The Design and Technical Performance of Two Aeroponic Systems in Ghana

Climate change and its associated variabilities is having major impacts on agricultural production across the globe. Sustainable production options that reduce the vulnerability of the food system to climate change impacts are being advocated for, with a lot of ongoing research in that direction. Aeroponics production, a soilless production system has been identified as a sustainable system that can produce food with less input (land per unit area, water, nutrient and energy). It also makes for an environmentally friendly production system. In areas of extreme soil degradation and limited land area and water, aeroponics have shown great advantages over geoponics and sustained production, thus improving on food security. The central and northern parts of Ghana where yams are predominantly grown, is challenged with access to fertile lands, rainfall variabilities and other associated threat such as pest and disease outbreaks and seasonal bush fires. The production of seed yam, which form about 25% of the production cost for yam cultivation is hampered by all these challenges. To abate these challenges and improve on the adaptation measures taken by farmers around the region, two aeroponic systems were developed in this research, to be used for the production of seed yams propagated from vine cuttings. Two designs were made: one power independent (the gravity-fed open loop system) and the other power dependent (pressurised close loop system). In the systems design, the following aspects were taken into consideration: selection of head control and emitter; design of laterals and pipe sizes (inlet and outlet pipes); and the selection of growth chamber and feed tank. Apart from the selection of the growth chamber and the design of laterals and outlet pipe, different design considerations were also taken into account for the gravity fed system. This included the selection of drip lines and emitter flow rate. Technical evaluation of the aeroponics systems were done to ascertain its effectiveness as a fertigation system based on the performance indicators for a sprinkler and drip irrigation system. Results from the technical evaluation gave a mister discharge for the power dependent system ranging from 59.00-60.5 kPa. The emitter flow rate, the equivalent evaluation parameter for the power independent system also ranges from 0.10-0.12 L/h. There was a linear correlation between the mister operating pressure, mister discharge and swath diameter for the power-dependent system. For a Christensen’s Coefficient of Uniformity (CU) and Distribution Uniformity (DU) values of 97.52% and 96.16% respectively, the power dependent system can be said to be very efficient in its operations. The same could be said for the power independent system having a CU and DU of 94.49% and 90.80% respectively. These two developed systems have shown their capability to be adopted for u se in seed yam production to reduce some of the associated challenges, especially, access to land, water, seasonal bush fires and pest and disease outbreaks.