RHP advice coir substrate for strawberries 

28 july 2017

The last time there has been discussion in the sector concerning the use of coir substrate for strawberries. Because of that discussion RHP has listed the following points of notice and advice values.

• Si (Silicium) is an element that is usually present in small amounts in substrates. Si plays a role in building cell walls. Strawberry is sensitive to higher concentrations of the element Si which results in albino fruits. Despite the fact that RHP coir substrates are cleaned, they can still contain Si. Coir substrate is not the only source of Si. The quality of the water that is used by the grower is just as important. The use of spring water doesn’t need to be ruled out, but the level of Si in the water needs to be sufficiently low. The Si level in the irrigation water should not be higher than 0,2 mmol/l.
• Analysing Si in coir substrate in the BaCl2-extract (Barium chloride) is of no use, because Si is probably not bound to the complex as positive element.
• A low starting fertilization in the culture can lead to more problems with the Ca/Mg/K proportions (Calcium/Magnesium/Potassium).
• When using coir substrates the advice is to start with an EC of 0,75 mS/cm (in the 1:1,5 extract). Growers are wise to monitor the Ca and Mg values from the beginning and, if necessary, adjust more (than one is used to), and reduce K in proportion.

Advice values coir substrate (start) for the 1:1,5-extract, water and BaCl2.

Values based on the methods performed by Dutch laboratories.

* For sensitive strawberry species a maximum of 0,1 mmol/l.