Associação entre a produção da soja em Marechal Cândido Rondon-PR e o fenômeno el Niño/oscilação Sul: análises episódicas

Abstract

Despite significant technological advancements, Brazilian agriculture remains intrinsically dependent on climatic conditions, with soybean being one of the most vulnerable crops. This research aimed to evaluate the influence of rainfall variability on soybean yields in the municipality of Marechal Cândido Rondon – PR, covering the period from the 2009/2010 to 2022/2023 harvest seasons. The methodology adopted a quanti-qualitative approach based on episodic analysis, correlating daily precipitation data and crop phenological phases with productivity indices that showed significant deviations (above or below one standard deviation from the historical average). The role of the El Niño/Southern Oscillation (ENSO) phenomenon during these periods was also investigated. The results demonstrated that the total accumulated rainfall volume during the growing season is not the primary indicator of productive success. Instead, the temporal distribution of precipitation specifically the occurrence or absence of rain during the critical stages of flowering and grain filling (December and January) proved to be the determining factor for local yields. It was observed that a regular distribution of rain during these critical months was capable of neutralizing the drought effects expected in La Niña years, resulting in high yields; a phenomenon discussed here as the "La Niña paradox." Conversely, prolonged dry spells during the reproductive stage were decisive in crop failures, even in years with apparently adequate total rainfall volumes. This study concludes that the quality of episodic rainfall distribution supersedes the generic influence of ENSO, suggesting that short-term monitoring of water conditions is more strategic for local producers than exclusive reliance on seasonal climate forecasts.