This strategy features in the framework of Agenda 21 as formulated at UNCED (Rio de Janeiro, 1992), now coordinated by the United Nations Commission on Sustainable Development and implemented through national and local authorities. Agenda 21 recommends increased efficiency and productivity in agricultural water use for better utilization of limited water resources. It also recommends developing long-term strategies and practical implementation programmes for agricultural water use under scarcity conditions with competing demands for water.
Intercropping can increase the efficiency of water use by crops when they are growing together. At Machakos, Kenya a pure maize crop utilizes only 30% of the available rainfall, while a maize-leucaena system utilizes 76%.
Novartis Seeds has a programme to develop water-efficient and salt-tolerant crops, including genetically engineered varieties of wheat. Researchers in Mexico have announced the development of drought-resistant corn that can boost yields by a third. Biotechnologists are converting annual crops into perennial ones, eliminating the need for yearly planting.