Efeitos climáticos no desenvolvimento e produção da cultura do milho e nas operações mecanizadas em um LATOSSOLO VERMELHO Distrófico típico

Abstract

The sustainability and efficiency of agricultural production systems depend on a deep understanding of edaphoclimatic interactions, especially in the face of increasing climate variability. This thesis aimed to evaluate the impacts of global climate change on irrigation demands and maize crop yield, as well as to determine the temporal probability for executing mechanized operations in a typical Dystrophic Red Latosol in the municipality of Lavras, MG. The research was structured into two complementary methodological axes. In the first axis, the impacts of the Coupled Model Intercomparison Project Phase 6 (CMIP6) projections, obtained through the MIROC6 model and corrected by the Quantile Delta Mapping (QDM) algorithm, were quantified on the water balance and yield of both main (safra) and off-season (safrinha) maize crops. Simulations were conducted using the AquaCrop software under the historical reference climate and the shared socioeconomic pathways SSP245 (moderate mitigation) and SSP585 (high emissions) up to the year 2099, evaluating temporal dynamics using Mann-Kendall and Kruskal-Wallis non-parametric tests. In the second axis, the probability of occurrence of workable days was estimated based on a 30-year historical climate series (1995 to 2024), integrating the daily sequential water balance method with soil physical properties and probability theory through first-order Markov chains. The results of the first article evidenced asymmetric ecophysiological responses between seasons: for the main crop, extreme forcing (SSP585) imposed severe rainfall suppression and thermal stress that shortened phenology and lowered median yield to 11,710.0 kg/ha, with a continuous degradation trend, whereas the off-season crop exhibited high volatility with recurrent reproductive failures and structural collapses, while the SSP245 scenario preserved system productivity stability. The second article attested to a severe temporal restriction for agricultural traffic, where summer excess rainfall raised the relative soil water storage (RSWS) above 90% (plastic state with compaction risk), and late-winter drought reduced RSWS below 40% (hard consistency making tillage unfeasible), concentrating the primary friability window in the autumn (April and May) with high internal fragmentation. It is concluded that the combination of severe climatic forcings and restricted operational windows requires overcoming static agricultural calendars, demanding a mandatory transition to precision adaptive irrigation systems and the dynamic resizing of machinery fleets to optimize short workability intervals, supporting the formulation of proactive public policies for agricultural adaptation and natural resource conservation.