Agroclimatic constraints for rainfed agriculture in the Bolivian Altiplano

The agroclimatic potential was analyzed for four locations in the Bolivian Altiplano (highland) and used to delineate regional agroclimatic variability. A downward trend from North to South was observed in temperature, the onset and the duration of the rainy season, indicating that climate-wise crop production is only possible during 5 months in the north and less than 4 months in the south. A clear negative relationship between the day of onset and the duration of the rainy season was detected. Even in years with 50% dependable precipitation, the cumulative rainfall depth is less than the reference evapotranspiration calculated by the Penman-Monteith equation, and the erratic occurrence of long dry spells seriously affect crop growth. The adverse climatic conditions call for an agroclimatic-based action plan to improve the agricultural output of a region blessed with high and fairly constant levels of radiation. Actions worth to be considered are the introduction of deficit irrigation, protected intensive cropping, and the cultivation of crop species and varieties that require a short growing season, tolerate low water availability, and are resistant to early or late frosts.