Towards a measurement-based approach to estimate farm-specific ammonia emissions
With feed management parameters and the slurry manure composition as indicators of the AEP
E. van Hamel (TU Delft - Technology, Policy and Management)
Jan Willem Erisman – Mentor (Universiteit Leiden)
José M. Mogollón – Mentor (Universiteit Leiden)
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Abstract
The research focuses on a novel measurement-based approach to estimate the farm-specific ammonia emission potential (AEP) in the dairy sector. By measuring and evaluating the feed-manure chain, feed management strategies and manure parameters influencing AEP can be identified. Ammonia emissions from dairy farms are not only considered to be an important driver of biodiversity loss, but are also responsible for nutrient losses in the farm cycle. Currently, farm-specific ammonia emissions are calculated using the Kringloopwijzer model, which tends to over- or underestimate actual ammonia emissions. Therefore, the possibilities of a measurement-based approach are evaluated.
This study analyses the relationships within the feed-manure-AEP sequence. A comprehensive approach is used, involving 23 manure parameters and 12 feed management parameters. The most important predictors of the AEP include N, TAN, Norg, N90, and the C/N ratio, whilst urea in milk, pH, and DS showed low significance. Silage maize and VEM are identified as feed management parameters with a positive indirect relationship with the AEP, whereas other roughage and fresh grass exhibit a negative indirect relationship. The calculated TAN value plays a central role in the emission calculations of the Kringloopwijzer model. There are concerns about the accuracy of this value as well as the absence of other manure parameters in the calculation, highlighting the need for further research. Currently, it is uncertain whether the AEP measurements will be suitable for an emissions-based policy, due to the incapacity to directly represent actual ammonia emissions and the uncertainty regarding the interpretation of the results caused by the period prior to the measurements. Nonetheless, the measurements are valuable in assessing the influence of the manure composition on the AEP, and how it has been affected by feed management strategies.