A comparative economic evaluation of annual castor, sorghum and sunflower production in semi-arid environments of Zimbabwe

A two-season (1992/93 and 1993/94) field study was conducted to compare the economic returns of castor (cvs 'Hale', Guarani', 'H22' and 'Aruna') with sunflower (cv 'Mopane) and a white-seeded sorghum (cv 'SV 2'), in some semi-arid environments of Zimbabwe. Castor is currently undergoing a strong promotion drive for production, while sorghum and sunflower are already established in the cropping systems of the smallholder farmers in these environments. Trial fields were on medium-grained granitic sands (~ 8% clay and >85% sand) in Natural Regions (NR) III (Mlezu), with a mean annual rainfall of about 700 mm and IV (Makoholi and Matopos, with a mean annual rainfall of 650 and 572 mm, respectively). From seed yield data pooled over the two seasons, returns per dollar invested in producing a crop ($3.53, $5.04 and $6.82 for castor; $3.22, $1.66 and $1.72 for sunflower and $0.68, -$0.59 and -$0.78 for sorghum at Matopos, Makoholi and Mlezu, respectively) were calculated using the 1994/95 producer prices of $2150, $1500 and $750 t-1 for castor, sunflower and sorghum, respectively. A break-even analysis also showed that a farmer expecting a minimum rate of return of 75% above the total costs that vary, would still find it profitable to grow castor even at 50% yield reduction, with the lowest yield attained (356 kg-1). Despite a 57% lower net gain from sunflower compared to castor production, production of the former was also profitable in these environments. Results from the study suggest that growing white-seeded sorghum cv 'SV 2' was unprofitable. Implicitly, the latter might only be acceptable as food security crop at the household level rather than a cash crop, even under semi-arid conditions, as long as yields and the formal market price paid to the farmer remained very low. The results also indicated that castor production was more favourable in NR III than in IV