Environmental controls of lucerne [Medicago sativa L.] growth across a climatic and edaphic gradient

Lucerne is one of the most valuable forage species because of its high productivity and nutritional traits. However, the knowledge of spatio - temporal variability and environmental controls of its growth generated from the simultaneous study of several sites and throughout several years is extremely scarce. Five - year biomass data were analyzed from four rain fed sites located across a climatic and edaphic gradient in Argentina. The aims proposed were to characterize annual and seasonal lucerne growth, to analyze environmental controls of spatial and temporal growth, and to compare water use efficiency (WUE) among sites. Annual growth differed significantly among sites, ranging between 7,514 and 14,262 kg DM/ha. This range at the spatial scale was mainly explained by variations in annual rainfall and WUE among sites. Seasonal growth depended on incident radiation and actual evapotranspiration. Interannual variability of lucerne growth was explained by precipitation occurred during the growing season in the driest sites, on sandy soils with less water retention capacity. Knowing the sources of variability of lucerne growth, would allow developing more efficient livestock management due to less uncertainty on the forage production dynamics.