Variabilidade têmporo-espacial das chuvas e temperatura do ar nas microrregiões do entorno de Unaí, noroeste do estado de Minas Gerais: síntese climática e impactos na produção de soja

Abstract

The static and dynamic factors of the climate influence directly and / or indirectly the human activities in geographic space. In this perspective, the climate plays a fundamental role in agricultural activities by supplying the necessary for the full development of crops (solar radiation, temperature, rainfall, etc.), and the interactions between climatic factors provide conditions that impact, positively or negatively, the productivity among the harvests. Research that analyzes the contribution of climate to fluctuations in soybean productivity in Brazil from a theoretical and methodological perspective of Geographic Climatology are still incipient, especially with regard to the influence of factors of different spatial and temporal scales. The objective of this research was to understand how the temporal-spatial variability of climatic elements are related to variations in soybean productivity in six micro-regions around the municipality of Unaí-MG, between the agricultural years 1995/1996 and 2014/2015. It was used daily data from 22 meteorological stations from INMET and 100 pluviometric stations from ANA, whose flaws were verified and filled by statistical techniques. The analysis was based by descriptive and exploratory statistical techniques, classification of pattern periods of rainfall intensity (monthly, seasonal and annual), calculation of the climatological water balance and establishment of respective indexes and the temporal-spatial compartmentation of climatic units by statistical techniques of Analysis Factorial and Grouping. Once identified the active atmospheric systems and constructed the graphs of Rhythmic Analysis and the characterization of agricultural production, the spatial delimitation and the temporal conditions of the crops were made and defined by using the NDVI (Normalized Difference Vegetation Index) technique. As a result, it was detailed the average climatic conditions for the years 1995/1996 to 2014/2015 and the agricultural years 2004/2005 and 2014/2015 (high and low regional soybean productivity, respectively), in addition to defining the impact on production agricultural. In 2004/2005, a year of high productivity, there were favorable climatic conditions (rain supply and water surpluses in the rainy season) at all stages of phenological development of the crops, as a result of the synoptic configuration and regular performance of the Cold Fronts, Convergence Zones and Continental Equatorial Mass (mEc), in regional rainfall genesis, with better performance of crops located in the climatic transition and higher altitude areas (climate units 2.D.III, 3.PIII, 4.PI and 4.P.II ). The low productivity of the 2014/2015 harvest was caused by the warmest and driest January of the 20 years analyzed, related to the atmospheric blocking in the South-Central Region of Brazil that limited the incursion of frontal systems, the formation of Convergence Zones and the transport of humidity by the mEc, compromising the rainfall volumes and producing water stress in all climatic units, especially in the areas of lower altitude (unit 2.D.II).