Science - November 4, 2004

Sustainable home gardens disappearing in Tanzania

Traditional home gardens where bananas are grown are dying out in northwest Tanzania. These were a highly productive and sustainable form of agriculture according to Freddy Baijukya.

For his PhD research, Baijukya made a broad inventory of the changes that these home gardens have undergone since the 1960s. Banana is no longer the most common food crop; it has been overtaken by root crops such as sweet potato and cassava. The area of grass land round the home gardens has declined by an average of forty percent, and the number of farming families that also keep livestock near the homestead has gone down by 85 percent.

Baijukya regards these as very unfavourable developments. The indigenous banana varieties in Tanzania and the neighbouring countries, known as the East African highland bananas, were an important source of calories for the local population. Baijukya: ‘This banana variety contains many essential nutrients, including all sorts of vitamins and minerals that are not found in cereals and root crops.’ The rest of the plant was also put to a variety of creative uses: many African dishes can be prepared in banana leaf instead of aluminium foil, and the dried leaves can be used as mulch to prevent erosion on fields.

The disappearance of the banana has also led to the disappearance of good soil and nutrient management practices, warns Baijukya. According to oral tradition, farming families allowed visitors to urinate on their home gardens. This improved soil fertility and was regarded as a sign of respect. Modern hygiene and pit latrines put an end to this practice. Livestock keeping near the home gardens was also an important part of the sustainable farming system. The manure was used to enrich the soil in the home gardens, creating ‘islands’ of fertile soil. Nowadays much of the grassland has been converted to maize mono-cropping. Baijukya advises farmers not to stop altogether with livestock keeping, and at least to keep sheep or goats for their manure. / HB

Freddy Baijukya graduates on 8 November. His supervisor was Professor Ken Giller of the Plant Production Systems group.