Irrigation Glossary

Tail water Surface runoff resulting from crop irrigation. Irrigation practices such as flood irrigation and sprinkler irrigation can result in applied water in excess of the infiltration rate of the soil. Sloped fields can allow for the excess water to run off the field, and discharge to a drainage channel or natural water body. Tailwater can carry pollutants such as silt, nutrients (from fertilizers), and pesticides.

Tee A T-shaped fitting used to tap into a length of pipe at a 90-degree angle for the purpose of beginnig a branch line.

Tensiometer Instrument, consisting of a porous cup filled with water and connected to a manometer or vacuum gauge, used for measuring the soil-water matric potential.

Textural class Classification used to convey an idea of the textural makeup of soils and to give an indication of their physical properties. Three broad groups of these classes are recognized - sands, loams, and clays. Within each group specified textural class names have been devised

Texture (soil) Relative proportions of sand, silt and clay in a given soil.

Thrust block Normally, concrete poured in place at changes in direction of water flow in piping systems to prevent movement of the pipe.

Tilth The state of aggregation of a soil especially in relation to its suitability for crop growth

Time Term used to describe the duration of an operation, e.g. an irrigation event.

Timer or Controller A device that switches on irrigation valves and lets them run for a preset time before switching them off.

Total dissolved solids Total dissolved mineral constituents of water.

Trajectory Angle above horizontal of the stream of water as it leaves the sprinkler head.

Transition Fitting Any one of several fittings that joins pipes made of dissimilar materials, such as copper and plastic, plastic and cast iron etc...

Translocation Movement of water to other areas than where it was applied.

Transpiration Liquid movement of water from the soil, into the roots, up the plant stems, and finally out of the plant leaves into the air as vapor.

Traveler (traveling gun) irrigation: Large rotating sprinkler(s) mounted on a trailer to deliver water in a circle. The sprinkler and associated trailer are towed through the field by any of several means. Travelers are also called cable-tow, hard hose and hose drag.

Triangular spacing Sprinklers are spaced in a triangular pattern.

Trickle irrigation Also known as drip irrigation or microirrigation is an irrigation method which minimizes the use of water and fertilizer by allowing water to drip slowly to the roots of plants, either onto the soil surface or directly onto the root zone, through a network of valves, pipes, tubing, and emitters.

Turbine pump Pump having one or more stages, each consisting of an impeller on a vertical shaft, surrounded by stationary and usually symmetrical guide vanes. Combines the energy-imparting characteristics of axial-flow and propeller pumps.

Turbulent flow Flow in which the fluid particles move in an irregular random manner, in which the head loss is approximately proportional to the second power of velocity.

Turgid State of a plant cell when the cell wall is rigid due to the hydrostatic pressure of liquid in the cell.