[USCC] P accumulation in manured fields

[Tim Evans]

Is it a relevant question to ask what we mean by sustainable development?

The phosphate industry says that at the current rate of exploitation we
shall run out of useful rock-P in 100 or at best 250 years.  We cannot exist
without P so I believe that when we have P in the anthropogenic cycle we
should not squander it by seeking to immobilise it when we have it in
organic resources just so that more can be applied to a particular piece of
land.  Wherever farmers are using mineral-fertiliser-P there is an
opportunity to substitute P recycled in organic resources.  "New" P is
always associated with some cadmium so whenever "new" P is applied to land
we are applying "new" Cd - this might be a miniscule risk, but it is part of
the story.  When we recycle P we recycle Cd that is already in the
anthropogenic cycle.
 
For future generations we need to recognise that P is a finite resource and
to recycle it when we have it in the anthropogenic cycle.  We should not
squander it.  

Of course we also need to consider the rest of the environmental footprint
of our recycling activities, so AD with maximum solids destruction and
biogas utilisation and improved ease of dewatering are useful components for
many situations.  It's all a balance, or as Barry Commoner said "Everything
is connected to everything else".

regards

Tim

Dr Tim Evans
TIM EVANS ENVIRONMENT
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