RHS research changes approach to plant nutrition in the transition to peat-free soils

Experience from the Royal Horticultural Society shows that an excess of fertilizer in peat-free mixtures can restrict shoot and root development. Three-year commercial trials in British nurseries covered various plant groups and seasons. In particular, some peat-free grown plants did not experience a lack of nutrients even after 14 months, whereas control samples with a reduced proportion of peat and equivalent top dressing showed deficiency.

The data obtained indicate that such substrates may initially contain more available nutrition than assumed. Manufacturers include nutrient packages in the formulations, and the ingredients themselves are capable of releasing elements upon decomposition. The application of additional fertilizers without assessing the current balance creates a risk of its disruption. Specialists recommend that commercial producers, together with substrate suppliers, test different fertilizer application rates to optimize costs and prevent nutrient losses.

An important factor remains irrigation management, since excessive irrigation can leach nutrients from containers. In turn, Agriton notes the need to study the role of compost, soil biology, and local organic materials such as green waste. For their primary processing, the Bokashi fermentation method using the Actiferm microbial inoculant is being studied, although the fermented material is not a finished compost or substrate and requires further testing.