Irrigation scheduling

Irrigation scheduling

Irrigation scheduling is the process used by irrigation system managers to determine the correct frequency and duration of watering.

The following factors may be taken into consideration:
* Precipitation rate of the irrigation equipment - how quickly the water is applied, often expressed in inches or mm per hour.
* Distribution uniformity of the irrigation system - how uniformly the water is applied, expressed as a percentage, the higher the number, the more uniform.
* Soil infiltration rate - how quickly the water is absorbed by the soil, the rate of which also decreases as the soil becomes wetter, also often expressed in inches or mm per hour.
* Slope (topography) of the land being irrigated as this affects how quickly runoff occurs, often expressed as a percentage, i.e. distance of fall divided by 100 units of horizontal distance (1 ft of fall per convert|100|ft|m|abbr=on would be 1%).
* Soil available water capacity, expressed in units of water per unit of soil, i.e. inches of water per foot of soil.
* Effective rooting depth of the plants to be watered, which affects how much water can be stored in the soil and made available to the plants.
* Current watering requirements of the plant (which may be estimated by calculating evapotranspiration, or ET), often expressed in inches per day.
* Amount of time in which water or labor may be available for irrigation.
* Amount of allowable moisture stress which may be placed on the plant. For high value vegetable crops, this may mean no allowable stress, while for a lawn some stress would be allowable, since the goal would not be to maximize production, but merely to keep the lawn green and healthy.
* Timing to take advantage of projected rainfall
* Timing to take advantage of favorable utility rates
* Timing to avoid interfering with other activities such as sporting events, holidays, lawn maintenance, or crop harvesting.

The goal in irrigation scheduling is to apply enough water to fully wet the plant's root zone while minimizing overwatering and then allow the soil to dry out in between waterings, to allow air to enter the soil, but not so much that the plant is stressed beyond what is allowable.

In recent years, more sophisticated irrigation controllers have been developed that receive ET input from either a single on-site weather station or from a network of stations and automatically adjust the irrigation schedule accordingly. When properly set up and maintained, these controllers do tend to conserve water over conventional human scheduling as the program is updated at least daily. []

Other devices helpful in irrigation scheduling are rain sensors, which automatically shut off an irrigation system when it rains, and soil moisture sensing devices such as tensiometers and gypsum blocks.

ee also

*Frequency domain sensor
*Neutron probe
*Nonlimiting water range
*Time Domain Reflectometer


* [ Irrigation Association Smart Water Application Technology] - site with generic information on smart controllers

Wikimedia Foundation. 2010.

Поможем сделать НИР

Look at other dictionaries:

  • Irrigation in viticulture — A vineyard with a drip irrigation system running along the bottom of the vines The role of irrigation in viticulture is considered both controversial and essential to wine production. In the physiology of the grapevine, water is a vital component …   Wikipedia

  • Deficit irrigation — (DI) is a watering strategy that can be applied by different types of irrigation application methods. The correct application of DI requires thorough understanding of the yield response to water (crop sensitivity to drought stress) and of the… …   Wikipedia

  • Lift irrigation scheme — Irrigation Schemes mainly comprise canal irrigation and lift irrigation schemes. In such schemes, the most important and yet the most neglected portion is distribution of water. Let us first consider lift irrigation schemes Importance of lift… …   Wikipedia

  • Glossary of environmental science — This is a glossary of environmental science.Environmental science is the study of interactions among physical, chemical, and biological components of the environment. Environmental science provides an integrated, quantitative, and… …   Wikipedia

  • Evapotranspiration — (ET) is a term used to describe the sum of evaporation and plant transpiration from the earth s land surface to atmosphere. Evaporation accounts for the movement of water to the air from sources such as the soil, canopy interception, and… …   Wikipedia

  • Distribution uniformity — or DU in irrigation is a measure of how uniformly water is applied to the area being watered, expressed as a percentage. The distribution uniformity is often calculated when performing an irrigation audit. The DU should not be confused with the… …   Wikipedia

  • Tensiometer — A tensiometer is a device used to determine matric water potential Psi m (soil moisture tension) in the vadose zone. The tensiometer consists of a glass or plastic tube with a porous ceramic cup, and is filled with water. The top of the tube has… …   Wikipedia

  • Soil physics — is the study of soil physical properties and processes. It is applied to management and prediction under natural and managed ecosystems. Soil physics deals with the dynamics of physical soil components and their phases as solids, liquids, and… …   Wikipedia

  • Nonlimiting water range — The Non limiting water range (NLWR) represents the range of water content in the soil where limitations to plant growth (such as water potential, air filled porosity, or soil strength) are minimal. John Letey (1985) from UC Riverside introduced… …   Wikipedia

  • Pan evaporation — is a measurement that combines or integrates the effects of several climate elements: temperature, humidity, solar radiation, and wind. Evaporation is greatest on hot, windy, dry days; and is greatly reduced when air is cool, calm, and humid… …   Wikipedia

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”