Agroecology is deeply rooted in the ecological rationale of traditional small-scale agriculture, representing long established examples of successful agricultural systems characterized by a tremendous diversity of domesticated crop and animal species maintained and enhanced by ingenuous soil, water and biodiversity management regimes, nourished by complex traditional knowledge systems. Such complex farming systems, adapted to local conditions, have helped small farmers to sustainably manage harsh environments and meet their subsistence needs without depending on mechanization, chemical fertilizers and pesticides, or other modern agricultural technologies. As an applied science, agroecology uses six principles (see table below) fundamental to the design and management of sustainable agroecosystems, taking advantage of natural processes and beneficial on-farm interactions in order to reduce off-farm input use and improve farm efficiency. A key principle of agroecology is the diversification of the farming system through practices such as mixed cropping, intercropping, agroforestry, and livestock integration. These practices amplify the positive effects of biodiversity on productivity through better use of sunlight, water, and soil resources, and the enhanced regulation of pest populations. Crop diversification schemes are multi-functional as their adoption usually means favorable changes in various components of the farming systems at the same time, activating key processes such as recycling, biological control, antagonism, and allelopathy, which are essential for agroecosystem sustainability and productivity.