Association between El Nino Southern Oscillation and corn yield in Rio Grande do Sul State

The high interannual variability of corn yield in Rio Grande do Sul State is determined mostly by the variability of rainfall, which is mainly associated to El Nino Southern Oscillation (ENSO). Current availability of seasonal ENSO forecasts shows the possibility of using this information to minimize losses and maximize yield. However, it is necessary to assess the vulnerability of corn yield to this phenomenon. The objective of this work was to quantify the association between corn yield and rainfall variability due to ENSO. In order to perform the analysis, historical series of yields, monthly rainfalls, ENSO (El Nino and La Nina) phases, Sea Surface Temperature (SST) in equatorial Pacific, and the Southern Oscillation Index (SOI) were used. Results show that there is a strong trend for El Nino to favor corn crops, providing opportunities for high yields, while in years when La Nina occurs there is a high frequency of low yields. The rainfall most associated with corn yields is the integrated one from October to March. This information is useful for decision making as to crop management alternatives when there is a forecast of El Nino or La Nina.