Hydrogel glossary
The terms you will meet on data sheets, in crop guides and in conversations with suppliers.
23 of 23 terms
- Absorption under load (AUL)
- How much liquid an SAP absorbs while pressed under a set weight, usually 0.3 or 0.7 psi. Key for hygiene products.
- Basal application
- Fertiliser or soil inputs applied at sowing or planting, before the crop grows. Hydrogel is often mixed with the basal dose.
- Black cotton soil
- Heavy, clay-rich soil (vertisol) common across the Deccan, including Nashik. Swells when wet and cracks when dry.
- Centrifuge retention capacity (CRC)
- Liquid an SAP keeps after being spun in a centrifuge, in grams per gram. Shows how firmly water is held.
- Certificate of Analysis (CoA)
- A batch-specific document reporting the measured test results for the material actually supplied.
- Counter-ion
- The mobile ion (sodium or potassium) paired with the charged groups on the polymer chain.
- Crosslinking
- Chemical bridges between polymer chains that stop SAP dissolving and set the balance between absorption and gel strength.
- Deionised water
- Water with dissolved salts removed. Used for headline absorption figures, which are higher than in field water.
- Free swell capacity
- Total liquid absorbed by an SAP with no load applied, in grams per gram.
- Gel blocking
- When swollen gel forms a layer that stops liquid reaching dry particles behind it.
- Gel strength
- How firm a swollen gel is. Firmer gels resist pressure and gel blocking but usually absorb less.
- Hydrogel
- A water-swollen polymer network. In agriculture, the common name for SAP applied to soil.
- Murrum
- Coarse, gravelly weathered rock soil found across Maharashtra. Drains fast and holds little water.
- Particle size distribution
- The share of particles in each size band, measured by sieving. Reported on the CoA.
- Polyacrylate
- The polymer family most SAP is made from, based on acrylic acid.
- Residual monomer
- Unreacted acrylic acid left in the polymer, in ppm. Kept low in hygiene grades.
- Root zone
- The soil volume where a crop's active roots take up water and nutrients.
- Safety Data Sheet (SDS)
- A standardised document covering hazards, handling, storage, PPE and first aid for a material.
- Sodicity
- Soil damage caused by excess sodium, which disperses clay and harms structure and drainage.
- Starch-grafted polymer
- An SAP whose absorbent chains are attached to a starch backbone, raising the bio-based content.
- Super absorbent polymer (SAP)
- A cross-linked polymer that absorbs and holds many times its own weight in water.
- Technical Data Sheet (TDS)
- A grade-level document listing typical properties, specifications and usage guidance.
- Wetting zone
- The patch of soil moistened by a single dripper. Hydrogel should be placed inside it.