Effect of the corn-cowpea association on the organic carbon dynamics of the soils of two plots in real culture in northern Côte d'Ivoire

Declining soil fertility is a major factor in low agricultural production and increases food insecurity in northern Côte d'Ivoire. The objective of this study is to understand the real influence of cowpea in the corn-cowpea association modalities on the evolution of organic carbon (C) and nitrogen (N) contents in the soil on the scale of plot compared to control soils without cowpea and fallow more than 30 years. In this perspective, two farmer field plots were conducted in a participatory manner with two groups of corn producers in the localities of Kolokaha and Sohouo (Department of Korhogo) in order to assess the effect of the semi density of cowpea (Vigna unguiculata L.) on the initial physical and chemical characteristics of the soil. In the open field, four (4) treatments corresponding to corn in pure culture (T0); corn + cowpea interposed online (T1-SNL); corn + cowpea in double intersected line (T2-SNDLI) and corn + cowpea staggered (T3-SNQ) were tested in three (3) completely randomized blocks with three repeats. Thirty-two (32) composite soil samples from natural fallows and T0, T1-SNL and T2-SNDLI treatments were taken and analyzed in the laboratory. The results show a clear improvement in the organic carbon and nitrogen levels, and above all an increase in the soil pH in the plots in associated crops. The combination of corn and cowpeas is an alternative to good soil fertility management and could be recommended in rural areas.