Workers in Argentine soy-processing plants have gone on strike just as farmers are collecting the crop.

The job action that began Monday threatens to paralyze output from Argentina, the world’s biggest supplier of soy meal for livestock feed and soy oil used in food and biofuels.

The strike is a protest against proposed income-tax and work-rule changes included in President Javier Milei’s signature reform legislation, which lawmakers are debating. The walkout adds to woes for soy crushers such as Cargill Inc. and Glencore’s Viterra Inc., who’ve seen slow bean deliveries on the Parana River as heavy rains delayed harvesting.

SOEA, a labor group representing workers at plants in Parana port district San Lorenzo, which accounts for about 70% of Argentine soy shipments, went on strike early Monday, said union official Martin Morales. The Federation of Oilseed Industry Workers, whose members crush soy in other districts along the Parana and along the Atlantic coast, joined the strike, said spokesman Ernesto Torres.

“The labor reform included in the bill isn’t anything like a modernization; it’s a regression,” the federation said in a statement.

Most soy plants on the Parana, including those operated by Cargill, Cofco Corp., Louis Dreyfus Co., Viterra and Bunge Global SA, have closed their doors to truck deliveries, according to shipping and port agencies in Rosario.

A prolonged strike could cripple shipments of Argentine meal and soy oil. That’s what happened in December 2021, when workers stayed home and processing plunged to a two-decade low.