First of all by analysing it to see if the elements given by the factory is correct.

Then go for response test on crops used by the contry on station and on field together with farmers.

Kiari is correct. Its the comprehensive understanding of the product first before application in the field. First, its knowing or understanding the chemical properties of the fertilizer and its capabilities in improving the growth of the crops. Second, which your problem exist is the fertilizer trial. It can either be field or pot experiment, depending on your preference. Yet to have a more feasible way of testing, pot trial can be done. You are going to test the fertilizer if it will work using the soil of your country. By then, you will know the capabilities of that fertilizer by noting the responses of your crops which can be assessed through ocular observation or laboratory quantification. From planting to harvesting, the most critical part is the yield performance which you can assess if your fertilizer can boost the yield potential of your elemental crops for your country... .  

University system

.Analyse the product, determine target crops, conduct lab experiment, on-station and multi locational on-farm trials. you need to determine rate application method (single or split dose)

OK , Thanks Hakeem.