Guano (from the
Quechua
'wanu', via
Spanish) is the
excrement (
feces and
urine) of
seabirds,
bats, and
seals. Guano
manure is an effective
fertilizer and
gunpowder
ingredient due to its high levels of
phosphorus and
nitrogen
and also its lack of odor.
Superphosphate made from guano is used
for
aerial topdressing.
Soil that is deficient in organic matter can be made
more productive by addition of this manure.
Usage
Guano consists of
ammonia, along with
uric,
phosphoric,
oxalic, and
carbonic
acids, as well as some earth salts and impurities. Guano also
has a high concentration of
nitrates.
Currently vast volumes of phosphorus are needed to produce
fertilizer, as it is an essential plant
macronutrient. Guano is rich in phosphorus and is an intensely
effective phosphorus fertilizer.
History
Mining guano.
The word "guano" originates from the
Quichua
language of the
Inca civilization
and means "the droppings of sea birds".
Incas collected guano
from the coast of Peru
for use as
soil enricher. The Incas assigned great value to guano,
restricting access to it and punishing any disturbance to the birds
with death.
Guano has been harvested over several centuries along the coast of
Peru, where islands and rocky shores have been sheltered from
humans and predators. The
Guanay
Cormorant has historically been the most important producer of
guano; its guano is richer in nitrogen than guano from other
seabirds. Other important guano producing species off the coast of
Peru are the
Peruvian Pelican and
the
Peruvian Booby.
The high concentration of nitrates also made guano an important
strategic commodity.
The War of the Pacific (1879 to 1883) between
the Peru-Bolivia
alliance and
Chile
was primarily based upon Bolivia's attempt to tax
Chilean guano harvesters and over control of a part of the Atacama Desert
that lies between the 23rd and 26th parallels on
the Pacific coast. The discovery during the 1840s of the use
of guano as a
fertilizer and
saltpeter as a key ingredient in
explosives made the area strategically
valuable.
In this context the US passed the
Guano Islands Act in 1856 giving citizens
discovering a source of guano the right to take possession of
unclaimed land and entitlement to exclusive rights to the deposits.
However, the guano could only be removed for the use by citizens of
the United States. This enabled US citizens to take possession of
unoccupied islands containing guano.
By the end of the 19th century, the importance of guano declined
with the rise of artificial fertiliser, although guano is still
used by
organic gardeners and
farmers.
Sourcing
The ideal type of guano is found in exceptionally dry climates, as
rainwater drains the guano of nitrates.
Guano is harvested on
various islands in the Pacific Ocean
(for example, the Chincha Islands) and in other oceans (for
example, Juan de Nova
Island
and Christmas Island
). These islands have been home to mass
seabird colonies for many centuries, and the guano has collected to
a depth of many
metres. In the 19th century,
Peru was famous for its supply of guano.
Bat guano is usually mined in caves and this mining is associated
with a corresponding loss of
troglobytic
biota and diminishing of
biodiversity. Guano deposits support a great
variety of cave-adapted invertebrate species, which rely on bat
faeces as their sole nutrient input. In addition to the biological
component, deep guano deposits contain local
paleoclimatic records in strata that have
built up over thousands of years, which are unrecoverable once
disturbed.
The greatest damage caused by mining to caves with extant guano
deposits is to the bat colonies themselves. Bats are highly
vulnerable to regular disturbance to their roosts. Some species,
such as
Phyllonycteris
aphylla, have low fat reserves, and will starve to death
when regularly disturbed and put into a panic state during their
resting period. Many species will drop pups when in panic, with
subsequent death, leading to a steady reduction in population.
Research in Jamaica has shown that mining for bat guano is directly
related to the loss of bat species, associated invertebrates and
fungi, and is the greatest threat to bat caves on the island.
Properties
In
agriculture and gardening guano has a
number of uses, including as: soil builder, lawn treatment,
fungicide (when fed to plants through the
leaves),
nematicide (decomposing microbes
help control
nematodes), and as
composting activator (nutrients and microbes
speed up decomposition).
See also
References
- http://www.bbc.co.uk/dna/h2g2/A765678
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