Right now in many parts of the Southeast, golf course superintendents are dealing with dry conditions, which means more irrigation. For many of you, that entails using a recycled water source. While using recycled sources reduces strain on groundwater and potable water supplies, recycled water comes with its own set of challenges for a golf course – including salinity and sodicity. These terms are often confused, but they are two different things and have different impacts on turfgrass management.
High salinity levels are caused by the accumulation of soluble salts in the rootzone and are common with recycled water use due to the elevated levels of total dissolved solids (TDS). These soluble salts disrupt the osmotic potential that plants rely on to absorb water into roots and can lead to wilt, stress and poor turf performance, especially during dry spells like we are experiencing now. On the other side of the coin, high sodicity is a separate issue that results from the buildup of exchangeable sodium, which displaces calcium and magnesium on soil particles, breaking down the soil structure and causing poor infiltration and many other problems.
Superintendents may mistakenly treat all salt-related issues with the same solution – applying gypsum without knowing if high sodium is the culprit. A high EC (electrical conductivity) reading may indicate salinity, but it does not confirm sodicity. To manage the risks of recycled water effectively, it is crucial to conduct soil and water analyses, including SAR (sodium adsorption ratio) and ESP (exchangeable sodium percentage) tests. Then, a decision can be made on whether a gypsum application is appropriate to displace sodium from the soil or if a flushing program to leach out salts is really required. Remember, applying gypsum helps remedy sodic soils, it will not reduce salinity.
If you would like to go deeper on this subject, the USGA has a great resource for you now with the new USGA Water Conservation Playbook. This is a totally free, comprehensive resource available for download. Within the Playbook, you will find detailed information about many water-related subjects, including an entire chapter on using recycled water, which takes an in-depth look at salinity and sodicity issues. The Green Section team is here as a trusted partner to support you and your course for the long term.
Southeast Region Agronomists:
Jordan Booth, Ph.D., senior director, USGA Course Consulting Service – jbooth@usga.org
Chris Hartwiger, director, Agronomy – chartwiger@usga.org
Chris Neff, agronomist – cneff@usga.org
Mitch Leininger, agronomist - mleininger@usga.org