Sustainable intensification of crop production in agro-sylvo-pastoral territories through the expansion of cattle herds in Western Africa

Vigan, A.; Vayssieres, J.; Masse, D.; Manlay, R. J.; Sissokho, M.; Lecomte, P.

Abstract:

In agro-sylvo-pastoral villages ofWest Africa, biomass management ensures the sustainability of mixed-farming systems especially in maintaining soil fertility. Traditionally, agriculture and livestock activities are strongly linked. Cattle herds\’ mobility leads to a positive nutrient and carbon transfer from rangelands to individual cultivated fields. In some regions, demographic growth and subsequent decline in rangelands lead to herd depletion, a phenomenon that disturbs the traditional system and threatens food security. The village of Sare Yero Bana is located in sub-humid area, region of High Casamance in Senegal. The aim of this study was to assess the sustainability at village level by comparing the changes in farm functioning and the nitrogen balance between the years 1997 and 2012. In 1997, it was based on measurements of all biomass flows (including the weight and nitrogen content analysis) and in 2012, it was updated on the basis of an exhaustive farm survey. Total increase in cultivated areas (+35%) from 1997 to 2012 did not significantly affect rangeland available for herds, with more than 200ha still available for 485 tropical livestock units. Total animals increased by +17% over the same period. In both years, crop fields\’ nitrogen inputs were mainly ensured by manure. Fertility transfers from rangelands to cultivated fields increased; this partially explains a +36% crop production growth. In a context of a relatively stable village population and the development of staple crop market, nitrogen exports via harvest showed an increase of +20% (groundnut principally). These remained globally balanced by important nitrogen inputs corresponding to an increase of fertility transfers by the herds (+9.6 kgN.ha−1.yr−1), and to the recent use of mineral fertilizers (+6.4 kgN.ha−1.yr−1). The village nitrogen balance remains stable and close to equilibrium (respectively -4 and -2 kgN.ha−1.yr−1 in 1997 and in 2012). This study stresses the important role that cattle herds can play towards food security in regions of Western Africa where rangelands still remain. Moreover, in Sub-Saharan Africa, livestock contributes significantly to climate change via greenhouse gas emissions. Thus, the study also underlines the importance of taking into account the indirect positive effects of livestock on other agricultural productions in greenhouse gas balances, such as the input of organic fertilizer.

Year:

2014

Type of Publication:

In Proceedings

Book title:

Proceedings of the Livestock, Climate Change and Food Security Conference, Madrid

Pages:

127

Organization:

INRA and the AnimalChange European Project

Month:

19-20 May 2014