Research
New research demonstrates the advantages of growing with the Air-Pot system.
Air-Pot system – the only container to completely eliminate root circling and accelerate growth by up to 75%.
Two sets of recently published research from Holland and Germany, have found that the British designed and made Air-Pot container was the only type of pot to eliminate root circling entirely, and that the resulting healthy root system lead to better tree health and faster growth.
In the Dutch trial, independently verified by Cultus Crop Research BV, three species of tree grown in Air-Pot containers were found to grow on average 68% faster than those in the open field, with Tilia growing an astonishing 75% faster.
In the German trial, conducted by Dr Axel Schneidewind of Saxony-Anhalt State Office for Agriculture and Horticulture, five different containers were used to assess the development and impact of circling roots on Tilia, a species of landscape tree commonly planted throughout Europe. Only Air-Pot containers did not cause root circling. Circling caused by the other four containers negatively impacted the health and growth of the trees, both in the nursery and after they had been planted into the landscape.
Holland trial 2018-2019
In 2017 Carpinus, Tilia and Liquidambar trees were grafted and then spent a year in the Air-Pot U system, ensuring that they started with a healthy root structure. In October 2018 a third were planted in the field and the others in either 7.5litre or 45litre Air-Pot containers. In both sizes of Air-Pot container the trees put on more growth than in the field, with the greatest difference in the 45 litre.
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This exceptional rate of growth makes it possible to take a year out of production time, allowing a 50% increase in turnover from the same area of land.
Holland trial 2019-2020
The trial continued in 2020 with the trees in the 7.5 litre containers potted on to 100 litre.
At the end of the second year of the trial the field grown trees were still smaller in height and stem diameter than those grown in Air-Pot containers. The trees in 45 litre Air-Pot containers had an increased stem diameter of 43% – 55% and those in transplanted from the 7.5 to the 100 litre 26%-41%.
For example the Carpinus in the 45 litre containers had a girth 10-12, while the field grown trees only averaged 6-8. The Liquidambar 14-16 compared to 10-12.
For more detail please download the independent report for the second year of the trial.
German trial 2008-2019
Starting in 2008 Tilia were grown in five different types of container – standard hard walled tub, Pot-in-Pot, Plantinbag®, Arbro-Perf® and Air-Pot®. Over three years their roots were regularly assessed for root circling and deformity. All of the containers showed some level of damage to the roots apart from the Air-Pot container where no circling roots were found.
Number of circling roots found in the different container types
In 2011 all the trees were planted into the landscape where their roots and growth continued to be assessed for a further eight years.
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After four years
One tree from each pot type was lifted from the field and the roots examined. In the photographs you can see that the root deformities that had developed in the other types of container have got worse….and will continue to worsen.
Only the Air-Pot grown tree has continued to develop a healthy root structure.
After eight years
On four of the trees the root deformity has got so bad that it is threatening the life and stability of the trees. It is highly unlikely that any of these trees would reach maturity.
Once again the tree from the Air-Pot container has a heathy radial root structure with no deformity.
The root deformity also clearly affected the trees’ rate of growth. This difference will only increase as the trees mature.
The results have surprised academics and growers alike. Although the detrimental effects of root circling, which come from growing in all standard containers, have long been recognised, the extent of the benefits of growing in Air-Pot containers had not been independently confirmed in trials.
Tony Kirkham, head of the Arboretum at Royal Botanic Gardens Kew, is one of the system’s greatest champions and comments:
“When you buy a car, it’s important to look under the bonnet and see the engine. A tree is no different – it is the root system which powers the growth of the tree. Look after the roots first to secure the long-term survival of the tree. That is what the Air-Pot container does, it develops radial, healthy roots to ensure that trees thrive for generations to come.”