Options for farm diversification through integrated aquaculture-agriculture (IAA) are being embraced globally as a competitive alternative to traditional agriculture because of their high environmental sustainability, resource use efficiency and overall productivity. Despite these numerous ecosystem benefits of IAA, the practice of IAA especially integrated rice-fish (IRF) farming in developing countries such as Nigeria, poor knowledge of water management within the rice and fish ecosystem can pose a challenge to adoption. A better understanding of the water utilization dynamics of IRF for food production could significantly fit IRF into the process of addressing sustainable development goals (SDG), such as SDG 2—zero hunger, SDG 12—responsible consumption and production, and SDG 14—life below water. This study, therefore, investigated the water utilization, water quality performance and nutrient requirement dynamics of the IRF system using an MSU/USAID/FAO IRF plot in the University of Ibadan, Nigeria as a case study.
This study was carried out on the MSU/USAID/FAO IRF plot (22m by 15m) for 16 weeks in the Department of Aquaculture and Fisheries Management, University of Ibadan, Ibadan, Oyo State, Nigeria. Fourteen days old rice seedlings were transplanted at a spacing of 20cm by 20cm on the IRF plot platform. Three weeks after the rice transplanting, 1500 Clarias gariepinus (4.0±1.5g) were stocked into the (fully filled with water) IRF platform. The fish were fed to satiation thrice daily using IRF project-formulated diets. This experiment was repeated thrice (in three cycles of an operation lasting 16 weeks each) in a completely randomized design. Biweekly water quality parameters and monthly composite soil samples were collected monthly. Water productivity, efficiency and consumptive water use were calculated following standard methods. Data were analysed using descriptive statistics, and ANOVA at α0.05.
The water and soil quality parameters were as presented in tables 1 and 2. All parameters examined were within acceptable limits for fish and rice culture. The number of plankton ranges from 50 x 103/m3 to 230 x 103/m3 while in abundance ranges from 148 to 208 (Table 3). The value recorded for both number and abundance fluctuated according to the week of culture with the highest recorded at week 4 of the experiment in all the cycles. The result for consumptive water use (m3), water efficiency (kg/ha cm) and water productivity (kg/m3) were 440±20.62, 0.9±0.02 and 900±80.2, respectively (table 4).
The IRF shows good consumptive water use and efficiency and increases water productivity. This clearly indicates that efficient application of the IRF could help confront issues of freshwater insufficiency, reduce water footprint, and increase water productivity.