Evaluating drip irrigation in commercial tea production in Tanzania: Fid-Bau Portal

Evaluating drip irrigation in commercial tea production in Tanzania

Möller, M. / Weatherhead, E. K.

Abstract This paper evaluates the performance of the first drip irrigation scheme in commercial tea production in Tanzania with a view to making recommendations for improved management and providing data for investment decisions. Uniformity, efficiency and adequacy of irrigation were calculated and the scheduling of irrigation water was reviewed. Operators were interviewed to highlight the main benefits and problems of the system. Investment and recurrent costs of drip and overhead sprinkler systems were quantified and compared. Root development was assessed qualitatively using excavation pits. Irrigation uniformity DU and efficiency ranged between 88 and 95% in the 10 out of 14 irrigation blocks where endline pressures were at least 0.5 bars, and between 77 and 89% in the four blocks were endline pressure was less than 0.5 bars. Scheduling drip irrigation using tensiometers offered potential water savings of 26% in comparison to a water balance schedule, but these are not currently realised. Gross marginal income was very sensitive to tea price and yield. Economically optimal fertilizer rates vary in dependence of tea price and yield and appear to be lower than the current level of 300 kg N $ ha^{−1} $. The higher costs under drip, compared to overhead sprinklers, were mainly for purchase and installation and fertilizer. The costs of labour for applying water and fertilizer were reduced by nearly 50%. At average 2002 tea prices of 1.31 US$ $ kg^{−1} $, drip irrigation would improve the grower’s gross margin if an additional yield of at least 411 kg $ ha^{−1} $ was achieved. The main threats to drip system performance are discussed. Future research efforts should aim at establishing the yield response of tea to water and fertilizer under drip irrigation.