By Dr. Paul Bierman, University of Vermont and Dr. Amanda H Schmidt, Oberlin College — The Conversation US — 10 June 2020
A recently published study by US and Cuban geoscientists shows that Cuban rivers are cleaner than the mighty Mississippi — because Cuban farmers practice organic farming and conservation agriculture to reduce soil erosion and nutrient loss.
Cuban farmers use about half as much fertilizer per acre as their US counterparts (3 versus 6 tons per square kilometer per year in 2016). As a result, rivers in central Cuba contain much lower concentrations of dissolved nitrogen than the Mississippi River. On average, the Cuban rivers analyzed contained 0.76 milligrams of nitrogen per liter of water, compared to 1.3 milligrams per liter in the Mississippi from 2012-2019.
American crop yields per acre are higher than Cuba’s, thanks partly to fertilizer use, but the trade-off is stark. Nutrients that pour off US farm fields and flow down the Mississippi River create the Gulf of Mexico dead zone — a patch of ocean where oxygen levels are so low that almost no marine life survives, covering an average of 6,000 square miles in recent years.
The researchers note that Cuba’s country-wide experiment in organic agriculture, which began when the Soviet Union broke apart in the late 1980s and Cuba lost access to fertilizers and heavy equipment, may offer a blueprint for more sustainable approaches to feeding the world.