niisutuse

Irrigation, or niisutus in Estonian context, is the artificial application of water to soil or land to assist crop growth, maintain landscapes, and reduce the impacts of drought. It supplements insufficient or irregular rainfall, enabling crops to be grown in arid and semi-arid regions or during dry seasons. Efficient irrigation seeks to deliver the right amount of water at the right time with minimal losses.

Historically, irrigation emerged in ancient Mesopotamia, Egypt, the Indus Valley, and China as early canal and flood systems. In modern agriculture, irrigation uses pumps, pipes, irrigation canals, and reservoirs to move water from surface and groundwater sources to fields. Water sources include rivers, lakes, groundwater, and, increasingly, treated wastewater.

Common irrigation methods are grouped into surface, sprinkler, drip, and subsurface systems. Surface irrigation relies on gravity to spread water over the soil surface. Sprinkler systems spray or rotate water through nozzles. Drip irrigation delivers water directly at the plant roots through emitters. Subsurface systems place laterals below the soil surface.

Farmers and managers optimize irrigation with scheduling based on evapotranspiration, soil moisture, rainfall forecasts, and crop growth stage. Tools such as soil moisture sensors, weather data, and automated controllers help improve water-use efficiency. Key goals include reducing runoff, leaching of nutrients, and energy costs while maintaining yields.

Irrigation is essential for global food production, particularly in dry, desert, or seasonally dry regions. It also supports urban green spaces and manufacturing crops. Challenges include water scarcity, groundwater depletion, salinization, salting of soils, and energy use. Advancements in precision irrigation and digital agriculture aim to increase efficiency and sustainability.