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Drip Irrigation

Drip or trickle irrigation is an extremely efficient method of applying water and nutrients to crops. For many crops, the conversion from sprinkler to drip irrigation can result in water use reductions of 50% and can double yields.

This is a result of improved water and fertility management and reduced disease and weed pressure. When drip irrigation is used with polyethylene mulch, yield increases can be even greater.

These benefits are only possible when a drip irrigation system is properly designed, managed, and maintained. Irrigation system design is a complex engineering practice, and is beyond the scope of this introduction. However, information in this site will point out the many factors related to system design that users of drip irrigation should understand in order to assure that the system is properly designed and used. System component characteristics, basic design principles, and practical applications and guidelines related to these items will be discussed in publications within this section.

Irrigation water management and system maintenance are also extremely critical in order to succeed with drip irrigation. A simple and highly effective water management technique using tensiometers will be described in this publication. Clogging and prevention and use of chlorine as a means of preventing clogging by biological and chemical contaminants will also be discussed.

Although many advantages favor installation of a drip system, there are some limitations as well.

Advantages

  1. Smaller water sources can be used, as trickle irrigation may require less than half of the water needed for sprinkler irrigation.

  2. Lower operating pressures mean reduced energy for pumping.
  3. High levels of water management are achieved because plants can be supplied with precise amounts of water.
  4. Diseases may be lessened because plant foliage remains dry.
  5. Labor and operating costs are generally less, and extensive automation is possible.
  6. Water applications are precisely targeted. No applications are made between rows or other non-productive areas.
  7. Field operations such as, harvesting can continue during irrigation because the areas between rows remain dry, resulting in better weed control and lower production costs.

  8. Fertilizers can be applied efficiently through the drip system.
  9. Watering can be done on varied terrains and in varied soil conditions.
  10. Soil erosion and nutrient leaching can be reduced.

Disadvantages or problems

  1. Initial investment costs may be more on a per acre basis than other irrigation options.
  2. Management requirements are somewhat higher. A critical delay in operation decisions may cause irreversible damage to crops.
  3. Frost protection that can be achieved by sprinkler systems is not possible with drip systems.
  4. Rodent, insect, or human damage to drip tubes may cause leaks.
  5. Filtration of water for drip irrigation is necessary to prevent clogging of the small openings in the drip/trickle line.
  6. Water distribution in the soil is restricted.

Drip Irrigation System Components

A drip irrigation system has SIX major components.

  1. Delivery system

    • Mainline distribution to field - Sub-mainline
    • Feeder tubes or connectors
    • Drip tube or tape
  2. Filters

    • Sand
    • Screen
    • Disk
  3. Pressure regulators

    • Fixed outlet
    • Adjustable outlet
    • Valves or gauges
  4. Chemical Injectors

    • Positive displacement injectors
    • Pressure differential injectors
    • Water-powered injectors
  5. Controllers

    • Manual
    • Computer

How these components are put together, and which options are chosen, will depend on the size of the system, the water source, the crop, and the degree of sophistication desired.

At the Center for Plasticulture, research on the use of drip irrigation and evaluation of drip irrigation components is being conducted in both the field and high tunnels. In this section the results of research is presented and publications on drip irrigation are available.