Hydrogel science — Published
Lab numbers vs field water
Headline absorption figures are measured in deionised water. Field water carries dissolved salts, and every SAP absorbs less as salt content rises. A grade that absorbs 400 g/g in deionised water may absorb a fraction of that in saline water.
Hard water and calcium
Calcium and magnesium (water hardness) reduce absorption more strongly than sodium because each ion bridges two charged sites on the polymer. Borewell water in parts of Maharashtra can be hard enough for this to matter.
Fertiliser in the root zone
Concentrated fertiliser around a granule temporarily raises the salt content of soil water and lowers absorption. Mixing hydrogel with basal fertiliser is still common practice for even spreading; it is the steady-state soil water that matters.
What to do
If your irrigation water is saline or hard:
Share a water test with Sarovar's technical team before choosing a grade or rate.
Expect to use the upper end of the dosage range.
Request a field trial to measure the effect in your own conditions.