Global Maize Project in Argentina: Balcarce, Buenos Aires

A long-term field experiment was 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. 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 has been 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 2014/15 season. Maize yields were of 7.4 t/ha and 9.2 t/ha in FP and EI treatments, respectively - a significant difference of 24%. Wheat yields were 4.6 t/ha in FP and 5.2 t/ha in EI treatments - a significant difference of +14%. Full season soybeans yielded 2.9 and 3.3 t/ha in FP and EI treatments, respectively - a significant difference of 12%. No differences were found in yields of double-cropped soybean, 1.3 t/ha in both FP and EI treatments.

Summarizing the first six years of this field experiment, EI resulted in higher maize and wheat yields and more efficient water use (kg grain/ha/mm) than FP. Nitrogen physiological use efficiency (kg grain per kg N uptake) in maize was not reduced with EI despite the increase in N uptake, and water productivity (kg grain/total annual precipitation) was increased with EI. Partial factor productivity of N fertilizer (PFP-N) was high, averaging 185 and 159 kg maize per kg fertilizer 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.