Box 3.3 Indigenous management of microclimate in Tanzania

In 1980, the indigenous knowledge on microclimate management in Tanzania was tapped via a newspaper contest. Of the many replies, only examples of mulching practices are given here .

Materials used as mulch include tree leaves, dried or green banana leaves, grass, straw, chopped maize stalks, Intercrop residues, prunings, weeds, ash, animal dung and household rubbish. Fallen leaves, creeping plants and short intercropped plants were mentioned as having natural mulch effects. Creeping cover crops are also believed to trap dew under certain conditions. In some places, rock mulches are used because of their potential to absorb daytime heat and release it at night.

In rainfed production of rice, tomato and maize in dry areas, a soil mulch layer is created by tillage. The topsoil becomes drier but remains in good condition to receive seeds, and moisture in deeper layers is conserved. In some areas, only the places where seeds are sown are deeply hoed, in the belief that accumulated loss of the topsoil moisture will be slower.

Flood water is used to suppress weeds in rice growing, for soil protection in sugarcane fields and over artificially hardened soil in some coffee-growing areas with heavy rainfall .

In wetter and colder areas or seasons, ridges promote good drainage and root growth. Dark, rotten weed residues are often placed on top of the ridges to absorb heat and thus increase soil temperature (Stigter 1987a).