Page 360 - FRUTAS DEL TRÓPICO

360 Frutas del trópico

that are characterized by high infiltration rates should receive smaller irrigation volumes at
a higher frequency than low infiltration soils.

Runoff or surface runoff is the portion of precipitation that moves over land and out of

the field. One method for estimating the portion of precipitation that becomes surface runoff

is the Soil Conservation Service (CSC) curve number (CN) method (SCS, 1972; 1985). The

CN method calculates runoff volume as a function of precipitation, soil group, and land use. In

an efficient irrigation system, there is no surface runoff from irrigated waters.

Soil moisture sensors

A more direct method for determining soil moisture for irrigation purposes is the use of soil

moisture sensors. Three terms are often used when describing soil moisture: saturation, field

capacity, and wilting point. Saturation refers to a soil moisture level that has almost all of the

soil pores filled with water. Field capacity refers to a soil moisture level that results when all

the gravitational water has been drained and no further movement of water due to gravity is

significant. The wilting point describes a soil moisture level where there is no longer moisture
present that is available to the plant. Yield reductions are often associated with crops that are

subject to wilting point soil moisture levels.

The ability of a plant to use water within the soil is dependent on the tension associated

with the water, or soil moisture tension. Soil moisture tension is often expressed as a unit of

pressure, such as bars. As soil moisture tension increases, the energy required by the plant to

absorb the water from the soil increases.

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