Water Status And Growth Of Plants In Pvc Cylinders Installed Vertically In The Field

Increasing the efficiency of irrigation water use is critical in water-scarce countries such as Barbados. Planting in pots can ensure that most of the applied irrigation water is available exclusively to the target plant, but plant growth may be restricted due to large fluctuations in soil moisture availability and temperature, reduced rooting volume and pot drainage issues. Planting in open-ended PVC cylinders installed vertically in the field should help to ensure that applied water remains largely within the root zone of the target plant, while avoiding many of the problems associated with potted plants above the soil surface. This study assessed the effects of planting in buried PVC cylinders on water status and growth of two crop species (sweet pepper and bean) in a heavy clay soil. A split-plot experimental design was used with two main plot (height of cylinder protruding above the soil: 0 and 3 cm) and three sub-plot (buried depth of cylinder: 0, 15 and 30 cm) treatments. Cylinders (internal diameter: 16cm) were hammered into loose dry soil. Irrigation was applied as needed to supplement rainfall by manual sprinkling with a garden hose. Soil moisture status and plant growth were not significantly affected by the height of cylinder above the soil surface. As the length of buried cylinder increased, moisture content in the top 5 cm of soil within the cylinder also increased and ponding was often observed in the 30 cm cylinders. Plant growth was not significantly affected in the 15 cm cylinders but was reduced for both crops in the 30 cm cylinders. Excessive rainfall during the study period resulted in supra-optimal soil moisture conditions within the buried cylinders. Significant effects on soil penetration resistance suggested that there was soil compaction within the PVC cylinders, which was likely due to hammering during the installation process and/or swelling of soil within the cylinders on re-wetting. This approach appears to have some potential for increasing the efficiency of irrigation water use and is likely to be beneficial under low rainfall conditions with more precise water application.