README.md
In sashahafner/ALFAM2: Model on Ammonia Emission from Field-Applied Manure

ALFAM2

Model for ammonia volatilization (loss) from field-applied manure.

Maintainer

Sasha D. Hafner. Contact information here: https://au.dk/sasha.hafner@bce.

Installation

Installation of packages from GitHub requires a package called devtools. You can run the code below to install devtools and ALFAM2.

If you don't already have it, first install devtools from CRAN.

install.packages("devtools")

Then install the latest ALFAM2 release with the following command.

devtools::install_github("sashahafner/ALFAM2@*release", build_vignettes = TRUE)

You can just pull from the master branch (sashahafner/ALFAM2), but you may get some new changes not yet included in a release.

You can get any specific release (e.g., to check out a specific version used in a particular paper) with this syntax:

devtools::install_github("sashahafner/ALFAM2@v3.2", build_vignettes = TRUE)

See the Releases page for all available releases. The @v3.2 bit in the command above is from the release tag.

For other branches using the ref argument.

Package use

Once the package is installed, load it.

library(ALFAM2)

And see a vignette to get started.

vignette("ALFAM2-start")

Model description

The following paper describes the model in some detail:

Hafner, S.D., Pacholski, A., Bittman, S., Carozzi, M., Chantigny, M., Génermont, S., Häni, C., Hansen, M.N., Huijsmans, J., Kupper, T., Misselbrook, T., Neftel, A., Nyord, T., Sommer, S.G., 2019. A flexible semi-empirical model for estimating ammonia volatilization from field-applied slurry. Atmospheric Environment 199: 474-484. https://doi.org/10.1016/j.atmosenv.2018.11.034

Download a copy here.

As shown in the figure below, the ALFAM2 model tracks applied ammonia (as "total ammoniacal nitrogen", TAN) after field application. The numerical value of the "primary" parameters shown below (r and f terms) determine the rate and trajectory of emission. The value of these parameters are determined by the value of predictor variables and the "secondary" parameter set.

schematic