Examples of some of the key specific strategies of sustainable agriculture are: organic farming, low external input sustainable agriculture, integrated pest management, integrated production and conservation tillage. Moreover, increased diversity of food crops available to farmers resulted in more varied diets, and thus improved nutrition. For 20,000 farmers in Tigray, previously one of the most degraded regions of Ethiopia, crop yields of major cereals and pulses have almost doubled through the use of ecological agricultural practices such as composting, water and soil conservation activities, agroforestry and crop diversification (UNCTAD, 2009a). Today, LDCs have lower productivity in agriculture than half a century ago: between 1983 and 2003 agricultural productivity declined in two thirds of the LDCs for which data were available (UNCTAD, 2006).