Guano collection structures at Islas Ballestas

Guano (from the Quechua 'wanu', via Spanish) is the droppings of seabirds, bats, and seals. It 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 much more productive by addition of this manure.