Water Management
Sustainable Growing

Caté’s extensive comparative trials with meaningful insights for tomato cultivation

Anna Woronowicz
November 8, 2023

Stonewool vs. Coco in Soilless Tomato Cultivation.

Caté, the renowned applied research station in Saint Pol de Léon, situated at the heart of Brittany’s thriving vegetable and horticultural region, has concluded a series of comprehensive comparative trials focusing on stonewool and coco growing media for soilless tomato cultivation. The trials, spanning multiple seasons, have yielded remarkable insights into the agronomic, environmental, and economic advantages of these two media.

The trials, conducted over the course of almost three years, were orchestrated in partnership with Grodan. The tests aimed to investigate the performance of stonewool and coir-based growing media in enhancing tomato cultivation, focusing on factors such as yield, volume, quality, water efficiency, and disease management.

Early Findings Highlight the Potential of Stonewool

The initial trial, carried out in 2021 with the Luminance cluster variety, showcased promising outcomes that underscored the potential of stonewool. The results, favoring Grodan’s growing medium, exhibited significant benefits in terms of yield, particularly during the early cultivation period. Notably, stonewool demonstrated an edge in both cluster harvest numbers and average fruit weight compared to unwashed coco. While the yield convergence occurred at the culmination of cultivation, stonewool displayed a 35% reduction in growing medium volume per m², enhancing flexibility and irrigation management, especially in warmer conditions.

Advanced Irrigation Management and Enhanced Yield

Building on the success of the initial trial, Caté, in collaboration with Grodan, initiated a second round of tests in 2022. This phase included an exploration of two variants of stonewool growing media, each with distinct widths, pitted against the commonly employed coir medium in Brittany. The trial aimed to enhance irrigation management and balance the energy consumption of different tomato varieties. Grodan’s innovative growing medium was selected for its potential to achieve more sophisticated irrigation control.

The results of the 2022 trials reaffirmed stonewool’s effciency. Both variants of Grodan’s growing medium showcased superior performance in terms of yield, fruit size, and disease resilience. The trial revealed that the broader Grodan medium exhibited increased yield, larger fruit size, and greater resistance to botrytis. Additionally, stonewool demonstrated improved water efficiency compared to coir, with optimal water-to-product ratios.

Stonewool’s Capacity for Consistency and Stability

lain Guillou, the driving force behind Caté’s soilless experimentation, emphasized the significance of volume in stonewool growing mediums. He noted that larger volumes contributed to enhanced uniformity, stability, and balance among plants, ultimately leading to better fruit weight and overall plant performance. The results showcased that the combination of precise dosing, watering management, and optimal volume in Grodan’s stonewool slabs resulted in unparalleled plant balance and impressive outcomes.

Table below presents average of the test results over 2 seasons:

Growing medium Yield in % Volume of growing medium in litre/m2 Yield per litre of growing medium in % % mortality due to Botryris (end of cultivation) Amount of water Used in litre/kg product.
Grodan 106,2% 8.43 139,6% 7,5% 16.18
Coco 100% 11.08 100% 14% 17.55

Looking forward

The culmination of these trials emphasizes the potential of stonewool as a versatile and powerful growing medium in soilless tomato cultivation. With a focus on precision, consistency, and optimal irrigation management, the partnership between Caté and Grodan continues to drive advancements in the field, contributing to more sustainable and productive agricultural practices.

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