Global Maize Project in Argentina: Balcarce, Buenos Aires

A long-term field experiment was established at Balcarce, Buenos Aires, Argentina in the 2009 to 2010 growing season under a maize-wheat/double cropped-soybean rotation, with both crop phases occurring each year. The treatments included current Farmer Practice (FP) and Ecological Intensification (EI) practice. For the treatments, they differed by cultivar, planting date, pest and weed control, and nutrient management practice. In the 2014/15 season, the crop rotation was modified to a maize full-season soybean-wheat/double cropped soybean rotation, adding a third phase to the experiment.

Climatic conditions were normal during the 2015/16 season. Maize yields were 9.5 t/ha and 9.1 t/ha in FP and EI treatments, respectively. There was a non-significant difference due to a short dry period near anthesis, which affected the early planted EI maize. Wheat yields were 3.8 t/ha in FP and 7.7 t/ha in EI treatments with a significant difference of +100%. Full-season soybeans yielded 3.5 and 4.6 t/ha in FP and EI treatments, respectively and had a significant difference of 30%. The double-cropped soybean was not planted due to severe drought in January 2016.

Summarizing the first seven years of this field experiment, grain yields were 17% and 46% higher in EI than FP for maize and wheat, respectively. Results from the first six years have shown that EI resulted in more efficient water use (kg grain/ha/mm) and productivity (kg grain/total annual precipitation) than FP. Nitrogen (N) physiological use efficiency (kg grain/kg N uptake) in maize was not reduced with EI, despite the increase in N uptake. Partial factor productivity of N fertilizer (PFP-N) was high, averaging 185 and 159 kg maize/kg N for FP and EI, respectively. Partial N budgets (PNB) have been negative, averaging -49 and -26 kg N/ha for FP and EI, respectively. These values of PFP-N and PNB would indicate that soil N is being depleted and that N fertilizer rates would need to be increased for sustainable production.