HO-156
YARD  AND GARDEN
HORTICULTURE DEPARTMENT • COOPERATIVE EXTENSION SERVICE • PURDUE UNIVERSITY • WEST LAFAYETTE, INDIANA 47907
DESIGNING IRRIGATION SYSTEMS FOR THE NURSERY
by Lawrence D. Cammarata, graduate In landscape management and David F. Hamilton, assistant professor of horticulture
Introduction
It is probably impossible to produce the highest quality nursery crops in the quickest period without supplemental water even though well-distributed and frequent rainfalls reduce the amount of water needed. Rainfall frequency and rate also influence cultural practices such as fertilization, and insect, disease, and weed control. Complete dependence upon rainfall to produce nursery crops is extremely risky (1).
Irrigation governs the amount and fluctuations of soil moisture which in turn affect plant growth rate, plant quality, root growth, severity of pest infections, soil salinity, labor efficiency, and in the end, production costs. Good water management requires knowledge of the basic principles of water application and water movement in soil. Knowledge of equipment, layout, and design principles also facilitate control of irrigation systems (1).
Initial planning of a system is the most important step toward insuring an effective irrigation setup. The design and layout of an underground sprinkler system involves arranging the sprinklers, the piping, and the controls together in a system that best fits conditions of the area to be watered (5). Accurate analysis of the field conditions is necessary for a satisfactory system.

Site Information
Start the system by making a list of pertinent site information. Make a plot plan of the nursery to properly locate lining-out beds, growing-on areas, stock blocks and other areas with plants. Also, locate buildings, roadways, and sources of water which could affect the design. Be sure accurate and sufficient measurements are taken so that scale drawings can be made (3, 4, 5, 6).
Soil type must be known to ensure proper rate of water application. Note all areas according to soil type. Areas with different soil types may require varying frequencies of water application and will have to be controlled separately. Examples of such areas are nursery rows in clay loam which may require less irrigation than the same plants in a sandy loam (4, 5,6) (Table 1). Water-holding capacity of the clay loam is greater than the sandy loam.
Measure elevation changes on the site to determine gains and losses in water pressure throughout the system resulting from changes in slope. For every foot of elevation change, there is again or loss of 0.433 PSI in the system (4, 5, 6) (Table 2).
Determine wind velocity and direction to plan maximum efficiency in spacing of sprinklers. Also, wind influences the type of sprinkler that can be used (1,2, 4, 5, 6).
Locally enforced building and water codes may regulate the type of materials, equipment and methods of installation for the system (4). Indicate the water source, the location and the type, such as well, stream, pond or city water.
With a well and pump, one must determine the location and capacity
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