Does fertilizer lose effectiveness?

[George.com]

I am not sure however it will likely lose its flavour if left on the bed post overnight.

rob

[Walter R.]

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.

The rains did not materialize and there is no rain in sight for the next 2 weeks. Now the fertilizer granules sit on top of the ground. Do the granules release the nitrogen into the air without exposure to rain? Like sublimation?

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,

[Frank]

Don't know, but speaking as a chemist, inorganic salts (K and P) should not sublime. Organic nitrogen like urea might. Sounds like you used a lot of fertilizer to me.

Frank

[JoeSpareBedroom]

400 lbs? What is the square footage of the actual garden beds?

[Walter R.]

There are no garden beds. It's like an informal park, with grass, trees, weeds, shrubs (lots of junipers) and iceplant. Plus an orange grove of 10 trees.

Does 400 lb sound like too much? Maybe I can save some money. The stuff is growing voluptuously.

[Phisherman]

No, the nitrogen, potash, and phosphorous are salts that do not sublime nor lose their effectiveness. This is particularly true of inorganic fertilizers.

Like

Do not consider reapplying fertilizer until another season or at least rains a dozen times. It is hard to say how long the fertilizer stays put without a watchful eye. Soil test kits are reasonably priced. It is often a good idea to alternate inorganic with natural (organic) fertilizers.

[Phisherman]

For a one-acre lot I'd use about 80 pounds. I agree with the others--

400# sounds high.

[Jangchub]

He said in his original post he has an acre.

[Kay Lancaster]

//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".

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.

[JoeSpareBedroom]

Right, but without one more piece of information, I considered that data incomplete. The data is now complete. You know that.

[JoeSpareBedroom]

Who (or what) told you to use that much fertilizer?