For planners

Water retention you can specify in a tender.

RETENTIS® is a soil-integrated retention measure to increase the amount of plant-available water during the establishment phase of trees, shrubs, hedges and lawns. Without additional technical complexity.

Download White Paper (German)Discuss your project

Tried and tested

The data basis for your planning

Municipal planting substrate

+86 %

more stored water directly after 35 mm of rainfall, with 2% RETENTIS®.

Source: Substrate trial

Same trial

−49 %

less water draining through the substrate unused.

Source: Substrate trial

Common beech without water

+13 days

longer vitality: only on day 30 instead of day 17 had half of the seedlings dried out.

Source: Drought stress trial with beech seedlings

Planning basis

What you need for the tender

Classification per FLL

The white paper places its use within common planning standards such as the FLL recommendations and DIN 18919.

Approved

National approval under § 9 of the Austrian Fertilizer Act 2021 (until 2033), marketable EU-wide under Regulation (EU) 2019/515.

Bio-based & microplastic-free

Lignin-based, no synthetic polymers, listed on the FiBL and EasyCert lists.

Calculate quantities

Calculation tools for material requirements by area, substrate volume or number of plants.

Dosage

Typical applications in planning

ApplicationDosageHow to apply
Planting pits 10 kg/m³ Mix thoroughly with the excavated soil, place evenly around the root ball
Plantings (perennials, ground cover) 200 g/m² Work into the soil to a depth of 20 cm
Seeding 100 g/m² Work into the soil to a depth of 10 cm
Turf 100 g/m² Work into the soil to a depth of 10 cm
Soil and substrate mixes 10–20 g/l Mix in evenly
Root dip gel 0.5–0.7 kg per 10 l water Let swell for 10–15 minutes, dip roots for a few seconds

What matters is even distribution in the rootable space and good initial watering so the gel is fully activated. RETENTIS® does not replace professional irrigation; it makes it more effective.

Source: RETENTIS® technical data sheet (German), May 2025, V 1.2, and White Paper 2026

Technical Specifications

Organic water and nutrient storage granulate based on lignin, without synthetic polymers. It absorbs water, stores it as a reservoir and releases it gradually in the root zone. Dissolved nutrients can be buffered and their leaching reduced.

  • Form: black-brown granulate
  • Base component: lignin (without synthetic polymers)
  • Particle size: 0.5–4.0 mm (≥ 90 % within range)
  • Density: approx. 700 kg/m³
  • Bulk density: 600–750 g/l
  • Water storage capacity: up to 10 g water/g (≈ 10 l/kg)
  • Active life: 3–5 years (in the soil)
  • pH value: 6.4–7.0
  • Solubility: forms a gel with water
  • Storage class: LGK 13 according to TRGS 510
Technical data sheet (PDF)

Installation and execution notes (relevant for tenders)

  • Mix dry and uniformly with soil / earth / substrate.
  • Do not apply superficially; typically incorporate at a depth of 10–30 cm (project-specific).
  • Water thoroughly after installation to initiate swelling.
  • Standard fertilisation can be maintained; mixing with fertiliser is permitted.
  • For planting containers: slightly brownish drainage water may occur initially; provide saucers if required.

Practical note for designers and site supervision:
The mixing zone, quantity, installation depth and homogeneity, as well as delivery notes and batch numbers, should be clearly documented in the execution documentation.

RETENTIS® Planning Tools & Calculators

Our calculators help planners quickly and transparently determine the required quantities of RETENTIS®, the treated substrate volume and the associated costs. The landscaping calculator for perennial, shrub and area plantings is open to everyone; the tree planting calculator for applications in the root ball zone is available to AgroBiogel partners.
Simply open the appropriate calculator, enter the relevant parameters and use the results directly for planning, scenario comparison and cost estimation.

Vorschau GaLaBau Rechner

RETENTIS® Landscaping Calculator for Perennials & Shrubs

This calculator helps landscape architects and planners determine the required quantities of RETENTIS® for perennial, shrub and area plantings.

Click “Open Landscaping Calculator” to start planning.

RETENTIS® landscaping calculator for perennials and shrubs
AgroBiogel GmbH – Landscaping

How to Use the RETENTIS® Landscaping Calculator for Perennials & Shrubs

Calculation Mode

In “Number of Plants” mode, the calculation uses 0.1 kg of RETENTIS® per plant, for example for specimen shrubs, woody plants or individual plantings. In “Area” mode, the calculation uses 0.2 kg of RETENTIS® per square metre, for example for perennial planting areas or mixed plantings of normal density. The modes “kg/Litre Substrate – 10 g/L” and “kg/Litre Substrate – 20 g/L” are intended for very high planting densities of approximately 15–20 plants per square metre, particularly in very sandy, highly permeable substrates. In these modes, the substrate volume is calculated from the entered area and the mixing depth.

Input Parameters

Depending on the selected mode, enter the number of plants, the area in square metres, and the plant density (plants per square metre). In addition, specify the thickness of the mulch layer and the substrate layer in centimetres. (The thickness of the mulch layer does not affect the calculation.) The RETENTIS® mixing depth in the substrate defines the upper zone where the granulate is actually incorporated, for example the top 10 cm. A mixing depth of 10–20 cm is recommended. The price per kilogram of RETENTIS® can be adjusted to calculate the total cost and the cost per plant.

Results & Visualization

Click “Recalculate” to process the entered values. The calculator provides the total number of plants, the total quantity of RETENTIS®, the amount per plant or per square metre, the total price, and the average cost per plant. The cross-sectional diagram on the right automatically adjusts to the entered layer thicknesses and the selected mixing depth, illustrating the position of the RETENTIS® granulate within the substrate.

Dosage Guidelines

If the number of plants per square metre is below three, a note appears indicating that the calculation should preferably be carried out per plant. The kg/litre variants intentionally result in higher application rates and are intended only for very dense plantings and sandy substrates. Their use should always be technically justified and assessed on a project-specific basis.

Documentation and Reset

The “Download results (CSV)” button allows the calculation to be documented and the data to be used in quotations or project documents. The “Reset calculator” button restores all inputs to the default values so a new calculation can be started quickly and cleanly.

Vorschau Baum Rechner

RETENTIS® Tree Planting Calculator

The calculator determines the RETENTIS® requirement for tree plantings, including quantities, treated substrate volume and a cost overview. It is available to AgroBiogel partners and appears right here after logging in.

Without partner access, you can calculate the requirement for planting pits, areas or containers with RETENTIS®Calc. For your specific project, we are happy to do the calculation with you: office@agrobiogel.com

Using the RETENTIS® Tree Planting Calculator

Calculation Basis

First, the project-specific basic data for the tree planting are entered. This includes the number of trees to be planted and the planting pit volume per tree in cubic metres. In addition, the share of the substrate per tree that will actually be mixed with RETENTIS® is defined (e.g. in the root ball zone). Based on this, the calculator determines the total treated volume and the resulting RETENTIS® requirement.

Input Parameters

In addition to the number of trees and the planting pit volume, the desired application rate in kg of RETENTIS® per m³ of substrate is entered. By default, 10 kg/m³ is preset (recommended dosage in the root ball zone). The price per kilogram can also be entered so that the calculator determines not only the material quantity but also the project-related costs. Project details can optionally be added in the notes field.

Results and Visualization

Click “Recalculate” to process the inputs. The calculator provides the total RETENTIS® requirement, the treated substrate volume, the total price, and the price per tree. The diagram on the right automatically adapts to the inputs and schematically shows the tree planting structure with RETENTIS® applied in the root ball zone.

Dosage Guidelines

The calculation results can be used for internal planning, cost estimation, and project documentation. Optionally entered notes help assign the results to specific construction projects or project stages. The results should be checked against the technical specifications and the specific project design before tendering and execution.

Reset and New Calculation

For a new calculation, the inputs can be adjusted and recalculated. This allows different scenarios (e.g. varying dosages or treated substrate volumes per tree) to be quickly compared and evaluated.

Vorschau Praxisleitfaden RETENTIS®

RETENTIS® practical guide

Using RETENTIS® correctly
The practical guide shows the correct dosage and application of RETENTIS®, with clear tables, step-by-step graphics and practical tips for sustainable water storage in the soil. Available in German.

Download practical guide (PDF, German)

Tender specification text

Supply and install/incorporate an organic water storage granulate based on lignin/wood (without synthetic polymers) to increase water and nutrient retention in the root zone; water storage capacity up to 10 g water/g; active life 3–5 years; installation by homogeneous mixing with soil/substrate; incorporate dry; do not apply on the surface.

Supplier:
AgroBiogel GmbH
Königstetter Straße 128-134
3430 Tulln
Austria
Mobile: +43 664 4202 158
E-mail: office@agrobiogel.com

Equivalence criteria

Only materials and measures to increase water availability in the soil that are bio-based, microplastic-free and free from synthetic polyacrylate superabsorbent polymers (SAP) shall be considered equivalent.

Request tender text

Delivery, Packaging & Storage

Delivery forms:

  • Paper bag 20 kg (on CP1 pallet, 25–40 bags, 500–800 kg)
  • Big bag on CP1 pallet, 500–750 kg

CP1 pallets (1000 × 1200 × 138 mm)

Easy storage: keep cool and dry

Non-hygroscopic: does not clump, stays free-flowing

Shelf life: unopened > 24 months

Let's run the numbers for your project.

We support you with quantity calculation, tender text and installation.

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