Cuba and the US have much in common when it comes to ecosystems and agricultural practices, but little scientific data is available for comparing and contrasting the two.
Recently however, scientific experiments have been conducted to compare how rivers are affected by the agricultural policies of the two countries. Cuba’s sustainable approach to agriculture has yielded some great results, specifically in terms of water pollution.
Background
The history of agriculture in the American South is somewhat similar to that of Cuban agriculture, at least when it comes to what’s being grown and for how long. Both rely on sugarcane production and cattle farming: traditions that span centuries.
Both of these practices affect the rivers of the region, however, mostly in negative ways. Simply put, cattle contaminate the waters with harmful bacteria such as Escherichia coli, which appear in tests of drinking water.
The Difference
Both countries relied on mass scale farming up until the 1990s. In the US, this was accomplished by individual farmers, aided by public agricultural policy. In Cuba, however, mass scale farming was done mostly by publicly-owned farms.
The difference came about in the 1990s, when Cuba made a transition to a more sustainable farming policy that focused on small-scale farming and no-tillage practices. This was done partly out of environmental concern, as well as necessity as most materials and machinery used for large-scale farming were acquired from the USSR.
The Methodology
The methodology used to compare and contrast the rivers was simple, yet effective. Traces of the same biochemical were searched for at the same time in the rivers of both the US and Cuba, and the results were compared.
This was done during the wet season in order to get the most exemplary results. The sites were selected to include: a range of land uses, underlying upstream rock types, discharges and basin sizes–while avoiding rivers that had major dams. The criteria was designed to provide a diverse outlook on how the waters were effected.
The Results
River water samples from central Cuba contained high concentrations of dissolved material. Conductivity and total dissolved load were high (130–1380 μS/cm and 117 to over 780 mg/L, respectively. Stream water, except for that which was sampled from forested catchments, was turbid. Sample pH was near neutral to slightly alkaline with high values of bicarbonate alkalinity (65–400 mg/L). As, Ba, Cr, Mn, Ni, Sr, and U were present in some or all of the Cuban river waters analyzed.
Dissolved oxygen measurements ranged from 59% to 145% (average 97%). Using basin-specific precipitation, along with run-off estimates (Beck et al., 2015, 2017) and total dissolved solids (TDS) from each Cuban water sample, we estimate chemical weathering rates between 42 and 302 t km–2 y–1 with a mean of 161 ± 66 t km–2 y–1.
Interpretation
The interpretation of these results is universal, as data produced by the studies were conclusive. For instance, research shows a connection between the types of rocks found in the river basin, and the chemicals present in the river water. This further suggests the presence of a weatherable mineral along flow paths in the Cuban rivers.
Human Activity
Beyond the effects of bedrock, there are also changes in the chemical content of rivers caused by human activity. This is consistent with the level of activity needed to maintain and feed livestock in the areas, meaning there is a higher human effect where there is a greater population of livestock.
The concentration of N and P is present in Cuban rivers, but is lower than concentrations of such elements in rivers of the U.S. The same can be said for the concentration of fertilizer accumulated over time. In Cuba, it peaked in 1978 and has declined steadily every since, while in the U.S. the numbers only grow.
Implications
There are some clear implications of this research that should help create policy and move farmers toward a different approach to agriculture. It can be concluded that the farmland tended in eco-friendly ways has considerably less damaging impact on local rivers.