RAINFALL VARIABILITY AND RISKS OF DROUGHTS FOR SOYBEAN CULTIVATION IN WEST OF PARANÁ STATE

Droughts periods are extremely harmful to crops yields and, thus, studies which identify the frequency and intensity of these events are relevant for agricultural planning and decision-making. The objective of this study was to carry out the evaluation the variability of rainfall and determine the frequency of dry periods during the soybean cycle, in the West of the State of Paraná. For this purpose, meteorological data from 48 meteorological stations were used. Rainfall variability was analyzed at annual, monthly and 10-day scales, and the frequencies of 10-day dry spells from September to March. There was variability of rainfall in the study area, but with sufficient rainfall for the needs of soybean cultivation. The topography favors the distribution of rainfall in the region of this study. The South region has the highest average rainfall, while the North region has the lowest. The frequencies of dry periods for moving periods of 10 days reached a maximum of 35% between the months of September and March in the region. The lowest risk periods are during the entire month of October, followed by December 10th to January 5th. The greatest risks of dry periods are concentrated in the month of September, due to the irregular beginning of the rainy period. The results can aid the farmer in decision-making to avoid climatic risks.