4. Economic analysis of soil erosion effects in alley cropping, no-till, and bush fallow systems in southwestern Nigeria.
IITA Research No. 3, 1991, pp. 1-5
Based on a simulation model, this paper uses a capital budgeting approach to determine how land-management technologies are compared with each other and with traditional bush fallow systems in southwestern
Nigeria, taking into account both the short-term and long-run impact of soil erosion on agricultural productivity and profitability.
The analysis is also conducted under two population density scenarios (high and low), which permits to verify the hypothesis that there exists a positive correlation between population density and agricultural intensification. This study thus differs from previous economic analyses in that the productivity effects of soil erosion and population growth rate are assessed.
Five land-management technologies in maize production are evaluated in the study.
They are continuous alley cropping systems with leucaena (Leucaena leucocephala) hedgerows planted at 2-m and 4-m intervals, continuous no-till system, and two traditional bush fallow systems with 25% an 50% farming intensities.
Shifting cultivation is typical of traditional agricultural systems in tropical Africa.
The International Institute of Tropical Agricultural (IITA) has concentrated its research efforts over the past two decades on developing sustainable soil management technologies, which enhance food production and preserve the natural resource base.
Although some economic analyses are available on the viability of improved land-use systems in sub-Saharan Africa, none of them accounts for the erosion process with its resultant long-term impact on costs and returns.
These results confirm the hypothesis that there exists a positive correlation between intensity of land use and population density. The argument is that for given agroclimatic conditions, increases in population density will gradually move the agricultural system from forest fallow to annual cultivation. Thus intensive cultivation of permanent fields in the frontier, using labour-demanding technologies (such as the 4-m alley cropping) or external input demanding technologies (such as the no-till system), becomes the norm only when arable land is exhausted. It can, therefore, be concluded that where land value rises due to land shortages, farmers with lower discount rates are likely candidates for the adoption of the 4-m alley cropping system compared to the no-till. For those farmers exhibiting high discount rates under high population density conditions, research should focus on reducing the establishment cost of the 4-m alley cropping system to make it competitive with the no-till system.
To test if the technologies fit into the farmers' production plan, economic analysis based on a whole-farm modeling approach is necessary.
Whole-farm models reflect the basic production processes involved in agricultural (e.g., nitrogen-fixing capabilities of leguminous trees) as well as many of the resource characteristics and constraints with which farmers must work (e.g., labour, land, and credit, to name a few). This further research should now be a priority.
1257 92 - 13/55
Erosion and desertification control
Review, book, developing countries, soil conservation, conservation practices, watershed management, grassland management, research, organisation, education, extension, environment
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