Global Maize Project in Argentina: Balcarce, Buenos Aires

A long-term field experiment was first established at Balcarce, Buenos Aires, Argentina in the 2009/10 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. Treatments 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 (or barley)/double cropped soybean rotation, adding a third phase to the experiment.

Climatic conditions were normal during the 2016/17 season. Maize yields were significantly higher (+18%) under EI (9.2 t/ha) than under FP (7.8 t/ha). Barley was the winter crop this season, and grain yields were 5.1 t/ha in FP and 6.3 t/ha in EI treatments with a significant difference of +23%. Double-cropped soybeans were not planted due to severe drought in January 2017.

Summarizing the first eight years of this field experiment, grain yields were 17% and 42% higher in EI than FP for maize and wheat (or barley), 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.