Embrapa Agrossilvopastoril is closing the first 12-year cycle of the largest experiment in the world with crop-livestock-forest integration systems (ILPF), in Sinop (MT). The research brought results that help to make recommendations on the use of the arboreal component in these production systems.
The definition of the strategy for using trees in integration systems varies between properties, depending on the producer's interest. Factors such as destination of the wood, consumer market, method of harvesting, use of trees as an addition or replacement for income, characteristics of the property, among others, must be evaluated. This makes each project unique. However, decision-making must be based on technical foundations such as those obtained in the research.
The work used eucalyptus (clone H13), as it is a fast-growing species, with developed silvicultural techniques and multiple uses. The trees were tested in a crop-forest integration system (ILF), livestock-forest integration (IPF) and ILPF, in addition to the monoculture used as a control. Planting initially occurred in rows of three rows 30 meters apart and, after interventions, some of the treatments had the external rows removed and remained as simple rows spaced 37 meters apart.
The research followed the entire development of the trees, management operations such as branch pruning and thinning (selective cutting of trees), growth data, biomass and carbon accumulation, border effect of rows, wood stock, among others.
Over the 12 years, the integrated systems produced between 87 m³ and 114 m³ of wood per hectare (ha). The volumes varied according to the number of trees grown until the end of the experiment. However, the more trees, the greater the impact on grain and forage production within the production system.
“When we talk about integration systems, we have to think about the productivity of the entire system. If I increase the number of trees, there will be a reduction in crop and livestock production. Therefore, the greater number of trees has to make sense in the overall assessment”, explains researcher Maurel Behling.
The control area, with eucalyptus monoculture, produced 350 m³/ha over the 12 years, falling within the average annual increase of H13 in forestry areas in Mato Grosso, which is 32 m³/ha.
Data on growth in height, diameter at breast height (DBH) and wood volume measured over the years indicated that the integrated systems provide the so-called border effect. It is the effect caused to the external trees of the monoculture because they receive more light, water and nutrients than those inside and because they have less competition with neighboring trees. In the ILPF, this effect was observed in the triple row rows, with the middle tree having the lowest DBH, as well as the trees in the treatment with only eucalyptus.
The border effect was even more pronounced when evaluating biomass and carbon accumulation in trees. The ILPF system, which initially had triple rows and became simple rows after cutting the lateral lines, was the one that accumulated the most carbon, exceeding 30 kg/year per individual. The value was statistically different from the others and was well above around 20 kg/year per tree in monoculture.
“In addition to favoring the gain in volume of trees, with greater potential for use at the sawmill, there is a higher rate of carbon accumulation in trees at ILPF. It is a carbon that will theoretically have a longer life cycle than that used as biomass”, highlights Behling.
The researcher also remembers that carbon is not only stored in wood. Trees in the production system still leave a large volume of carbon in the area in the form of leaves, branches, litter and organic matter
“Around 10 tons of waste per hectare that remains originates from the useful area with trees. This is without considering stumps and roots, which on average represent 20% of the tree’s total biomass”, informs the researcher.
Behling emphasizes that the results obtained in this experiment, added to the experiences of producers in Technological Reference Units in Mato Grosso, provide support for decision-making in planning ILPF systems.
According to him, if the objective is to add income or improve thermal comfort for cattle, systems with simple lines are more suitable. If the producer wants a model with a greater number of trees and for their sale to compensate for production losses in crops and livestock, it is possible to create rows of multiple lines.
“If the objective is to produce biomass, for example, it is important to adapt the number of lines to the machine park that will carry out the harvest, in order to make the cost viable”, advises the researcher.
Analysis of the market that will consume the wood is another key factor in system planning. Wood sent to the sawmill has greater added value, but it depends on there being a processing structure. In the mid-north region of Mato Grosso, for example, the recent emergence of corn ethanol plants has changed the scenario compared to 2011, when the experiment began. Currently the demand for biomass for boilers is large and tends to be even greater in the coming years with the opening of new plants.
“In the case of eucalyptus sawn wood, it is not yet a reality in the region, but there is already demand for treated wood for fence posts, posts and civil construction”, reports Behling.
The first cycle of the ILPF experiment focusing on beef cattle farming and grain production is being finalized with the clear cutting of eucalyptus trees after 12 years. Throughout the experiment, there are still 3.666 trees remaining, occupying an area of 43 hectares, 3 ha with monoculture and 40 ha with IPF, ILF or ILPF. Preliminary data indicate a total volume to be harvested of 3.568,33 m³ of wood. Considering the value of 100 reais per stereo meter, it is almost 514 thousand reais. If the sale were to the sawmill, the value would be even higher. It should be remembered that in addition to timber, the area also produced meat and grain.
With the end of this cycle, new work should begin in the next rainy season. This time, in addition to eucalyptus, teak will be used as an arboreal component of the system. A consortium with the two species will also be tested, since teak loses its leaves during the dry season, reducing shade for the animals. The idea is that eucalyptus contributes to maintaining thermal comfort and scaling the revenue obtained from trees.
The ILPF experiment focusing on beef cattle farming and grain agriculture at Embrapa Agrossilvopastoril is one of the largest, if not the largest, in the world, with integrated systems organized in randomized blocks and with four replications. There are a total of 72 hectares, with ten different treatments. In addition to crops, livestock and forestry alone, different strategies and arrangements for ILP, IPF, ILF and ILPF are evaluated.
The planning of the experiment was carried out shortly after the creation of Embrapa Agrossilvopastoril, through a meeting with the participation of experts from several Embrapa Units. Since installation, in the 2011/2012 harvest, researchers from different specialties have carried out studies in this area, analyzing aspects of soil, water dynamics, microclimate, forage farming, animal and plant health, microbiology, and greenhouse gas emissions, among others.
Among the highlighted results is the PPS System (Precocity, Productivity and Sustainability), a strategy for managing livestock farming using ILP and IPF.
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