08 July
31 December 2008

Les engrais : techniques d’application

Fertilizers : application techniques


The application of agrochemical products and especially of fertilizers remains a problem at all levels. Producers of simple and complex compound fertilizers or of bulk blends still don’t know which physical properties products must have to meet the requirements of users (blenders, farmers, …). On the other hand, manufacturers of distributors try to fit the different fertilizers, while increasing continually the working widths, so as to meet farmers’ need. At last, farmers and contractors must spread with precision the different available fertilizers.


It is necessary to define standard physical characteristics in order to have fertilizers susceptible of being mixed without any risk of segregation and being spread even on big width, with an easy adjustment. At last, we also have to make farmers and contractors aware of the application techniques, that is, the choice of the equipment and their adjustment, the distinction of fertilizers qualities.

Description of tasks

In order to reach these objectives, the Department carries out researches at several levels : for farmers and contractors, a service aiming to test spreading devices is proposed. This low cost service gives the possibility of checking and adjusting the spreading quality if necessary. A field testing method was developed and compared to the official method in a testing hall. New testing methods are tested in order to obtain more pertinent measurements. This service led to an appraisal and trainings ; for spreaders manufacturers, the field tests provide very useful information in order to improve their device. The testing method is at present standardized and is also used to test the new developments proposed by the firms ; At last, a collaboration with producers of fertilizers is essential in order to define the requirements for the physical properties of fertilizers’ particles. An ISO 17025 accreditated laboratory was developed for this purpose. One of the main problems studied concerns the bulk blends.

Results obtained

Spreading tests on the field show the difficulty for users to obtain a good distribution of fertilizers. The developments proposed by manufacturers do not manage yet to solve this problem, especially as working widths increase. The contact of the physical properties of fertilizers and the weight distribution shows that the shape and density of the particles play a quite considerable part. The size also plays a part but is moreover a source of segregation during the outflow if the granulometric distribution of the product increases. This can lead to a segregation in the case of bulk blend.


CRA-W : the Biometry Unit for its support in the data analysis and the adjustment of the testing protocol, the Quality of Agricultural Products Unit for the development of the chemical analysis of fertilizers by means of the reflectrometry techniques in the near infrared.


University of Liège – Mica Laboratory and Occhio society, AFSCA, European Blenders Association (EBA), AFCOME, manufacturers of spreading devices, producers of fertilizers

CRAW off coordinator

MISERQUE Olivier (Attaché scientifique) Département Génie rural Chaussée de Namur, 146 B-5030 Gembloux Téléphone direct :62 71 55 Téléphone département :+ 32(81) 61 25 01 Fax département :+ 32(81) 61 58 47 E-mail :miserque@cra.wallonie.be


  • Federal Scientific Policy
  • Association Européenne des mélangeurs d'engrais
  • Private equities
  • FASFC - Federal Agency for the Security of the Food Chain