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and improved nutrient buffering

Humic acid coloured perlite for higher consumer acceptance

Despite perlite being a 100 % pure natural product, consumers tend to associate its white colour with being an artificially made or chemical product. This leads gardeners selling organic herbs to concerns about customer acceptance. Knauf introduced dark-coloured Perligran® Organic. The perlite is mixed with humic acid, a natural colouring, which gives it a darker colour and improves the nutrient buffering. "This way we do not only improve the quality of potted herbs, but also gain a significantly better consumer acceptance", Knauf sales manager Dirk Mühlenweg explains.

Perligran Organic is made from volcanic substances, just like the regular Perligran. It was developed especially for substrates for organic potted herbs, organic vegetable growing and even organic hobby gardening with a longer period of use. The product is trending, especially in soft fruit and vegetable farming. Here it is used as a mineral substrate additive and as a mineral soil improver.

Dirk Mühlenweg showing Perligran granulate

Water balance
Dirk Mühlenweg explains how the mineral granulate optimises the air and water balance in substrates and natural soil thanks to its natural attributes.
"Its openly porous structure ensures optimal substrate and soil ventilation, a high water storage capacity and instant rewettability. And thanks to a thorough screening the products are almost free from fine particles, so irrigated soil will not be compacted but perfectly ventilated instead." 

Especially herbs need a loose, well-ventilated and well-drained substrate, as they only grow when the soil is not too wet. "For example an open-air herb spiral is always placed in a sunny space and equipped with soil that is as loose as possible. Like this, herbs grow best. Even a bit of dry stress helps to harvest the most aromatic herbs that are rich in essential oils. Herbs from the Mediterranean Macchia area also prove this, as they grow in the blazing sun and on poor soil. Herbs taste and smell better, when they are not always supplied with water and nutrients", says Dirk. According to him, that's why perlites are the product of choice for herb growers. "Even more when the substrate is supposed to be peat-free or peat-reduced. Most alternative substrate materials like compost, wood fibres or coconut fibres are way too heavy and store too much water for organic herb farming."

The white-coloured classic product was already approved in organic substrates and as a soil improver for organic gardening and farming in Germany and Switzerland. Thus it was also added to the FiBL list. 

Colouring the perlite
But despite perlite being a 100 % pure natural product, consumers tend to associate its white colour with being an artificially made or chemical product. This leads gardeners selling organic herbs to concerns about customer acceptance. Knauf therefore coloured their Perligran Organic with humic substances, giving it a more natural appearance. "The humic substance is a natural and organic-farming-compliant and also leads to an improved nutrient buffering on top", says Dirk. "Fertilizer is stored and slowly dispended to the plant later. Also the plants’ uptake of nutrients in the substrate is easier and more efficient. This special substance, which also occurs in compost, wood or coconut fibres or peat, additionally enhances microbiological activity in the substrate. The enhanced activity leads to stronger and more resistant plants." 

For more information:

Publication date: 2/13/2018
Author: Arlette Sijmonsma



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