Growth and Ethanol Yield Responses of Sweet Sorghum [Sorghum bicolor (L.) Moench] Varieties to Nitrogen Fertilizer Rates

Abstract

Purpose: Soils of the experimental area are low in vital nutrients such as nitrogen. Fallow is no longer possible because of increasing pressure on arable land. The limited available chemical fertilizers must be inevitably and judiciously used for optimum yield. The study was carried out to assess the response of sweet sorghum varieties to varying nitrogen fertilizer (N) rates. Research Method: Sweet sorghum varieties (NTJ-2, 64 DTN, SW Makarfi 2006 and SW Dansadau 2007) were alloted to the main plots and nitrogen fertilizer (0, 40, 80, 120 and 160 kg N ha-1) to the sub-plots of a split-plot design, in three replicates. Data on growth and yield characteristics were collected and analysed. Findings: Variations were observed among the four varieties of sweet sorghum; SW Dansadau 2007 had greater growth and yield characteristics. N fertilizer had positive effects on the growth characteristics and ethanol yield of the crop. 80 kg N ha-1 resulted in increase of most parameters and ethanol yield, beyond which there was either no significant difference or a drop in the values of these parameters. Thus the use of 80 kg N ha-1 would result in optimum yield of sweet sorghum in the study area. Limitations: The requirement of 80 kg N ha-1 may not be generalized for the entire southern guinea savanna agro-ecological of Nigeria as the study was carried out only in one location. Originality/Value: These findings would assist farmers in the study area identify the most promising sweet sorghum variety and the optimum fertilizer rate for its production.