Science finally unearths why soil carbon is so valuable
A radical new way of thinking about soil has solved the mystery of why adding organic material like manure improves flood and drought resilience, climate control and crop yields - universal ‘ecosystem services’ that are widely recognised as worth billions to the global economy.
Founded on more than 50 years’ worth of data from a unique field experiment, researchers have demonstrated that common farming practices drain the soil of carbon, altering the structure of soils’ microscopic habitat and, remarkably, the genetics of microbes living within it.
The team of microbiologists and physicists, led by Rothamsted Research, considered almost 9,000 genes, and used X-ray imaging to look at soil pores smaller than the width of a human hair, and in concert with previous work, have started forming what they envisage will be a universal ‘Theory of Soil’.
In healthy soils, relatively low nitrogen levels limit microbes’ ability to utilise carbon compounds, so they excrete them as polymers which act as a kind of ‘glue’ - creating a porous, interconnected structure in the soil which allows water, air, and nutrients to circulate.
Writing in the journal Scientific Reports, the researchers reveal that the Victorian-era switch from manure to ammonia and phosphorous based fertilizers has caused microbes to metabolise more carbon, excrete less polymers and fundamentally alter the properties of farmland soils when compared to their original grassland state.
Lead researcher Professor Andrew Neal said: “We noticed that as carbon is lost from soil, the pores within it become smaller and less connected. This results in fundamental changes in the flow of water, nutrients and oxygen through soil and forces several significant changes to microbial behaviour and metabolism. Low carbon, poorly connected soils are much less efficient at supporting growth and recycling nutrients.”
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Posted On: 30/06/2020