Cost calculation
Production costs, gross revenue, net profit, benefit cost ratio (BCR) and return on investment (ROI) were calculated following the standard method of Hari et al. (2004).
Statistical analysis
All the data were subjected to statistical analysis (Gomez and Gomez 1984). Single factor analysis of variance (ANOVA) with the help of MS Excel and computer software SPSS (version 7.5) were used at 1% and 5% levels of probability between the treatment and control series