Kennisprogramma Circulair Terreinbeheer : Jaarrapportage 2022

Summary

The chemical composition of 134 organic soil improvers including bokashi and various forms of treated and untreated clippings and/or leaves collected from green spaces in cities has been determined. The samples originate from pilots associated with ‘Circulair Terreinbeheer’. In 2021 and 2022 the focus was on the determination of macro- and micronutrients, organic matter and relevant contaminants including heavy metals, PAH’s, dioxins, various PFC’s and residues from plant protection chemicals. These data are needed to evaluate the agricultural and environmental impact of such organic soil improvers. To estimate long term effects on soil organic matter, the stability (humification coefficients) as well as agronomic value (availability of N and P) has been measured in a selection of these products. These selected products also have been used in a large-scale field experiment at three experimental farms of WUR (Lelystad, de Marke and Vredepeel). Here, these products have been applied in a regular agricultural production system (maïze) in a randomized block design. In 2021 and 2022 the effects of these products on microbiological parameters as well as organic matter and the soil nutrient content and crop production have been determined.