Caracterização da estação de cultivo em Alagoas: análise temporal e espacial

Abstract

The study of agroclimatologicals aspects of a given is fundamental for the establishment and development of economical activities of the agricultural sector. The Brazilian Northeast, located between 01°S to 18°S and 35°W to 47°W, presents high temperature along the whole year in contrast the great temporal and spatial variability of the rains. The objective of this research is to determine the occurrence of pluvial and decendial precipitation for 25%, 50% and 75% of probability using the method of percentis and relating the characteristics of the cultivation station in the state of Alagoas. Thhree methods were selected to accomplish the objective, the médium (the pluvial mean precipitation) method, the probable precipitation of 20 mm and the method of probable precipitation to 75% of probability and evapotranspiration. Another aim of the study is to relate those characteristics with the productive cycle and the hydric demands of the cultures. The pluvial precipitation data analysed in this work were obtained during the period of 1913 to 1985 along 36 cities of Alagoas distributed in climatic microzones (Countries, Coast, Forest and Rural). The results indicate that the place of the Country they stand out Água Branca, Mata Grande and Traipu as presenting period raining periods with the probable decidial of 20 mm to 75% probability. The cities of the Coast, Forest Zone and Rural present decendial period with probable rain to 75% of probability. The analysis of the most representative cultivation, was the one with a completed period of climatological data series (1913 to 1985). It tends to be the most significant sample of the climatology for the studied region. The most suitable method for defining the characteristics of the cultivation station is the one that considers the probable decendial rain with 75% of more probability of the evapotranspiration, because the risk of raining at the Begin of the period is minimized. The relationship between the demand mean hydric of the culture (bean, corn, cotton and soy) with the mean hydric regional reserve was adjusted for all the áreas. However the 75%, of probability considered for some country West áreas of Alagoas have not showed characteristics of the grow station, that is, the agro-cultivation under rainfed condition occurs with 25% probability.