On 10/8/2007 9:33 AM, Academia wrote:
I was wondering if there is more than one kind of fertilizer chemical.

"Academia" wrote in message
...
If you use fertilizer containing weed killer they want you to put it on
wet grass and do not wash it off the grass.

But if you use fertilizer without weed killer they want it washed off of
the grass. Why? Is this fertilizer different chemically?



Thanks




I shop with a calculator. I buy the fertilizer that has the most
nitrogen per dollar.

Nitrogen is the first number of the three numbers. It's the percentage
of nitrogen in the total weight the the fertilizer. Thus, a 20-10-10
fertilizer is 20% nitrogen. A 20 lbb sack of 20-10-10 contains 4 lbb of
nitrogen. (The second number is the percentage of phosphorus; the third
is the percentage of potassium.)

I take the weight of the bag and multiply by the percentage of nitrogen
and divide by the price. Whichever lawn food gives the highest result,
I buy. Generally, it's the house brand of the store where I'm shopping.

I buy the lawn food WITHOUT weed killer. Thus, I can also use it on my
shrubs and in my flower beds.

For a special jolt (e.g., for roses and trees), I also use ammonium
sulfate, which is about 50% nitrogen. This is too strong to use on
lawns. It's also not suitable for acidic soils because it will make
them even more acidic. (My soil is quite alkaline and needs
acidifiers.) It has no phosphorus or potassium, but those are not
significantly deficient in my soil.

--
David E. Ross
Climate: California Mediterranean
Sunset Zone: 21 -- interior Santa Monica Mountains with some ocean
influence (USDA 10a, very close to Sunset Zone 19)
Gardening pages at http://www.rossde.com/garden/