Stonemeal project Ethiopia

Rock as multifunctional soil improver

Over the last one and half year MetaMeta obtained a thorough knowledge of the available rock dust types in Ethiopia and their potential. We learned that rock dust can be effective as soil improver, fertilizer, water retaining agent, liming material and carbon dioxide sequestration. The efficiency of each process depends on the mineral composition of the host rock, the dust particle size, soile type, climate, and crop type. As these variables differ between the project locations, we will use the first year of the project to test the most suitable rock dust composition – composed of basalt, serpentine, olivine, zeolite and other volcanic rock material- in each location. Farmers of each locality are enthusiastic and they will be involved from the demonstration phase onwards by maintaining demonstration plots and collection of sample material.
Supervision in each area is performed by local NGOs, government workers who are trained in the period from March 9 to April 5, 2013. Based on the results, the peer farmer groups of the demonstration phase will train their fellow farmers how to produce best rock dust mix from nearby quarries and mines, and how to apply the rock dusts to their lands. The experiences and the enthusiasm of farmers encourage MetaMeta in this project, as local inspired people are key to secure sustainability of projects.

 

Carbon sequestration

All project locations will contribute to carbon dioxide concentration by stabilizing and building organic matter in the soil as well as ‘enhanced weathering’  of the rock dust. Enhanced weathering means that rocks are degraded faster than in natural conditions, as the rock dust was created from mining, grinding and milling the rock. The small particle size allows however also the acceleration of the chemical and biological weathering proces. During this proces, which is particularly known for olivine and serpentine rock dust, carbon dioxide is being sequestered. Also other rocks, like basalts are able to sequester carbon dioxide, although the process is slower. As the project evolves around development of local fertilizers, we will use the rock dust as much as possible on places it is located. This means that:

  • The olivine and serpentine rocks, located in the Westers Welega region, will be used for the project sites in Gimbi and Yubdo.
  • The basalt rocks, common to the dozens of quarries around Addis and its Northern plateau, will be used in the demonstration plots of Rema, Holeta and Solulta.
  • Volcanic rocks, including zeolite and tuffs, common in the recent volcanic Rift Valley, will be used for the project sites in Arsi Negelle and Ziway. 

Focus in each location will be to explore the potential of each rock dust type to address key agricultural problems with which farmers are confronted in each area. These are basically as follows:

  • Western Ethiopia: Soil acidity is a key productivity constraint in this region as soil pH does not often exceed 5 to 5.5. As a consequence, yields of farmers are limited. In order to increase soil pH, Ethiopia’s central government is now assessing ways to use own geological resources as liming agents. One of the projects developed by the government is called ‘the limestone project’ in which limestone from the central region is tested. First field results are promising, however transportation of the central located limestone to the western region induces high costs to government, as well as farmers. As also serpentine and olivine are known for their high magnesium contents, being released during weathering, we will assess their capability to work as liming agent.  This would result in cost reduction for smallholder farmers and the government, as well as allowing widespread carbon dioxide reduction.
  • South Oromia Zone, Central Rift Valley (CRV), Lake Region: A key problem faced in this area is ineffective over-fertilization by smallholder and larger farmers. This practice, by farmers along the shores of lake Ziway, causes gradual increase of nutrient levels in the lake. As the lake is the main drinking water reservoir to the population of Ziway town, authorities are increasingly concerned about farmers fertilizer use. Another group of farmers in CRV is located in Abyatta Shalla National Park. Although being a National Park, population is quite high and farmers live in mutual agreement with nature. As production is very low in last five years, communities are part of the World Food Program. In order to decrease community dependency on food aid several initiatives started assisting farmer communities to raise production of their own farms. Chemical fertilizer use, being part of this, however did not yield any significant growth: corn yields remain below 3 ton per hectare although chemical fertilizer gifts are 150 kg/ha. Both communities would benefit from lower chemical fertilizer use amounts, to safe costs, increase yields and safe the environment they living in. In the project we will specifically address the capability of the zeolite sources in this area, to act as agent to improve fertilizer and water retention efficiency.
  • Oromia Special Zone: Around the capital Addis Abeba the rock dust project will contribute to activities of Oromia Special Zone Department to make the catchment around Addis climate resilient. Two specific activities taught to farmers are composting – each farmer in the catchment is learnt to make 24 m3 of compost each year – and application of limestone to increase soil pH. In the rock dust we will facilitate both project components by optimizing compost process and liming techniques.
  • Rema village: This remote village some 200 km North of Addis is difficult to reach through the boulder roads which makes it a 5 to 8 hour journey. Chemical fertilizers are not used and biological fertilizers (crop residues, cow dung) hardly. The chemical fertilizers are not imported due to bad road conditions, and biological fertilization is not practiced as crop residues are used as cow fodder and cow dung is sold on the market and used as fuel for cooking. In the rock dust project we will focus on use of composting technique and production of biofertilizer; while providing other opportunities for cooking.