Estimating ammonia emission after field application of manure by the integrated horizontal flux method: a comparison of concentration and wind speed profiles

Abstract

The integrated horizontal flux method is commonly used to estimate ammonia emission from field‐applied manure. The method involves measuring the wind speed and ammonia concentration at various heights on a post in the middle of a manured plot. Wind speed and concentration profiles are subsequently fitted to these measurements. The product of the profiles represents the amount of ammonia displaced by the wind, and the calculated ammonia emission is based on integrating the product of the profiles along the height. A crucial step is the functional form of the profiles, and linear relationships employing the logarithm of the height are generally used. In this study, 160 Dutch emission experiments on grassland were re‐analysed to evaluate alternative profiles for the concentration and wind speed. It is shown that an exponential concentration model usually provides a better fit than the commonly used profile and that the measurement error for the concentration should be modelled by means of a gamma distribution. Based on the re‐analysis, this new model reduces the calculated ammonia emission by around 10%. It is further shown that adding a displacement parameter to the wind speed model only has a minor effect on the calculated emission. Finally, a simulation study reveals that misspecification of the concentration profile may lead to a relative bias of up to 27%, that the precision of the estimated emission can be improved by increasing the number of concentration measurements near the ground and that wind speed measurements at three heights could suffice.

Emissies naar lucht uit de landbouw berekend met NEMA voor 1990-2020

“…De emissiefactoren zijn voor de gehele tijdreeks weergegeven in Bijlage 17. De huidige emissiefactoren voor mesttoediening op grasland zijn gebaseerd op Goedhart et al (2020); zie ook .…”

Cropland soil nitrogen oxide emissions vary with dairy manure incorporation methods

“…Higher frequency, automated chamber sampling could better capture episodic emissions across the entire year (e.g., Anthony et al., 2023) that are missed with periodic sampling and reduce uncertainty ranges for estimating the dependence of emissions on management practices. Alternative open‐path measurement approaches that do not require flux chambers, including integrated horizontal flux (e.g., Goedhart et al., 2020) and open‐path eddy covariance flux (e.g., Pan et al., 2022) methods, are also promising. Third, further investigations could focus on treatment effects of additional manure incorporation methods (e.g., strip till) and nitrification inhibitors (Halvorson et al., 2016; Venterea et al., 2005).…”

Managing organic resources in agriculture: future challenges from a scientific perspective

“…• Between management strategies, e.g., grazing decreases the risk of NH 3 and CH 4 emissions, but increases risk on NO 3 leaching and N 2 O emission (Bussink, 1994;Velthof et al, 1996;Corré et al, 2014); • Between technical measures; e.g., slurry injection reduces NH 3 but increases N 2 O emission (Velthof and Mosquera, 2011;Goedhart et al, 2020) and acidification of slurry reduces NH 3 emissions but may increase sulfate leaching or N 2 O emission (Velthof and Oenema, 1993;Loide et al, 2020);…”