Guano is the excrement – feces and urine, of seabirds, cave dwelling bats, and seals.
• Guano manure is an effective fertilizer.
• This is due to its high levels of phosphorus and nitrogen and its lack of odor.
• It was an important source of nitrates for gunpowder.
• Soil that is deficient in organic matter can be made more productive by addition of Guano.
• Bat and seal guano are lower in fertilizer value than bird guano.
• The word “guano” originates from the Quichua language of the Andes.
• It means “the droppings of sea birds”.
• Andean peoples collected guano from the coast of Peru for use as soil en-richer.
• The rulers of the Inca Empire assigned great value to guano.
• They restricted access to it.
• They also punished any disturbance to the birds with death.
• Guano has been harvested over several centuries along the coast of Peru.
• 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.
Composition of Guano
Guano consists of:
• Ammonium oxalate
• Some earth salts
• High concentration of nitrates
Bird guano has a fertilizer analysis of:
• 11 to 16 percent nitrogen.
• 8 to 12 percent equivalent phosphoric acid.
• 2 to 3 percent equivalent potash.
Sourcing of Guano
• The ideal type of guano is found in exceptionally dry climates.
• Rainwater drains the guano of nitrates.
• Guano is harvested on various islands in the Pacific Ocean and in other oceans.
• For example, the Chincha Islands and Juan de Nova Island and Christmas Island.
• These islands have been home to mass seabird colonies for many centuries.
• The guano has collected to a depth of many meters.
• In the 19th century, Peru was famous for its supply of guano.
• Bat guano is usually mined in caves.
• 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.
• Bat feces as their sole nutrient input.
• Deep guano deposits contain local pale climatic records in strata that have built up over thousands of years.
• These 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.
• These will starve to death when regularly disturbed.
• Many species will drop pups when in panic.
• This leads to a steady reduction in population.
Properties of Guano
• Guano has a number of uses in agriculture and gardening.
• This includes:
- Soil builder
- Lawn treatments
- Fungicide (when fed to plants through the leaves)
- Nematicide (decomposing microbes help control nematodes)
- As composting activator (nutrients and microbes speed up decomposition)