Tillage and SOC
Tillage: Conventional vs. No-Till
Impacts
The impacts of no-till and conventional deep tillage on SOC is hotly debated, and appears to be influenced by climate, soil type, crop type, and accompanying farming practices.
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Most research agrees that SOC increases in the top 10cm of soil under no-till conditions, but there is little agreement beyond that. Some research suggests that below 10cm, no-till soils actually decrease in SOC whereas conventional- till soils increase in SOC. This means that in the whole soil profile, from top to bottom, conventional till and no-till soils are not significantly different in terms of SOC content. However, other research indicates that no-till has a higher overall SOC concentration.
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Given the negative impact of tilling on soil erosion and runoff, no-till remains an attractive option, even if it does not lead to an overall increase in SOC.
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How does it work?
Tillage disrupts soil biological communities and physical soil structures.
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Fungal communities that deliver nutrients to roots are broken up by plowing. Clumps of soil called macroaggregates are destroyed by plowing, and this exposes the SOC inside of these aggregates to air and heat, which causes the carbon to convert into carbon dioxide and leave the soil.
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