A study finds a persistent yield gap, which is the difference between crop performance in research plots and farm fields, in biologically managed systems that are not apparent in conventionally managed systems. A commonly cited solution for increasing food production for a growing global population is closing yield gaps, because yields are typically lower in farm fields than in research plots. In a study comparing yields of different cropping systems at different scales, Alexandra Kravchenko and colleagues grew crops for 6 years with conventional, low-input, and biology-based management techniques on farm-sized fields, large 1-hectare research plots, and small 0.02-hectare research plots. Field-scale yields matched plot-scale yields for conventional management but tended to be lower than plot-scale yields for low-input and biology-based or organic managements. For maize, soybeans, and wheat, low-input management produced similar yields to conventional management in research plots, but yielded less than conventional management in farm-sized fields. The findings suggest that conventional management is more resilient to the variable climate and soil conditions of farm-sized fields than alternative practices, which are especially reliant on timely interventions to address weed and soil fertility problems. According to the authors, the results underscore the importance of developing new technologies to close yield gaps using biological or organic management. - Read at PNAS.org
Article #16-12311: “Field-scale experiments reveal persistent yield gaps in low-input and organic cropping systems,” by Alexandra N. Kravchenko, Sieglinde S. Snapp, and G. Philip Robertson.