摘要：This article discusses the seasonality of the prices of soybeans to producers, from January 2000 to December 2016, in the state of São Paulo (SP). Considering price as the most important variable in commercialization decision of this commodity, the seasonal variation index (IVEP) of soybean marketed in state of São Paulo, Brazil was analyzed, as well as the lower and upper confidence limits (LICP and LSCP), in period of 2000 to 2016. Using time-series concepts and the ARIMA technique, the soybean price trend was analyzed during the period considered with a prices provision of that product was made for the following twelve months in 2017. The results showed that the prices of the bag of soybean varied greatly, both within the same year and over long the period studied (from 2000 to 2016). Due to the higher soybean supply in the first half of each year due to the harvest of the product, the soybean prices are lower during this period and increase during the second semester. In the period from March to May of each year, although the price practiced by the market is lower, historical prices show that the producer can sell his product at a great price, without many risks of losses. The forecast of soybean bag prices for the months of 2017, shortly after the period studied, using the ARIMA model was robust, showing a good performance, with small forecast errors.
