Épocas de semeadura da soja com base em risco climático e potencial produtivo em Uruçuí – PI

Abstract

Soybean stands out as the main oilseed crop cultivated in Brazil; however, it still faces several constraints that limit its full productive potential, especially those related to climatic conditions. To mitigate these risks, the proper definition of sowing dates is essential to ensure high crop yields, particularly in regions with high climate variability, such as Uruçuí, Piauí State. The objective of this study was to evaluate soybean sowing dates in Uruçuí based on climatic risk and productive potential. The research was conducted as a case study. Data were obtained through documentary analysis and the application of mathematical models, considering historical meteorological series and production costs for the municipality of Uruçuí, as well as soybean cultivars recommended for the studied region. Water availability was the main factor determining sowing dates; the decendial periods from July I to October II were considered unsuitable due to the low ratio between actual evapotranspiration and crop evapotranspiration (ETR/ETc). Yield and economic viability varied according to water availability, with the reproductive stage being the most sensitive to water deficit. Cultivars belonging to maturity group II showed superior performance and a higher probability of covering production costs due to their longer phenological cycle. The most favorable sowing windows were concentrated in October III, November II and III, and December I. Overall, suitable sowing dates extended from October III to February I for both maturity groups (I and II), with an extension to February III for group II cultivars. Compared with the Agricultural Climate Risk Zoning, the study demonstrated the possibility of anticipating sowing dates and differentiating management recommendations according to the maturity group of the cultivars