Water is a precious resource and in countries where water is scarce it is important to water your garden, whether you are growing vegetables, herbs or flowers or fruits, in a smart way. Successful irrigation will not only save water, but will also yield a better product from your garden. Standing in the garden with a hosepipe in the hand and watering is very inefficient and wasteful. Furthermore watering your garden hosepipe in hand has to be done frequently else you will probably end up with compacting the surface, and wetting the crust, increasing the loss of moisture from the garden soil by evaporation and with the deeper layers of soil remaining dry.
There is a certain amount of time that elapse before the water percolate to an effective depth. Most irrigation systems are designed in such a way so as to take the percolation rate of different types of soil into account when calculating the rate at which the sprinkler system delivers water to the soil. This rate is in most cases calibrated in hours rather than minutes. (TIP: When making use of sprinklers, do so at night since there is greater loss of water when you irrigate your garden during the day. Factors such as the heat of the day, wind, hot and dry conditions can amount to a 50% water loss.)
It's preferable for sprinkler irrigation systems to wet the soil to the plants' root depth. With vegetable and flower gardening it is practical to wet the garden soil to a depth of approximately 30 cm (12 inches). That should be sufficient to accommodate the bulk of the root system. That essentially means that you need to apply 30 mm (1 inch) of water. The general rule of thumb in watering is that 1 mm of water will wet 1 cm of soil. To determine the effective irrigation depth you will need to check the water depths by placing cylindrical containers such as food cans or even tumblers in the soil. Then you will be able to see how long it takes to reach a depth of 30 mm in the containers. On the following day you should dig in the area and observe the effective depth penetration. You will notice that with sandy soil you will be wetting more than in the case of clayey soil.
You should also check that there is no runoff of water to prevent wastage. Now I must admit that this measure might seem like a waste of water, but you will find that you will actually be using less water using this method than by watering with a hosepipe on a more frequent basis. The intervals between sprinkler irrigations, using the above method, are determined by temperature, humidity and maturation of the crop. It is therefore better to dig into the soil to check the moisture content and observe the condition of the leaves and flowers/fruits or visible vegetables to determine when to irrigate again.
Another factor that has to be understood for effective watering of your garden is the movement of water in the soil. Movement of water in the garden soil is dependent on and influenced by gravity and capillary action. Capillary action actually defies gravity. This can be seen in the following: if you place blotting paper in a liquid it will rise up the paper. The same phenomenon can be witnessed in soil when moisture will move upwards through minute passages or capillaries, which are the gaps that exist between the soil particles. The closer together the capillaries, the higher the water will move.
Thus the more compact the garden soils, the more moisture will reach the surface where there is the danger of the water being lost to the air. The looser the garden-soil surface, the more moisture can be conserved by the soil because the capillary action is then broken. By loosening the garden soil and by applying a layer of mulch you can preserve moisture. This mulch layer can be compost, plant residue, bark chips, even pebbles or nut shells. Loose soil in conjunction with organic material will lose less water, is thus more efficient for gardening purposes, will retain more moisture resulting in less irrigation required.
Mulching is an efficient form of water conservation that can be practiced by the home gardener. Use mulch liberally in any type of garden, vegetable garden, under shrubs, in cutting gardens, flower gardens, between garden ornaments and other forms of garden décor and wherever it is practical to cover up the garden soil so as to prevent unnecessary moisture loss.
In a Pop-up irrigation system the pipes are buried under the ground and the sprinkler is designed to pop up when the water is turned on or when the tap is opened. Also in a pop-up sprinkler irrigation system the spray from one sprinkler needs to reach as far as the next sprinkler in the system to prevent the occurrence of any dry patches when irrigating. When using this type of irrigation system make sure that you select the type of sprinkler nozzle shape that will match the shape of the garden so that only the plants are watered and not your paving for instance. A serious disadvantage of using a pop-up sprinkler irrigation system is that the spray from the sprinklers can be obstructed by elements in the garden. These elements include foliage, tree trunks or even containers. This obviously causes dry patches. Always consider these types of obstacles and the future growth of plants that are in your garden or that you intend growing in your garden during the design phase. (TIP: You can make use of risers on standpipes above the plants.)
Mist sprayers on the other hand are much less expensive and can be installed by any DIY enthusiast. If your garden is full of perennials then a mist sprayer irrigation system is an ideal choice, provided that they are high enough to be able to spray over the plants. Mist sprayer irrigation system is also excellent to use in vegetable gardening and even beds where you grow your annuals. The major disadvantage of using a mist sprayer irrigation system is that the droplets are so tiny that they can easily be blown away and thus makes it a foolhardy choice if you happen to live in a windy area. What is more is that if you have pets, like dogs, and even people working in your garden, they can easily damage your mist sprayer irrigation system. Furthermore the fine spray of this irrigation system is incapable of reaching and penetrating through dense foliage and you will undoubtedly encounter dry spots under your shrubs.
Probably the best type of irrigation to practice is drip irrigation. Drip irrigation involves the application of water to the soil beneath the plant at a very slow rate of flow. Together with a sprinkler irrigation system you will be able to save water. Drip irrigation is quite a deceptive form of irrigation in that the garden soil may appear to be dry, when in fact it has sufficient moisture. There is an onion-shaped pattern of wetting that forms below the dripper points and you should actually dig down to get an idea of how long your drippers of your drip irrigation system should stay open. It is best to purchase a good quality drip pipes that has a wall diameter of at least 0.6 mm. They may be more expensive, but it will be more beneficial to buy since it will last longer and will save you money over time and will result in fewer problems associated with leaks.
Different types of garden soil play a role in drip irrigation. Clayey, loamy and sandy soil all has a different absorption pattern. To accommodate for the differences in garden soil types, the type of tubing used in an irrigation system must be carefully selected according to the space of the emitters.
A drip irrigation system has a very complex design and installation process. A sprinkler system is so much easier to install as a do it yourself project and the drip irrigation system should preferably be done by a technically skilled and experienced technician. It is strongly recommended to make use of an irrigation specialist when contemplating the installation of a drip irrigation system for your home garden. It is also advisable to check that the specialist you hire to install your drip irrigation system is registered with the proper authorities and associations as is relevant to the area where you live.
A drip irrigation system has a high level of water efficiency because the water drips directly into the soil where the water and moisture is required. There is less wastage of water compared to the other types of irrigation systems that can be used in a garden. None of the droplets are blown away by the wind, or can evaporate without moistening the soil where it is required. The network of pipes is buried underground, or laid on top of the garden soil, covered by a layer of mulch which all makes for good gardening sense.
A drip irrigation system is the ideal type of irrigation for large shrubberies because there is no interference from the foliage and thus no dry spots. Furthermore, plants that might be vulnerable to fungal attacks benefit greatly from a drip irrigation system as the foliage does not get wet which could provide a breeding ground for fungi. Also awkwardly shaped areas in your garden, as well as narrow areas in your garden can also benefit from drip irrigation, where the conventional sprinkler irrigation system or the mist sprayer irrigation system may be wasting water by over spraying; it is not the case with a drip irrigation system.
A drip irrigation system is extremely useful in areas that are hard to reach with normal conventional irrigation systems such as sprinklers and hosepipes. Narrow beds and irregular shaped beds can effectively be irrigated using a drip irrigation system. (TIP: Many sprinkler irrigation systems can be converted to a drip irrigation system.)
Mentioned above are the different types of irrigation systems that can be used in home gardens. There is no hard and fast rule that says that you must only make use of one type of irrigation system in your garden. You could even make use of a combination of all the types of irrigation systems that will suit your garden's watering needs. Your own hybrid irrigation system that will work for you, for example, using drip irrigation in one part of the garden and a pop-up irrigation system in another section of the garden. It is best to talk to an irrigation specialist who will be able to assist you with the design and correct layout.
It is also quite important to check your water pressure before starting on an irrigation system project in your garden. If you do not have enough pressure then it could result in your irrigation system working inefficiently. On the other hand if you have too much pressure it can result in your irrigation system causing the water to atomize and be blown away. It is a good idea to divide your irrigation system into a number of circuits, rather than one huge watering circuit, with only as many sprinklers on a circuit as the water pressure can support. With clever planning the layout of your garden can work in conjunction with the concept of zoning your home garden to areas of high, medium and low water use zones. Each of these zones would then have a dedicated irrigation circuit that must service the garden.