2.6. Statistical Analysis

A normality test was applied to the data on soil and plant parameters. As the distributions were not normal, even after Box–Cox transformations, the non-parametric test of Mann–Whitney (MW) was used to compare concentrations between Penga Penga and Kalebuka and between mango and S. guineense. To compare the rhizosphere of the two species, the Mann–Whitney test was performed separately in each district. The proportion of leaves and fruits with values above the limit recommended by the FAO and WHO [23] was calculated by dividing the number above the limit by the total number of samples. All statistical analyses were performed using R Studio 3.1.