Statistical analysis
With the help of ANOVA coupled with SPSS 13.0 software, an analysis was made concerning the significance of influence of the planting density on all the parameters measured and the effect of pipe position, planting density and soil depth on soil water content. A regression analysis was then made to determine the different relationships, such as the relationship between soil water content and moisture suction, the relationship between the root density and soil depth using the least square method. Data were transformed when necessary to obtain a linear relationship.