TY  - PRO
AU  - Tanner,D.G.
AU  - Asefa Taa
AU  - Kefyalew Girma
ED  - Centro Internacional de Mejoramiento de Maiz y Trigo (CIMMYT), Addis Ababa (Ethiopia)
TI  - Determination of economic optimum fertilizer levels using discrete and continuous analytical methods
SN  - 92-9146-058-3
PY  - 1999///
CY  - Addis Ababa (Ethiopia)
PB  - CIMMYT
KW  - Crop management
KW  - AGROVOC
KW  - Economic analysis
KW  - Ethiopia
KW  - Fertilizer application
KW  - Fertilizers
KW  - Prices
KW  - Production factors
KW  - Triticum aestivum
KW  - CIMMYT
N2  - The determination of economic optimum fertilizer rates is fundamental to profitable bread wheat (Triticum aestivum) production. However, the derivation of economic optimum nutrient rates is complex and is dependent upon fluctuating nutrient and grain prices and changing crop management practices. Economic optimum N and P205 nutrient rates were determined following discrete and continuous analytical methods using data generated in a series of on-farm fertilizer trials conducted in Ethiopia during 1988-90 and 1995-97 across a range of agro-ecologies. The data were first subjected to ANOVA and then regression coefficients derived from response surface equations were used to determine the continuous economic optimum fertilizer rates. Discrete analysis of the actual N-P205 treatments following partial budget methodology was used to determine the discontinuous economic optimum rates. Optimum N and P205 levels for each agro-ecological zone were established based on specified ranges for nutrient and grain prices using both methods. The optimum rates generated by the two analytical methods lacked close agreement for the obvious reason that the continuous method is based on a smoothed regression curve while the discrete method is based on actual data points. However, the relative ratios of N and P205 rates were generally consistent between the two methods. The use of regression-derived response coefficients in continuous economic analysis facilitates the construction of dynamic and robust recommendation tables for dissemination to extension staff. Furthermore, the continuous method facilitates interpolation thereby accommodating intermediate price levels
UR  - http://hdl.handle.net/10883/1244
ER  -