Project planning, beneficiaries and results
Rationale Project Set Up
The stonemeal project is composed of three sub-projects with different objectives:
Objective 1: Stonemeal for increased soil fertility and yields for smallholder farmers
This project is currently running and will continue to the end of 2016. This year demonstration plots will be established at seven sites distributed throughout Ethiopia. The test plots have a typical size of 1 to 3 hectare and have a total size of 14 hectares. Based on the test results, over 4000 smallholder farmers will be trained from 2014 to 2016. Total trained farmers and total land size is 1100 farmers on 550 hectare in 2014; 2600 farmers on 1300 hectare in 2015; and 4100 farmers on 2100 hectare in 2016. The distribution of the demonstration plots, stonemeal type used, area and number of farmers over the project period are presented in table 1: Project area and connected farmers over the period 2013 – 2016.
Objective 2: Olivine and Serpentine application for soil reclamation of current unproductive lands – using Nickel farming
This project will start when the licensing system of the Ministry of Mines will re-open again. According to forecasts of our staff in Ethiopia the opening date might take several months, estimated to be somewhere in between May and July 2013. The project start is therefore estimated to be in May 2014. The project aims at testing of reclaiming acid (pH < 5 – 5.5) soils by integrating olivine and serpentine dust into the soil. Over a period of three to five years nickel liking plants will be produced for nickel removal. After this period the land will be tested, like the trials in the stonemeal project, for its suitability for crop production. The size of the initial farm is 200 hectares.
Objective 3: Testing suitability of olivine and serpentine for liming soils of productive land
As liming of soil using olivine/serpentine requires large quantities, in the order of 10 – 40 ton per hectare, the release of heavy metal concentrations is expected to increase as well. Mobility of the heavy metals and impact on soil and crop quality need therefore to be tested on forehand. If not, potential toxic levels may, instead of increasing crop yield due to liming, rather reduce crops yields. For example, during the field visits it was observed that only minor natural vegetation was growing on the serpentine/olivine deposits. On the other hand, farmers claimed the production of ‘teff’ on the serpentine/olivine hill sides was very good instead. In order to guarantee the benefit of the project to the farmers, in the short and long term, this sub-project will test nickel accumulation in soil and crop, and the impact of the nickel on the teff yield. To this purpose olivine/serpentine dust will be tested during three teff seasons on three hectare of the serpentine/olivine hill and three hectares of a red soil in the surroundings.
Carbon dioxide sequestering minerals in the rocks used in stonemeal project
Gimbi-Yubdo – Welega Region:
The deposits of which we took the samples are serpentine, with olivine fractions, probably from dunite origin. Typical composition of the rock in for example the Tulu-Dimtu mountain range is:
- Serpentinite 60-90 %. 1.13 ton serpentine sequesters 1 ton CO2 using the formula: Mg3Si2O5(OH)4 + 6 CO2 + 5 H2O → 3 Mg+ + 6 HCO3– + 2 H4SiO4 (Source: Pers. Comm. Prof. Schuiling, January 31, 2013)
- Olivine 5-30 %. 0.79 ton olivine sequesters 1 ton CO2 using the formula: Mg2SiO4 + 4 CO2 + 4 H2O à 2 Mg2+ + 4 HCO3– + H4SiO4 (Source: Shuiling and Praagman)
Rema village Getaw farm, Holeta FTC, Holeta Marginpar & Solulta FTC
The geology in this area is dominantly basalt, sandstone, limestone and gypsum. Typical basalt composition in this area is 48.84% SiO2; 15.52 % Al2O3; 10.38 % Fe2O3; 1.66 % TiO2; 0.37 % P2O5; 9.52 % CaO; 6,60 % MgO; 3.95 % Na2O; 1.01 % K2O. For the stonemeal we only use basalt for fresh application and integrating it in composting processes.
- Basalt 100 % – 2.6 ton basalt sequesters 1 ton CO2 (Source: Oelkers et al, 2008: Mineral Carbonation of CO2).
Ziway town (RCWD, HoA-REC/N, SEDA) and Arsi Zone (ANCEDA)
Samples from this area are from recent volcanic origin, and carbon dioxide sequestration unknown yet. Laboratory results are expected in first week of February 2013. Among the volcanic rocks are also zeolites, but these are not included for the CO2 sequestration totals obtained in this project.
Role of using CO2 sequestering minerals in the stonemeal project
All minerals in the projects are meant to play a role in improving soil and crop health, with the ultimate objective that farmers’ crop yields and income increase. This way we aim to assist Ethiopia in its agricultural programs bringing the smallholder agricultural sector to a higher level. The first role of the located deposits of serpentine, olivine, basalt and volcanic rocks is the provision of nutrients to the crops. These are Magnesium and Silica for the olivine and serpentine rock dust and Calcium, Magnesium, Silica, Potash and Phosphorous for the basalt and volcanic rocks/tuffs. Secondary, the exploited minerals will be used for soil structure stabilization/improvement by organic matter stabilization – improving compost quality – and aggregate stabilization. Thirdly, serpentine and olivine dust will be tested in its ability to be used as substitute as liming agent – increasing soil pH.
Total applied stonemeal and CO2 sequestration by mineral weathering
The following assumptions are made for the calculations presented in table 2: Carbon dioxide sequestration through chemical weathering of applies stonemeal during the project.
- Average particle size of the stonemeal in the project sites will be 200 μ.
- Particles of this size will weather in a period of 3 to 4 years for olivine and serpentine; for basalt the process is longer, around 5 years.
- RCO2 values for olivine, serpentine and basalt are resp. 0.79, 1.14 and 2.6 (Oelkers et al, 2008). A value of 0.79 for olivine means that in practice 0.79 ton olivine is able to sequester 1 ton of CO2.
The total CO2 sequestration by weathering of the applied stonemeal during project period – and continuing over the year 2017 – is 16,634 ton CO2.
It is the purpose that above mentioned have wide spin-off effect in whole of Ethiopia, using existing communication channels of several initiatives and organizations. The optimal institutional method for upscaling the stonemeal technique will be developed in the latest two years of the project. Several organizations have already expressed interest to assist in upscaling, once the technique is established:
- ATA – Agricultural Transformation Agency
- CASCAPE Project; and
- NGOs (RCWD, ANCEDA, HoA-REC/N and SEDA).
A stonemeal introduction day will be held in Ethiopia this year prior to the start of the project in 2013 with the Dutch Embassy and key international agricultural and geological experts.