OT: FYI: Fertilizer

Guano (Spanish from Quechua: wanu) is the accumulated excrement of seabirds or bats. Guano is a highly effective fertilizer due to the high content of nitrogen, phosphate, and potassium, all key nutrients essential for plant growth. Guano was also, to a lesser extent, sought for the production of gunpowder and other explosive materials.

The 19th-century seabird guano trade played a pivotal role in the development of modern input-intensive farming. The demand for guano spurred the human colonization of remote bird islands in many parts of the world.

Unsustainable seabird guano mining processes can result in permanent habitat destruction and the loss of millions of seabirds.

Bat guano is found in caves throughout the world. Many cave ecosystems are wholly dependent on bats to provide nutrients via their guano which supports bacteria, fungi, invertebrates, and vertebrates. The loss of bats from a cave can result in the extinction of species that rely on their guano. Unsustainable harvesting of bat guano may cause bats to abandon their roost.

Demand for guano rapidly declined after 1910 with the development of the Haber–Bosch process for extracting nitrogen from the atmosphere

Guano is one of the habitats of the fungus Histoplasma capsulatum, which can cause the disease histoplasmosis in humans, cats, and dogs. H. capsulatum grows best in the nitrogen-rich conditions present in guano.[50] In the United States, histoplasmosis affects 3.4 adults per 100,000 over age 65, with higher rates in the Midwestern United States (6.1 cases per 100,000).In addition to the United States, H. capsulatum is found in Central and South America, Africa, Asia, and Australia. Of 105 outbreaks in the U.S. from 1938–2013, seventeen occurred after exposure to a chicken coop while nine occurred after exposure to a cave.Birds or their droppings were present in 56% of outbreaks, while bats or their droppings were present in 23%.Developing any symptoms after exposure to H. capsulatum is very rare; less than 1% of those infected develop symptoms. Only patients with more severe cases require medical attention, and only about 1% of acute cases are fatal. It is a much more serious illness for the immunocompromised, however. Histoplasmosis is the first symptom of HIV/AIDS in 50–75% of patients, and results in death for 39–58% of those with HIV/AIDS. The Centers for Disease Control and Prevention recommends that the immunocompromised avoid exploring caves or old buildings, cleaning chicken coops, or disturbing soil where guano is present