Impacto das mudanças climáticas sobre o rendimento do milho (zea mays) em sequeiro na bacia do Rio Limpopo

Abstract

The Mozambican part of the Limpopo River Basin, located in the southern part of the country, specifically in the province of Gaza, is characterized by the occurrence of low yields of rainfed maize, conditioned essentially by the irregular and erratic distribution of precipitation. This trend has been observed since the end of the 18th century, being essentially conditioned by the variability and climatic changes that were observed, with the consequent increase in food insecurity in the region. Thus, the study of precipitation behavior in the past (1981-2000) and in the future (2081-2100) is essential to assess its impact and propose strategic adaptation measures on rainfed corn production in the Limpopo River Basin in particular the districts of Xai-Xai and Chókwé. To reach the objective, daily rainfall, reference evapotranspiration and temperature data for the past (1981 to 2000) and future (2081 to 2100) were used for the districts of Xai-Xai and Chókwé, obtained through the models CSIRO (dry scenario) and IPSL model (wet scenario), for later simulation of yields, in the Aquacrop 4.0 model. considering the cultivation in sandy and clayey soils dominant in the Limpopo River basin. The results showed that there were no significant differences in annual precipitation in the CSIRO model, in the district of Chokwé, as well as in the district of Xai-Xai. However, significant increases in annual precipitation were projected by the IPSL model, in the district of Chokwé (23%), as well as the district of Xai-Xai (29%). The CSIRO and IPSL models, in both districts, showed significant changes with increases in the maximum, minimum temperature and reference evapotranspiration. In the Xai-Xai district as well as in Chokwé, in the CSIRO and IPSL models, there were no significant differences in sowing dates. The combination of the factors of mulch management, fertilizers and water conservation, provided greater yields, since this increases the moisture in the soil and reduces the evaporation of water in the soil, increasing the amount of water for transpiration of the crop. (TRADUÇÃO NOSSA)