Work

Linking soil chemistry to carbon sequestration in agricultural farmlands of southern Texas

Year: 2026

Type: article

Abstract: The global quest for environmental sustainability necessitates the adoption of ecofriendly approaches for carbon storage in the soil which is the phenomenon known as carbon sequestration. This soil carbon sinking capacity is majorly controlled by soil properties especially the soil chemical compositions. This study evaluated the impact of soil chemistry on carbon sequestration. Here, soil extractable minerals and extractable organic carbons (EOC) were quantified from three different agricultural farmlands with soil samples taken from two depths, each in 27 sampling points that were evenly distributed across each of the farmlands. The results showed that within the topsoil, calcium (Ca) was the most abundant mineral in plot 1, followed by plot 3, and plot 2 had the lowest amount. Iron (Fe) concentrations also followed the same trend as observed with calcium. The observable difference between aluminum (Al) concentrations across the plots were minimal. Plot 3 recorded high concentrations of potassium (K), magnesium (Mg) and phosphorus (P). Whereas plot 2 had the highest amount of manganese (Mn). However, within the subsoil, the values of calcium were highest in plot 1, followed by plots 2 and 3. Aluminum concentrations within plots 1 and 2 were similar. A similar trend was observed with magnesium, potassium and phosphorus whose concentrations across plots 1, 2 and 3 were almost the same. Manganese showed a higher concentration in plot 2 as compared to the other plots. While boron (B), chromium (Cr), copper (Cu), and zinc (Zn) concentrations across the plots were very minimal. The distributions of these soil minerals correlated with soil extractable organic carbon (EOC). Within plot 1 topsoil, Al and Ca correlated positively with EOC. While Mg negatively correlated with organic carbon. The Fe ions, though correlated positively with EOC, were evenly distributed across increased Fe concentrations. In the subsoil, an increase in Al and Ca did not result in an increase in EOC. Interestingly, Fe correlated positively with EOC in the subsoil. In plot 2 topsoil, Fe and Mg correlated positively with EOC, but did not change with an increase in Al, Ca, Na, Mg and K concentrations in the subsoils. In plot 3, an increase in Ca, K, Na correlated positively with an increase in EOC. But within the subsoil Al, Ca and Na correlated positively with EOC. The study showed the variability in metal oxide stock with soil depth across the different farmlands. Interestingly, our study showed that despite increase in the abundance of Al, Fe and Ca, soil carbon sequestration was not improved as the correlation result between the extractable cations and EOC are weak or negative. Hence, the hypothesis of more minerals equals to more carbon is null.

Source: Discover Soil.

DOI: 10.1007/s44378-026-00290-1