Water saving techniques and practices for on-farm surface irrigation systems

Water saving from irrigated agriculture is a world-wide priority facing the increasing water demand by multiple non­agricultural users and the variability in climate regimes affecting the availability of water resources. A major irrigation challenge is maintaining agricultural production and farmer’s income, with less water use. It needs the adaptation of irrigated agriculture through a change in the technology and practices aiming the water productivity improvement, compatible with the technical know-how of the farmers and the economic sustainability of the farms. This presentation refers to the surface irrigation systems, the oldest and most widely used irrigation method, comprising traditional systems developed over millennia, and modern ones with mechanized and often automated water application. They adapt well to non-sloping areas, to low to medium soil infiltration characteristics, to most crops, and to crop mechanization as well as to most environmental conditions, but they are still used in various regions of the world in a precarious and inefficient way, so there is a significant margin of progress for saving water and improving its productivity. The water saving technologies consider several aspects, including agronomic, soil management, irrigation scheduling, inflow and cutoff control, the precise land-leveling, runoff reuse, monitoring. Modern methods provide water and energy saving, control of environmental impacts, labor saving, and cropping economic success. These systems, when properly designed and managed, have a significant impact in the water use and productivity, and thus a competitive advantage relative to pressurized systems. This paper presents the main technical aspects of modern surface irrigation systems, their capabilities to reduce water demand, and the challenges to increase water productivity. It is illustrated with case studies where innovative practices have been applied.