Question
what do the three numbers mean on a bag of fertilizer?
Ex., 10-10-10. What do those numbers mean?

Answer
Basic Fertilizer 101: The FIRST number is the percentage of NITROGEN that is Guaranteed to be in the product.  SECOND measures PHOSPHORUS.  THIRD measures POTASSIUM (aka POTASH).

Artificial (i.e., 'chemical') fertilizers -- the kinds you buy in the garden center made by Scotts or Monsanto or Stern's -- usually post very high numbers on the bag.

Organic fertilizers (i.e., 'soil amendments' like Bone Meal, Bloodmeal, Manure) usually post very low numbers on the bag.

Most people look at the Organic and then at the Chemical and think the Chemical is obviously better becuase those numbers are much higher than the Organic stuff.

So they'll look at a bag of Scotts Turf Builder with 2 percent Iron, 29-2-4.  And next to it, there'll be a bag aged horse Manure, .7-.3-.6..  They think, WOW!  Look at how much better the Scotts Turf Builder is!  Plus it has IRON to keep my Grass healthy!  WOW!

Big mistake.

Bob, do you enjoy your dinner?

I mean, do you REALLY enjoy sitting down to dinner, and eating a big juicy steak, or maybe you like Sushi, or maybe you are into Mexican food.  Lobster.  Roast Turkey.

If you break down all that food into nutrients, there's not a whole lot of NPK.  But we don't say, Let's all stick an IV in our arm and inject our food straight into our bloodstreams.  Because we'd all have the same problem as diabetics, having to measure our blood constantly to see what we need, unable to keep everything just right.  Life would be a living hell, to have to shoot up with Meat (Protein or N) and water (H2O) and juice (I think that's Potassium and Magnesium) etc.  Not only would this be no fun to live this way.  But we could never do as good a job as when we were getting those nutrients out of the woods and the farms and the sky and the water.

When you put down Manure, it CANNOT be used by the Grass.  Critics like to say it's 'inefficient.'  Sure, it's inefficient.  You are not feeding the Grass NPK.  You are feeding the MICROBES, and THEY are using it the way you use a big hamburger, to make NPK which the Grass LOVES.

But the Grass does not sit down for one meal.  The Grass is GRAZING all day long.  If the weather is Cool, the microbes are making tiny snacks for the Grass.  If it's hot, and metabolism is up for EVERYBODY, the microbes are making 3 course lunches and dinners.  If the day is short, meals are short.  Grass grows best when you feed it in little doses, all the time, when it's hungry.

But that big dose of NPK?  If you're realllllly hungry, Bob, you'll LOVE that NPK.  You'll eat it in a single gulp, because you know another one won't be coming for a while.  And so you eat fast, stuff yourself, and Green up so much you practically glow in the dark.  Because that NPK is GONE after a few hours of application.  And as it's running through the Soil and leaching out, it is pouring Salt ALL OVER THE MICROBES, not to mention the Earthworms and other living things down there.  Fertilizers are SALT.

Wouldn't it be much nicer to have a home where they feed you all the time?  That's what the Organic Amendments (which some people like to call 'fertilizers') do.

Would you rather shoot up your dinner?  Is this effective?  Is it healthy?  NPK from Scotts Turfbuilder with Iron, anyone?

And about that 'Iron'... There's PLENTY of Iron in Soil.  You don't need to put Iron on your Grass any more than you need to put Iron on your Car.  When Grass gets Chlorotic, it's almost always because someone screwed up the chemical fertilizer routine.  The Grass cannot use the Iron it has, and it becomes Chlorotic.

That's life.

So now I suppose it's probably time for lunch.  I don't know about you, but I'm getting hungry.

Let me know if you have any questions.  Sorry to get so long winded.  It's genetic.  Thanks for writing.