longevity of phosphate boom

I'd be interested in comments on how long people think this boom in phosphate might last.

On one hand we have a very tight market and growing demand driven by biofuel farming and soaring food prices (etc).

On the other hand we have the likes of Morocco and more recently the Saudis talking of expanding phosphate production substantially, and I also see growing disquiet about the wisdom of the big push into biofuels -- particularly the EU who are increasingly unsettled at the consequences of the move towards biofuels (ie its impact on food prices, increased Amazonian deforestation by displaced cattle farmers, etc etc).

Which of these forces will dominate, and over what time frame? Is this fertiliser boom just a short term spike (next year or three), or here for the long term?