Changes in version 0.1.5 (2018-04-02)                  

  - Specify that the dataset were about United States of America (USA).
  - Update the titles of vignette.
  - Removed the documention about installing the package via Github.

                 Changes in version 0.1.4 (2018-04-02)                  

  - Added manure data from 1982 to 2012 (every five years).
  - Update the column names: Fertilizer -> Nutrient.
  - Added another column: Input.Type to indicate the nutrient input
    type.
  - Update readme and related articles.
  - Fixed the failed build of vignettes.

                        Changes in version 0.1.3                        

  - Added a NEWS.md file to track changes to the package.
  - Added the data sources and processes codes.
  - Added a license file and code of conduct.
  - Enable website for project using pkgdown.

                 Changes in version 0.1.2 (2018-03-23)                  

  - Passed CRAN checks and available at CRAN.

                        Changes in version 0.1.1                        

  - Update the description to pass the CRAN comments.

                        Changes in version 0.1.0                        

  - Decided to change the type of package into a pure data package.
  - Removed irrelevant codes.