Compost and biochar are commonly used as soil amendments to increase organic matter content and fertility by improving physical, chemical and biological soil conditions. Additional benefits of compost and biochar addition to soil are promotion of soil biological activity, reduction of erosion losses, decrease of bulk density, improvement of structural stability, nutrient availability and plant uptake, increase of water holding.
Standard application dosages of compost and biochar in the soil are, respectively, 5’000-20’000 kg/ha and 100-2’000 kg/ha, according to soil conditions and crop uptakes. The application is done at soil preparation, after ploughing and before harrowing, in order to mix the products within the first 20 cm of the soil layer. In comparison to manure, it is possible to start planting soon after their application, and they can also be applied during the cropping season.
Compost and biochar are also interesting as a peat substitute and for growing media, in particular after recent increasing concern of the environmental impact of peat extraction and the damage of peat lands natural habitats by the horticulture industry that lead to the adoption of alternative substrates.
Standard application dosages of compost and biochar in growing media are, respectively, 5-20% and 0.1-2% v/v, according to substrate conditions and crop uptakes. The application is done at industrial scale by producers of growing media or by farmers when preparing the potting substrate, mixing the products before planting. It is recommended to wait 1-2 days before using the prepared potting mix and to do not sterilize the substrate after the application of compost or biochar.