31 may 2021
During the online technical meeting on 30 October, Hans Verhagen reported on the research results of the collective research programme. An important conclusion then was that the methods for measuring nitrogen fixation and germination and growth inhibition in raw materials could be improved. This now results in the introduction of new methods.
The nitrogen fixation method is replaced by the new nitrogen immobilisation test. This test provides more information about the use of nitrogen by a particular raw material than the previous test. It is important that this information is passed on by the raw material supplier to the substrate producer. He can then determine per recipe whether extra nitrogen is being used. In specific cases, the user of the substrate, the grower, also has to be informed. The grower then knows what to expect and whether he needs to adjust his additional fertilisation. The nitrogen immobilisation test takes a total of 9 weeks. Reports are made 3 and 6 weeks after the start of the test.
The plant response test replaces the bio assay test and growth test. The plant response test is an EN method. This method has two variants. If the dosage of the raw material to be tested is less than 35% (volume percentages), the mixture test is chosen. The product to be tested is then mixed in the specified dosage and then tested. If the dosage is equal to or higher than 35%, another variant is chosen: the extraction test. As with the old tests, germination and growth are determined compared to the reference. The mixture test takes 5 weeks and the extraction test takes 6 weeks.
New sample forms have been developed for the products to be analysed with the new methods. These will be available for download from June 1st at My RHP. By using these new forms, the correct data is collected and the chance of errors is small. The forms can indicate the required data and the amount of material required for each new method. So don't use the old forms anymore and quickly download the new ones!
All new methods will be introduced from June 1st. Minerva will be able to assess the results of the new methods from July 1st.