The Eleventh Regional Wheat Workshop For Eastern ... - Cimmyt

Response offour bread wheat varieties to N fertilizer - Mansoor et al.
close to or exceeded 100%. This indicates that it would be economically optimal for smallscale
wheat producers to shift from their local wheat variety by purchasing commercial seed
of Kware. On the other hand, the other two improved wheat varieties would only be
economically attractive, but not optimal, if wheat seed prices are reduced to approx. 200
Tshs/kg (Table 2c).
The MRR analysis of the four N rates was repeated under four different price scenarios,
varying the price of N and wheat grain (Tables 3a, 3b, 3c and 3d). The results of the MRR
analysis were consistent with the agronomic analysis of N rates: across the four price
scenarios, the rate of 30 kg N/ha proved to be the economic optimum. Only in the most
unfavorable scenario (i.e., Table 3d - wheat grain price low and N price high) did the
application of 30 kg N/ha result in an MRR below 100%; however, even under this scenario,
the 30 kg N rate provided an MRR of 67% relative to nil application. In all scenarios,
treatments receiving N at higher rates (i.e., 60 and 120 kg N/ha) were dominated by the 30 kg
N/ha treatment (CIMMYT, 1988); that is these treatments cost more and produced a lower
net benefit. Thus, the application of 30 kg N/ha appears to be a "robust" technology to
recommend to small-scale wheat farmers.
CONCLUSIONS
The improved wheat varieties, particularly the variety Kware, had a marked effect on wheat
grain yields across the two sites and three seasons included in the current study. Wheat grain
yield increments with Kware, Tausi and Mbayuwayu varieties were 32, 14, and 7%,
respectively, of the yield of the farmers' local variety. By comparison, the incremental wheat
grain yields when 30, 60 and 120 kglha ofN was applied were 18, 15, and 23%, respectively,
of the yield with nil N applied.
Of the three new wheat varieties, Kware was economically optimal across a range of wheat
grain and seed prices. The other two varieties were sensitive to changes in prices, and would
only be attractive to small-scale farmers if wheat seed prices were significantly reduced from
the current level. Application of 30 kg N/ha in the fom1 of urea was economically optimal
relative to the nil application treatment.
Small-scale wheat farmers in Karatu District should be advised to adopt the wheat variety
Kware and to apply 30 kg of N/ha in the form of urea. By adopting this recommendation,
farmers will increase their total wheat production and economic profits.
Further research may be required to address the anticipated long-term impact of mining soil
P. On-farm studies of wheat grain yield response to P application are proposed for this area.
REFERENCES
CIMMYT. 1988. From Agronomic Data To Farmer'Recommendations: An Economics Training Manual.
Completely Revised Edition. CIMMYT, Mexico, D.F., Mexico.
Nyaki, A.S., Mansoor, H.A. and Ngatoluwa, R.T. 1993. Soil Fertility And Chemistry. Report Presented To
Annual Wheat Coordinating Committee Meeting. Arusha, Tanzania, 11-12 Nov., 1993. Selian ARl,
Arusha, Tanzania
Stonehouse, H.B and Duff, J.P. 1973. Soils OfKaratu-Oldeani Area OfTanzania. A Report For The Agronomic
Research Project Sponsored By The Canadian International Development Agency. Agriculture Canada,
Ottawa, Canada.
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