(38)In order to enable economic operators to demonstrate and the competent authorities to verify that EU fertilising products made available on the market comply with the requirements of this Regulation, it is necessary to provide for conformity assessment procedures. Decision No 768/2008/EC establishes modules for conformity assessment procedures, from the least stringent to the most stringent, in proportion to the level of risk involved and the level of safety required. In order to ensure inter-sectoral coherence and to avoid ad-hoc variants, conformity assessment procedures should be chosen from among those modules. It should be possible for manufacturers to choose a more stringent conformity assessment procedure for the assessment of an EU fertilising product eligible for a less stringent procedure, since this might enable the manufacturers to streamline their administration without jeopardising the conformity of the EU fertilising product. Furthermore, it is necessary to adapt the modules established by Decision No 768/2008/EC in order to reflect specific aspects of fertilising products. In particular, it is necessary to reinforce the quality systems and the involvement of notified bodies for the conformity assessment of certain EU fertilising products derived from recovered waste.