Climate Change Impacts on Regional Maize Yields and possible Adaptation Measures in Argentina.

TRAVASSO, M.I,; MAGRIN G; RODRÍGUEZ G; SOLMAN S.; NÚÑEZ M.

Estambul, Turquía

Conferencia; Global Conference on Global Warming; 2008

University of Ontario

Maize is the second most important crop in Argentina covering roughly 3.6 million hectares with a production close to 22 million tons. Considering maize exports, Argentina is positioned in the second place at the world scale supplying 16% of world’s exports. The Pampas Region is the main contributor to national production (92%) and it includes diverse environmental conditions: from humid-subhumid in the northeast to semiarid in the western bound. As maize is mostly cropped under rainfed conditions it is highly dependent on rainfall occurred during the growing season. Future climatic projections suggest changes in precipitations and temperatures that will affect crops productivity. In this work the impact of future climate on regional maize yields was assessed by means of a crop simulation model considering 12 zones in the Pampas Region regrouped according to the soils, climate and land use. Climatic inputs to the crop model were generated by the regional model MM5/CIMA, developed for 2081-2090 under the SRES A2 and B2, considering grids of 40 km*40 km. The Soil Productivity Index was used to define the aptitude (agriculture, agriculture-livestock, and livestock-agriculture) in each zone and the physicochemical characteristics corresponding to the predominant soil series for each category and zone were used as soil inputs. Crop model runs were carried out under typical crop management conditions with and without considering the fertilization effect of CO2. Results obtained indicate that, without considering the effect of CO2, the impact of future scenarios will be negative in most of the region attaining mean reductions of 9% and 6% under A2 and B2 respectively. However, a great spatial variability was observed and yield changes could range between increases of 46% under B2 and decreases of 17% under A2. Enhancing CO2 would lead to increase maize yields by 19% under A2 conditions and 11% under B2, although negative impacts could still occur. Possible adaptation measures related to changes in sowings and supplementary irrigation were assessed as a way to overcome future negative impacts. Without considering CO2 effects anticipating planting dates by 15-30 days could be beneficial, increasing yields under B2 and reducing loses under A2. Irrigation requirements could on average increase in the central and northern parts of the region and decrease in the southern one. However, if CO2 effects are considered, an overall decrease in water requirements could be expected because of the enhanced crop’s water use efficiency under CO2 enriched environments. Uncertainties related to future scenarios and crop responses to CO2 are also discussed.