Interannual variability of soybean yield in the argentine pampas and its relationship with synoptic weather types in Southern South America

BETTOLLI, M.L., VARGAS W., PENALBA O

Whisler, Canada

Conferencia; 17 th Conference on Applied Climatology,; 2008

AMS

The Argentine Pampas Region spreads over 600000 square km and is one of the most important crop producing regions worldwide. In particular, soybean is one of the most important crops in the Argentine agriculture jointly with maize, wheat and sunflower. The beginning of the soybean crop cultivation in Argentina was in the early 1960s with ten thousand sown hectares. Nowadays, over 12 million hectares are cultivated, contributing in a high percentage to the global trade of soybean and its by-products. In the region chosen it is often possible to find extreme climate situations, which are persistent in some cases, and which have a significant socio-economic impact. Agriculture is mainly developed without artificial irrigation; therefore, rainfall and its spatial-temporal variability are crucial for successful harvests. Local and daily scale variables depend on the larger scale atmospheric fields, among other conditions. Consequently, an objective classification of daily circulation fields is proposed by using a long database in order to relate these weather types to soybean yield variability in the Argentine Humid Pampas. In order to conduct this study, two datasets were used: on one hand, the soybean yield series of 58 provincial departments supplied by Argentina’s Secretaría de Agricultura, Ganadería, Pesca y Alimentación in the period 1973-1999. These provincial departments are located in the region of interest. This work focuses on yield (estimated as the ratio of total production to area harvested) as an indicator of a crop’s vulnerability to climate variability. Previous studies revealed that soybean yield shows spatial coherence at the local scale. For this reason, the following index was considered in order to characterize each soybean campaign in a regional way, NYI: number of provincial departments with negative soybean yield anomaly.