A critical examination of crop-yield data on vegetables, maize (Zea mays L) and tea (Camellia sinensis) for Sri Lankan biofilm biofertilizers

With increasing global interest in microbial methods for agriculture, the commercialization of biofertilizers in Sri Lanka is of general interest. The use of a biofilm-biofertilizer (BFBF) commercialized in Sri Lanka is claimed to reduce chemical fertilizer (CF) usage by ~ 50% while boosting harvest by 20–30%. Many countries have explored the potential of biofilm biofertilizers, but have so far found mixed results. Here we review the BFBF commercialized in Sri Lanka and approved for national use. We show in detail that the improved yields claimed for this BFBF fall within the uncertainties (error bars) of the harvest. Theoretical models that produce a seemingly reduced CF scenario with an “increase” in harvests, although this is in fact not so, are presented. While BFBF usage seems to improve soil quality in some instances, the currently available BFBF promoted in Sri Lanka appears to have negligible impact on crop yields. We also briefly consider the potentially negative effects of large-scale adoption of microbial methods. The manner whereby a poorly-tested but product of biotechnology gained government and institutional acceptance is of global relevance in the rush to adopt new climate-mitigating technologies.