African Crop Science Journal
African Crop Science Society
ISSN: 1021-9730 EISSN: 2072-6589
Vol. 9, Num. 3, 2001, pp. 567-575
African Crop Science Journal, Vol. 9. No. 3, pp. 567-575
A COMPARATIVE ECONOMIC EVALUATION OF ANNUAL CASTOR, SORGHUM
AND SUNFLOWER PRODUCTION IN SEMI-ARID ENVIRONMENTS OF ZIMBABWE
D. HIKWA, M. MURATA and H.H. DHLIWAYO
Department of Research and Specialists Service, Agronomy Institute, P. O.
Box CY 550,
Causeway, Harare, Zimbabwe
Received 27 July, 1998
Accepted 22 March, 2001
Code Number: cs01075
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
Key Words: Break-even price, gross benefit, minimum acceptable rate of
return, net benefit, total costs that vary
Une étude en champs de deux saisons (1992/93 et 1993/94) a été
conduite pour comparer des revenus économiques de 4 cultivars de castors
(Hale , Guarani, H22, et Aruna) avec le cultivar de tournesol, Mopane et un
cultivar de sorho à graines blanches, SV2, dans quelques environnements
semi-arides du Zimbabwe. Actuellement, le costor est entrain de traverser une
période d'importante promotion de production, alors que le sorgho
et le tournesol sont déjà établis dans ces environnements.
Des essais en champs étaient établis sur des sables à graines
moyennes granitiques (~8% argile et >85% de sable) dans les Régions
Naturelles (RN) III (Mlezu), avec une précipitation moyenne annuelle
d'à peu près 700 mm et IV (Makoholi et Matopos), avec des
précipitations moyennes de 650 mm et 572 mm respectivement. A partir
des données des rendements des graines combinées pour deux saisons,
des revenus par dollar investi dans la production de la culture ($3.53, $5.04
et $6.82 pour castor; $3.22, $1.66 et $1.72 pour le tournesol et $0.68, $0.59
et $0.78 pour le sorgho à Matopos, Makoholi et Mlezu, respectivement)
ont été calculés sur base des prix d'un producteur
de 1994/95 de $2150, $1500 et $750 t-1 pour le castor, le tournesol
et le sorgho, respectivement. Une analyse partielle a montré aussi qu'
un agriculteur expectant un taux minimum de revenu de 75% au dessus des coûts
totaux qui varient, trouverait encore profitable cultiver le castor même
à une réduction de 50% du rendement, avec le rendement le plus
bas obtenu (356 kg). Malgré le plus bas bénéfice net du
tournesol de 57% comparativement au castor, le dernier était aussi profitable
à cultiver dans ces environnements. Des résults de cette étude
suggèrent que cultiver un cultivar de sorgho à graines blanches,
SV n'était pas profitable. Conséquement le dernier pourrait
être acceptable comme une culture de sécurité alimentaire
plutôt qu' une culture de rente, même dans les conditions
semi-arides, bien que les rendements et le prix du marché informel payé
au fermier restent très faibles. Les résultats ont montré
aussi que la production du castor était plus profitable dans la RN III
que dans RN IV.
Mots Clés: Prix partiel, bénéfice total, prix minimum acceptable,
taux de revenu minimum acceptable, bénéfice net, coûts tataux
Sunflower (Helianthus annuus L.) and sorghum (Sorghum bicolor
(L.) Moench) are reported to have drought evading characteristics during certain
phenological stages of their growth. As a result, they are well established
in the cropping systems and are widely grown by smallholder farmers in many
semi-arid areas of Zimbabwe, particularly in Natural Regions (NRs) III, IV
and V, with annual long-term mean rainfall of 650-800, 450-650 and below 450
mm, respectively (Vincent and Thomas, 1961). Castor (Ricinus communis
L.) on the other hand, is a crop that has been undergoing a promotion drive
for production in similar environments of Zimbabwe since the mid 1980s.
Most of the sunflower produced in Zimbabwe is used for oil extraction and
it ranks third after cotton seed and soybean in the edible oil seed industry.
Production of the crop in Zimbabwe is dominated by smallholder growers who
produce over 90 percent of the national crop (Commercial Agriculture in Zimbabwe,
1986, 1991; AMA, 1989, 1992). Between 1983/84 and 1994/95 season, sunflower
was a 'controlled commodity', meaning that its disposal on the
formal market was controlled by the Grain Marketing Board (GMB), with prices
paid to the producer determined by a process of negotiation between the farmer
organisations, the GMB and the Ministry of Agriculture. Since the commodity
'de-control' in 1994/95 season, the GMB acts as a residual buyer
with a 1994/95 producer price of Z$1500 per metric tonne of clean seed.
Sorghum is the third most widely grown summer cereal in Zimbabwe after maize
and pearl millet. It is estimated that over 200,000 ha are grown annually
by communal area farmers who now account for about 98% of the crop (CSO, 1970-1993).
Like sunflower, disposal of sorghum on the formal market was also controlled
by the GMB until the 1994/95 season. However, the GMB now acts as a residual
buyer and offers a price of Z$750 per metric ton of grain.
Weiss (1983) reported that although there were strong indications that castor
originated from the eastern Africa sub-continent, it has spread to many parts
of the world and established itself as a 'native' plant. In Zimbabwe,
it can be seen growing in the wild and particularly around cattle kraals (pens)
where there is manure. Uses of castor oil and its derivatives are wide ranging
and include production of sebasic and undecyclenic acids used in manufacturing
plasticisers and nylon. Some of the uses include production of greases and
lubricants for jet engines, making ink and paint oils (Zimmerman et al.,
1958). If properly treated, the cake, after oil expression, can be used as
a fertiliser (Fundire, 1991). In Zimbabwe, most of the oil and its derivatives
are used to prepare the trinepon range of products, vinyl floor tiles, paints,
putty, antiseptics and disinfectants (Hikwa, 1989). Therefore, its strategic
value to Zimbabwe as a country cannot be overlooked.
Following the re-introduction of an active castor research programme in
1982/83, the area under this crop has been increasing slowly, but steadily.
The promotion drive for castor production has largely been done by two companies.
One of these companies (Trinidad Industries) has been able to acquire and
sell seed, as well as review its producer price annually to attract more growers.
The current 1995 producer price offered by Trinidad Industries is Z$2150 per
metric ton of clean seed.
The facts that castor is a crop being promoted for production in the smallholder
sector of the semi-arid areas of Zimbabwe and also the fact that sunflower
and sorghum are already established in these cropping systems,were taken into
account in conducting this study. The crops were compared for their potential
economic returns to the farmer, with the main aim of providing information
that would enable the farmer to make informed decisions on choice and extent
of production of any of the three crops.
The main objective of the study was to evaluate and compare the economic
returns of castor with those of possible competitor cash crops (sunflower
and sorghum) on smallholder farms in semi-arid areas (Natural Regions III
and IV) of the country.
MATERIALS AND METHODS
This comparative study was conducted over two seasons (1992/93 and 1993/94)
at three research station locations in Natural Regions III (Mlezu) with a
long-term annual mean rainfall of about 700 mm and IV (Matopos and Makoholi,
with long-term annual mean rainfall of 572 and 650 mm, respectively) (Whingwiri
et al., 1987). Fields used at all three locations were on medium grained
sandy soils derived from granite, with about 8% clay and more than 85% sand
(Chemistry and Soils Research Institute Guidelines, 1985).
Open pollinated castor cultivars 'Hale' (ex-USA), 'Guarabi'
(ex-Brazil), 'Aruna' (ex-India mutant, which is not yet on the
local market) and a hybrid 'H 22' (ex-Israel) were compared with
sunflower hybrid 'Mopane' (ex-Crop Breeding Institute (CBI), DRSS1 )
and a white-seeded open-pollinated sorghum cultivar 'SV 2' (ex-CBI,
DRSS). Duration to maturity of the castor cultivars used is 100-120 days for
'H 22', 120-130 days for 'Hale' and 'Guarani',
140-150 days for 'Aruna', 110-115 days for the sunflower cv 'Mopane'
and 115-125 days for the sorghum cv 'SV 2'. Sunflower rows were
spaced at 90 cm apart with 30 cm between plants in the row, giving a plant
density of 37000 plants ha-1. Sorghum was sown in rows 75 cm apart
with an in-row spacing of 13 cm between plants, resulting in a plant density
of 100,000 plants ha-1. Castor cultivars were spaced according
to their growth habits. Cultivars 'Hale and 'Aruna' were
in rows 90 cm apart with 50 cm between plants in the row. Row spacing for
'Guarani' and 'H22' was 100 cm, with in-row spacings
of 100 cm and 150 cm, respectively. Gross plots were 45 m2 for
'Hale', 'Aruna' and 'Mopame'. Those of
Guarani, 'H22' and 'SV 2' were 24 m2. The
trial was laid out in a randomised complete block design with four replicates.
Compound 'L' (5% N; 18% P205; 10 K2O;
8% S; 25% B) was used as a basal dressing on sunflower at a rate of 250 kg
ha-1. Ammonium nitrate (34.5% N) was later applied at six weeks
after planting at a rate of 45 kg ha-1. Sorghum and castor both
received 250 kg ha-1 compound 'D' (8% N; 14% P2O5;
7 K2O; 6.5% S) at planting. Ammonium nitrate at a rate of 30 kg
ha-1 was later applied to sorghum at boot stage and to castor at
primary flower initiation.
Several steps were followed in calculating economic returns from the three
crops, using partial budgets. Data from each crop were pooled over the two
seasons (1992/93 and 1993/94) and subjected to analysis of variance to estimate
seed yields per hectare. The estimated yields (kg ha-1) were then
adjusted downwards by 5% for castor and 10% for sunflower and sorghum. Since
the study was done on stations these adjustments were estimated to be the
amount of yield loss that could occur under farm management. A higher coefficient
of adjustment was used for sunflower and sorghum because of their proneness
to bird damage. Gross benefits were derived by using the formula GB = FP X
Yadj, where GB - gross benefit, FP = farm price and Yadj. = adjusted yield.
The farm price was derived by subtracting cost of transporting produce to
the market and cost of labour for harvesting and shelling from the producer
price of a crop. The 1994/95 producer prices were $1500, $750 and $2150 per
metric ton for sunflower, sorghum and castor, respectively. To estimate net
benefits ($ ha-1), total costs that vary (TCV) were substrated
from the GB, i.e., GB-TCV = NB, where NB = net benefit. TCV included cost
of seed and labour for planting and weeding in each crop and additionally,
for bird scaring in sunflower and sorghum. Returns per dollar invested were
based on the formula NB/TCV.
In addition to calaculating net benefits and returns per dollar invested,
a break-even analysis was done on yield adjusted by various percentages (50,
30 and 20), with a minimum acceptable (to the farmer) rate of return of 75%
above TCV. The assumption was that if a farmer were to consider growing any
of the three crops in the semi-arid environments of NRs III and IV, he/she
would find it attractive if the rate of return was 75% or more than what was
invested in producing the crops. At each yield adjusted level, a break-even
price ($ kg-1) was calculated. The minimum acceptable price (MAP)
would ensure that in addition to covering TCV, a farmer would also make a
profit of 75% in this case.
Cost of seed was based on 1994/95 retail prices ($15.00 for open pollinated
castor cvs 'Guarani', 'Aruna' and 'Hale';
$35.00 for hybrid cv 'H22'; $3.20 for sorghum cv
'SV 2' and $17.00 kg-1 for sunflower cv 'Mopane'),
to which transport costs from point of purchase to the farm were added. Transport
costs were based on 1994/95 rates of $0.10 kg-1 of seed (Diyo Transport,
Masvingo). Labour was valued at $9.60 per 8 hour day. Sowing dates for the
crops are shown in Table 1.
The 1992/93 season was wetter than the 1993/94 season and the NR IV sites
received more rainfall than the NR III site. In both seasons, there was variation
in both timing and length of dry spells at all sites.
Pooled results of the two seasons (1992/93 and 1993/94) show that castor
cultivars 'Aruna' and 'Guarani' produced similar yields
at Matopos. However, due to the differences in variables costs (attributable
to differences in amounts of seed used according to spacing of each cultivar),
'Guarani' gave a higher net return per dollar invested than 'Aruna',
while 'Hale' was the least remunerative of the four cultivars
at this site (Table 2). At Makoholi,
'H22' had the highest yields and net returns per dollar invested.
Yields and returns of 'Hale' were again inferior to the rest of
the cultivars at this site. At Mlezu, 'Aruna' gave the highest
yields, whereas 'Guarani' gave the least. The best economic returns
were realised from growing 'H22', while again 'Hale'
was the least profitable at this latter site (Table
Grain yields of sorghum were highest at Matopos and lowest at Mlezu (Table
3). The low yields at Makholi and Mlezu were attributed to stunted growth
and die-back, particularly in the first season. The resultant net returns
of sorghum at the two sites were negative (Table
Best yields of sunflower were achieved at Matopos (Table
3). It is also at this site where the largest sunflower heads were observed.
This is supported by work done in other studies in which positive correlations
between head size and seed yield were established (Alessi et al., 1977;
Hikwa and Kangai, 1992). Sunflower yields at Makoholi and Mlezu were comparable
and so were the net returns.
Castor had higher yields than sorghum and sunflower at Makoholi and Mlezu,
and this resulted in higher net returns of castor compared to the other crops
(Table 3). However, sorghum had very
good yields at Matopos, but because of the lower formal market price of $750
t-1 compared to $2150 and $1500 t-1 for castor and sunflower,
respectively, the crop was not profitable. However, when the informal market
price ($2000 t-1) of sorghum was considered, the crop at Matopos
realised a net gain of $4.26 per dollar invested as opposed to the negative
return of $0.32 observed when the formal price was used to calculate returns
The break-even price (BEP) for castor cultivars at Matopos ranged between
$0.29 and $0.90 kg-1. Correspondingly, the MAP also ranged between
$0.51 and $1.58 kg-1 (Table 5).
Castor cv 'Guarani' had the lowest BEP, while 'Hale'
had the highest at all three levels of yield adjustment at this site. The
BEPs were not very different when yields were reduced by 20% or 30%. However,
a yield reduction of 50% resulted in a substantial increase in BEP and correspondingly,
an increase in the price that would be acceptable to the farmer (Table
5). Compared to castor, sorghum and sunflower on average required lower
BEPs and hence lower MAPs to satisfy the 75% acceptable rate of return at
yield reductions of 20 and 30% at the Matopos site.
At Makoholi, the MAP for castor ranged between $0.33 and 1.60 kg-1,
with cv 'H 22' having the lowest BEPs and 'Hale'
the highest again. Due to very low yields of sorghum, very high prices were
required to break even at all yield adjustment levels (Table
The BEPs for castor were lowest at Mlezu where 'Hale', which
had the highest BEPs, had values ranging from $0.31 to $0.49 kg-1
(Table 7). The BEPs required for sorghum
were four times those of castor and sunflower at the latter site.
Due to their high plant population of 22 222 plants per ha, field establishment
of castor cultivars 'Hale' and 'Aruna', required double
the amount of seed per ha than for 'H22' and 'Guarani'.
The two cultivars also required more labour hours for planting, thinning and
weeding because of close spacings. As a result, their variable costs were
double those of 'H 22' and 'Guarani'. Despite similar
variable costs between cultivars 'Hale' and 'Aruna',
better net returns per dollar invested were achieved with 'Aruna'
because of better yield performance than 'Hale'. Given the small
margins in returns per dollar invested in producing hybrid 'H 22'
compared to the open pollinated cvs 'Guarani' and 'Aruna',
it may be logical (for now) that farmers settle for production of open pollinated
cvs with a similar performance to the latter two, since their seed
cost per kilogramme is $20.00 less than that of hybrid 'H 22'.
Overall, castor production was more profitable at the NR III site (Mlezu)
than at the NR IV sites (Makoholi and Matopos), as reflected by the yields
as well as the returns per dollar invested.
Across cultivars and sites, the net returns from growing castor were 57.1%
more than those of sunflower cultivar 'Mopane'. If at the lowest
yielding site (Makoholi) yields of sunflower cultivar 'Mopane'
were to be reduced by 50%, the MAP of $1.22 kg-1 based on 75% acceptable
rate of return above the TCV was $0.28 less than the $1.50 kg-1
offered by the GMB. Therefore, the growing of sunflower cultivar 'Mopane'
in these environments was still profitable despite the percentage reduction
in net gain when compared to castor.
The study also seems to suggest that growing of the white-grain sorghum
cultivar 'SV 2' was unprofitable as long as the formal market
price of $2.00 kg-1 was maintained; profitability from growing
the cultivar seems to be only possible with yield levels well above 500 kg
ha-1, as demonstrated by the good net gains at Matopos. By comparison,
yield levels attained at Makoholi and Mlezu were such that even if the informal
price were to be paid it would still not be profitable to grow the crop.
The main conclusion that can be drawn from this comparative study is that of
the three crops evaluated using the current yield levels and producer prices
offered on the formal market, castor production is the most profitable, followed
by sunflower in the sandy soils of the semi-arid environments. Unless much higher
yields than those attained at Makoholi and Mlezu are achieved, production of
the white-seeded sorghum cultivar 'SV 2' may be shunned by farmers
and if at all it is produced, it may be primarily for food security at the household
level rather than a cash crop, even in these harsh environments.
The authors would like to acknowledge the Agronomy Institute Crop Productivity
Unit Teams at Makoholi Experiment Station, Cotton Research Institute (Kadoma
and Mlezu) and Matopos Research Station under the leadership of H.H. Dhliwayo,
M. Chisenga and C. Ndebele, respectively, who meticulously collected data in
this study. Our thanks also go to M. Mudhara for his valued comments on the
economic analysis, and to B. Nhamburo for assisting in logging the raw data
into the computer.
Agricultural Marketing Authority (AMA), 1989. Oilseeds
situation and outlook report for 1988/89. AMA, Harare, Zimbabwe.
Agricultural Marketing Authority (AMA), 1992. Oilseeds
situation and outlook report for 1991/92. AMA, Harare, Zimbabwe.
Alessi, J., Power, J.F. and Zimmerman, D.C. 1977. Sunflower
yield and water use as influenced by planting date, population and row spacing.
Agronomy Journal 69:465-469.
Central Statistical Office (CSO). 1970-1993. Statistical
Yearbooks. Agricultural Statistics. Government Printer, Harare, Zimbabwe.
Chemistry and Soils Research Institute, 1985. A guide
to the meaning of soil analysis. Department of Research and Specialist
Services, Ministry of Agriculture, Harare, Zimbabwe.
Commercial Agriculture in Zimbabwe, 1986. Oilseeds.
Annual report for 1985/86, pp 76-79.
Commercial Agriculture in Zimbabwe, 1991. Oilseeds.
Annual report for 1990/91. pp. 76-79.
Fundire, J. 1991. Report on the evaluation of castor cake
as fertiliser. Soil Productivity Research Laboratory, Chemistry and Soils
Research Institute, Department of Research and Specialist Services, Harare,
Hikwa, D. 1989. The present status of castor (Ricinus
communis L.) in Zimbabwe. The Zimbabwe Science News 23:6-10.
Hikwa, D. and Kangai, J. 1992. Response of sunflower cultivar
Msasa to time of planting, inter-row spacing and plant density. Zimbabwe
Journal of Agricultural Research 30:173-187.
Vincent, V. and Thomas, R.G. 1961. An Agricultural survey
of Southern Rhodesia (now Zimbabwe). Part 1 - Agro-ecological survey. Government
Weiss, E.A. 1983. Oilseed crops. Tropical Agriculture
Series. pp. 31-99.
Whingwiri, E.E., Natarajan, M., Kanyanda, C.W. and Van Lindert,
H.J.A. 1987. Agroclimate and soil characteristics of the research centres
in the Department of Research and Specialist Services. Zimbabwe Agricultural
Zimmerman, E.H., Miller, M.D. and Knowles, P.F. 1958. Castorbeans
in California. California Agricultural Experiment Station. Extension Services.
Circular 486. p. 10.
© Copyright 2001, African Crop Science Society
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