WS3.1 – Climate change: Agriculture, food security and human health 9 th European IFSA Symposium, 4‐7 July 2010, Vienna (Austria) 1300 Contribution of tillage practices on adaptation to climate change and variability on agricultural productions in semi‐arid areas of central Tanzania Brown Gwambene and Amos E. Majule Institute of Resource Assessment, University of Dar es Salaam; gwambene@gmail.com, gwambene@ira.udsm.ac.tz, amajule@ira.udsm.ac.tz Abstract: Climate change and variability have threatened agricultural productions and adversely affected the natural resource base, which provides a living for more than half of the world’s poorest people. Unpredictability of onset rainfall and an increase in the mean temperature have affected the growth and crop yields. Other consequences have been observed in reduced access to water resources, increase of diseases, frequency of food shortage and declining in soil moisture levels over much of semiarid areas due to the prevailing dry conditions. Further decrease in soil moisture has favoured drying up of field crops that were at harvesting maturity. Crop yields are poor as a result of false start and poor rainfall distribution. Farmers have developed coping strategies to adapt to the adverse impacts of climate change. Some of these strategies such as proper tillage practices, use of improved, early mature and drought resistant varieties over semiarid areas have shown a success under the fluctuating climatic conditions. The tillage practices in particular are used for rain water harvest and improvement of soil moisture and fertility. This study investigated the contribution of tillage practices on adaptations to the impacts of climate change and variability in semi‐arid areas so as to increase agricultural production and improve food security. Keywords: Climate change and variability, food security, tillage practices and Agriculture production Introduction In dry areas, moisture is a most limiting factor for crop production and it contributes to insecure household food security (Majule et al., 2007a). In these areas average rainfall is less than the potential moisture losses through evaporation and transpiration. The areas receive annual precipitation between 250‐600 mm with dryland‐farming or rainfed‐farming practices (Oicha and Klik 2009). Adverse weather (with low and highly unpredictable rainfall), low soils fertility with low soil organic matter (SOM) and nutrient contents constrain crop production, and there is a high risk of very low production levels or even crop failure, particularly under poor crop/agricultural land management. The dry land occupy about 63 million km 2 or 47% of the surface of the earth and subdivided in hyper ‐ arid (16%), arid (26%), semi‐arid (37%), and dry sub‐humid (21%) areas (Oicha and Klik 2009). In Tanzania the semi‐arid area occupy about one‐third (295,000 km 2 ) of the total land area and extends from North East to South West across the central part of Tanzania (Swai, et al., 2007). The sustainability of the dryland ecosystem and its agricultural production depend strongly on proper and effective land‐use and management (Gwambene, 2007). Further agricultural production strongly depends on availability and condition of soil and water resources. For example soil aggregation is one of the main factors controlling the chemical, physical, and biological processes that contribute to soil productivity and agricultural sustainability. Managed tillage practices improve soil aggregation that contributes to the improvement of nutrient and water flows in the soil. Tillage increases soil fertility through mineralization of soil nutrients and creates a good soil tilt for root and crop growth (Oicha and Klik, 2009). In central Tanzania smallholder farmers have for many years been using the hand hoe for tilling, weeding and all other field cultivation practices (Majule et al., 2007a; Kumwenda, 2009). Due to the