A/HRC/16/49 promotion of agricultural biodiversity at ecosystem, farm system and farmer field levels, which is materialized by many agroecological approaches.49 Following Hurricane Mitch in 1998, a large-scale study on 180 communities of smallholders from southern to northern Nicaragua demonstrated that farming plots cropped with simple agroecological methods (including rock bunds or dikes, green manure, crop rotation and the incorporation of stubble, ditches, terraces, barriers, mulch, legumes, trees, plowing parallel to the slope, noburn, live fences, and zero-tillage) had on average 40 per cent more topsoil, higher field moisture, less erosion and lower economic losses than control plots on conventional farms. On average, agroecological plots lost 18 per cent less arable land to landslides than conventional plots and had 69 per cent less gully erosion compared to conventional farms.50 29. More frequent and more severe droughts and floods can be expected in the future; agroecological modes of farming are better equipped to support such shocks. The agroforestry programme developed in Malawi protected farmers from crop failure after droughts, thanks to the improved soil filtration it allowed.51 Indeed, on-farm experiments in Ethiopia, India, and the Netherlands have demonstrated that the physical properties of soils on organic farms improved the drought resistance of crops.52 30. In addition, the diversity of species and of farm activities that agroecological approaches allow are ways to mitigate risks from extreme weather events, as well as from the invasion of new pests, weeds and diseases, that will result from global warming. The agroecological practice of cultivar mixtures bets on genetic diversity in the fields in order to improve crop resistance to diseases. In the Yunnan Province in China, after diseasesusceptible rice varieties were planted in mixtures with resistant varieties, yields improved by 89 per cent and rice blast disease was 94 per cent less severe than when the varieties were grown in monoculture, leading farmers to abandon the use of fungicidal sprays.53 31. Agroecology also puts agriculture on the path of sustainability by delinking food production from the reliance on fossil energy (oil and gas). It contributes to mitigating climate change, both by increasing carbon sinks in soil organic matter and above-ground biomass, and by avoiding carbon dioxide or other greenhouse gas emissions from farms by reducing direct and indirect energy use. The Intergovernmental Panel on Climate Change (IPCC) has estimated the global technical mitigation potential for agriculture at 5.5 to 6 Gt of CO2-equivalent per year by 2030.54 Most of this total (89 per cent) can come from 49 50 51 52 53 54 “The use of agrobiodiversity by indigenous and traditional agricultural communities in adapting to climate change,” Synthesis paper, Platform for Agrobiodiversity Research – Climate Change project, Bioversity International and The Christensen Fund, 2010. Eric Holt-Giménez, “Measuring Farmers’ Agroecological Resistance After Hurricane Mitch in Nicaragua: A Case Study in Participatory, Sustainable Land Management Impact Monitoring,” Agriculture, Ecosystems and the Environment, 93:1-2, 2002, pp. 87-105. F.K. Akinnifesi et al., “Fertiliser trees for sustainable food security in the maize-based production systems of East and Southern Africa. A review,” Agrononomy for Sustainable Development, 30:3, 2010, pp. 615-629. F. Eyhord et al., “The viability of cotton-based organic agriculture systems in India,” International Journal of Agricultural Sustainability, 5, 2007, pp. 25-38; S. Edwards, “The impact of compost use on crop yields in Tigray, Ethiopia,” FAO International Conference on Organic Agriculture and Food Security, Rome, 2-4 May 2007. Y.Y. Zhu, et al., “Genetic diversity and disease control in rice,” Nature, 406, 2000, pp. 718–722. IPCC, Climate Change 2007: Mitigation of Climate Change, Contribution of Working Group III to Fourth assessment Report, 2007: section 8.4.3. 13