Main Article Content
Farm-level use of soil amendments and definition of typologies: implications for the design of balanced nutrient management systems in the derived savanna of the republic of benin
Abstract
The use of chemical fertilizers by smallholder farmers in sub-Saharan Africa (SSA) is usually estimated to be low and organic inputs have been advocated as an alternative technology for the alleviation of soil fertility constraints. However, no quantitative data are yet available to substantiate these assumptions in the derived savanna (DS) of West Africa.
A farm survey was carried out with 232 farmers carefully selected in three villages located in the ecoregional benchmark area of the DS in the Republic of Benin. The main objective was to determine the current availability and use of organic and inorganic inputs by farmers as a perequisite for the design of balanced nutrient management systems. A secondary objective was to propose a typology of farmer
that could participate in the development of balanced nutrients technologies. About 60% of the farmers investigated still practiced fallow but differences existed between villages. The average length of fallow was only 1 year for leguminous crops, 4 years for leguminous trees, and 9 years for fallow with palm trees. On average, 46% of all
the farmers used inorganic fertilizers but this varied between 3% and 98% of farmers in the three survey villages. The quantities applied were limited; on average, the application of inorganic N amounted to 24 kg N ha-1 only. About 41% of farmers were found to apply less than 30 kg N ha-1, 16% between 30 and 60 kg N ha-1, 43% applied
more than 60 kg N ha-1. The rates varied with the planted crop. For the commonly used, one third urea was combined to two thirds NPK. Then, for this combination of chemical fertilizer, 180 kg ha-1 were applied to cotton, 107 kg ha-1 to tomatoes, and only 76 kg ha-1 to maize, the main food crop of the study area. The use of organic inputs was still at a very early stage. About 9% of farmers apply only organic inputs to the fields while 18% combine them with inorganic fertilizer. Only 4.4% of the fields received organic fertilizer applications. Information on the quantity of organic inputs was not collected. However, most of the crop residues are either burnt (33% of respondents for maize) or thrown away (17% for maize). The use of chemical fertilizers (and organic inputs) was remedy nitrogen deficiency that is considered the most limiting soil nutrient in the maize-based systems of the DS. On the basis of thelimited quantity of N applied to the crops, farmers were classified into two a-priori
groups using a threshold of 30 kg N ha-1, and multiple quantitative variables were fitted in a discriminant analysis to validate the typology. About 82% of farmers were well classified into two groups that had the characteristics of the a-priori groups. There were two other groups (18%) that were atypical. The two groups with 82% of well-classified individuals were suitable for the selection of farmers to conduct applied research or for the development of activities because they represent the general pattern in the supply and use of soil nutrients in the study area. Although
basic research can be done with the four farmer groups, the two atypical groups were most suited for process-level studies to improve the understanding of factors that lead to improvements in the efficiency of a cropping system.
A farm survey was carried out with 232 farmers carefully selected in three villages located in the ecoregional benchmark area of the DS in the Republic of Benin. The main objective was to determine the current availability and use of organic and inorganic inputs by farmers as a perequisite for the design of balanced nutrient management systems. A secondary objective was to propose a typology of farmer
that could participate in the development of balanced nutrients technologies. About 60% of the farmers investigated still practiced fallow but differences existed between villages. The average length of fallow was only 1 year for leguminous crops, 4 years for leguminous trees, and 9 years for fallow with palm trees. On average, 46% of all
the farmers used inorganic fertilizers but this varied between 3% and 98% of farmers in the three survey villages. The quantities applied were limited; on average, the application of inorganic N amounted to 24 kg N ha-1 only. About 41% of farmers were found to apply less than 30 kg N ha-1, 16% between 30 and 60 kg N ha-1, 43% applied
more than 60 kg N ha-1. The rates varied with the planted crop. For the commonly used, one third urea was combined to two thirds NPK. Then, for this combination of chemical fertilizer, 180 kg ha-1 were applied to cotton, 107 kg ha-1 to tomatoes, and only 76 kg ha-1 to maize, the main food crop of the study area. The use of organic inputs was still at a very early stage. About 9% of farmers apply only organic inputs to the fields while 18% combine them with inorganic fertilizer. Only 4.4% of the fields received organic fertilizer applications. Information on the quantity of organic inputs was not collected. However, most of the crop residues are either burnt (33% of respondents for maize) or thrown away (17% for maize). The use of chemical fertilizers (and organic inputs) was remedy nitrogen deficiency that is considered the most limiting soil nutrient in the maize-based systems of the DS. On the basis of thelimited quantity of N applied to the crops, farmers were classified into two a-priori
groups using a threshold of 30 kg N ha-1, and multiple quantitative variables were fitted in a discriminant analysis to validate the typology. About 82% of farmers were well classified into two groups that had the characteristics of the a-priori groups. There were two other groups (18%) that were atypical. The two groups with 82% of well-classified individuals were suitable for the selection of farmers to conduct applied research or for the development of activities because they represent the general pattern in the supply and use of soil nutrients in the study area. Although
basic research can be done with the four farmer groups, the two atypical groups were most suited for process-level studies to improve the understanding of factors that lead to improvements in the efficiency of a cropping system.
