How does a hydrogel work in the soil?

Dry periods are no longer the exception but part of everyday life in agriculture, horticulture and urban greening. Many people ask: is there a way to equip soils so that they store water for longer and supply plants better? This is exactly where hydrogels such as RETENTIS® from AgroBiogel come into play.

What is a hydrogel?

Hydrogels absorb and store large amounts of water, often many times their own weight. What makes them special: they release this water again as soon as the soil dries out and the roots need it. You can think of them as tiny sponges distributed in the soil.

RETENTIS® is a lignin-based granulate, i.e. based on a natural wood component that is produced as a by-product of the pulp industry. It is listed for organic farming (FiBL and EasyCert). This sets it apart from synthetic hydrogels, which mostly consist of petroleum-based polyacrylates.

How does water storage in the soil work?

1. Mixing into the soil: RETENTIS® is worked directly into the soil at planting, not scattered on the surface.
2. Water uptake: after rain or irrigation, the granulate absorbs water and swells into a gel.
3. Release as needed: as soil moisture drops, the gel gradually releases the water to the root zone.
4. Long-lasting effect: depending on soil type and conditions of use, RETENTIS® remains active in the soil for 3–5 years.

What this means for plants and soils

• Fewer waterings: the root zone stays moist for longer between two waterings. In the greenhouse trial in Almería, tomatoes managed with 20% less water and still yielded more than the fully irrigated control (to the trial report).
• Less drought stress: in the trial with one-year-old European beech seedlings, the first plant with RETENTIS® failed on day 27 instead of day 9 (to the trial report).
• Nutrients in the root zone: dissolved nutrients can be buffered and leaching losses reduced.
• No synthetic polymers: no microplastics entering the soil.

Who is a hydrogel useful for?

• Farmers who want to use irrigation water more efficiently.
• Hobby gardeners who want to water less often.
• Towns and municipalities that need to get new plantings through heat waves.
• Forestry businesses, where young trees struggle to establish in dry summers.