Brazilian here. Perfectly safe (color-wise; of course it can be polluted as hell despite its color, just like any other river).
Our ground/mud has a different color. Some areas on the south even have a red soil (very fertile, but makes everything about ground level look dirty very quickly):
https://en.m.wikipedia.org/wiki/Red_soil
There’s great variety of water colors even in the same area, just search for images “meeting of the waters Manaus”:
Just jumping in to say that red soils are not very fertile. They are nutrient-poor in the necessary macro-nutrients (nitrogen, potassium, and phosphorus) and have a very poor ability to retain water. They are very rocky - little organic matter content - which limits both water retention and cationic exchange capacity (affecting N+ and K+ bioavailability), and tend to be acidic.
Cultivation is possible, but it requires large amounts of fertilizers and soil conditioning agents (liming to raise pH and add calcium, addition of organic matter). In effect, recreating an artificial soil that is closer in nutrient availability to the black soils present in the world’s most fertile regions (which today are also heavily fertilized).
I wrote red soil, but more specifically, where I lived there was Terra Roxa (purple soil?), which seems to be a kind of red soil according to the English Wikipedia page:
https://en.m.wikipedia.org/wiki/Terra_roxa
Brazilian here. Perfectly safe (color-wise; of course it can be polluted as hell despite its color, just like any other river).
Our ground/mud has a different color. Some areas on the south even have a red soil (very fertile, but makes everything about ground level look dirty very quickly): https://en.m.wikipedia.org/wiki/Red_soil
There’s great variety of water colors even in the same area, just search for images “meeting of the waters Manaus”:
Just jumping in to say that red soils are not very fertile. They are nutrient-poor in the necessary macro-nutrients (nitrogen, potassium, and phosphorus) and have a very poor ability to retain water. They are very rocky - little organic matter content - which limits both water retention and cationic exchange capacity (affecting N+ and K+ bioavailability), and tend to be acidic.
Cultivation is possible, but it requires large amounts of fertilizers and soil conditioning agents (liming to raise pH and add calcium, addition of organic matter). In effect, recreating an artificial soil that is closer in nutrient availability to the black soils present in the world’s most fertile regions (which today are also heavily fertilized).
I wrote red soil, but more specifically, where I lived there was Terra Roxa (purple soil?), which seems to be a kind of red soil according to the English Wikipedia page: https://en.m.wikipedia.org/wiki/Terra_roxa
And it is the prevalent soil on the north of the state of Paraná, regarded as Brazil’s agricultural barn: https://en.m.wikipedia.org/wiki/Paraná_(state)
So it does confuse me that the state’s soil would be unfertile, as I grew up learning how good it was and surrounded by prosperous farms.
The Portuguese Wikipedia page does talk about it being fertile (no English translation): https://pt.m.wikipedia.org/wiki/Terra_roxa
So maybe it isn’t a type of red soil in the end; or there are some types of red soil that are (very) fertile.
terra roxa is a type of latossolo in english latosol
For a satellite view
https://maps.app.goo.gl/HRcrSgpJ9HGUhC9L9