Grain Legumes and Green Manures for Soil Fertility in ... - cimmyt

ean residual fertility effects on maize have been
demonstrated under farmer management, boosting
adoption of soyabean BNF by smallholder farmers.
Mineral fertilizer inputs (e.g, Cu, Mg, P, K) will continue
to be required to prevent nutrient mining of
soils. Extension messages must continue to emphasize
the critical importance of inorganic fertilizer
amendments.
An important benefit of soya bean BNF has been the
boost in household incomes from grain sales by
farmers (Table 3). A critical element in the promotion
program was the consolidation of loads so that
economies of scale have enabled the relatively small
production by each farmer to be sold on the lucrative
commodity exchange as part of a large batch.
Thus the conceptual model for promoting BNF includes
produce marketing as a key element.
A study of the economic potential of soyabean
showed that the crop was most profitable for the
poorest farmers as it had lower input costs but gave
the highest return on investment (Rusike et al.
2000). Poor farmers who adopted soyabean for the
first time between 1997 and 2001 have testified that
they earned more money from soya bean sales than
from any other crop that they have ever grown
(Table 4). The significant boost in family dietary
protein availability (Table 4) is a critical element of
household food security, a key benefit of BNF
among rural communities where poor nutrition
among the HIV-infected is contributing to the high
death toll from AIDS related illnesses.
Table 3. Soyabean grain sales by smallholder farmers from
four locations over 4 marketing seasons in Zimbabwe
. location Amounts sold (metric tl
96/97 97/98 98/99 99/2000
Guruve 6.2 53 153 210
Kazangarare 58 280 475 580
Sadza 0.5 3.5 7 10.2
Senge 0.2 6 11 18.1
Total sold 64.9 342.5 646 818.3
Only sales facilitated by the Soyabean Promotion Task Force are reflected;
farmers also used other marketing outlets.
Table 4. Grain, protein and cash returns from soyabean for Tapera
smallhold farm in Zimbabwe (1998)
Soyabean Total grain yield Protein from 150/0 Cash from 70%
variety (kg/hal seed retained grain sold
(kg/hal
(US$ equivl
Magoye 2100 126 471
local 1900 114 302
Roan L800 168 496
Nyala 3100 186 560
Average smallholder planting: 0.4 ha; average yield: 0.8 t/ha; average price; US
$360/t (2001).
Conclusions
Our experiences with developing and implementing
a research-extension model for promoting BNF
technology among peasant farmers in Zimbabwe
offers lessons for similar initiatives in developing
countries. Previous experiences of promoting promiscuous
soyabean in Nigeria (N. Sanginga, pers.
comm.), Malawi and Zambia (Mpepereki et al. 2000)
also point to the need for integrated approaches that
address both the scientific-technological and socioeconomic
aspects in a holistic way (closing the
loop). Demonstration of multiple benefits of N­
fi xing soyabean, use of promiscuous varieties, training
women in home processing, adapting soya bean
to local diets and facilitating input/output marketing
(all carried out in the context of a clear conceptual
framework with stakeholder participation),
have resulted in rapid adoption of soyabean by
thousands of smallholder farmers, thereby strengthening
their food security in a sustainable way. An
integrated program of adaptive and applied research
ro support the soyabean BNF promotion initiative
has provided a scientific basis for a technical
backup service to adopting farmers. The success of
such a promotion program depends on the number
of actual and demonstrable benefits to the smallholders
and the commitment of all stakeholders to
implement its various facets in a coordinated way.
Marketing, both in terms of inputs and outputs, is a
key driving force for soya bean BNF technology
adoption. More BNF grant funds must go into activities
that directly benefit farm families than project
personnel salaries and per diems. Legume BNF
can make a difference to rural livelihoods.
Acknowledgements
We thank the Rockefeller Foundation for funding
our soyabean BNF research and extension work in
Zimbabwe.
References
Javaheri, F. 1981. Release of four new soya bean varieties.
Mimeo Government of Zambia, Lusaka.
Kasasa, P., Mpepereki, S. and Giller, K.E. 1998.
Nodulation and yield of promiscuous soyabean
(Glycine max L. Merr.) varieties under field conditions.
In: Waddington, S.R., Murwira H.K.,
Kumwenda J.D.T. Hikwa D. and Tagwira, F.
(eds). Soil Fertility Research for Maize-based Farming
Systems in Malawi and Zimbabwe. SoilFertNet/
CIMMYT, Harare, Zimbabwe. pp. 93-103.
Kasasa, P. 1999. Quantification of nitrogen fi xation
by_promiscuous soya bean in Zimbabwean soils.
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