The objective of this study was to evaluate quantitatively the magnitude of the spatial and temporal variation for 7 soil physical properties on a conventionally-tilled Nigerian Paleustult. A 0.4-ha plot was disc-ploughed, disc-harrowed twice, subjected to tractor-wheel traffic at regular space intervals and then seeded to maize (Zea mays, L.). There were significant differences in the physical properties owing to tillage position (spatial variability) and date of sampling (temporal variability), more so in the 0–10-cm layer than in the 10–20-cm layer. In the surface layer, bulk density (Db) and penetrometer resistance (PR) were significantly higher (P ⩽ 0.01) along the tyre marks (maximum Db = 1.76 Mg m−3) than in the uncompacted crop row (maximum Db = 1.35 Mg m−3) and interrow positions (maximum Db = 1.46 Mg m−3). Saturated hydraulic conductivity (Ksat), total porosity (TP) and macroporosity (M) were significantly lower along the tyre mark than in the crop row and interrow positions. Ksat ranged from 0.6 to 42.8 cm h−1, TP, from 0.34 to 0.50 cm3 cm−3 and M from 0.06 to 0.25 cm3 cm−3 along the tyre mark and crop row positions, respectively. Significant temporal changes were noticed only in Ksat, soil moisture content (MC) and PR. Ksat increased steadily with time along the tyre mark, but showed an irregular trend in the other two positions. PR did not change with time along the tyre marks but it increased significantly with time along the other two positions. MC changed according to the periodicity of rainfall. Only TP varied, owing to tillage position × date interaction. The 10–20-cm layer was spatially less variable but temporally more viarable than the surface layer. Only Ksat and PR showed significant changes owing to the tillage positions, but Db, Ksat, PR and moisture retained at 10 kPa suction (τv10) showed significant temporal changes. Only τv110 varied owing to position × date interaction in this layer.
Soil and Tillage Research 10/1988; 12(3):285-298. DOI:10.1016/0167-1987(88)90017-7