Circulair terreinbeheer voortgangsrapportage 2024: Resultaten 2021-2023/2024 van de pilots, veldexperimenten en laboratoriumproeven

The chemical composition of organic soil improvers including bokashi and various forms of treated and untreated clippings and/or leaves collected from green spaces in cities, nature and infrastructure has been determined. The samples originate from pilots associated with ‘Circulair Terreinbeheer’. The main aim of the monitoring study was to determine the amount of macro- and micronutrients, organic matter and relevant contaminants including heavy metals, PAH’s, dioxins, various PFAS 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 thereof (humification coefficients) as well as the 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. From 2021 until 2024 the effects of these products on microbiological parameters as well as the soil organic matter content, the soil nutrient content and maize production have been determined.