ABSTRACT

A self-watering portable mobile raised bed integrated with a sub-surface irrigation system was designed, developed and evaluated. The system can be operated in urban dwellings where farming is constrained by land non availability, space and labor. Three water absorbent materials namely: Wood shavings, Palm fruit fiber and Saw dust were tested for their water holding capacity and upward release of the withheld water for soil absorption. The result showed that with absorbent thickness of 15cm and soil bed depth of 20cm from the absorbent top, the volumetric flow rate was 0.03 illitres/sec; 0.Ol9litres/sec and 0.023 litres/sec for wood shavings, palm fruit fibre and saw dust, respectively. At these flow rates the application efficiencies were 63%, 65% and 60% for wood shavings, palm fruit fiber and saw dust, respectively. The transitional period for wood shavings, palm fruit fiber and saw dust were 0.42 hrs, 0.33 hrs and 0.25 hrs respectively. At this period, the volume of water stored by wood shavings, palm fruit fiber and saw dust were 100.285 litres, 62.697 litres and 59.570 litres respectively. It took wood shavings, palm fruit fiber and saw dust 0.5 hrs, 0.42 hrs and 0.33 hrs respectively to release its water to the closest overlying layer of soil. Statistical analysis using a one way ANOVA at 95% (0.05%) confidence level showed no significant difference between the volumes of water stored in the root zone for the three fibers. The self watering raised soil bed can be used to cultivate crops especially in urban settings where arable land is not available. The system can also be adapted to other crops, other agro based fibers , it can also be expanded to include digital additions to suit the users.