TerraCottem's most frequently asked technical questions

Frequently Asked Technical Questions

The following is a list of our most frequently asked technical questions. Click on the question to view the answer.
These F.A.Q.'s are designed to provide a better understanding of our soil conditioning technology and soil amendments in general.
Water availability
... Polymers
  • All products containing hydroabsorbent polymers (also known as hydrogels or superabsorbers) are basically the same?
False – Although on the exterior one hydroabsorbent polymer may look similar to another, their chemical construction, the physical structure of the network, and especially the cross linking density can be vastly different and will affect how they absorb, store and release their contents, and will determine their toxicity, longevity and suitability for use in growing plants.  Caution must be exercised, as many are sodium-based (poly-acrylic acid sodium salts, sometimes referred to as sodium polyacrylate (or PAA)), manufactured principally for use in baby diapers and other sanitary ware, for use as flocculants and for chemical liquid waste disposal, making them unsuitable for use with plants or turf.  Unfortunately, some of these products are repackaged and sold for use in horticulture. Only polymers that are of salts of potassium and/or ammonium are suitable for agricultural and horticultural uses.
Furthermore, the TerraCottem soil conditioning technology simply contains those hydroabsorbent products that have demonstrated the best results on plant growth and water efficiency, in independent efficacy trials carried out by and/or on behalf of TerraCottem.
  • So how does this make the TerraCottem soil conditioning technology different from other products using hydroabsorbent technology?
Years of testing at the University of Ghent and independent laboratories demonstrate that the best results, over a number of plant growth and water-use efficiency parameters, were achieved with a carefully balanced composition of hydroabsorbent, nutrient and growth-stimulating components.   Each TerraCottem component has its positive impact on plant growth but it is above all the synergetic effect of all the product’s scientific balanced components which makes the TerraCottem soil conditioning technology so unique and successful.
With the full backing of an internationally-recognized university, a heritage linked with its initial use in United Nations’ and other humanitarian projects, and a client base on five continents which includes top professionals in the relevant markets, the TerraCottem soil conditioning technology has a credibility rarely matched in the industry. 
TerraCottem does not produce for other brands.  You will only find the quality and efficiency of the TerraCottem soil conditioning technology under the TerraCottem brand name. 
...Water availability
  • The higher a soil amendment’s water retention capacity, the more water will be available to the plant?
False – The water retention capacity is not necessarily relevant in terms of performance, as high water retention capacity does not necessarily mean high water availability.  While most hydroabsorbent polymers (primarily produced for the diaper and sanitary ware industry) can absorb hundreds of times their own weight in water, they are designed to irreversibly bind the moisture and so compete with the plant roots for the same water.  As a result, no water is made available to the plant.  Additionally, no water retention capacity is absolute.  The higher the level of minerals or impurities in the water, the lower the water retention capacity is.  Even given the same water quality, when mixed into the ground the water retention capacity will decrease with higher soil pressure.  
  • All the water absorbed by a hydroabsorbent polymer is available to the plant?
False - Many hydroabsorbant polymers do not have the ability to make the water they absorb available to the plant, and, if available, it may only be for a short period of time. The hydrogels incorporated into the TerraCottem mixture do make more than 95% of this water available, for an extended period of time.
  • Plant roots will have to compete with the hydroabsorbent polymers present in the TerraCottem soil conditioners for the same water?
False - The hydroabsorbant polymers in the TerraCottem mixture were chosen for, amongst other things, their ability to absorb, retain and then make water available to plant roots. The hydrogels contained in TerraCottem have absorption tensions which allow plant roots to pick up the water on demand, yet ensure that the hydrogels remain humid over a long period of time and are not dried out by the surrounding soil.
... Fertilisers
  • Do the TerraCottem soil conditioners absorb water-soluble fertilizers?
Yes. The TerraCottem soil conditioners can absorb and retain fertilizers added to the growing medium in which it is mixed.
  • Salts, and chelated iron products added to soil treated with the TerraCottem soil conditioning technology will degrade or destroy the product?
Salts, fertilizers and minerals do not decrease the lifespan of any of the TerraCottem soil conditioner, but do have an effect on its water retention capacity.
  • How does the TerraCottem soil conditioning technology act to reduce the level of salinity and impurities found in the soil and water?
Due to the chemical composition of the cross-linked hydroabsorbent polymers that are partially neutralized by potassium and ammonia salts, there is a preference for absorbing K+ - over Na+ - ions. This results in a lower salinity level of the water inside the polymers offering the plant’s root system a better growing environment.
... Practical
  • The TerraCottem soil conditioning technology may promote the creation of root rot?
False – Root rot is often caused by a surplus of water in the soil, where poor soil structure prevents the water from draining off or being used effectively by the plant, and limits or prevents oxygen from circulating, eventually asphyxiating the plant roots.
In soil treated with a TerraCottem soil conditioner, water absorbed by the product is not free, but contained within the hydroabsorbent components and released only on plant demand.  As plants only absorb the water that they need, the rest remains in the polymers. These swollen particles open up and aerate the growing medium helping reduce compaction and root rot. 
  • Why are some of the hydroabsorbent components visible on the surface after the first irrigation, and how long will they remain?
If the TerraCottem soil conditioners are mixed thoroughly with the soil, root zone or growing medium, a few particles will be visible on the surface after watering. However, upon contact with ultraviolet light (sunlight) these remaining particles will disintegrate and disappear within a matter of days.
  • When should the TerraCottem soil conditioning technology be applied?
When planting or just before seeding, sodding or sprigging.  It has to be worked into the soil to a depth of 20 cm/8 in. 
  • Can the TerraCottem soil conditioning technology be used in conjunction with other products and techniques?
Yes. The TerraCottem company is not aware of any other soil amendment, technique or product (e.g. sub-soil heating, geotextiles, Desso GrassMaster, SubAir, etc.…) not compatible with the use of any of the TerraCottem soil conditioners. The products are often used to compliment the effects of other products and techniques.
  • The TerraCottem soil conditioning technology cannot be used on areas treated with pesticides and herbicides 
False – The hydroabsorbent components used in the TerraCottem soil conditioners can only absorb cations and anions with a regular, small ion volume.  Most benzene-based organic pesticides and herbicides (as well as hydrocarbons, alcohol and other organic solvents) cannot penetrate the polymer structure due to their significantly higher molecular volume (prove this for yourself by adding rubbing alcohol to a spoonful of the mixture and see what happens).  For this reason, most benzene-based organic pesticides and herbicides may be used on areas treated with any of the TerraCottem soil conditioners, with no negative effects.  Should you have any doubts, test it first by pouring a watery solution of the product over a spoonful of the TerraCottem soil conditioner.
  • How often should areas treated with the TerraCottem soil conditioning technology be fertilised and irrigated?
Customary types and rates of fertilizer and irrigation should be used on areas treated with a TerraCottem soil conditioner, according to the recommendations of the project manager, architect or consultant.  After plants and turf have been established, lower rates of both irrigation and fertilizer may be evaluated in order to find the most effective one.  Significant reductions in irrigation (up to 50%) and in fertilization (up to 40%) are repeatedly reported by TerraCottem customers and have been proven by independent Universities and laboratories. 
  • Realistically, what kind of savings can be achieved by incorporating the TerraCottem soil conditioning technology into the growing media?”
  1. Cost of Inputs: Clients using the TerraCottem soil conditioning technology report water savings of between 40 – 75%, and fertilizer savings of between 20 – 60%.
  2. Maintenance costs: Time, labour and input costs associated with the replacement of dead plants and the maintenance of areas treated with the TerraCottem soil conditioning technology are between 25 – 75% less than in areas not treated with the product.
  3. Replacement costs: The TerraCottem soil conditioning technology allows a reduction in plant mortality of between 20 – 100%.


  • In colder climates, the polymers within the TerraCottem soil conditioning technology may freeze, causing problems?
False – The TerraCottem’s polymers freeze at –2º C, and are therefore not affected by overnight frosts.  Freezing the TerraCottem soil conditioners has no detrimental effect on the product, treated soil or plants whatsoever.  As TerraCottem’s polymers freeze at lower temperatures than water in the soil, water remains available at lower temperatures and for a longer period of time, possibly lengthening the growing period by up to several weeks.
  • What should be done with soil treated with the TerraCottem soil conditioning technology after it has been used (for example, the soil from containers or pots which are being replanted?).
Soil treated with the TerraCottem soil conditioning technology retains the product’s benefits for many years.  By adding this soil mixture to other matter from the containers (i.e. dead flowers, root systems, plants, leaves, etc.…) to a compost pile, this composted soil can be used in ornamental beds, gardens and other landscaped areas the following season. The components that have been consumed by the plants during the previous growing season can be replenished by adding TerraCottem Complement.
... Environmental
  • All hydroabsorbent products are safe to use for growing plants?
False – Hydroabsorbent polymers all contain a certain quantity of monomer residues from the manufacturing process. A hydroabsorbant (co)polymer cannot release harmful monomers during natural degradation processes. However, during the manufacturing process, it might occur that not all monomers are transformed into these stable polymers. All TerraCottem soil conditioners have extreme low monomer contents (acrylamide 0.0006% w/w; acrylic acid 0.0023% w/w), way below the threshold value described in EU Directive “1999/45/EG” (Art. 3, chapter 3): acrylamide < 0.1% w/w; acrylic acid < 1% w/w. These levels are scrupulously monitored, both internally and externally. Nevertheless, on the market, one can find polymers that do not have these safety levels and are therefore not fit for growing plants. 
The polymers contained in TerraCottem are cross-linked polymers. They are exempt from REACH registration. The raw materials and monomers used to produce these polymers are pre-registered and are registered respectively according to their tonnage band. Furthermore, neither substances of the SVHC list (List of Substances of Very High Concern) nor of so-called candidate list in its present form, are used for manufacture. 
  • Is polyacrylamide toxic?
Some of the hydroabsorbant polymers present in the TerraCottem soil conditioners are cross-linked co-polymers of polyacrylamide and polyacrylate. Polyacrylamide is not toxic, but un-polymerized acrylamide is, since the acrylamide monomer is a neurotoxin.  Therefore, products containing high acrylamide monomer residue could be of concern. However, the TerraCottem soil conditioners’ hydroabsorbant co-polymers are both manufactured and selected in such a way that the monomer residue after production is negligible and guaranteed to be well below any dangerous levels set by governmental agencies worldwide. And once enclosed in the co-polymer, it is chemically impossible for the acrylamide to be freed from the end structure.
  • How long does the TerraCottem soil conditioning technology remain active in the soil?
The nutrient starter component and trace amounts of growth stimulating agent are designed to perform during the initial growth phase after incorporation, and the slow-release fertilizer component has a 6 – 12-month utility, depending on the average temperature.
While the different hydroabsorbent components of the TerraCottem soil conditioning technology have high but varying levels of mechanical and biological stability, the longest-lasting components have demonstrated a lifespan of more than eight years in practical applications.
It is the synergy of all the components of the TerraCottem soil conditioning technology which determines the product’s effectiveness in the growing medium, and which makes it a soil conditioner. 


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