The Golden State: Where & How to Live, Secure, Visit, Enjoy and Thrive in California

Sprinkler Irrigation

Sprinkler irrigation also affords the following added advantages over surface irrigation. (1) It reduces drainage problems through positive control of applied water. (2) It saves water due to a uniform application, and through complete control of water which may be applied where and when it is wanted. (3) It saves labor over certain types of surface irrigation but generally is comparable. (4) There is a better incorporation of fertilizer due to uniform water coverage. (5) It improves growth and root structure since all feeder roots are active due to a better food supply made possible by uniform water distribution, which results in larger production and improved quality. (6) It eliminates ditches and furrows thus making farm work-easier. (7) It saves wear and tear on farm equipment. (8) It reduces insect infestation, especially red mite in apple orchards according to present data.

Preliminary Design Factors

The design of a sprinkler irrigation system is based on several factors:
(1) Available watei
(2) Soil types and depth
(3) Crop
(4) Amount and frequency of irrigation
(5) Relative land elevation
(6) Pressure head
(7) Wind
AVAILABLE WATER is the amount of water supplied by an irrigation development through ditches and pipe lines, the amount of water available from rivers, lakes, and other natural sources, or the amount of water available from wells.

SOIL TYPES AND DEPTH. There are three main soil types; light, medium and heavy textured, and each type has a different water holding capacity. The light textured soils vary from 5% of total volume for sand to 11% for loamy sand. The medium textured soils vary from 13% for sandy loam to 20% for loam. The heavy textured soils vary from 20% for silt loam to 35% for clay. In all of these soils plants cannot obtain sufficient water below a certain percentage held in the

soil. This is called the wilting point and is approximately 35% of the water holding capacity. Therefore, the water in the soil must not be allowed to drop below this wilting point if the plant is to maintain a uniform growth. This means that the amount of water to be added each irrigation is the difference between the water holding capacity and the wilting point.

All soils vary in depth from 8 inches to over 6 feet and as the depth of the soil determines the volume, it also controls the amount of water held by the soil. It therefore follows that in order to apply water to a soil, its texture and depth must be known. Any water applied beyond the holding capacity of the soil is wasted, either by penetrating below the root zones in a deep soil, or by collecting on hard pan in the shallow soils.