APPLICATION OF DSSAT TO FORECAST GRAIN YIELD OF MAIZE (Zea Mays) IN SOUTHERN HIGHLANDS OF TANZANIA

Abstract

Maize is the major staple food crop feeding the majority of Tanzania population and contributes over 25% of the agricultural GDP. About 80% of the maize produced within the country is grown by peasants who own not more than l Oha of the land. The Southern highlands zone is the most popular maize producing area accounting for about 35% of the National maize output. The zone comprises with four administrative regions viz. Ruvuma, Iringa, Mbeya and Rukwa. The average yield of maize production in Southern highlands zone is about 2.19 t/ha and for the whole Tanzania is about 1.55 t/ha. Due to this output data, maize production in Tanzania is very low compared to developed country such as United states of America(USA) with an average of maize production of 9.59 t/ha. Apart from changing weather condition, poor agronomic practices have also been the cause of low maize output. The farmers of the area have been following the traditional agronomic practices over the last several years. They have not yet entered the intensive cultivation practices therefore low soil fertility management, use of poor quality seed etc are in practice with the majority of the farmers. The objectives of this study is to suggest suitable agronomic practices (variety, nitrogen dose and spacing) for the selected sites of southern highlands zone of Tanzania using CERES Maize simulation model of DSSAT as a tool for improvement of maize productivity. The simulation study was undertaken for ten selected locations (Ihumbu, Mwazye and Nyera, Santilya Lupa-tinga tinga, Mbinga, Ilembula, Mbatimira, Lukuyu and Usevia), with five maize varieties (Kitumani Composite I, H614, H626,H511, and H612), five nitrogen doses (0, 50, 100, 150 & 200 kg -N/ha) and three spacing (90x5Ocm, 90x30cm and 60x3Ocm) . A total of 750 DSSAT model simulations were run to work out the impact of treatments on grain yield of maize. The overall average yield recorded was 3028 kg/ha. Santilya recorded the average grain yield of 4198 kg/ha. The maize cultivar H614 recorded the average grain yield of 4490 kg/ha. The nitrogen dose of 200 kg N/ha recorded the average grain yield of 4077 kg/ha. The spacing of 60 x 30 cm recorded the average grain yield of 3363 kg/ha. However the highest grain yield was recorded as 9591 kg/ha at Santilya uses maize cultivar H614, 200 kg N/ha nitrogen dose and 60 x30 cm plant spacing. This confirms need of improving agronomic practices to increase maize productivity in Tanzania.