Police estimated the number of tractors clogging the streets of Brussels at 2,700. Many were decorated with big signs reflecting the farmers' anger.
"Proud to be a farmer," read one.
Agricultural organisations said in a joint statement that the nitrogen agreement as it now stands "will cause a socio-economic carnage". They wanted the agreement to better reflect future prospects for the farm sector.
"We are all convinced that something has to change nitrogen-wise, but the agricultural sector should not be treated differently to the industrial sector", protester Leen Engelen said, referring to one of the disputed points in the draft bill.
Comment: That farmers are unfairly targeted is just one of many points that reveals this is an attempt to shutdown food producers.
Many who came to protest in Brussels on Friday feel the same way.
"Our sector is already making a lot of effort and is willing to do so as well, but (the government) expects more and more from us while the industry sector is also expanding", said Liesje Van Loon, who owns a goat farm.
Relatively large numbers of livestock and heavy use of fertilizers, as well as traffic and construction, have led to levels of nitrogen oxides in the air and water in both Belgium and the Netherlands that are higher than EU regulations and that threaten the environment.
The planned move to limit emissions in Flanders has caused a crisis within the Flemish regional government that was not resolved during 16 hours of talks earlier this week. Belgian media reported Flemish Minister-President Jan Jambon wants to make the final decisions by this weekend.
In the Netherlands, farmers have refused to cooperate with the government on measures to limit nitrogen emissions, which would significantly reduce livestock in the country.