significantly increases crop yields in
1996, the Institute for Sustainable Development (ISD) in
Preliminary data collected in 1998 had already shown that using compost gave similar yield increases as chemical fertilizers. Data collected in 2002, 2003 and 2004 showed that, on average, composted fields gave higher yields, sometimes double, than those treated with chemical fertilizers. (See TWN Info Service on Sustainable Agriculture, 28 May 2007).
In a new paper written for the UN Food and Agriculture Organization (FAO), statistical analysis on a larger data set over the years 2000 to 2006 inclusive confirms that compost use has increased yields in all the crops analysed.
Up to and including 2005, yield data had been collected from 779 farmers’ fields – 3 plots in each field. In 2006, additional yield data from 195 farmers’ fields was collected during the harvesting season. In total, data was collected from 974 fields from 19 communities.
Grain and straw yield data were obtained for barley, durum wheat, finger millet, hanfets (a mixture of barley and durum wheat), maize, sorghum, teff, faba bean and field pea.
Except for field pea, the compost generally doubled the grain yield when compared to each respective check (crops grown without any inputs). (For field pea, the increase in yield was approximately 28%.) The difference was significant (95% confidence limit). The application of compost also increased straw yield compared to the check, but not to the same extent as it increased grain yield.
The use of compost also gave higher yields than the use of chemical fertilizer, though differences in the yields from compost and from chemical fertilizer were not as great as the differences between the use of compost and the check. For sorghum and faba bean the yields from the use of compost and chemical fertilizer were similar. But the yield difference for all the other crops was greater with that from the compost treatment being always higher than that from the use of chemical fertilizer.
The results also showed that compost not only increases the overall biomass yield, but also increases the proportion of the grain to straw in the yield.
Other benefits of using compost include the restoration of soil fertility. The residual effect of compost in maintaining soil fertility for two or more years was soon observed and appreciated by the farmers. They are thus able to rotate the application of compost on their cultivated land and do not have to make enough to apply to all their cultivated land each year. The reduction of difficult weeds, such as Ethiopian wild oats Avena vaviloviana, and improved resistance to pests, such as teff shoot fly, has also been noted by the farmers.
Since 1998, the Bureau of Agriculture and Rural Development of Tigray Region has adopted the making of compost as part of its extension package and by 2007 at least 25% of the farmers are making and using compost. A reflection of the success of this approach is that between 2003 and 2006, grain yield for the Region almost doubled from 714 to 1,354 thousand tonnes. Since 1998, there has also been a steady decrease in the use of chemical fertilizer from 13.7 to 8.2 thousand tonnes.
Making and using compost is also being promoted in other regions of the country, particularly through the “Community-based Participatory Watershed Development” project of the Ministry of Agriculture, and the Land Rehabilitation Project of the Environmental Protection Authority.
The paper documenting
the increase in yields was written by Sue Edwards, Arefayne Asmelash
and Hailu Araya from the ISD, and Dr Tewolde Berhan Gebre Egziabher,
Director General, Environmental Protection Authority,