Global Maize Project in Argentina: Balcarce, Buenos Aires

A long-term field experiment was established at Balcarce, Buenos Aires, in the 2009/10 growing season. The crop rotation was maize-wheat/double cropped-soybean, with both crop phases occurring each year. Soil samples were collected during site establishment to characterize initial conditions, especially the carbon content in the entire soil profile. Treatments included current farmer practice (FP) and Ecological Intensification (EI) practice. Treatments differed in cultivars, planting dates, pest and weed control, or nutrient management practices. Maize crop in the 2011/12 season grew under dry climatic conditions, which affected the expression of an improved potential yield in the EI treatments. Maize yields were 4.98 t/ha, and 6.57 t/ha for FP and EI treatments, respectively - a significant difference of 32%. Wheat crop was less affected by the dry season, and wheat yields were 3.94 t/ha for FP and 5.23 t/ha for EI, which again was a significant difference of (+33%). Double cropped-soybean was planted immediately after the wheat harvest in early January, but the crop was lost because of the severe dry conditions during January.

Considering the first three years and the three crops involved in the maize/wheat/double cropped soybean, the EI treatment significantly improved water use efficiency (determined as kg grain per mm of ET) over FP, but the two treatments did not differ much in the capture of water (ratio of ET/total precipitation). The EI treatment also showed higher N use efficiency and N removal and less negative N balances, but lower partial factor productivity of N as compared to the FP treatment for the maize crop. Preliminary determinations of N₂O-N emissions in the 2011/12 maize crop showed similar emission rates in the FP and EI treatments. Satellite field experiments evaluating hairy vetch as cover crop for maize showed a significant N supply from the winter legume to the summer crop without negative effects on yield even in dry years. IPNI-24