Leibniz MMS Days 2023 - Abstract
Effective feed management decisions are critical for reducing greenhouse gas (GHG) and nitrogen (N) emissions in livestock farming systems. Empirical and statistical models are useful for assessing mitigation strategies, such as GHG calculators, while process-based (PB) simulation models can provide greater insight into the impact of biotic and abiotic drivers on GHG and N emissions. These models use mathematical equations to describe processes like fermentation, nitrification, and denitrification, requiring great input parameters. A cascade of PB models that simulate the variation in emissions and the total farm budget can be used to assess the downstream impact of diet on GHG emissions. However, this approach has not been used yet. This study aims to describe how to implement this method using a set of PB models applied to two case study farms. The Dutch tier 3 model, Manure DNDC model, and DNDC model were used to simulate emissions from dairy cattle grazing and confinement systems. The results showed significant differences between the PB model results and the current generic emission factors used in national inventories. In addition, the confinement system's cumulative NH3 and CH4 barn emissions were accurately simulated by the manure-DNDC model. This indicates that PB models are useful tools for simulating GHG emissions and can aid in the dairy industry's efforts to achieve sustainability.