Abstract: An experiment was conducted between August and November, 2008 at Wuya-Bida to determine the profitability of integrating fish culture into rice farming. Two treatments (mono-rice and rice-fish) in triplicate were used. The area of each plot was 144 m2 and the mono-rice plots consisted of only rice farming while the rice-fish plots had rice farming incorporated with the raising of Oreochromis niloticus and Clarias gariepinus fingerlings. The fish were fed with compounded feed and wheat offal and at the end of the experimental period of 60 days, O. niloticus fingerlings had a mean weight gain of 47.60±1.86 g in the rice-fish plots while C. gariepinus fingerlings had a mean weight gain of 110.80±2.92 g. C. gariepinus fingerlings performed better than O. niloticus fingerlings. Values for physicochemical parameters showed that both pH and dissolved oxygen were outside the favourable limits (pH: 6.5-9, DO: >5 mg L-1) recommended for warm water aquaculture in the rice-fish plots. Cost-benefit analysis showed that the integration of fish into the rice system confers substantial profitability on the system going from the production, total and net income differences between mono-rice and rice-fish plots. However, cost-benefit ratio of the mono-rice plots was slightly better than that of the rice-fish plots.
INTRODUCTION
Poverty and malnutrition is a huge problem in Africa partly due to the lack
of food security (Defoer et al., 2004). However,
food security as well as poverty alleviation and socio-economic growth in Africa
can be enhanced by the adoption of rice-fish farming which entails the growing
of rice and fish concurrently or rotationally in the same compartments. It can
also be done by growing of rice and fish in separate compartments, using the
same water (Ahmed et al., 1992; Halwart
and Gupta, 2004). In shallow water rice-fish farming, the water level is
less than 50 cm while in deep water rice-fish farming, the water level is 50
cm and above. According to FAO (1993), the vast majority
of the world’s rice-fish farms are shallow water farms. Rice-fish farming
is the most widely practised of all forms of integrated fish farming worldwide.
Huge areas of land (especially in Asia) are used globally for rice-fish farming.
According to Halwart (1998), the total rice farming area
is about 148 million ha worldwide and about 90% of the world’s rice farming
area is in Asia. About 42.3 million ha of land is used for rice farming area
in India while about 33 million ha is used in China. About 1.2 million ha of
Chinese rice farming area is used for rice-fish farming. The major fish species
cultured in Asian rice farms are the carps (common carp, grass carp, black carp
etc.); Tilapia sp. (especially O. niloticus); silver barb and
catfishes. In Africa, fishes usually cultured in rice fields are the Tilapia
sp. (O. niloticus and O. mossambicus), Clarias and
carp sp. In Egypt, fish production from rice-fish farming accounted for 32%
of the total fish production from aquaculture in 1995 even though, rice-fish
farming area declined from 224,917 ha in 1989 to 172,800 ha in 1995 due to the
adoption of improved rice varieties and subsequent conversion of rice-fish areas
to monoculture rice. In Madagascar, about 1,100 tons of fish were produced as
at 1995 from about 13,500 ha of rice farms under FAO/UNDP assistance. Miller
et al. (2006) concluded that since Nigeria has about 2 million hectares
of irrigated and swampy rice areas, there’s great potential for successful
rice-fish farming. Okoye et al. (1999) carried
out an experiment to compare yields from rice-fish farms in two ecological zones
of Nigeria namely, Gwagwalada in the central zone and Dadin Kowa in the north-east
zone. The experiment was done with a polyculture of Clarias, Tilapia
and Common carp and the projected total income from the Gwagwalada area with
a fish stocking density of 1,325 fingerlings was
MATERIALS AND METHODS
Study area: The experiment was conducted at the rice farm of Edusoko and Sons Farm, Wuya-Bida, Niger State. The rice farm is basically rain fed but the experiment was done towards the end of the rainy season and this entailed the pumping of water from a nearby stream in order to maintain specific water levels. A rice nursery was made and rice seedlings were transplanted from it into the rice plots.
Preparation of mono-rice plots: Six plots (each of area 144 m2) were used for the experiment consisting of two treatments (mono-rice and rice-fish) and two replicates. A rice nursery was prepared with FARO 52 rice variety (120 day maturity period) obtained from the National Cereals Research Institute, Badeggi. The mono-rice plots were prepared and bunds of height, 0.3 m were made around each rice plot. Herbicides were used to kill weeds and the plots were fertilized with Nitrogen, Phosphorus and Potassium (NPK) fertilizer (20:10:10) at a rate of 220 kg ha-1 and urea at a rate of 56 kg ha-1. The 4-week-old seedlings were transplanted into the plots at a spacing of 20 cm between rows and lines. The rice plots were then flooded after the seedlings were transplanted. The water level was maintained at a minimum of 10 cm throughout the experimental period. The plots were weeded as the need arose and pesticides were also used to kill pests like stem borers, leafhoppers, snails etc.
Preparation of rice-fish plots: The rice-fish plots were also prepared and two trenches (each of dimension: 12x1x0.5 m) were dug opposite one another at the periphery of each plot. The trenches were dug in order to provide a place of deeper refuge for the fish when water level is to shallow for them. Bunds of height 0.6 m were made around each rice-fish plot. The rice-fish plots were fertilized with NPK and urea at the same rate as the mono-rice plots and seedlings were transplanted into them. The rice-fish plots were flooded with water after the seedlings were transplanted and the water level was maintained at a minimum of 20 cm throughout the experiment. Weeding of the plots was done adequately. No herbicide or pesticide was used in the rice-fish plots.
Stocking of fish: Fish was stocked into the rice-fish plots 35 days after transplanting at a density of 2 fingerlings m-2 as recommended by Onuoha (2006). Two hundred Oreochromis niloticus fingerlings (mean initial weight 3.9±0.17 g) and 100 Clarias gariepinus fingerlings (mean initial weight 2.2±0.25 g) were stocked into each rice-fish plot at a stocking ratio of 2:1. The fingerlings were fed compounded feed of 40% crude protein content in the morning and with wheat offal in the evening everyday.
Sampling of rice-fish plots: The pH, temperature, dissolved oxygen and conductivity of water in the flooded rice plots were measured before the fish were stocked. The plots were sampled weekly and this involved the measuring of the weights, total and standard lengths of fish; pH, temperature, dissolved oxygen and conductivity of water. Temperature and DO were measured with HACH dissolved oxygen meter (model DO 175); pH with Jenway pH meter and Conductivity with ELE conductivity meter (model DA-1). No pesticide was applied on the rice-fish plots.
Harvesting of rice and fish: The period from the planting of the rice seeds through transplanting to maturity was 123 days. The rice seedlings were transplanted 28 days after the nursery was made and the fish was stocked 35 days after the rice seedlings were transplanted and the fish spent 60 days in the rice-fish plots. The rice was harvested from the mono-rice plots and rice yield determined. The rice, followed by the fish, was also harvested from the rice-fish plots and yields of both rice and fish were determined and this was used to determine the viability of the rice-fish system.
RESULTS AND DISCUSSION
Fish production: The mean growth parameters of fish in the rice-fish plots are shown in Table 1. O. niloticus fingerlings in the rice-fish plots grew from an initial weight of 3.9±0.17 g to 51.50±1.77 g i.e., a weight gain of 47.60±1.86 g in 60 days. C. gariepinus fingerlings in the rice-fish plots had a mean weight gain of 110.80±0.92 g. The same profile is observed in mean values for total and standard lengths viz., C. gariepinus fingerlings performed better than O. niloticus fingerlings. This may be due to the fact that during feeding, C. gariepinus fingerlings out-competed O. niloticus fingerlings in picking the compounded feed. O. niloticus were only able to feed on wheat offal which by its nature, spreads all over the water surface. O. niloticus had already started breeding in the plots which means they had grown into breeders. No fish mortality was recorded throughout the experiment.
| Table 1: | Growth parameters of fish in the rice-fish plots |
Single factor ANOVA showed no significant difference (p>0.05) in the mean values of all the parameters in the replicates for both O. niloticus and C. gariepinus. But the mean values for the same parameters for O. niloticus were significantly different (p<0.05) from those of C. gariepinus. values of physicochemical parameters are shown on Table 2. Temperature ranged from 33.5 to 30.1°C. DO values in the rice-fish plots were lower than the 5-15 mg L-1 range recommended for good growth and reproduction of fish (Boyd, 1998). This may be responsible for the lower-than-expected growth of the fish. The DO of the stream water used to maintain the water level in the two plots was 4.34 mg L-1. Conductivity ranged from 60-70 μS cm-1 while pH was lower than the 6.5-9 range recommended for warm water aquaculture (ASA, 1999).
Rice production: Production from the three mono-rice and three rice-fish plots are shown in Table 3. The mono rice plots produced more rice than the rice-fish plots and this is probably due to the fact that they had more area for rice growth than the rice-fish plots which had part of their area used for rearing fish.
| Table 2: | Mean values of physicochemical parameters |
| Table 3: | Production and cost-benefit analysis of mono-rice and rice-fish production (after 123 days for rice and 60 days for fish) |
The cost-benefit analysis of mono-rice and rice-fish sections of the experiment is also shown in Table 3.
It is obvious from Table 3 that rice-fish farming is a potentially profitable enterprise and will provide both carbohydrate and protein to the ordinary fish farmer in addition to making available more income for his needs. Table 3 shows that the integration of fish into the rice system confers substantial profitability on the system going from the total and net income differences between mono-rice and rice-fish plots. However, the experiment failed to achieve the higher rice yields in the rice-fish plots as stated by Kogbe et al. (2000) and Yaro (2000). While rice yield from the mono-rice plots was 78 kg, that from the rice-fish plots was 60.5 kg. In addition, the cost-benefit ratio of the mono-rice plots was slightly better than that of the rice-fish plots.
CONCLUSION AND RECOMMENDATIONS
The results of the experiment shows that rice-fish farming is more profitable than mono-rice farming and that in a situation where rice production fails, a farmer can minimise the loss he would have incurred from the production of fish. However, the experiment failed to achieve the expected higher rice yield from the rice-fish plots compared to the mono-rice plots and it is recommended that further studies be carried out to determine why this is so.
ACKNOWLEDGMENTS
The authors are grateful to the management and staff of Edusoko and Sons Farm, Wuya-Bida for the use of the farm for the experiment and the first class cooperation given to us. Special thanks go to the Executive Director and management of the National Institute for Freshwater Fisheries research, New Bussa for sponsoring the research.