The comparative productivity of organic agriculture

Nitrogen cycling in a hypothetical scenario of generalised organic agriculture in the Seine, Somme and Scheldt watersheds

“…This procedure implicitly assumes that organic farming techniques produce yields similar to conventional agriculture, when similar levels of total (organic and mineral) fertilisation are applied. A number of studies have compared the yield of organic and conventional agriculture for different crops within the same pedo-climatic context in industrial countries Stanhill 1990): they concluded that the former is approximately a mean 10% lower than the latter. This can be explained by lower fertilisation as well as by a lower control of pests and adventices.…”

“…This paper explores a more radical scenario consisting in a complete conversion of the agriculture of the three basins to organic agriculture (OA), defined, according to Stanhill (1990), as agricultural production practices ''which seek to minimize the flow of inputs and outputs which sequester non renewable resources across the boundaries of the Table 1 Estimation of Anthropogenic N-autotrophy and heterotrophy of the Seine, Somme and Scheldt watersheds in the current situation (a) (as described in Billen et al 2009a) and according to the two scenarios of shifting to organic agriculture of the entire present agricultural area (b and c) 3S Seine, Somme and Scheldt watersheds production area'', thus excluding the use of synthetically compounded fertilisers and the importation of livestock feed. We are aware that such a scenario has a low level of short-term socio-economic realism.…”

Diversification practices reduce organic to conventional yield gap

“…Although the terms 'organic' and 'sustainable' agriculture are not equivalent, studies of organic agriculture have revealed better performance than conventional systems on some (but not all) sustainability metrics, including species richness and abundance, soil fertility, nitrogen uptake by crops, water infiltration and holding capacity, and energy use and efficiency [26][27][28][29][30][31][32]. Here, we provide the most comprehensive calculation of the yield gap between organic and conventional agriculture, building on the work of others [33][34][35][36].…”

“…Second, each of the above studies used different analytical methods to combine the data across the different substudies. For example, the reviews of de Ponti et al [35], Stanhill [33] and Badgley et al [34] did not account for the sampling variance within studies, which is the recommended practice to deal with heteroscedasticity in the sample of studies [38]. Seufert et al's [36] meta-analysis, while accounting for sampling variance, combined nested data (e.g.…”

“…Early reviews comparing organic to conventional agriculture found yield gaps of 8 -9% in developed countries [33,34], but yield gains of as much as 180% in developing countries. Two recent meta-analyses, however, found organic yields to be 20 -25% lower than conventional yields [35,36].…”