The environmental and biodiversity benefits of organic farming are widely recognized, but there is still controversy about the effects of organic production methods on the nutritional composition of food and human health. In the first part of this article therefore, we critically review the evidence that organic farming methods improve the nutritional quality of food crops. Moreover, we summarize our current understanding of how quality gains are linked to the implementation of the “innovations” introduced into conventional crop production during the intensification or “green revolution” of agriculture over the last 100 years. In the second part of the article, we critically review the evidence for the range of health benefits related to organic food consumption. Specifically, we describe and discuss the results from: (i) dietary intervention studies which have found that organic food consumption substantially reduces pesticide exposure in humans and affects feed intake, growth, hormone balances and immune system responsiveness in animal models; (ii) human cohort/epidemiological studies which have reported significant positive associations between organic food consumption and the lower incidence of a range of diseases including obesity, metabolic syndrome, cancer, hypospadias, pre-eclampsia, eczema and middle ear infections in infants; (iii) interactions and trade-offs between diet (e.g., whole-grain, fruit and vegetables and reduced red-meat consumption) and food types (organic versus conventional) concerning public health and future food security. The article also identifies knowledge gaps and highlights the need for (i) long-term, factorial field experiments to understand the relative effects of agronomic and pedoclimatic drivers on crop quality and safety, and (ii) clinical trials and additional human cohort studies to confirm the positive health outcomes linked to organic food consumption. The main conclusions from our review are that there is growing evidence that (i) agricultural intensification has resulted in a reduction in the nutritional quality of food and the sustainability of food production, and (ii) organic farming practices not only improve food quality and human health, but also food security. This is particularly true where current nutritional guidelines (increasing whole-grain, fruit and vegetable products, while reducing red-meat consumption) are implemented.

Climate change in southern Africa is predicted to be severe, and animal agriculture will suff er the most. However, there exist wild legumes that have survived under harsh environmental conditions and contribute to a varied diet for the grazing ungulates. This study tested the chemical composition of four wild herbaceous legumes each from Tswapong and Ngamiland districts in Botswana (Chamaecrista abscus, Chamaecrista rotundifolia, Crotalaria sphaerocarpa, Tephrosia lupinifolia, Tephrosia purpurea, Indigofera sp., Zornia glochidiata.). These plant species were previously found to fi x nitrogen in the soil by the SASSCAL research Task 316, and the plant selection was also guided by informed focus discussions with farmers. For Tswapong the results show that C. rotundifolia and T. purpurea had the highest level of crude protein (CP) while Z. glochidiata had the least CP. In vitro gas production showed high gas yield for Z. glochidiata, and a small volume of gas was produced by T. lupinifolia. Condensed tannins (CT) were higher for Z. glochidiata and C. rotundifolia but lower for T. purpurea and T. lupinifolia. CT were at similar concentration for C. rotundifolia and Z. glochidiata. No relationship was detected between condensed tannins and crude protein. With regard to samples from Ngamiland, there was no diff erences among plant species for acid detergent fi bre (ADF), whereas other parameters measured were signifi cantly diff erent among the legume plants. Indigofera sp. had the highest CP, while Crotalaria sphaerocarpa had the lowest. In general, levels of crude protein were diff erent among the legumes investigated but overall were higher than in natural grass, indicating their importance in providing protein to grazing ungulates in rangelands. Their high protein content also suggests the plants' potential as protein supplements if domesticated as fodder crops. However, palatability, toxicity, and intake should be tested in future studies before any recommendations are made.Resumo: Prevê-se que as alterações climáticas no Sul de África sejam severas, e a agricultura animal será a que irá sofrer mais. Porém, existem leguminosas silvestres que sobreviveram sob condições ambientais severas e contribuem para uma dieta variada dos ungulados de pastagem. Este estudo testou a composição química de quatro leguminosas herbáceas silvestres, cada uma dos distritos de Tswapong e Ngamiland no Botswana (Chamaecrista abscus, Chamaecrista rotundifolia, Crotalaria sphaerocarpa, Tephrosia lupinifolia, Tephrosia purpurea, Indigofera sp., Zornia glochidiata). Foi previamente descoberto pela equipa de trabalho 316 do SASSCAL que estas espécies de plantas fi xam azoto no solo, tendo a selecção de plantas sido também guiada por discussões de foco informado com agricultores. Para Tswapong, os resultados mostram que C. rotundifolia e T. purpurea tiveram os níveis mais elevados de proteína bruta (CP), enquanto que Z. glochidiata teve a menor quantidade de CP. In vitro, a produção de gás mostrou um elevado rendimento pela Z. glo...