Assessment of the Effect of Climate Change on the Productivity of Rainfed Maize (Zea mays L.) Using Crop Growth Model AquaCrop in Central Mexico

Rainfed agriculture in Mexico is characterized by the threat of crop failure due to multiple stress factors, the most significant of which are adverse climatic conditions. Maize is one of the most important staple crops, used for both consumption and livelihoods. However, climate variability and change are threatening to exacerbate yield gaps and increase variability in yields from one year to the next, particularly due to changes in temperature and rainfall. Therefore, using the CMIP6 GCM ACCESS-ESM1-5 and the AquaCrop model, the impacts of climate change on maize yields were assessed for the SSP2-4.5 and SSP5-8.5 scenarios in the study area known as the Atlacomulco Rural Development District (ARDD), considering a projection towards three horizons, 2021–2040, 2041–2060, and 2061–2080, compared to a historical period (1985–2020). Through the metrics used for the validation of the AquaCrop model, it was possible to determine that the simulated values were satisfactorily adjusted to the yields measured by the Agricultural and Livestock Information System (SIAP) from 2003 to 2020 (0.7 ton ha−1 < RMSE > 1.3 ton ha−1; 0.1 < d-index > 0.8; 0.2% < NRMSE > 0.7%; −0.7 < EF > 0.3 and 0.4 < r > 0.8). Future climate change estimates in the ARDD indicate that the average temperatures could increase by between 1.8 and 2.8 °C, while the effective precipitation tends to decrease by up to 7.5−11% through SSP2-4.5 and SSP5-8.5, respectively, during the agricultural cycle. The model results indicate that by the year 2080, maize production in the ARDD will increase from 3.5 ton ha−1 (historical) to 4.2 ton ha−1 and 4.4 ton ha−1, which represents an increase of 21% and 24% for SSP2.4.5 and SSP5-8.5, respectively.