Science in Society Archive

Biogas Plant for Smallholder Farmers in Ethiopia
Showcased by Award-Winning Team for Sustainable Development

Biogas plants provide organic fertilizer and sustainable energy to increase crop yield and supply households with clean safe energy Sue Edwards with Fentaw Ejigu and Hailu Araya from Institute of Sustainable Development

Editor’s note

Anaerobic digestion can provide both energy and food security for small productive farms while mitigating greenhouse emissions, as I-SIS has been stressing for many years (see [1] Sustainable Agriculture and Off-Grid Renewable Energy, SiS 51). It is now showcased by Institute of Sustainable Development based in Addis Ababa, which has won the 2011 Gothenburg Award for Sustainable Development jointly with Kofi Annan, former Secretary General of the United Nations [2]. The prize of one million Swedish Krona is shared equally between the winners.

Ethiopia is a mountainous country in the Horn of Africa with over 45 percent of the land more than 1 500 metres above sea level. That is where the majority of the population, particularly smallholder farmers, live. They practice mixed farming, combining arable crops with livestock

Livestock play a pivotal role in smallholder farming, providing draught power for ploughing fields, dung for fertilizing the soil and for cooking alongside fuel wood. Livestock also provide a cash reserve by supplying meat and milk to the urban population. However, due to poorly managed grazing, deforestation, and climate change, farmers are facing land degradation from the loss of soil and nutrient depletion. To make things worse, families live with indoor air pollution cooking with dung and biomass on inefficient fires, and water pollution from poor or non-existent sanitation. These factors severely undermine the health and productive capacity of the farming households, particularly women and children.

The National Biogas Programme for Ethiopia (NBPE)

The NBPE is a project developed by the Ethiopian Government and SNV (The Netherlands Development Organization) with the support of HIVOS, a Dutch international development funding organisation; its coordination office is in the Ministry of Water and Energy. The project aims to help 14 000 Ethiopian smallholder farming families install and manage anaerobic digester plants, to provide them with an alternative, renewable, clean, and safe energy (biogas, 60 % methane) for cooking and lighting, as well as a readily available organic fertilizer (bioslurry) to improve crop yields. Households are also encouraged to attach a toilet to the biogas digester to improve sanitation.

The NBPE is working in the four main crop growing regions of the country: Amhara, Oromiya, Southern Nations, Nationalities and Peoples (SNNP), and Tigray Regional States. The first biogas digester plants were built in 2009. By the end of August 2011, 1 634 biogas digesters were installed and working.

In the latter part of 2009, the Institute for Sustainable Development (ISD) based in Addis Ababa was invited to be a partner in the NBPE with special responsibilities for the effective and efficient use of the ‘bioslurry’ residue of biogas production. ISD has pioneered the use of compost with smallholder farmers in Ethiopia, and understands ecological organic agriculture well (see [2] Greening Ethiopia for Food Security & End to Poverty, SiS 37.

Impacts of bioslurry compost on crop yields

In Ethiopia, the average cultivated area per household is 0.96 ha and the average yield of cereals is below 2 000 kg/ha. Food security is thus an over-riding concern for nearly 40 percent of smallholder farming families. Use of chemical fertilizers is very low; consequently there is an opportunity for good quality organic fertilizers to help farmers increase their productivity.

ISD has developed a method to record crop yields from farmers’ fields (see [3] The Tigray Project, SiS 23). When the crop is mature, the farmer and his/her development agent harvest three one-metre squares from a field. The crop is threshed (the process of loosening the edible part of the grain from the chaff), the grain and straw is weighed, and then returned to the farmer with the development agent recording the yield data, the farmer's name, the crop and the input used. The straw is important because this is the main source of animal feed during the long dry season. Samples of the same crop are taken from good, average, and poorer fields. The inputs are bioslurry compost, no input (check) and chemical fertilizer (mostly urea) if the farmer so chooses.

The 2010 cropping season provided the first opportunity to find out if the use of bioslurry compost could improve crop yields in both grain and straw.

Yield Data from Tigray

The NBPE pilot woredas (districts) and villages from Tigray in 2010 were Hintalo Wejerat, villages Adi Gudum and Waza, and Ofla, villages Hashenge and Mankere. The data were taken from fields growing either wheat or barley, as these are the dominant crops in the villages. The climate in Hintalo Wejerat is semi-arid and the soils are thin and stony. Rainfall in the Ofla area is higher, soils are deeper, and farmers have become used to some chemical fertilizer.

Tables 1 and 2 give the grain and straw averaged yields converted to kilograms per hectare for wheat and barley from Adi Gudum in 2010.

Table 1 : Grain and straw yield of wheat in Adi Gudum, Hintalo Wejerat, 2010


Farmer's name

Average grain g/plot

Average straw g/plot

Grain average kg/ha

Straw average kg/ha

Grain increase over check


Abreha Moges



2 800

3 961


Berhanu G/Selassie



Belay Mores




Senay Teklu



1 711

3 072

Selemawit G/Mariam



Embaye Desta



Table 2 : Grain and straw yield of barley in Adi Gudum, Hintalo Wejerat, 2010


Farmer's name

Average grain g/plot

Average straw g/plot

Grain average kg/ha

Straw average kg/ha

Grain increase over check


Gidey Tekaye



2 628

4 056


Hindeya Muez



Felege Tsegaye




Kinfe Nuriyu



1 528

2 417

K/Mariam Haile



Dagnew Melew



The response to bioslurry compost application was large: the average yield of wheat grain increased by 64 %, while that of barley grain increased by 72 % over check. Even the farmers with poorer fields benefitted from the use of bioslurry. For wheat, the average yield for a poor field more than doubled from 1170 to 2450 kg/ha, while that for barley increased from 1150 to 2270 kg/ha.

In the village of Waza, farmers growing barley had included the use of chemical fertilizer in their treatments. The results are presented in Figure 1.

Figure 1 Yields of barley from bioslurry compost, chemical fertilizer and no input (check) in Waza, Hintalo Wejerat, 2010

As can be seen, bioslurry compost or chemical fertilizer almost doubled the yield of grain compared to check. Furthermore, the use of bioslurry was as effective, or slightly more so than chemical fertilizers. The impact on straw yield was smaller, indicating that improving the supply of nutrients to the crop resulted in a higher increase in the production of grain.

In Ofla, the bioslurry development agents focused on collecting crop yield data from farmers growing wheat. In Mankere, six farmers who had used all three treatments, compost, chemical fertilizer and check cooperated with the development agent who took data from a total of 541 m2 plots. The average grain yields were 4 500 kg/ha from the use of bioslurry, 4 600 kg/ha from chemical fertilizer and 3 600 kg/ha from check. In Hashengi, farmers were using an improved wheat variety, HAR 1685. The average grain yields were 4600 kg/ha from both the check and bioslurry, and 5300 kg/ha from the use of chemical fertilizer.

These data show that applying bioslurry and using chemical fertilizer both increase yields, significantly in Hintalo Wejerat. Chemical fertilizer only gave a higher yield where the farmers were using an improved variety of wheat that probably responded specifically to chemical input.

Government Policy

In September 2010, the government launched a five-year Growth and Transformation Plan (GTP). Agriculture is the major source of economic growth, while particular focus is given to empowering women and youth and ensuring their benefits. The making and use of organic fertilizers, particularly compost, is incorporated as part of the agricultural extension package. The importance of compost in sequestering carbon in the soil is recognized as one of the means to mitigate and adapt to the challenge of climate change.

The NBPE has the potential to contribute significantly to the target set for the use of compost and to improve food security by 2015 in Ethiopia.

To conclude

Biogas plants provide an alternative form of safer, cleaner energy to homes as well as organic compost to farms. The first data from field studies are showing improvements in crop yields equivalent in most cases, to chemical fertilizers.

The authors are from Institute for Sustainable Development, PO Box 171, code 1110, Addis Ababa, Ethiopia:

Article first published 07/12/11


  1. Ho MW. Sustainable Agriculture and off-grid renewable energy. I-SIS contribution to UNCTAD Trade and Environment Review 2011, ASSURING FOOD SECURITY IN DEVELOPING COUNTRIES UNDER THE CHALLENGES OF CLIMATE CHANGE: CONTINUING WITH BUSINESS AS USUAL APPROACHES IS NOT AN OPTION, 18 July 2011,; also From the Editors, Science in Society 51, 2-4, 2011.
  2. “Award Winners of the twelfth Gothenburg Award for Sustainable Development. Kofi Annan shares the award with food supply project Tigray in Ethiopia”. Press Release, Gothenbur 29 August 2011,
  3. Edwards S. The Tigray Project. Science in Society 23, 6-7, 2004.
  4. Edwards S. Greening Ethiopia for food security & end to poverty. Science in Society 37, 42-46.

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There are 3 comments on this article so far. Add your comment above.

Kaviraj Comment left 8th December 2011 03:03:34
How high is the cost of building a bio-fuel plant like that? I am going back to Haiti in January, to start an agrohomoeopathy project in Haiti to enable at least subsistence farming. I have been thinking about cheap ways to generate power and bio-gas is one of them. There are also cheap solar panels and less cheap wind generators as for instance used on river barges. Moreover, a bio-gas plant fits in better with what we are trying to achieve, since the conditions in Haiti are similar to Ethiopia. Scarcity of water, little topsoil and small yields. I would be delighted to hear the cost per unit and the yield in bio-fuel.

mae-wan Comment left 8th December 2011 03:03:08
Kaviraj, good idea! Note this is not a biofuel plant in the ordinary sense, especially not one that uses energy crops. It is strictly one that uses wastes. The cost will vary according to size. But you might like to read the ISIS article Biogas for China's Socialist Countryside here:

Luc Christiaensen Comment left 9th August 2012 00:12:40
Reassuring to see that smallholder biogas is also taking hold with success in Ethiopia. The article highlights the positive effects of the use of the bioslurry. This is to be expected in a country where chemical fertilizer use remains very low and soil degradation poses a major challenge. What about the other potential benefits of smallholder gas as well as the durability of the project? What about disadoption due to technical factors? The latest signs of China's experience seems encouraging (, even though China also seems to have given a go at it several times before smallholder biogas really took hold. It will be important to learn from this experience. I trust a rigorous impact evaluation scheme has been put in place and look forward to learning more about Ethiopia's experience with smallholder biogas.