That is on way (and cheap) of producing fertilizer. But surely investing properly to capitalize on the alternatives would be a smart thing to do.
Fertilizer "total" statistics give incomplete picture by themselves.
Need to look at such things as irrigation and water availability, soil health/analysis (of say Anatolia regions in TR case), what kind of food you growing and rotating on the land etc... how optimal all this is with each other before introducing fertilizer to the equation.
These factors all vary the kind of fertilizers you need (Nitrate vs phosphate vs potash) and each one impacts in different way pound for pound too depending on your inherent circumstances with the soil and foods you have chosen relative to the water + water infra etc.
Adding them together to get a final tonnage skips the important details....as to why the amounts demanded are what they are and what is then the local supply that can be feasibly invested into compared to importing.
For example the Haber process makes nitrate (through ammonia) relatively universal thing (though capital investment is heavy for sure to make it economical).... to do given the Nitrogen in the air....but phosphate, potash etc is much more restricted to where they are located in world in mines/salts etc.