Assessment of the physical and mechanical properties of the soils in the different agroecological zones of Benin

Abstract

The physical properties of soils are important for proper  monitoring of soil functions. In order to evaluate soil resistance to agricultural equipment, a study was carried out on the four main soil types (ferralitic, ferruginous, hydromorphic and vertisol) in the eight agroecological zones of Benin. The objective of this work was to determine the physical and mechanical parameters of the soils. A sampling of soil types by agroecological zone was carried out in 36 localities in Benin to record vertical and horizontal soil strengths using a compactometer and a penetrometer. These data were complemented by measurements of texture, density and water content of the soil samples. An
analysis of variance, polynomial regressions and Pearson correlation were performed between the parameters studied. It is noted that majority of soils assessed were sandy loam. The high sand content in most soils would be due to the depth considered (20 cm). The bulk densities range from 1.21 to 1.73gcm-3 and water contents from 4.9 to 35.11%. Vertical resistances range from 3.89 to 16.36 kg cm-2 and horizontal resistances from 1.03 to 4.44 kg cm-2. Strong soil resistances (vertical and horizontal) are recorded in the northern part of Benin where large proportions of the gravelswere observed in the samples taken. A positive correlation was observed between vertical resistance and horizontal soil resistance. It can be concluded that soil resistance in Benin vary from one agro-ecological zone to another, but the linking of soil properties is less significant between zones.

Keywords: Soil compaction, soil resistance, penetrometer, agroecological zones, Benin