Research study

Recycling of P and K in circular horticulture through compost application in sustainable growing media for fertigated strawberry cultivation

To diminish the share of peat in growing media used in substrate cultivation, composts (apart from biochar and locally produced plant fibres) have been proposed an interesting alternative for peat. In this study, published by Belgian researchers in 2017, the effect of compost addition to growing media for strawberry in greenhouse was assessed. The suppressive effect of compost addition against two important strawberry fungal pathogens (powdery mildew and anthracnose) and one foliar pest (aphids) was also examined.

The study was conducted in four full-scale greenhouse trials with different composts and other alternative growing media in a professional growing system for four years. The applied system was a double cropping system (spring/autumn). Compost amended substrates contained 20-100% (v/v) compost with different compost types tested:

  • Poplar bark, manure
  • Flax clay, cattle manure, pine bark
  • Green waste
  • Poplar bark, vermiculite


The study turned out, that growing strawberries on compost and other alternative substrates is possible, if the fertigation is adjusted. The plants made efficient use of the P and K in the compost under reduced P and K fertigation and the export and loss of nutrients with the drain water was reduced. The tested composts provided enough N during autumn culture to reduce N fertigation significantly (up to 50%), but in spring culture, these substrates needed an adapted fertigation scheme on N, P and K.

Degree of infection with powdery mildew and aphids was strongly positively correlated with the N status of the crop, pointing at the risks of high N supply for the crop. At the end of the autumn culture, no significant positive or negative effect of the compost treatments on the latent survival of C. acutatum on the strawberry leaves was found.

The full article is available until the 14 June 2018 under this link here.