Effect of agricultural machinery on physical and hydraulic properties of agricultural soils

The study assessed effect of farm machinery on both physical and hydraulic properties of agricultural soils used for rice cultivation in northern Ghana.  Two tractor models were used for the field experiment with field tests and soil sampling points classified as tractor tyre passage area (TTPA), ploughed area (PA) and unploughed area (UPA). The study used Randomised Complete Block Design (RCBD) with 3 blocks, 3 treatments, 9 replications and data were analysed using Graph Pad Prism, 8 software and Microsoft Excel 2016. Soil aggregate composition varied for the 3 study sites and sampling locations with a sandy loam soil textural class. Soil dry bulk density ranged from 1.11 to 1.61 g cm-3 with TPA recording 1.42 to 1.61 gcm-3 indicating high level of soil compaction. Unsaturated hydraulic conductivity of 2.01 × 10-4 to 1.05 × 10-3, 1.61 × 10-4 to 6.50 ×10-4 and 1.89 × 10-4 to 7.19 × 10-4 cm s-1 were recorded for PA, TTPA and UPA respectively. Low unsaturated hydraulic conductivities were recorded for TTPA compared to other treatments. Overall, average cumulative infiltration revealed a relatively lower infiltration for TTPA compared to PA and UPA. Specific TTPA for a typical ploughing activity was estimated as 2107. 0 and 2895.5 m2 ha-1 for two tractor models, translating to 28.6 and 21.0% ha-1. respectively. The study recorded appreciable soil compaction resulting from a typical tractor plough activity on agricultural soils which might negatively impact soil water conductivity as well as plant growth and development. Key words: Soil compaction, tractor plough, hydraulic conductivity, soil water infiltration, soil bulk density.