In 1988 the Foundation for Quality Control of Agricultural Machinery (SKL) was founded with the purpose to develop one uniform standard for testing the equipment. In that year the first official testing stations were founded and the first inspectors were certified. From that time the inspections were on a voluntary basis but stimulated by collectors from agricultural products like potato collecting companies and buyers from vegetables. There motivation to stimulate the testing was to have good quality crops and less pollutive production. During this period nearly 10% - 20% of all farmers participate in the inspection scheme.

In 1991 an agreement was made between the Dutch government and the agricultural sector to decrease the use of pesticides in the agricultural sector. One of the elements of this agreement was the introduction of a mandatory inspection of spraying equipment. In 1997 this was made effective by rules of the Product Boards for Agriculture and Horticulture that all field crop sprayers has to inspected every two years by an official SKL certified testing station. In 2002 the obligation for testing airassisted sprayers for orchards was introduced. In 2006 the frequency of testing is changed from every two years to every three years.

In the regulations of the Product Boards are the requirements the spraying equipment has to meet and is SKL pointed as the executing organisation for the inspections. From the start the system is chosen that approved testing stations carry out the inspections under supervision of SKL for the contract between SKL and the testing station see: SKL-Testing Station Agreement). These testing stations are in most cases dealers of agricultural equipment. To be certified the testing stations have meet requirements for their test equipment and the testing staff. SKL sets the regulations for the testing equipment (see Technical Requirements of the installation of a SKL testing Station) and performs the training of the inspectors in cooperation with a specialised training institute (the content and conditions for this training is given in: Final attainment level and examination SKL test operator).

The testing stations perform the test according to the actual testing standard (see Features for testing Field crop sprayers/Air-assisted sprayers for bush and tree crops already in use.) The results of the tests are filled in at a uniform testing form and all approved sprayers are fixed up with a sticker on which is a unique number and the date for the next inspection. The testing stations are reporting the results of all inspections to SKL. SKL registers all inspections in a database.

In order to get uniform performed tests on a qualitative high level SKL has developed a quality assurance system what is ISO9001: 2000 certified. Elements of the system are: uniform and clear standards for performing the tests on base of the regulations of the Product Boards, uniform standards for the testing equipment of the testing stations, periodical inspection of all testing stations, periodical test of the test equipment, good basis education and refreshing courses for the inspectors and random checks of inspected sprayers (for procedure inspection testing stations, see: Procedure for inspection of testing stations).

SKL has a testing scheme for field crop sprayers and air-assisted sprayers for bush and tree crops but since 2004 also a testing scheme for other types of sprayers what are used in greenhouses. This group of sprayers is gathered under the name engine tank sprayers. For this type of sprayers features for testing, requirements for the testing stations and a training for test operators for this type of sprayers is developed.