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 soil carbon content throughout the entire soil profile. Treatments included current farmer practice (FP) and ecological intensification (EI) practices. Treatments were created through the use of different cultivars, planting dates, pest and weed control, and nutrient management practices.

Grain yields in the 2014-15 season showed significant differences between FP and EI treatments for maize, wheat and double-cropped soybean. Maize yields were 8.6 t/ha and 11.7 t/ha for FP and EI treatments, respectively - a significant difference of +36%. Wheat yields were 3.6 and 4.0 t/ha; and double-cropped soybean yields 3.0 and 3.6 t/ha for FP and EI treatments, respectively. Cropping intensification (i.e., inclusion of a cover crop before maize) significantly decreased maize grain yield (-27%).

Summarizing the six years of field experiments, the EI treatment has significantly improved maize and wheat yields (+43% and +13%, respectively), but EI has not affected soybean yields. Water use efficiency (determined as kg grain per 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 N use efficiency. Partial factor productivity of N fertilizer (PFP-N) were high for both treatments, 104 and 109 kg maize per kg fertilizer N for FP and EI, respectively. Partial N budgets (PNB) have been negative, averaging -27 and -15 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 to maintain long-term sustainability.