Why does agriculture threaten and decrease the global carbon balance and stock?

Written by Selene Escobar, PhD, and Vanessa Hogan

Over the past four centuries, land used for grazing animals and planting crops has increased from an insignificant area, to cover about 30% of the global land mass, mostly at the expense of forests and grasslands. Therefore, agriculture, and especially the "expansion of agriculture", has profoundly distorted the global carbon cycle, due to the change of land use it causes.

When forests are converted into agricultural fields, where much of the carbon is found in the vegetation, there are huge carbon losses. In addition, agriculture eliminates much of the carbon acquired through photosynthesis. As a result, currently, there is much less carbon in the soil, and, especially in the covering vegetation, than there was before the expansion of agriculture.

In agricultural systems, most of the carbon is stored in the soil, and very little in the covering vegetation. Furthermore, in land dedicated to agriculture, crops are harvested, and that carbon is then consumed by humans (as food for people and livestock, as raw material for industries, as biofuels, etc.) and does not return to the soil. Also, carbon is also released from the soil into the atmosphere through the respiration of the microorganisms in the soil that break down organic matter (for example, dead leaves, senescent plants, animal carcasses, etc.)

In the majority of ecosystems, carbon is found mostly in the soil, its covering vegetation and in the atmosphere. Usually, the amount of carbon in the soil is greater than the amount of carbon in the vegetation, with one important exception: in tropical rainforests, the amount of carbon in the soil and in the vegetation is almost the same.

The greatest carbon stock can be found in the soil of boreal areas, of humid temperate zones and of tropical rainforests; however, a large amount is also stored in the vegetation of tropical rainforests.

What can we do to prevent carbon loss caused by agriculture?

At Humans for Abundance, we focus on the restoration of tropical rainforests that have been converted into agricultural lands. We aim to return these lands to their natural state. This is achieved through the dedication of our restorers, who treat the soil with organic fertilizers and compost, and gather seeds of endemic plants and trees, to replant them on their land, which, until then, had been used for monocultures.

We also focus on permaculture. In the areas of the rainforest where agriculture must be practiced, the goal is to do so sustainably; that is, to use permaculture techniques. This is an agricultural system that imitates the natural environment: it combines a wide variety of native plants that are useful for humans on the same plot of land.

You can be part of the solution, too! Visit our eco-services section to find out how they work and how, with a couple of clicks, you can support our restoration and conservation efforts in the Amazon rainforest, therefore contributing to global carbon sequestration and the fight against climate change.

If you would like to help, please click on this link.

SOURCES:

Houghton, R.A. 2002, ‘The annual net flux of carbon to the atmosphere from changes in land use 1850–1990’, Tellus B: Chemical and Physical Meteorology, vol. 51, issue 2, https://doi.org/10.3402/tellusb.v51i2.16288