Analysis of farming systems establishes the low productivity of organic agriculture and inadequacy as a global option for food supply

Although generally presented otherwise organic agriculture (OA) is much less productive per unit area of land than conventional agriculture (CA) for two reasons. First, because the yields of individual crops grown in OA are generally less than those in CA. Second, because the reliance in OA on organic fertilizer, i.e. plant and animal manures, requires that additional land grown to legumes to provide nitrogen (N) must be included in the calculation of relative productivity. Compared with the commonly used crop-yield ratios of OA/CA productivity of 0.75–0.81, new analyses of the relative food productivity of various crop- and crop-livestock systems presented here report lower values in the range 0.30–0.74 with many less than 0.5. The OA/CA system ratios are higher in less favourable areas and lower in productive areas more suited to crop intensification. The implications for food security and nature conservation place OA at a disadvantage because transformation to OA would require substantial expansion of agricultural land, e.g. an OA/CA ratio of 0.5, would require a doubling of area under OA to maintain equal production. By contrast, higher yields in CA reduce the demand for land in agriculture and consequently can conserve land for nature.