Soil Organic Carbon Sequestration Strategy

Several practices and strategies that have been recommended to improve soil fertility for farming systems in Zambia also enhance SOC. These strategies and practices include:

1. Returning organic materials to the soil to replenish SOM lost through decomposition

2. Ensuring minimum disturbance of the soil surface

3. Reducing soil temperature and water evaporation through mulching with plant residues

4. Integrating planting of multipurpose trees and perennials

5. Improving fallows to increase production of organic materials

6. Using biofertilizers in legume production in order to improve biological nitrogen fixation (Lal, 1975; Peat and Brown, 1962; Sanchez et al., 1989)

These strategies will also enhance N supply, and SOC sequestration. The rate of SOC sequestration by adoption of recommended agricultural practices in tropical Africa is reported to be 0.1% to 0.2%. By expanding cropland area and adopting agroforestry techniques and recommended agricultural practices, it is possible to increase the potential SOC sequestration in croplands of the arable land in tropical Africa from 4 to

700 Tg (1012 g) over 50 years (Lal, 2001). In soils of the tropics a larger potential of SOC sequestration can be realized through restoration of degraded soils. This is especially true when the soils are used to grow trees and other perennials that have the potential to produce larger aboveground biomass usable as fossil fuel offset (Lal, 2001).

In ecosystems where soils such as acid savanna Oxisols and Ultisols are characterized by toxicity of Al and Mn and deficiency of P, Ca, Mg, and other bases, corrective strategies such as adopting recommended agricultural practices can enhance the SOC pool (Lal, 2001; Sanchez and Buol, 1975). In arid and semi-arid regions of Zambia, the inadequate supply of water can be mitigated through irrigation to enhance net primary productivity, and hence, raise the equilibrium level of the SOC pool higher than under natural ecosystem conditions (Lal, 2001).

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