Author: Drip Depot Staff
Planning your system
Start by making a sketch of the areas that you want to water. Make sure you note the locations of trees, shrubs, vegetables and ground cover. List your plants by categories: ground cover, shrub and trees. Based on the plant sizes, category and concentration, you will determine the necessary dripper flow rates and the micro sprinklers coverage. Show the site's water sources, retaining walls and paved areas. This will require measuring the area that you wish to water. We recommend using graph paper with 1/4" squares. This will make drawing to scale easier. 1/4" = 1 foot scale is usually appropriate for residential landscapes.
Determine soil types
When water is applied slowly to the root zone at a single point, it is acted upon by the forces of gravity (downwards) and capillary action (outwards), producing a wetted pattern characteristic of the soil type and application rate. To determine which type of soil you have in a given area, take a handful of dry soil, grip tightly and release. Sandy (coarse) soil Will crumble and fall apart Loam (medium) Will hold together but easily break apart Clay Will mold without breaking As described earlier, we recommend using drip irrigation on trees, shrubs, vines, vegetables, and any individual plant. Micro sprinklers are best used on ground cover, flower beds, groups of plants, hillsides and on very sandy soils as water will percolate downward before it can spread far enough horizontally. Avoid micro sprinklers in areas where it is windy; high winds will disturb the micro sprinkler spray pattern. Drip Soak er Tape is ideal for vegetable beds and planters and narrow planting areas. Laser drilled soaker hose is ideal for narrow planters and pots.
About the soil
The soil is a storage room of the plants nutrients, and the medium, through which water and nutrients move. It is the anchor for plants and the reservoir of water for plants' growth.There are various types of soil with differing characteristic, which determine what types of plants can be grown. Each type of soil will require a different layout. In sandy soil, the water will tend to go straight down, so we recommend using micro sprinklers or closely spaced, 12" apart, 1 gph or 2 gph drippers. In loamy soil, the water will move slowly and will spread evenly, so here you can use .5 gph or 1 gph drippers with a 16" to 18" spacing. In clay soil, the water will be absorbed very slowly, and we recommend a low flow such as .5 or 1 gph drippers at a wider spacing, 18" to 24" apart.
Soil water relationships
A micro irrigation system is essentially a transportation system which delivers water to a point in or near the root zone. The final link in this transportation system is the soil. The soil's physical and chemical properties determine its ability to transport as well store water and nutrients. In the next few paragraphs we will try to explain the soil and water relationship, and the mechanisms by which moisture is transported and stored within the soil.
Capillary moisture is the water held in pore spaces by the surface tension between the water and the soil particles. Capillary moisture is the primary force in spreading the water horizontally and it is a primary source of water to the plant.
Gravitational water is free water in the soil which will move downward under the influence of gravity. After the soil is saturated, the gravitational water will percolate downwards, leaving the soil at field capacity.
Field capacity is a measure of the water held by the soil against the influence of gravity. If soil is saturated by rainfall or irrigation and then allowed to drain freely for 24 hours, the soil is usually at field capacity. For most plants, a soil moisture content near field capacity is the ideal moisture level for vegetative growth, because there is a good balance between soil moisture tension and aeration. The soil will lose very little water after it has drained to field capacity if there are no plants growing in it. Plants will remove water by transpiration and reduce the soil moisture . On hot days, the plants may use water faster than the soil can supply the roots, or faster than the roots can supply the rest of the plant and the plant will wilt. Normally, given sufficient soil moisture (you can keep using your irrigation system) the plant will recover during the night.
Permanent wilting point is the soil moisture content at which the plant wilts and remains in a wilted state. Ceasing normal growth and transpiration. Moisture holding capacities of different soil
When designing your system, you have various options with your layout: you can select, button drippers, Multi outlet drip heads, laser drilled soaker hose, drip soaker line or micro sprinklers. Button drippers and multi-outlet drip heads are ideal for virtually all shrubs, trees or ground covers and the are most efficient when plants are not concentrated. To cover areas such as a vegetable garden, use drip soaker line. For flower beds or densely planted ground cover, use micro sprinklers or micro sprayers. Misters are most appropriate for hanging plants or any plant that benefits from moist foliage. These drawings illustrate some ways you may want to lay out a drip system in a landscape area or vegetable garden
Planning for the Future
In any design that you create, make sure to plan for the future. When plants mature, they may require more water. Watering times can be lengthened to meet those needs, but generally, more drippers should be added to supply the maturing plant. Also, new plants may be added to the landscape, so leave some room in the overall design by having about 20%-30% more water capacity available. 3/4" faucets and 3/4" anti-siphon valves will almost always provide more than enough water for most home landscapes and gardens sites.
Calculating total flow rates
To determine total flow within a drip system zone, simply add up the total number of drippers and their flow rates. The same method should be used for micro sprinklers or micro sprayers.
Example: You have designed a system using 40 drippers and 2 micro sprinklers. You have twenty 1 gallon per hour drippers = 20 gallons per hour, and twenty 2 gallon per hour drippers = 40 gallons per hour, and 2 micro sprinklers at 14 gallons per hour each, for a total of 28 gallons per hour. To calculate your total flow rates: add 20 gallons + 40 gallons + 28 gallon = 88 gallons per hour. Divided by 60 = 1.46 gallons per minute to supply these drippers and micro sprinklers. If in doubt about the capacity of your water source, time how long it takes to fill a measured bucket. For example: if it takes 20 second to fill a 5 gallons bucket, then the maximum flow rate available per hour is 5 gallons x 3 = 15 gallons per 1 minute x 60 minutes = 900 gallons per hour divided by 60 = 15 gallons per minute. Should the system require more water, divide the system by adding another valve. Maximum recommended flow rates for 1/2" .600 ID x .700 OD drip line is 220 GPH (3.6 GPM) and 1/4" .156 ID x .245 OD 35 GPH(.58 GPM)
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