The driest desert in the world has been transformed into a fertile oasis by Bird Poop

The Atacama Desert has a frightening reputation. The driest non-polar desert in the world, located along the Pacific coast in northern Chile, is a hyperarid Mars-like environment, an environment so extreme that when it rains in this parched place, it can bring death to the place of life.

However, life, even in the Atacama Desert, finds a way. Archaeological records show that this hyper-arid region supported agriculture several hundred years ago, cultures that in one way or another flourished to feed the pre-Columbian and pre-Inca peoples who once lived here. .

“The transition to agriculture started here around 1000 BC. C. and ultimately supported permanent cities and a sizable regional population, ”said a team of researchers, led by bioarchaeologist Francisca Santana-Sagredo from the Pontificia Universidad Católica de Chile. write in a new study

.

“How was this development possible, given the extreme environmental conditions?”

Thanks to Santana-Sagredo and his team, we have a solution to the mystery. It was already known that part of the puzzle could have been the use of ancient irrigation techniques, but the availability of water alone would not be the only prerequisite for a successful agricultural system in the Atacama Desert, according to the researchers.

Residing in previous research by the same team, analyzing chemical isotopes preserved in human bones and dental remains from pre-Inca peoples, the researchers suspected that the fertilizer was also used to help plants grow.

Now, in his new work, there is new evidence to support the hypothesis.

“We set out to collect and analyze hundreds of archaeological cultures and wild fruits from different archaeological sites in the valleys and oases of the Atacama Desert in northern Chile”, Santana-Sagredo and some of his co-authors . explain in perspective article

on research.

A total of 246 ancestral plants were analyzed – the specimens are conveniently well preserved by the drought of the Atacama – including corn, chili peppers, squash, beans and quinoa, among others.

(UC Anthropology)

Using radiocarbon dating and also testing the isotopic composition, the results showed a dramatic increase in the isotopic composition of nitrogen from around 1000 AD, such a high reading, in fact, has never been seen before. been seen in plants before, with the exception of some plants of the Antarctic Nunataks. where sea birds nest.

Among the plants analyzed, maize was the most affected and, at the same time (around 1000 AD), it also became the most consumed crop, according to a separate analysis of archaeological remains of human bones and teeth from area they showed high readings of nitrogen isotopes.

According to the researchers, “the most parsimonious explanation” for the increase in nitrogen values ​​is ancient bird droppings, technically known as guano, which had a history of use as a fertilizer at the time. pre-modern, probably even in the Atacama Desert. , such as the growth stimulator of pre-Inca cultures.

While the fertilizing abilities of seabird guano (also known as “ white gold ”) might have taken the agriculture of this ancient crop to a new level, securing manure would not have not an easy task, nor would it have been pleasant.

“Before [1000 CE] It is possible that people have used other types of local fertilizers like llama manure, but we believe that the introduction of guano has caused a considerable intensification of agricultural practices, a radical change which has increased crop production. , especially corn, which quickly became one of the main foods for human subsistence, ”explain the researchers.

“This change is remarkable also considering the human (and llama) labor costs involved: the guano had to be carefully collected from the coast and transported ~ 100 km [about 60 miles] interior. “

Despite the challenges, the new findings suggest that this is exactly what the desert dwellers of Chile did, and historical accounts centuries later suggest the practice continued well into the era of European contact; it’s just that we’ve never had any evidence to suggest that the custom began a whole millennium ago. Is.

“Ethno-historical records from the 16th to 19th centuries describe how local people traveled in small boats to obtain guano from the rocky islets off the Pacific coast, from southern Peru to the Tarapacá coast in northern Chile, and how guano seabirds were extracted, transported. interior and applied. in small quantities to achieve successful harvests, ”the authors write on their paper.

“Although in the earliest historical accounts it was said that guano was evenly distributed in each village, the same sources claim that access to guano was strictly regulated, justifying the death penalty for those who extracted more than that. that was authorized or entered the Guano territory of its neighbors, emphasizing its great value. “

The results are reported in Natural plants.