Associations between grain crop yields in central-eastern Argentina and El Nino-Southern Oscillation

Associations are investigated between yields of major crops in the Argentine Pampas (central-eastern Argentina) and EI Nino-Southern Oscillation (ENSO) phase. For maize and sorghum, higher (lower) yield anomalies occur more frequently than expected by chance alone during warm (cold) ENSO events. For both crops, the depression of yields during cold events is, on average, larger and less variable than yield increases are during warm events. A yield decrease during cold events also is observed in soybean yields, although the effect of warm events is not statistically significant. There is a marginally significant tendency for low sunflower yields to occur less frequently than expected during cold events. Wheat, the only winter crop considered, did not show an association with ENSO. Precipitation anomalies during October-February (the period with strongest ENSO signal in the Pampas) are summarized through principal component analysis. Precipitation anomalies during November-January are significantly correlated with maize, sorghum, and soybean yield anomalies. In turn, those precipitation anomalies show a distinct ENSO signal. Late spring-early summer precipitation, then, appears to mediate associations between ENSO phase and yields of maize, sorghum, and soybean in the Pampas.