On July 30, 2014, the Mexican Ministry of Economy decided to initiate an anti-dumping investigation on imports of ammonium sulfate from China and the United States of America. The product subject to investigation is classified under the following HS code: 3102.2101. The complaint was lodged on April 25, 2014 by Agrogen, S.A. de C.V. and Metalúrgica Met-Mex Peñoles, S.A. de C.V. The investigation started on the day following the publication of the resolution in the Official Journal of the Federation, i.e. on August 13, 2014.
 
On February 4, 2015, the Mexican authorities issued their preliminary resolution and decided to impose a provisional anti-dumping duty on imports of ammonium sulfate from China and the United States of America.
The amount of the duty imposed on imports originating in China is USD 0.1782 per kilogram. The amount of the duty imposed on imports originating in the United States of America is USD 0.1858 per kilogram.
This provisional anti-dumping duty entered into force on the day following the publication of the resolution in the Official Journal of the Federation, i.e. on February 20, 2015.
 
On September 25th, 2015, the Mexican authorities decided to impose a definitive anti-dumping duty on imports of ammonium sulfate from China and the United States of America.
The amount of the duty imposed on imports originating in China is USD 0.1703 per kilogram, at the exception of the company Wuzhoufeng Agricultural Science & Technology whose exports are subject to a duty of USD 0.0929 per kilogram. The amount of the duty imposed on imports originating in the United States of America is USD 0.1619 per kilogram, at the exception of the company Honeywell Resins & Chemicals, LLC whose exports are subject to a duty of USD 0.0759 per kilogram.
This definitive anti-dumping duty entered into force on the day following the publication of the resolution in the Official Journal of the Federation, i.e. on October 10th, 2015.

On 2 October 2020, the Mexican authorities initiated a sunset review of the antidumping duty imposed on imports of the subject good from China and the United States. This review follows the application lodged on 2 September 2020 by Agrogen, S.A. de C.V. The existing anti-dumping duty remains in force for the duration of the review.

On 31 March 2022, the Mexican authorities issued a regulation extending the definitive duty imposed on imports of ammonium sulfate from China and the United States of America following the conclusion of the sunset review. The duty on imports from China is USD 0.1703 per kilogram, at the exception of the company Wuzhoufeng Agricultural Science & Technology whose exports are subject to a duty of USD 0.0929 per kilogram. The duty on imports from the United States is USD 0.1619 per kilogram, at the exception of the company Honeywell Resins & Chemicals, LLC whose exports are subject to a duty of USD 0.0759 per kilogram. The duty is in force for a period of 5 years, since 10 October 2020.