Global Maize Project in Argentina: Oro Verde, Entre Ríos

This long-term maize-wheat/double cropped-soybean field experiment was established in 2009 at Oro Verde, Entre Ríos, Argentina. Soil samples were collected during site establishment to characterize initial conditions, especially the soil carbon content throughout the soil profile. Treatments included current farmer practice (FP) and ecological intensification (EI) practices. The treatments were created through the use of different cultivars, planting dates, pest and weed control, and nutrient management practices.

Grain yields in the 2016-2017 season showed significant yield differences between FP and EI treatments for maize and wheat, but not for double-cropped soybean. Maize yields were 6.8 t/ha and 8.4 t/ha for FP and EI treatments, respectively, with a significant difference of +23%. Wheat yields were 3.1 and 4.6 t/ha (+46%); and double-cropped soybean yields were 3 and 3.4 t/ha for FP and EI treatments, respectively. Cropping intensification (i.e., inclusion of a cover crop before maize) did not affect grain yields.

Summarizing the eight years of field experiments, the EI treatment has significantly improved maize and wheat yields (+43% and +22%, respectively), but EI tended to increase double-cropped soybean yield by just 8%. Water use efficiency (determined as kg grain/ha/mm of evapotranspiration or ET) improved under EI over FP, but the treatments did not differ much in the capture of water (ratio of ET/total precipitation). The EI treatment had higher physiological nitrogen (N) use efficiency. Partial factor productivity of N fertilizer (PFP-N) was high for both treatments, and partial N budgets (PNB) have been negative. 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 to maintain long-term sustainability.