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Irrigation methods

There are many irrigation methods: surface irrigation, micro-irrigation (drip irrigation, subsoil irrigation), sprinkling irrigation, lift irrigation, basin (inundation) irrigation, etc.

For each type of irrigation-based reclamation there is its special irrigation method and engineering. Irrigation method represents a set of the ways, facilities, and technical equipment used for water distribution over the irrigated field to humidify the surface air and plants, introduce water into the soil, convert it from the state of irrigating stream into the state of soil moisture, i.e. provide plants by sufficient quantity of water.

The basic requirements of plants and agricultural production with regard to irrigation methods are as follows:

  • keeping basic water, air (and feeding as appropriate) regimes in the root layer in line with the established boundaries (limits) of their regulation that allow obtaining a planned yield of crops;
  • creating favorable environmental conditions, i.e. microclimate;
  • minimizing unproductive water losses to filtration, evaporation and water escape;
  • preventing waterlogging and salinization of soils;
  • providing conditions for comprehensive mechanization and automation of the processes of agricultural production and rational use of irrigated areas;
  • reducing resource, material, and energy costs.

Correct selection of an irrigation method predetermines the structure and cost of the irrigation system, irrigation efficiency, including labour productivity during water application, ameliorative condition of the irrigated area, crop yield, and prime cost of the product obtained. As experience shows, no irrigation method can be suitable for all situations. In each case the irrigation method should be selected in accordance with the specific environmental and socioeconomic conditions.

When selecting an irrigation method, it is necessary to take into consideration the following key factors:

  • climatic conditions (area moisture content and wind speed). For example, the sprinkling irrigation method will be ineffective in highly arid zones with considerable air and soil moisture deficit. It will also be difficult to use at strong wind force;
  • soil conditions (speed of irrigation water absorption by the soil, filtration coefficient, depth of the soil layer, and degree of soil improvement/cultivation). So, sprinkling irrigation is not recommended for low-permeable soils;
  • landscape conditions (surface slope and leveling degree);
  • hydrogeological conditions (groundwater occurrence depth and salinity);
  • economic conditions (availability of human resources, experience of workers in the irrigation sphere, degree of field work mechanization, farming system, ensuring of good performance);
  • irrigation regime (permissible rates, time, and number of water application processes);
  • biological conditions (character of the development of crops the aboveground part and root system, duration of the growing period);
  • hydroeconomic activities (sufficiency of water supply to the farm, quality of irrigation water, sizes of irrigated areas);
  • economic indices (capital and operating costs).

Preference should be given to those irrigation methods and practices that provide higher labour productivity, automation of water distribution, maintenance of irrigated areas in good ameliorative condition, and high economic indices.

In the humid zone, sprinkling irrigation is prevalent; in the arid zone, the surface irrigation method prevails; in the sub-arid zone, both sprinkling and surface irrigation methods are widely applied.