Dutch farmers angry at government plans to cut emissions used tractors and trucks on Monday to block roads and supermarket distribution centers, sparking fears of food shortages in stores in the latest actions amid a summer of discontent in the country’s lucrative farming sector . The Netherlands’ busiest air hub, Schiphol Airport, urged travelers to use public transport to get to its terminals amid fears the blockades would also target airports. Fishermen acting in solidarity with the farmers also blocked some ports. The unrest among Dutch farmers was sparked by a government proposal to cut emissions of pollutants such as nitrogen oxide and ammonia by 50% by 2030. Provincial governments have been given a year to come up with plans to meet the target. A group of farmers in the province of North Holland held talks with two senior officials in the city of Haarlem. “Their concerns are understandable and have our full attention. Good to be and stay in conversation with each other,” one of the officials, Arthur van Dyk, wrote on Twitter. The reforms are expected to include the reduction of livestock and the purchase of certain farms whose animals produce large amounts of ammonia. Farmers argue that they are being unfairly targeted and given no perspective on their future. Police watched but did not immediately take action on Monday as about 25 tractors were parked outside a distribution center for supermarket chain Albert Heijn in the town of Zaandam, just north of Amsterdam. Placards and banners attached to the tractors read messages such as “Our farmers, our future”. A tractor at another demonstration, in the northern city of Drachten, urged people to “think for a moment what you want to eat without farmers”. The umbrella organization for supermarkets called on police to take action and warned of possible shortages on supermarket shelves. “Distribution center blockades are hurting the citizens of the Netherlands. Supermarkets are doing their best to keep stores stocked, but if the blockades continue, it could lead to people not being able to do their daily shopping,” the Central Food Trade Bureau said in a statement. Traffic authorities warned motorists to prepare for delays and possible slow tractor-trailers on the nation’s highways, but said there were few problems early Monday for commuters, possibly because many people chose to work from home rather than get stuck in traffic. Over the weekend, the government appointed an intermediary to lead talks between farmers’ organizations and officials drawing up pollution-reduction measures. But Prime Minister Mark Rutte has ruled out negotiating with farmers responsible for radical protests. The main agricultural lobby group LTO described the mediator, Johan Remkes, as “an administrative heavyweight with deep knowledge” of the issues and said it was open to talks with him. According to the LTO, there are almost 54,000 agricultural businesses in the Netherlands with exports totaling €94.5 billion in 2019.