Caracterização agroclimática e análise do rendimento agrícola do Estado do Maranhão, Brasil.

Abstract

The agroclimatic conditions predominant on a particular region, especially during growing season, are responsable for the agricultural yield variability in the cultivated areas. Considering this premise, this study aimed, by multivariate and geostatistical methods, to characterize the State of Maranhão is relation to climatic variables of interest for agriculture, to analyze the spatial variability of rainfall and its regionalization to create indicators, consisting of agroclimatic and oceanographic variables, to evaluate empirically the soybeans, corn and rice yields in the major producing regions. The results showed that the spatial variability of monthly precipitation can be detected and modeled in the State of Maranhão, been marked by geographical monthly trend and anisotropy in different directions and degrees in all months except January and September which showed standard isotropy. The spatial distribution of rainfall showed that the atmospheric systems responsible for producing rain do not happen with the same intensity in the different regions of the state. The regional rainfall differences were detected, defining ten homogeneous regions, covering areas with specific physiographic features, showing the dominant atmospheric systems in the state. The characterization of these regions in relation to the growing season and water balance confirmed the regional differences in the state. The technique of principal component analysis was effective in identifying ideals indicators for assessing the analysis of soybeans, corn and rice crops in the major producing regions, where the proposed empirical models showed good adjust, based in the coefficient of the regression adjusted e index of the Willmott (1985).