On Fri, 9 Feb 2007 12:10:58 -0800, Walter R. wrote:
I live in Southern California. In anticipation of promised rain, I applied
400 lbs of fertilizer (15-15-15 granules) to the iceplant and shrubs on my 1
acre lot.

//snip

400 lbs fertilizer/43560sq ft/acre = 0.0092 lbs fertilizer per sq ft
= 9.2 lbs per 1000 sq ft

each component was 15% by weight, so you've applied 1.38 lbs of N, P and K
per 1000 sq ft so you're just barely under the recommended maximum amount
of N to prevent burning of turf. Most groundcovers want about 1/2 lb
N per thousand sq ft per three months, and half that of P and K (barring
a soil analysis that will tell you what you actually need!).

Chances are your ice plant is going to get tall, overgrown, and may have
more disease problems and more "melting out".

IOW, should I re-apply the fertilizer if and when it looks like rain gain?
For how long is the fertilizer good if left on top of the ground,

Stop right there, do not pass go, do not collect any fertilizer until you've
had a proper soil analysis done. By applying so much fertilizer, you may
have contributed to soil salinization (a big problem in S. California),
water pollution (N washing into local streams), etc., etc.

Please get a soil analysis and follow the recommendations. Most California
soils have adequate K without any additional being added. P is often too high
already to be needed in areas where the soil has been fertilized before. N
is unstable, due to soil nitrogen cycles, and is often the only macronutrient
needed.
http://www.visionlearning.com/librar...wer.php?mid=98

http://www.ipm.ucdavis.edu/TOOLS/TUR...EP/soilan.html
http://www.aces.edu/department/crd/p...s/ANR-743.html
http://www.sfc.ucdavis.edu/Pubs/Fami...ing/tests.html