The agriculture ministry ignored warnings that equipment to detect how much manure farmers are selling or dumping is easy to manipulate for years, according to NOS and investigative news website Follow the Money.

The equipment monitors how much manure is loaded into lorries, but by simply increasing air pressure in the vehicles’ suspension, farmers can mimic these movements to their advantage, and claim they are getting rid of more manure than they actually are.

By law, livestock farmers have to dispose of part of the manure their livestock produce to manure processing plants or farmers with arable land at considerable expense. By manipulating the equipment, farmers can pretend they are offloading more manure than indicated, and illegally spread the manure on their own land, thereby cutting their costs.

The public prosecutor’s office warned the agriculture ministry about the practice as far back as 2019 but since then nothing has been done to replace the equipment, broadcaster NOS said.

Too much manure is bad for the soil and contaminates groundwater but, despite EU exhortations to tackle the problem, manure fraud is a persistent problem in the highly-intensive Dutch livestock sector.

In 2021, police uncovered an international case of manure fraud and just over a year ago three agricultural advisors were given prison sentences for setting up manure fraud on a large scale.

A spokesman for the ministry maintained that not all cases point to fraud and that “no figures exist of how often the system may be abused”.

Supervisory body NVWA admitted in 2020, when reports of fraud were mounting, that catching fraudsters in the act is almost impossible. There are a million manure transports every year of which just 1000 are checked on the spot.

The ministry said a new system, which allows real-time checks on manure transports, is now in place.