Comparing apples with oranges

A meta-analysis of agricultural systems shows that organic yields are mostly lower than those from conventional farming, but that organic crops perform well in some contexts, and that the factors that limit organic yields need to be better understood to enable meaningful comparisons between the rival forms of agriculture.

Abstract

A meta-analysis of agricultural systems shows that organic yields are mostly lower than those from conventional farming, but that organic crops perform well in some contexts. Agricultural scientists discuss whether the conclusions of the study should change farming practices and management. See Letter p.229 There is much debate over the relative merits of conventional farming, which has a large environmental impact on the land it uses, and organic farming, which may require greater land use for the same yield. Central to this debate — and the subject of some controversy — are the relative yields of the two farming systems. Seufert et al. present a meta-analysis of the available scientific literature on organic-to-conventional yield comparisons, and conclude that organic yields are indeed lower, but that the difference varies substantially according to crop type, growing conditions and management practices. For instance, for perennials grown on favourable soils organic yields are just 5% lower than conventional yields, but the yield difference between the most comparable conventional and organic systems is as high as 34%. The authors conclude that the factors that limit organic yields need to be better understood to enable meaningful comparisons between the rival forms of agriculture.