Agriculture is crucial to modern society, but all the technological farming advances in the world are useless without healthy soil—and healthy soil requires plenty of carbon. When organic matter breaks down in the soil, it releases carbon that fuels plant growth, allows the soil to store more water, and helps hold soil particles together. But when done carelessly, human activities like farming can deplete the soil’s carbon and render the land incapable of supporting life.
Many previous studies have measured concentrations of carbon in the soil from organic sources, and here Papanicolaou et al. contribute new results that account for the uneven slope of the ground, focusing on land that is constantly disturbed by human activities.
The team monitored organic carbon in hill slopes on developed land by dividing the slopes into two regions, the upslope and downslope. They developed a model to find out how much organic carbon was in each region, taking into account that water transports some carbon from one region to the other. Then they measured how soil organic carbon is redistributed during different crop rotations—a land management practice intended to preserve nutrients in the soil.
The results confirmed that less runoff on agricultural lands led to higher concentrations of soil organic carbon. The team’s eroded soil measurements showed that there was 4% more carbon at higher slope elevations than at lower elevations, suggesting that interrill erosion is at work. This happens when falling raindrops send soil particles flying, sometimes scattering them toward narrow soil channels called rills, which carry them away. Furthermore, the team found that land that had been cultivated using conservation tillage since the 1980s had been able to recover more than a fourth of the soil organic carbon it had lost.
Ultimately, the study provides supporting evidence for the benefits of conservation farming techniques, suggesting that damaged soil can be repaired over time. Information gained about the impact of hillslopes on carbon distribution in the soil will also be useful to scientists and farmers for managing farmland sustainably in the future. (Journal of Geophysical Research: Biogeosciences, doi:10.1002/2015JG003078, 2015)
—Shannon Kelleher, Writer Intern
Citation: Kelleher, S. (2016), Conservation farming shown to protect carbon in soil, Eos, 97, doi:10.1029/2016EO045355. Published on 3 February 2016.