Increasing productivity through irrigation: Problems and solutions implemented in Africa and Asia

Simultaneously, climate change threatens to disrupt growing seasons and rainfall across the globe. For food production to keep pace with population growth and resist the effects of climate change, the expansion of irrigation to non-irrigated farmland is critical. Innovative, affordable, and easy-to-implement technologies are needed for smallholder farmers to irrigate efficiently, mitigate greenhouse gas emissions, and help adapt to the effects of climate change. The United Nations predicts that between 2005 and 2050 more than half of the global population growth will occur in Africa, translating to an increase of 1.3 billion people in population. In the same timeframe, Asia will have added another 0.9 billion. The Food and Agriculture Organization of the United Nations (FAO) predicts that global food demand is going to have to increase by 70 percent between 2005 and 2050 just to keep up with expected global population growth. Historically and globally, agricultural intensification has been largely accompanied by the increased energy and water inputs to grow, process, and distribute agricultural products. Irrigation plays a crucial role in food production and improving food security by allowing achievement of full crop production potential in a given growing environment, fighting pests through products diluted in water, protecting sensitive crops from frost, adding nutrients that are dissolved in the water, improving land physical properties, and removing excess salinity from the soil. There is an enormous potential to improve agricultural productivity with irrigation in areas that depend on rainfall, such as Sub-Saharan Africa and large parts of Asia. The FAO reports that while only 20 percent of the global arable land in use is irrigated, it supplies 40 percent of the total food grown worldwide, producing more than 2.5 times the yield of rainfed crops. Africa irrigates just over 5 percent of its available cultivated land, representing the lowest percentage of any continent. As a result, it is also the continent with the highest potential for irrigation expansion, with about 42.5 million hectares of unirrigated land. Asia's irrigation rate is higher at 41 percent, but due to Asia's size the remaining unirrigated land also represents a large, untapped demand. Irrigation allows both higher yields within a crop cycle and, if climate allows, multiple crop cycles in a single growing season. Large quantities of crop production occur on small areas of irrigated land. There are multiple irrigation methods used by farmers worldwide, but most were developed for expediency and economic value generation rather than reduction of environmental impact and water efficiency. Use of pumps powered by increasingly expensive fossil fuels to flood or partially flood fields is still a common irrigation method that is water inefficient and pollutes the environment. Many of the poorest, off-grid farmers irrigate manually with buckets of water because they cannot afford to purchase or rent a fossil fuel-powered pump. Frequently, more sophisticated irrigation methods that cause little or no environmental degradation exceed the affordability of most smallholder farmers.