degradation. It is, therefore, an economic-financial problem for the rural producer.
According to data from the Climate Observatory, in recent decades the degradation of Brazilian pastures has also become a serious environmental problem as it is related to the two main sectors with the greatest participation in Brazilian greenhouse gas (GHG) emissions: agriculture and cattle raising and land use change. In 2021, Brazil emitted 2.4 billion tons of GHG, representing a 12.2% increase compared to 2020. This increase was only surpassed by 2003, when emissions grew by 20% and reached their historical peak. The acceleration is more than twice the estimated world average for the same year.
Recuperation of degraded pastures: an old problem with known solutions
Scientific papers discussing the degradation of Brazilian pastures, and particularly pointing out the need to recover them, have proliferated in Brazil since at least the 1960s. And they were driven by the expansion of cattle ranching in the Midwest, in the wake of the transfer of the capital to Brasilia, and of actions aimed at protecting the Amazon from the effects of agricultural projects, the construction of major roads and investment subsidies in the region through Sudam (Superintendence of Development of the Amazon).
Data from the Climate Observatory (SEEG, 2023) point out that currently the main source of carbon emissions from the soil are degraded pasture areas, with an estimated emission of 160 million tons of carbon dioxide equivalent (CO₂e). CO₂e is the metric used to calculate the emissions of various greenhouse gases (GHGs), which have different global warming potentials. For example, the global warming potential of methane gas (CH 4 ) is 21 times greater than the potential of carbon dioxide gas ( CO₂).
So we say that the CO₂ equivalent of methane is equal to 28. In degraded pasture, you have mainly CO₂ emissions because, with bare soil, there is rapid decomposition of soil organic matter that releases CO₂ into the atmosphere. Therefore, recovering pasture increases livestock productivity and the livestock farmer's earnings, promotes carbon removal, contributing to a low-carbon economy, and increases organic matter in the soil, improving fertility and forage quality. Pasture recuperation constitutes the number one program of the Sectorial Plan for Mitigation and Adaptation to Climate Change for the Consolidation of a Low Carbon Emission Economy in Agriculture (Plano ABC). In the Cerrado, for example, from 2014 to 2018, the ABC Plan financed the recovery of more than 93,000 hectares of degraded areas in the biome, training and supporting technical assistance for the adoption of low carbon emission technologies 7,800 rural producers in the Federal District, Bahia, Goiás, Mato Grosso do Sul, Maranhão, Minas Gerais, Piauí and Tocantins.
Pasture degradation is a process that advances over time when management conditions do not change, leading to a decline in pasture productivity. In the initial phases - slight degradation with some areas of uncovered soil or with invasive plants that cause the support capacity to fall to a maximum of 50% - it is possible to make a direct recovery to restore the productivity of the pasture. In general, in the uncovered areas herbicides are applied to control weeds and fertilizers are applied to adjust soil fertility. Also, in general it is not necessary to suspend the use of the pasture; but when this happens, this happens for a period of about 30 days.
But when more than 50% of the pasture is uncovered, it is necessary to do soil preparation, in addition to weed control, fertility correction, and forage replanting, the use of the area has to be interrupted for about 90 days. As pointed out by Embrapa researcher Moacir Bernardino Dias-Filho, depending on the situation, renovation can cost, on average, up to three times more than direct recovery.
A reclamation method for each situation
To minimize these costs, the recovery can be done through production systems that associate pasture with a crop (ILP), or with tree planting (IPF), or even with crop and tree planting (ILPF). These are the so-called integrated systems. We will initially approach the ILP. In this modality, the most common in Brazil has been to recover pasture by introducing a short-cycle crop with commercial value.
Since the 1970s, the CLI system has been adopted, especially in the southern states of Brazil, as an alternative to maintain soil coverage in winter and to obtain income in the off-season. In Rio Grande do Sul, CLI was intensified in the regions of the Middle Plateau and Missões, with the introduction of new species. Currently, CLI is used in the recovery of degraded pastures through the planting of annual crops, in rotation or consortia with forage plants, providing the producer with several benefits. What's more: it has also been adopted in non-degraded pastures because it generates diversified income for the producer. According to Eduardo Assad, Fauna Projetos' senior consultant, there has been a growth in the adoption of integrated systems in Brazil, which currently occupy an area estimated at over 17 million hectares, and of these about 80% are ILP, mainly in the states of Goiás, Mato Grosso and Mato Grosso do Sul.
CLI provides improved soil fertility and quality, increased carbon stock, reduced greenhouse gas emissions from livestock, and erosion control. This is because the grasses commonly used in tropical pastures accumulate forage, in quantities that allow them to feed the animals, when the animal load is adequate, and produce residues and roots that contribute to the improvement of soil structure and increase water infiltration and soil carbon stock, especially when compared to the conditions in exclusive crop areas.
Examples that work
In addition, the soil is kept covered throughout the year, decreasing the sediment load in waterways, which provides environmental benefits. These benefits were observed in the recovery of pastures on a farm located in Santa Rita do Passa Quatro (SP), by the Fauna Projetos consultant, Giuliano Wassall. When he started to follow the farm, Giuliano proposed to increase the beef cattle herd, to generate income, but realized that the forage production did not meet the animals' needs. It would be necessary to increase the stocking rate to close the account. Thus, he intensified the production system with ILP, in which the corn, after application of fertilizers and corrective, was sown at the beginning of the rainy season, and the forage was cultivated 36 days later, in December. In mid-March the corn was harvested and the pasture was cleared for the animals to enter. Giuliano divided the area into plots and adopted this system, in a rotational manner. Already in the first year it was possible to see improvements, and in five years the pastures were recovered.
