Farming systems that are both highly productive and minimise environmental harms are critically needed.
Photo: © O.Bexten/Rural 21

Cultivation practices reduce organic to conventional yield gap

Conventional agriculture is ecologically questionable but nevertheless regarded as considerably more productive than organic farming. Researchers in the USA have now examined how big the yield gap is between these forms of cultivation in a meta-study.

Agriculture today places great strains on biodiversity, soils, water and the atmosphere, and these strains will be exacerbated if current trends in population growth, meat and energy consumption, and food waste continue. Thus, farming systems that are both highly productive and minimise environmental harms are critically needed. “If we wish to preserve the Earth’s productivity in the long term, we have to develop and apply sustainable and proven practices as soon as possible,” Lauren Ponisio and her colleagues at the University of California in Berkeley claim. So far, however, organic farming has been regarded as not productive enough to meet the world population’s food demand. “This presents us with a dilemma,” the researchers state. “How can we maintain or enhance food production without sacrificing sustainability?” Previous comparisons demonstrated a plus of 20 to a massive 80 per cent for conventional cultivation.

In  their study, the scientists revisit this topic comparing organic and conventional yields with a new meta-dataset three times larger than previously used (115 studies containing more than 1,000 observations) and a new hierarchical analytical framework that can better account for the heterogeneity and structure in the data. Unlike their predecessors, the scientists excluded distorting results from the simple subsistence economy in developing countries in the study and chiefly concentrated on cultivating methods with comparable knowledge and technology standards.

The study has revealed that organic yields are only 19.2 percent (±3.7%) lower than conventional yields, a smaller yield gap than previous estimates. More importantly, the experts found entirely different effects of crop types and management practices on the yield gap compared with previous studies. For example, they detected no significant differences in yields for leguminous versus non-leguminous crops, perennials versus annuals or developed versus developing countries. Instead, the novel result came up, that two agricultural diversification practices, multi-cropping and crop rotations, substantially reduced the yield gap (to 9 ± 4 % and 8 ± 5 %, respectively) when the methods were applied in only organic systems.

Ponisio and her colleagues hold that this indicates that organic farming can indeed be a fully adequate alternative to conventional agriculture. “Further involvement in agro-ecological research and breeding of suitable varieties for organic farming could even completely close the remaining yield gap for some plants and regions,” says Ponisio. Moreover, she maintains, people will have no other choice in the long term. The researchers believe that switching to sustainable organic farming methods is simply a necessity. “We cannot continue to produce food without taking our soils, our water and our biodiversity into consideration,” Ponisio stresses.

(bild der wissenschaft/wi )

More information:
Lauren Ponisio (University of California, Berkeley) et al., Proceedings of the Royal Society B, doi: 10.1098/rspb.2014.1396