Dry drainage : an environmental and cost-effective concept in drainage of arid and semi-arid areas

الملخص EN

Sustainable agriculture can help food security and it depends on water and salt balance in the root zone especially in arid and semi arid regions of the world.

Although drainage systems can help us to reach these goals, some problems are associated with; among them high initial and maintenance costs and environmental threats from low quality and high volume of drainage water.

Recently more researchers lead their studies towards alternative environmentally friendly solutions.

At this study, Dry Drainage was examined as an environmental and economic alternative technique at the University of Tehran in July 2015 to in lysimeter scale.

Dry drainage is rather a new environmentally friendly concept in drainage of arid and semi-arid areas where the irrigation water is much less than the amount to satisfy the extent of the available land.

Dry drainage is used in some parts of our country as well as in China and Pakistan.

Dry drainage consists of parallel land strips cropped in every other strip.

The remaining strips act as the sinks which evaporate received water from the adjacent ones leaving salts behind in the soil of non-cropped strips mostly at the soil surface.

Dry drainage is not a sustainable method by itself, but it could be considered sustainable in the cropped strips in case of proper management.

In other words, parts of the land will be sacrificed to the benefit of the other parts i.e.

cropped strips.

Results showed that the amount of salinity at different soil layers of uncropped strips (evaporation strips) was higher than salinity of cropped strips.

Salinity of the soil at cropped strips was increased downward and conversely the salinity of the soil at non cropped strips was decreased.

While Dry Drainage could stabilize the soil salinity at near surface of cropped strips by 1.5 times of irrigation water salinity, salinity of the soil surface at non cropped strips was reached to 4.5 times of its initial condition.

The result shows that salinity was leached from cropped strips leaving them productive and healthy and accumulated at non cropped strips which eventually sacrifices as non arable land.