Climate and Grazing
Emerging land use practices rapidly increase soil organic matter (2015) === Converting degraded soils from cropping to intensively grazed permanent pasture in SE USA can increase soil organic matter remarkably quickly. However, this is not low input grazing. It took full fertilization (over 600 lb/ac N in 3 years), irrigation, grazing for optimal forage digestibility and protein content. The increase only lasted 6 years before leveling off. And the soils were sandy, starting with only 0.5% soil organic matter. https://www.nature.com/articles/ncomms7995?fbclid=IwAR1RIPYj3ua-rSlo9KAE0y4nzHalgye4s1az1qfMhzfxCmmKuTF8kimb4L4
On Pasture: Does Grazing Sequester Carbon? Part 1
- So far, we’ve read over 100 scientific papers published between 1998 and 2016. Each of those papers cite at least 50 additional papers that supported them in their work. And, of course, each of those support papers cite even more papers. It’s a lot to digest.
- Let’s start with the basics of what the research tells us. We’ll go into more detail in future articles.
- What we’ve learned from our reading so far:
- Grazing itself does not seem to have much influence on increasing carbon in the soil.
On Pasture: Does Grazing Sequester Carbon? Part 2 – Some Background https://onpasture.com/2017/10/09/does-grazing-sequester-carbon-part-2-some-background/
On Pasture: What 30 Years of Study Tell Us About Grazing and Carbon Sequestration
- About ten years ago, two scientists argued about these two things. One said that it was doubtful carbon increase was occurring due to grazing management, and if there were changes, it would be difficult to measure them. The other said that based on soil organic matter increases alone, soil organic carbon had to be increasing, and it was because of his grazing management. To resolve their disagreement, they did what scientists do – they set up experiments to answer the question.
- They now have nine years of data on the effects of management intensive grazing (or Adaptive Multi-Paddock grazing as it’s sometimes called in research circles) and it shows grazing has not increased carbon sequestration in the soil. In fact, the grazed only plots have continued to be a carbon source, not a sink.
- Other researchers might have told them to expect this result, as it turns out these kinds of studies have been going on for years. One scientist studying grazing and carbon sequestration on the shortgrass steppe told me that when he started he had very little gray hair, but now his hair is mostly gray and he’s retired. When I spoke to another scientist in this field he sighed and said, “We’ve got thirty years of data on this and it feels like people are just ignoring us.”