The Golden State: Where & How to Live, Secure, Visit, Enjoy and Thrive in California
Sprinkler Irrigation
Where a 40 foot spacing is usually used, you may have to put sprinklers every 20 feet on the lateral. In doing so reduce the gpm discharge per sprinkler to half the amount and you will maintain the same precipitation rate as with the 40 foot spacing.
Water Moves Straight Down
The problem in irrigation is to get the water to the roots. And farmers should remember that water tends to go straight down under the pull of gravity, rather than wander around sidewise in the soil.
L. H. Doncen and J. H. MacGillivray of the University of California conclude that the biggest single factor affecting the yield of crops is soil moisture. And in general that goes for all crops.
The pictures tell the story of what happens. In row irrigation, you get a little side traveling of the water, but deep penetration is straight down under the ditch, and deep-rooted plants experience thirst in the dry areas between. Broad irrigation runs, close together are the best bet.
Sprinkler irrigation gives wider penetration areas, but feathers out because less water falls in the outer zones. So there should be an overlap of sprinkled areas of about 50 per cent.
AMOUNT AND FREQUENCY OF IRRIGATION. As explained above, the soil texture and depth, together with the plant root depth, should govern the amount of water applied per irrigation. The frequency of irrigation is determined by the soil texture and depth, the root depth and the rate the plant uses the water. Information regarding all these factors can be obtained from your local Soil Conservation District and from your local County Agent. A basic rule for water requirements is: 4 inches of water per month will grow a crop the world around. The texture of the soil determines the rate of application; a light soil takes water very fast, and a heavy soil takes water slowly. Never attempt to apply water faster than the ability of the soil to absorb it, the water will puddle and run, causing erosion.
