Sunday, February 2, 2020









In Cuba, cleaner rivers 
follow greener farming

When the Soviet Union collapsed in the early 1990's, food production on the island of Cuba was disrupted—as the supply of Russian fertilizers, pesticides, tractors, and oil dried up. Under the stress of an imminent food crisis, the island quickly rebuilt a new form of diversified farming—including many urban organic gardens—that depended less on imported synthetic chemicals. Over the last two decades, Cuba blossomed into a world-class showcase of conservation agriculture, with improved soils and cleaner water.
At least that's been a popular story among journalists.
Now—for the first time in more than fifty years—a team of Cuban and U.S. field scientists have worked together to rigorously test a key aspect of this story: the impacts of contemporary agriculture on water quality in Cuba's rivers. Despite centuries of sugarcane plantations and other intensive farming, the international team discovered that none of the rivers they explored show deep damage.
Instead, the scientists measured much lower nutrient concentrations in all the twenty-five Cuban rivers they studied than are found in the U.S.'s Mississippi River. And they think Cuba's transition toward sustainable agriculture—and its reduced use of fertilizers on cropland—may be a primary cause.
"A lot of stories about the value of Cuba's shift to conservation agriculture have been based on fuzzy, feel-good evidence," say University of Vermont geologist Paul Bierman, who co-led the new research, "this study provides hard data that a crucial part of this story is true."
Bierman and geoscientist Amanda Schmidt from Oberlin College led the American half of the international team, while Rita Yvelice Sibello Hernández, a scientist with CEAC (Centro de Estudios Ambientales de Cienfuegos), an ecological research group, headed up the Cuban effort with CEAC science director Carlos Alonso-Hernández.
The new study, "¡Cuba! River Water Chemistry Reveals Rapid Chemical Weathering, the Echo of Uplift, and the Promise of More Sustainable Agriculture," was published January 30, in the early online edition of the journal GSA Today, the leading publication of the Geological Society of America.
Conversely, "Cuba has been having a forced experiment in organic agriculture since the late 1980s," says Oberlin's Amanda Schmidt. "So Cuba is a very interesting place to look at the effects of both conventional agriculture and the effects of organic agriculture at a national scale,"—and may suggest pathways to improve U.S. agriculture. Fertilizer use in Cuba peaked in 1978 and has been lower since, according to World Bank and other data. U.S. fertilizer use spiked after the 1960s and has remained at more than twice the Cuban use rate.
"There's a takeaway we bring back to the U.S.: our river waters do not need to look the way they do," says Paul Bierman—a professor in UVM's Geology Department, Rubenstein School of Environment and Natural Resources, and Gund Institute for Environment—"we can manage fertilizer differently." There are, of course, complex questions about yields, farm policy and more, but this newly reported data on the low levels of nutrient pollution found in twenty-five Cuban rivers, "suggests the benefits of Cuba's shift to conservation agriculture after 1990," the US/Cuban team writes, "and provides a model for more sustainable agriculture worldwide."


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