There are good reasons why fertilizer companies have dropped phosphorous from their ferts. One reason is that apparently there is enough P in the soil around our area anyway.
But there's a much more pressing reason to remove it from non-essential lawn fertilizer. The world is literally running out of Phosphorous! Scientists/Geologists say we will mine the last of the world's P supply in about 70 years..... Thats a really big problem, because it is 1 of 3 essential nutrients for plants. Imagine if someone told you the world was running out of Protein. Humans and animals would be screwed! Well, we need P to grow food crops, so I dont know what they'll do in 70 years or less, when they run out of P. Maybe they'll find a way of creating and spreading massive amounts of organic fert onto commercial produce fields.
But anyway, that explains P, but why are many companies now removing K from their fertilizers? I just noticed this about 6 weeks ago when buying some spring fert. The mix was now 19-0-0. I assumed that would make it less expensive, thats what common sense dictates, but greed seems to be overtaking common sense. Not only did the first supplier tell me the fert he carried wasnt going down in price since the Potassium was removed, it actually went up $1.50 per bag! So I went to another supplier, and his was also without K, and his price went down about .50 per bag. WOW, what a savings!
So why is this? Is there a legitimate reason for this, or is it just a way to cut costs? I'd hope that they will compensate for the missing spring potassium by adding K to fall fert, but we'll see......