Water Management in Horticultural Crops (1+1)

Sprinkler irrigation for different horticultural systems

Ground cover landscape irrigation

• Sprinklers waters a large area. They are particularly useful in irrigating ground covers. The objective in designing a superior landscape irrigation system is to apply the same amount of water over the area being irrigated within the same window of time; this concept is called distribution uniformity. It is a key element for a high quality irrigation design.
• Poor uniformity results in over watering in some areas and under watering in other areas. The amount of water is applied in terms of depth per unit area and time to the surface.
  
• The amount of water applied must not exceed the ‘infiltration rate’ and will vary greatly based on soil type and degree of compaction. Different areas of the landscape may well have different infiltration rates and water holding capabilities, therefore will have differing water requirements.
  
• Beds are different than sod, for example. For this reason a basic rule of landscape irrigation design is to never water beds and sod at the same time (in the same zone). It is impossible to do both things well simultaneously.
Bedding plants

• Bedding plants are typically grown on benches or on the floor with walk isles between the blocks of plants. Installation required for designing a system includes the width of other tables or blocks, length of the tables or blocks and the height of the plant material at maturity. This scenario usually calls for an overhead device being installed on lengths of tubing called drops. Sprinklers that produce small droplets are installed on the drops and spaced appropriately for the performance of the sprinkler.
• It is desirable that the pattern of the sprinkler be confined to the width of the table or block. These sprinklers are also equipped with anti-leak devices to assure that they start and stop simultaneously. Since cycle times are usually short, it is important that the best possible distribution uniformity be achieved. This is done by carefully selecting the flow rate of the device, the diameter of its pattern and the spacing required down the lateral to achieve the desired uniformity.
Propagation Systems

• Propagation systems are similar in all respects to bedding plants except that the irrigation device is most often some type of mister or fogger.
  
• In this application it is desired only to keep a small amount of moisture on the surface of what is being grown.
  
• The media is not saturated. This is where cycles of five seconds on, five minutes off from six o’ clock in the morning until six o’clock at night is followed.
  
• Since the droplet size of the devices available for this application is so small great care must be given to proper spacing of the devices.
  
• Typically the diameter of a mister would be limited to 150 cm (5 feet). If there is any wind movement in the green house it will greatly affect the pattern of the system.
Plantation crops
Tea

• Irrigation is found to increase yield in mature tea. In young tea, yield increases due to sprinkler irrigation when compared to sub-soil irrigation. Among different methods of irrigation, sprinkler irrigation is suitable for both young and mature tea.