Sub-Surface Irrigation

Though initially expensive - between $500 and $1000 per acre - and not suitable for many areas, the economical advantages of drip irrigation can be further enhanced by placing the irrigation tubing about 5 inches (about 12.7 centimeters) below the surface. Down there, the water really does get straight to where it's needed - the roots of the plant. Evaporation is greatly reduced, and there is no opportunity for surface runoff.


Photo courtesy USDA ARS
Photo credit Pete Mortimer
Soil cut away to expose a drip irrigation line in a tomato field.

A similar effect can be gained far more cheaply by making use of plastic mulch. Traditionally, mulch is a protective covering of organic material placed around plants to:

  • reduce evaporation
  • prevent the growth of weeds
  • help protect the roots from frost damage
It can also help keep fruit off the ground - anyone who's grown strawberries will appreciate the value of mulching with a layer of clean straw.


Photo courtesy USDA ARS
Photo credit Ken Hammond
These strawberries probably benefited from proper irrigation and mulching.

More recently, plastic mulch has become an integral part of many drip irrigation systems. By laying sheets of plastic across the fields, the horticulturalist can further improve conditions for their plants. However, there are concerns that extensive use of plastic mulch may have long-term detrimental effects on the environment, perhaps increasing the amount of rain and pesticides that runs off into nearby water.


Plastic mulch has become an integral part of many drip irrigation systems.