Análise prospectiva do sistema produtivo da soja no estado do Tocantins, considerando cenários de riscos hídricos e climatológicos

Abstract

Soy is one of the main commercial crops in the country, and at the same time it has influenced the change in land use, significantly in the deforestation of the Brazilian Cerrado. It is noteworthy that its demand is parameterized exponentially for various applications, cosmetics, food and biofuel generation, and that it is available as the major cause of territorial transformations in Brazil. Tocantins is on the list of federative units whose economic matrix is dominated by agribusiness, especially by the production chain of this oilseed. In view of the flexibility of state and federal laws in the treatment of some Conservation Units inserted in the Tocantins state limit, this work aims to prospect the advance of soy in the surroundings and in the interiors of these protected areas, as well as its dynamics from scenarios of climatic risks to the performance of this plant, which is highly correlated to water stress. Thus, a pedotransfer function was constructed to estimate the Available Water Capacity (AWC) in the State with Embrapa granulometric samples. This variable was considered an input for the water balance calculation simulation of 36 legume sowing dates to determine its Water Need Satisfaction Index (WNSI) by planting date. Other simulations were generated for two other climatic risk zonings of the crop under scrutiny, using simulated rainfall and average temperature averages simulated and corrected with observational data between 2021 and 2050 for 130 coordinates of pluviometric stations. Each zoning built belongs to a constant reflection of atmospheric radiation due to the concentration of greenhouse gases in the global circulation model MIROC5, RCP 4.5 W / m² and 8.5 W / m². These two paths representative of the climate were inserted as static variables in a model of uses and occupations (LUCC - land-use and land-cover change) of Dinamica EGO, which was calibrated for the weights of the transition probabilities and validated by the Hagen method (2003). Data from the State's forest inventory carried out by the State Government's Planning Secretariat (Seplan) allowed the quantification of carbon dioxide equivalent (CO2e) resulting from the transition from areas of natural vegetation to a soybean production system and the degree of deforestation in UCs and in their buffer zones. In both scenarios, the Bananal/Cantão Island was the most affected by the pressure from agricultural investments. It had at least one planting date of low risk to water deficiency, WNSI in the phenological phase of flowering and filling of grains above 0.65, being highlighted for being with low climatic vulnerability between the years 2021 and 2050, in the two projections made. These temporal space models also identified investment leakages in the largest municipal producers, Campos Lindos and Mateiros, as they are geographically positioned in high frequency areas of WSNI below 0.55, both in the trend view and in the pessimistic view regarding the treatment of climate change policies.