Longterm Gwp Effects Of Changing Tillage Practice

A change from CT to NT will lead to increasing carbon sequestration in soil for a limited time, depending on management and environmental factors. This will likely be for tens of years, after which a higher soil equilibrium organic carbon content will be reached. The rate of OC accumulation will follow a generally declining rate as OC accumulates, but actual patterns of OC accumulation may be complex, and can be expected to vary as soil faunal populations are reestablished and soil physical condition improves.

The long-term effect of the change from CT to NT on cumulative GWP will also be influenced by any permanent changes in greenhouse gas fluxes associated with the change in tillage practice. This concept is illustrated conceptually in Figure 17.2. The cumulative GWP benefit can be greater than that described by soil carbon sequestration alone, and will continue to rise indefinitely if other components contribute a net permanent reduction in GWP. In cases where other GWP components create a permanent net source of GWP that is initially less than the C sequestration benefit, the cumulative GWP will initially show a benefit before it reaches a maximum and then declines until the result is a net increase in GWP. Cumulative GWP outcomes will vary depending on the magnitude of the permanent GWP component and the timeframe considered. The analysis will be more complicated where a permanent GWP component changes over time from a source

Soil C sequestration

Plus permanent Beneficial component

Soil C sequestration

Plus permanent Beneficial component

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