(Braunschweig) For three years, the joint project ToPGa (‘Development and evaluation of peat-reduced production systems in horticulture’) investigated and evaluated how and whether peat-reduced substrates and production systems can be implemented in commercial horticulture. As a research and development project, the aim of the project partners was to clarify previously unknown relationships in peat-reduced production systems and to analyse the potential of new alternatives.

Annmarie-Deetja Rohr, who coordinated the project at the JKI, summarises: ‘Among other things, I was impressed by the results of the economic and ecological analysis, especially how differently peat replacement affects different crops and production systems. While complete peat replacement is already possible for one crop, this would not be economically viable for another crop with the current technical equipment.’ The situation would be similar for the life cycle assessments:

In addition to the proportion of peat in the substrate, whether and with which energy source the greenhouses are heated plays a considerable role, as does how the goods are packaged. In addition to peat replacement, the latter in particular would be a realistic way for colleagues to reduce the CO2 footprint of production.

Active microbiome is attractive to fungus gnats

‘The collaborative partners really went into depth in our investigations,’ says Rohr, ’at the JKI, for example, we looked at the microbial and fungal communities in peat substitutes. We found that the communities differ significantly between different substrate mixtures.’

The microbiome in turn influences how attractive the substrate is for fungus gnats, for example, which are important pests and pests in horticulture.  Researchers in the sub-project were able to show that source materials with high microbial activity, such as bark humus or green compost, were significantly more attractive to the insects than white peat or sphagnum.

At the end of the project, project coordinator Rohr points out: ‘It was clear to see that the three-year project period was simply too short for many issues. The versatility of the peat substitutes and the different requirements of the crops and cultivation systems make the matter extremely complex. There is therefore a clear need for more research.’