ABSTRACT
Agriculture ....................................................... 614 25.2.3 Impact of Farming Systems and
Agroforestry on Soil Organic Carbon ............ 615 25.2.4 Integrated Soil Nutrient Management.......... 617
25.2.5 Soil Organic Carbon Sequestration Strategy............................................................ 619
25.2.6 Carbon Stocks in Natural Ecosystems and C Loss with Land Conversion in Africa ........ 620
25.3 Potential for Sequestering Soil Organic Carbon in Zambia Soils............................................................ 621 25.3.1 Soil Organic Matter, Soil Carbon, and
Carbon Sequestration in Zambia ................... 623 25.3.2 Conservation Tillage, Cover Crops, and
Residue Management...................................... 627 25.3.2.1 Conservation Tillage ......................... 627 25.3.2.2 Management of Residual Organic
Matter and Soil Organic Matter Sequestration..................................... 627
25.3.3 Increasing Carbon Sequestration through Nutrient Recapitalization and Agroforestry ..................................................... 628
25.3.4 Mitigation Options in Zambian Forest Sector .................................................... 628 25.3.4.1 Maintaining Existing Stocks ............ 629 25.3.4.2 Expanding Carbon Sinks.................. 629
25.3.5 Characteristics of Mitigation Options ........... 630 25.5 Summary and Conclusion........................................... 630 References............................................................................. 631
Carbon (C) is one of the most important and abundant elements on Earth, occurring in five general pools, that is, soil organic C (SOC) and soil inorganic C (SIC), oceanic, geologic, atmospheric, and biotic components. Carbon pools are of immense significance to the growing human population, which depends on soil quality for agricultural sustainability, poverty alleviation, and improved nutritional and health status. Carbon is a constituent part of humus, which improves soil quality by binding soil particles into aggregates. It enhances the chemical and physical properties of the soil and crop productivity. Carbon also combines with oxygen to form carbon dioxide (CO2), a raw material for photosynthesis and, hence, an important component of dry matter for the
production of food and fiber. Carbon dioxide absorbs heat from sunlight, thus helping to keep the Earth warm. Increased concentrations of CO2 and other greenhouse gases will raise mean annual temperatures and cause excessive global heating, and melting of ice, glaciers, and permafrost. In turn, higher temperatures are expected to result in increased flooding in coastal areas from rising sea levels and droughts in low-rainfall areas, adversely affecting climate and agricultural production, especially in tropical and subtropical zones (Lal, 2001).
