The Role of Cajanus cajan in Enhancing Soil Fertility and Macrofauna Populations in Intensively Cultivated Systems in Korhogo (Northern Côte d’ivoire)

In the Korhogo department, it is almost impossible to practice fallowing. The aim of this study is to determine how the Cajanus fallow impact the soil the biological and physical soil fertility. Macrofauna and soil samples were taken in different cropping systems (Cajan + maize, Cajanus + groundnut, Cajanus + maize + groundnut, Cajanus) and compared with the control (soil that did not contain any legume). The population density and abundance of the different macrofauna sampled were calculated and compared by analysis of variance ANOVA at the threshold of 0.05. The results show that the cropping system based on Cajanus cajan favoured the repopulation of the soil with Termicidae, Lumbricidae and Formicidae to the control. These values varied from 90 to 340 individuals/m2 for Lumbricidae in the system based on Cajanus. compared to the control values lower than 5 individuals/m2. The comparison of the population density according to the type of tillage also shows that flat plowing systems stimulate increase Lumbricidae populations more than ridged soils (325; 275; 125 individuals/m2 on plowing. against 230; 100 individuals /m2 on ridge) respectively on Cajanus+ groundnut, Cajanus + groundnut+ maize and pure Cajanus. On the other hand, the intercropping which increased the number of Lumbricidae, Termicidae and Formicidae, whatever the type of tillage, are, respectively, Cajanus + groundnut, Cajanus + groundnut + maize, Cajanus + maize and pure Cajanus.The introduction of Cajanus into intercropping systems leads to an improvement in the physical and biological fertility of the soil.