Assessment of the Growing Season over the Unimodal Rainfall Regime Region of Tanzania

Abstract

Most part of Tanzania experiences unimodal rainfall. The characteristics of rainfall such as its onset and cessation dates, dry and wet spell lengths, frequency and number of rainy days can be, used to determine the nature of growing season length of growing season end of season and its geographical variation both latitudinally and longitudinally. This justifies the assessment of the crop growing season under unimodal rainfall regime by this category in order to adapt agricultural practices: which result in increased crop productivity. A water balance model was used to determine the end of growing season. The method of Sivakumar (2002) was used to evaluate dry spell of different lengths and their frequencies. The results show that on the mean the growing season starts in the first week of December in most of the region except in Kigoma where the season starts earlier in the second of week of November. The growing season ends in April in most of the years. Similarly, the length of the season was found to range between 131 and 150 days in Mbeya and Songea in the south and Kigoma to the west. In Dodoma and Iringa, the growing season is as short as 93 to 97 days. Variations of starting dates for the growing season with latitude were not statistically significant, but longitudinal variations in the mean starting dates of the growing season revealed some statistical significance. These results form a good basis for explaining the characteristics of the growing season in the study region.

Keywords: Agrometeorology, dry spells growing season, Tanzania, unimodal rainfall

Tanzania J.Agric.Sc. (2006) Vol.7 No.1, 16-26