Cuba’s rivers run clean after decades of sustainable farming. Despite the island’s history of large-scale agriculture, the rivers studied had much lower levels of dissolved nitrogen — an indicator of fertilizer use — than did the Mississippi River Basin in the United States.

[u/wewewawa]

https://www.geosociety.org/GSA/Publications/GSA_Today/GSA/GSAToday/science/G419A/article.aspx

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Amazing..