Impacto do fenômeno ENOS na demanda e deficiência hídrica do milho em terras baixas do RS

Abstract

This thesis aimed to analyze the impacts of El Niño and La Niña phenomena on the water behavior of maize in the lowlands of Rio Grande do Sul, Brazil, focusing on two complementary approaches: estimating crop water demand and evaluating crop water deficit. Two studies were conducted using historical climate data (2000–2024), phenological simulations of the P3016VYHR cultivar, crop evapotranspiration (ETc) calculations, and soil water balance based on the Thornthwaite & Mather (1955) and CN-SCS models. The analyses considered different sowing dates, respecting regional thermal constraints. The results showed that crop water demand ranged from 600 to 1000 mm, with the highest values observed during La Niña years, especially in municipalities such as Bagé and Santana do Livramento. These years also exhibited the highest water deficits, particularly during the reproductive phase. Conversely, El Niño years showed lower water demand and deficits, especially for late sowing dates. The integration of crop water demand and deficit results highlights the need for water management strategies adapted to climate patterns and sowing windows, aiming for greater efficiency in water use and increased resilience of agricultural systems in the face of interannual climate variability.