Abstract:
Soil moisture is important for crop cultivation and its adequacy to meet crop-water
requirements is determined by the degree of soil management practiced and the quantity of water
applied to the soil. This study investigates soil moisture dynamics on three plots: Bare (clean, weeds
removed), Weedy (kept weedy), and Mulched (cleared of weeds and fully covered with grass mulch)
during rainy and dry periods at the Teaching and Research Farm at the University of Cape Coast, in the
coastal savanna zone of Ghana. Soil moisture dynamics under different levels of soil compaction were
also studied. A Massey Ferguson tractor (MF265) was used to compact the soil at various levels by
making 0, 1, 5, 9 and 13 passes. During both the rainy and the dry periods, moisture retention in the soil
under bare, weedy and mulched plots increased with depth. During the rainy period, the mean soil
moisture retention was in the order: Mulched > Weedy > Bare at both 0–20 cm and 20–40 cm depths.
Within a 7-day period, soil moisture measurements from a day after heavy rainfall (intensity > 7 mm h-1)
gave mean moisture losses of 2.7, 4.1 and 3.9% for the Bare, Weedy and Mulched plots, respectively.
During the dry period, however, the mean soil moisture retention was of the order: Mulched > Bare >
Weedy at both 0–20 cm and 20–40 cm depths. Mean moisture loss during a 7-day dry period was 4.5,
2.9 and 3.4% for the Bare, Weedy and Mulched plots, respectively. Under different levels of soil
compaction, the mean moisture retention in the soil increased from 8.3% at 0 pass to 17.8% at 13 passes
within the 0–20 cm depth, whilst it decreased from 13.3 to 5.9% from 0 to 13 passes, respectively,
within the 20–40 cm depth. It was realized that at less than two passes, the mean soil moisture retention
within the 0–20 cm depth was less than the mean moisture retention within the 20–40 cm depth, but the
converse happened for more than two passes. The study showed that mulching the soil surface helped to
retain enough soil moisture during both the rainy and the dry seasons. Also, soil with high sand content
required some sort of soil compaction in order to retain enough moisture at the crop rooting zone
