Main research question/goal
The aim of this research is to optimize the quality (homogenisation, volume reduction, hygienisation, etc.) of stable manure and the solid fraction of slurry. Solid manure is a potentially valuable product for supplying organic matter to the soil. Several experimental setups will provide answers to questions like, Does composting of stable manure on headlands result in a lower risk for nutrient losses to ground and/or surface water? What is the difference in degradation process and product quality when compared to untreated manure stored on headlands? Is there a difference in the composting process when the stable manure is composted on headlands compared to when composted on a concrete floor? How do we optimise the composting process of the solid fraction after separation from slurry: can we reduce nutrient losses (to both soil and air) by means of addition of straw, clay minerals, biocatalysts and/or stable manure? What is the influence on compost quality? Research approach
We explore several options for processing and application of stable manure and the solid fraction of slurry, all suitable for specific business contexts. We assess the value of several residual flows, suitable to mix with these solid manure types, and we look for the composting technique that yields the best results. By means of compost experiments on field scale, both on a concrete floor and on headlands, we investigate how compost quality can be increased and nutrient losses decreased when storing and processing the solid manure types. We set up several windrows in which the manure will be blended (or not) with other (vegetable) flows or additives. By blending flows with a higher C/P-ratio than the solid manure types, we study whether the end product can the user value for agriculture can be (even) higher. For the additives, we verify whether these are able to limit nutrient losses during the process. At the start, during and at the end of the storage or composting, compost quality (nutrient content and availability, and compost stability) are determined, and we examine to what extent the compost releases or immobilises nitrogen. We also measure gaseous losses during the process.Relevance/Valorisation
Concern about the possible application of solid manure is increasing because of the stricter fertiliser standards for phosphate and the Manure Decree legislation regarding storage and transport of solid manure. These questions concern aspects about proper storage and conservation of these materials (how to avoid the risk of environmental pollution while maintaining product quality, how to keep this economically feasible, etc.), as well as hygienisation during composting. Composting stable manure and the solid fraction of slurry may offer some benefits in terms of application but also may limit nutrient losses during storage of these manure types.