Make the right choice and use of your water buffer
The first choice for a good crop is the right volume of substrate. As a grower it is important to have enough volume for the roots as well as the water, nutrients and oxygen availability for the plants. The selection of the right slab starts with good substrate system design. “In Cultilene we recommend 7 to 9 liters of stonewool per square meter depending on the dripper system” says Kim Harding, Manager Application Vegetables at Cultilene.
Differences in water availability
The water buffer - the amount of water in the substrate which is available for the plant - is crucial for a successful crop. This buffer is not only determined by the volume of substrate, but also by the water content of the substrate. The water content, which is measured by a sensor or by weight, gives an indication of the amount of water that is in the substrate. Not all of this water is necessarily available to the plant. "There are major differences in the water availability of substrates. In stonewool is a relatively large amount of water available", Harding explained. A fully saturated stonewool slab, in which the drain holes are already made, has a water content of about 85 percent. The stonewool fibers occupy approximately five percent of the substrate volume, leaving ten percent of the substrate with air. As the plant takes up water, then the space is filled with air, and therefore oxygen. This means that the ratio between water and oxygen (O2) can be controlled by the irrigation strategy. This strategy also affects the distribution of available water and nutrients and so the root distribution in the slab."
Large or small water buffer?
Several factors are important to get the right amount of water buffer. Local climate and growing conditions for example. A smaller buffer can be used when there is low light, low temperatures and high humidity when transpiration is lower. "The smaller water buffer is used quicker by the plant, which means you have a quicker reaction and can achieve dry back target levels easier," Harding explains.
The ideal water buffer also depends on the crop stage and target levels. "The water buffer must be adjusted accordingly. Not only does the plant need sufficient water and food, it is also important to take into account the drying back of the slab. A stonewool slab with a large water buffer dries back slower than a slab with a small buffer. When you have a small water buffer and you reduce it by 1 liter, it has more impact than if you reduce by 1 liter on a large water buffer. The effect on the plant is also different.
Cultilene cares
The Cultilene Substrate Calculator helps growers in good substrate design. This online tool provides a quick and easy way to choose the slab size and volume. The Substrate Calculator is in the Smart Root Zone Management (SRZM) Cultilene app, which can be downloaded for free from the App Store and the Google Play Store. This app contains guidelines for the cultivation and production of tomatoes, cucumbers and peppers and can help growers to achieve optimum plant balance. Cultilene has suggested in the Smart Root Zone Management (SRZM) target values for the water content in the substrate, the changes during the night and between the watering’s during the day. The app also explains how each grower can use the irrigation strategy to achieve certain changes. As well, Cultilene has specialists who can help Cultilene growers choose the correct water buffer and help to manage it properly. In short Cultilene Cares.
This tomato grower has gone for 8.5 liters per square meter of substrate. This is consistent with the growing system of the company, in which there are two blocks per slab of 1000 x 150 x 100 millimeters, with each block having two heads, and one dripper. The total slab volume is 15 liters, this means one dripper for 7.5 liters of substrate.
For more information:
Saint-Gobain Cultilene
Zeusstraat 2
5048 CA Tilburg
Netherlands
t + 31 (0)13 578 00 57
info@cultilene.nl
www.cultilene.com