Tech Notes Issue 17

Irrigation methods for Managing Turf Sites High in Salt

Maintaining turf on salt affected sites is one of the most difficult challenges a golf course superintendent or athletic field manager can face. Salt affected sites is a growing problem due to several factors including the increased use of irrigation sources that contain salt, salt water intrusion into coastal turf areas, and limitation of water use and the quality of water used in dry or arid regions.

Leaching is one management practice that is used to avoid salt build up in the soil. There are two leaching methods that are practiced. The first is termed flushing or leaching where irrigation water is applied in sufficient amount to move the salts downward out of the rootzone. The volume of water needed is dependent on the  amount of salts, and the soil type.

However, as a general rule 15 cm of water needs to flow in through the rootzone or soil  profile to drop the electrical conductivity (EC) of the soil by 50 percent. This is equivalent to 1.63 million liters per hectare. The amount can be reduced if done frequently or a smaller drop in EC is desired.

The second method of reducing salt concentrations is known as the leaching requirement. This is the minimum volume of water need to keep the salt concentration within the salt tolerance of the turfgrass species. In contrast to  leaching, which is done infrequently, this method is done each time irrigation is conducted. This method requires that you know the salt tolerance of the turfgrass species that you are attempting to manage.

Using a couchgrass athletic field as an example, if the irrigation water has a EC of  3.0 dS m^-1 and given the salt tolerance of the couchgrass is 8 dS m^-1, the leaching requirement is 3.0/8.0 x 100 which equals 38%. This means that each time you irrigate you would need to add 38% more water than you normally would. So if your normal watering time was 15 minutes, to account for the leaching requirement you would need to increase the  watering time 5.7 minutes (.38 times 15) for a total of 20.7 minutes.

Reference
Stowell, L.J, and W. Gelernter. 2008. Side effects. Golf Course Industry. September, pages 46, 48, 50, 52, 54.