Mark Tibbett's presentation is focused around one question: can we change the amount of carbon in soil through land management? Atmospheric carbon has risen 31% since 1750, and this is a concern within the context of global warming. One significant factor in that increase has been shifts in land use, such as native forest to crop, which allow a release in carbon from the soil to the atmosphere.
In Western Australia, soil carbon at a depth of 40 cm can be 2 -5 times greater than what would be found at a depth of 50 cm. This finding is similar to the Southern hemisphere and in tropical areas. Are there ways to manage the land that would allow carbon to be increased in the soil? Put simply, yes. By changing the land use and evaluating the significance of surface litter. This is not only important for climate change. There are many important benefits to carbon in the soil. It is a source of energy and a reservoir of nutrients. It improves the structural stability of soils at various scales and alters soil thermal qualities.
Tibbett's experience is in bauxite mining and he explains the basic process, and how it relates to soil quality. Once the plants and first two meters are stripped, the next six meters are drilled and blasted, and the following six meters are dug and loaded. Once the mining is completed, the site is prepared for restoration. Soils get layered back on and landscaping is added. "Direct return" is the goal of all mines. This means the top soil is removed in preparation for mining, and dropped onto a reclamation-ready mine site the same day. In this way the maximum integrity of the soil is maintained. Over many years surface litter in the reclaimed forest is evaluated and weighed. After 10-15 years, the litter is higher in the tropical and Mediterranean forests than native forests. This is expected partly because of stem density and partly because the entire forest was re-planted in a short period of time compared to the growth and development of a natural forest.
Tibbett's presentation discusses carbon content in soil with an awareness of the affects of mining to soil quality, and an understanding to broad benefits of carbon content in soil, to soil quality and climate change. This presentation was a part of the Alberta Soil Science Workshop, from February 2014.
