Agriculture Reference
In-Depth Information
thus not being of current concern. Phosphorus (P) is also mined, but its re-
serves are projected to only last between 50-130 years, given today's rate
of application and the growing population's food demand as a guideline
for production needs [1,108]. Phosphorus is not found as a free element
on Earth, but instead is bound up as phosphates, typically found within
inorganic rocks. Reserve supplies are even less evenly distributed than
oil and are found primarily in China, U.S., Morocco, and in small South
Pacific Islands [108]. In the U.S., phosphate is mined primarily from a
single location in central Florida, supplying 75% of the phosphorus used
by U.S. farmers, which corresponds to 25% of the world's phosphate re-
serves. However, the supply at this particular location is expected to only
last several more decades [108]. Using the same modeling tools for ana-
lyzing oil production, phosphate follows a similar parabolic curve, with
world production projected to reach its peak in 2030 [1]. Phosphorus is
capable of leaching from sandy soil, and has been carelessly applied in
over-abundance for decades, with a wasteful use of a finite resource as
well as environmental pollution resulting in eutrophication of water bod-
ies [1,108]. Three countries consume over 50% of the world phosphate
annually mined, with China being the major consumer (30%) followed by
India (15%), and the U.S. (11%) [109].
Phosphorus is considered a non-renewable resource, but there is pos-
sibility of it being recycled to some extent. During crop production, phos-
phorus is translocated from the soil to plant tissues, and subsequently con-
sumed by humans and livestock. Little of the phosphorus available in the
plant tissues is metabolically used by humans or livestock, and is therefore
excreted [109]. Much of the phosphate in plant cells is stored as phytates
(hexakisphosphate, IP6), which are not digested by monogastric animals.
Phosphorus can then be recycled by collecting the excreted material, and
reapplied to production fi elds in the form of manure or compost [1,108].
Even though recyclable, it is important to stress that once the supply of
inorganic phosphorus has been exhausted, there is no other source nor is
there any suitable phosphorus substitute in agriculture [1,108]. The con-
sequence of phosphate depletion can be seen in Nauru, a South Pacifi c
Island (in Micronesia, formerly known as Pleasant Island). After 90 years
of intense phosphate mining (mostly consumed by the U.K., Australia, and
New Zealand), 80% of central Nauru is now abandoned wasteland, and the
