The main factor associated with soybean yield decline in Rio Grande do Sul (RS) is the irregular distribution of precipitation, with the El Niño Southern Oscillation (ENSO) being the main responsible for the precipitation variability. The objective of this work was to analyze the relationship between climatic indicators associated to ENSO and soybean yield in the State. Soil productivity series from 87 municipalities were evaluated between 1984 and 2013. These series were ordered in three groups of similar behavior (high, medium and low productivity). The mean profiles of these groups were correlated with Sea Surface Temperature anomalies in the Niño 3.4 region, the Southern Oscillation Index (IOS) and the ENSO Index Multivariate (MEI) with different lags. IOS and MEI showed higher correlations with productivity in periods of higher water requirement of the crop. Episodes of El Niño have been associated with increased productivity and in situations of neutrality and La Niña the influence of the phenomenon is less evident. Moreover, the absence of a significant correlation in the time of crop preparation and the beginning of planting evidences the need to include new indexes in the discussions of agricultural planning in the State.
