Research Article

Biological Nitrogen Fixation by Local and Improved Genotypes of Cowpea in Burkina Faso (West Africa): Total Nitrogen Accumulated can be used for Quick Estimation

Table 1

Main physicochemical characteristics of the topsoil (0-20 Cm).

Clay (%)6
Sand (%)72pH H2O6.1
Silt (%)20pH KCl5.2

Organic C (%)0.59Ca++ (cmol+ kg−1 soil)1.10
Total N (mg kg−1)410K+ (cmol+ kg−1 soil)0.05
Total P (mg kg−1)79.0Mg++ (cmol+ kg−1 soil)0.40
Avail.-P Bray I (mg kg−1)5.0ECEC (cmol+ kg−1 soil)1.70
Available K (mg kg−1)543