Between January 8th and January 18th, C-Quest Capital and Brinkman Associates undertook fieldwork to gain a preliminary assessment of the contribution of Gliricidia sepium (Gs) to soil organic carbon levels in the deep soil profile up to 3 metres in small-holder farms in and around he Luangwa Valley in Zambia. The assessment is part of a broad-based partnership between the Community Markets for Conservation Ltd (COMACO) and C-Quest Capital to, inter alia, develop agricultural and forest carbon assets for trade on the world markets. COMACO has selected Gs as the main element in its legume-based agroforestry systems it promotes to its 65,000 member farmers to increase crop yield and improve climate resilience. This work has been funded by the Royal Norwegian Embassy (RNE) in Lusaka. The Gs agroforestry carbon project is a key element of the World Bank BioCarbon Fund COMAC Landscape management REDD + project in preparation with the support of CQC.
The following are some observations from this fieldwork. A formal report will be made available to COMACO and RNE when soil samples have been analyzed and the results processed.
Deep profile Soil Organic Carbon (SOC)
- Not clear how much SOC there is in deep profile as soils in part of the area were deep sand and not clay, completely contrary to soil maps (which are more or less useless). In those clay soils we sampled, there is a lot of deep rooting and conversion. In sandy soils, roots pass right through the sand to the old historic topsoil layers and branch laterally into them at a metre plus (wherever these remnants are). Samples will tell the story. See picture.
- Gliricidia (Gs) clearly has a beneficial impact on crop production. In evidence everywhere. Good photos attached.
- Lateral rooting of Gs is impressive. See photos at 3 years. But spacing seem overdone and will recommend half to one third planting density. Lowers seed needs, farmer labor burden etc;
- Above and below ground biomass production also impressive. Good prospects for creating a market for fuel wood that can be used in modern Cookstoves (even such low density wood);
- Now intend to develop an additional sampling program for destructive sampling of Gs biomass by soil type and age cohort to set up this part of the BioCF project. Think the Norwegians will fund;
- Also clear that top layer SOC contribution of residues retained from crops and Gs is impressive and likely adding significant SOC. Samples will reflect some of this although top soils are mostly high carbon already. We’ll see. Easy to add this dimension in the The Earth Partners (TEP) Verified Carbon Standard (VCS) SOC methodology;
- As a result of the fieldwork CQC proposed to use the TEP methodology for both Gs biomass and SOC.