Sodium adsorption ratio interpretation, sodicity hazard for soil and drip, blending and gypsum.
How do I read the SAR value in my water test and is my water safe for drip?
RRamesh Chandra Nair6mo ago · 182 views
4 Answers
🌾Farmer.in Krishi TeamExpert ✓5mo ago
SAR (sodium adsorption ratio) compares sodium to calcium and magnesium in your water and tells you the risk of the water making your soil sodic and sealing it up. As a rough guide, low SAR water (often below about 10) is generally safe, medium SAR carries some hazard especially on heavy soils, and high SAR water steadily damages soil structure and infiltration. SAR is read together with EC and RSC, not alone. To manage borderline water, add soil gypsum to supply calcium, keep drainage good, blend with better quality water if available, and maintain organic matter. The water itself can still run through drip, but watch for clogging from associated salts. Get a full water test and follow your soil lab or KVK on gypsum and blending; do not over apply.
SSasidharan Pillai5mo ago
Read SAR along with EC and RSC, not by itself like the team says. My SAR looked borderline but the RSC was the bigger problem and that is what I had to manage with gypsum. Looking at one number alone gave me the wrong idea until the lab person explained the whole report.
VVenugopal Menon4mo ago
On my heavy clay field the borderline SAR water sealed the surface and water stopped soaking in. The same water on a lighter field nearby was fine. So the hazard depends a lot on your soil type, not just the water number. Gypsum and keeping organic matter up helped my clay take water again.
KKrishnan Kutty Nair4mo ago
If you have a cleaner water source, even rainwater stored in a pond, blending it with the high SAR water brings the risk down nicely. I top up my tank with monsoon runoff and mix, and the soil stays in better shape than running the tubewell water straight. Blending is often cheaper than fighting the soil.