Fish is one of the main sources of animal protein used in the diet of the human population. In most of the developing and under developing countries, large numbers of populations suffer from malnutrition. Thus, it is encouraged to have fish as food in the human diet. Generally, fish culture is carried out in open pond system. The production level is not uniform throughout the year due to fluctuations in water temperature. Water temperature directly influences the growth and fish food production in its environment. Greenhouse pond, is a good alternative to enhance the water temperature in the colder period of the year and encourage proper growth of fish as compared to an open pond.
Fish production requires energy input in various forms. Energy use in fish production has become more intensive, with the increasing use of fertilizers, balanced feed, aeration, high stocking density and maintenance of water quality parameters in addition to the proper management practices. Efficient use of the energy resources is important in terms of increasing production, productivity and sustainability of rural living. Energy use pattern and contribution of energy inputs vary depending on farming system. Several authors have focused on energy use in greenhouse (Ozkan et al., 2004; Canakci and Akinci, 2005) mainly for agriculture crops. Singh and Pannu (1998) studied the energy requirements in fish production and energy ratio of a village fish pond in the state of Punjab, India. Tiwari and Sarkar (2006) analyzed the energy use pattern for production of fish in a smaller cemented greenhouse tank, to determine the energy input-output ratio and their relationship with Labeo rohita fish. However, the studies related to the energy consumption in greenhouse fish production are very limited. Therefore, the main objective of this study is to calculate energy output-input ratio, specific energy and energy productivity in greenhouse earthen fish pond.
MATERIALS AND METHODS
Greenhouse fish production (Fig. 1) experiment was conducted
in the farm of CIFA, Bhubaneswar during 28 October, 2002 to 27 March, 2003.
The place is located in the eastern part of India (Latitude-20°15´,
Longitude- 85°52´, and altitude 33 m above mean sea level).
|| View of the experimental greenhouse
||Energy equivalents inputs-outputs analysis in fish production
|| Embodied energy used for construction of Pond (11x7x1m)
The inputs and outputs used in fish production were converted to the form
of energy to evaluate the output-inputs ratio. The energy equivalents of inputs
used in the fish production are illustrated in Table 1. The
input energy is classified as direct and indirect energy. The indirect energy
are fertilizer, lime, chemicals, etc., while direct energy include human energy,
power, diesel, feed, fish seed, etc.
In order to analyze the energy input-output ratio, one open and one greenhouse
pond was used for this purpose. The embodied energy used in both the ponds is
shown in equal, as size and shape of the ponds are same (Table
2). The effective greenhouse area and water volume were 104 and 50 m3,
respectively. The different material used to construct the typical aquaculture
greenhouse including man-hour is given in Table 3. To calculate
the annual embodied energy, the life of greenhouse was considered as 25 years
(Tiwari and Sarkar, 2007). Under this circumstances, greenhouse embodied energy
was 382.17 MJ per production area of 50 m3 for five months operation.
|| Embodied energy used for construction of arch shape greenhouse (13x8
|For 5 months operation the total energy required: 382.41MJ
Before stocking the fish, the ponds were prepared as per the recommended standard
aquaculture practices. The ponds were filled with water and the fertilization
was carried out with application of cow dung at the rate of 10 tons ha-1
year-1, one fifth of which was applied two weeks prior to stocking
of fish fingerlings as basal dose. The remaining amount was applied in equally
divided doses at fortnightly intervals. Inorganic fertilizers in the form of
nitrogen and phosphorus were applied fortnightly in split doses. The water level
in the experimental ponds was maintained at 1.0 m during the study period, compensating
the loss of water due to seepage and evaporation. Liming by CaCO3
at the rate of 80 kg ha-1 was done in a interval of one month to
maintain the desired pH of water and also for pond hygiene. Advanced carp fingerlings
and ten days old post-larvae of prawn (Macrobrachium rosenbergii) were
stocked in the open and greenhouse ponds. The stocking density of fishes was
10,000 nos ha-1 and prawn was 25,000 nos ha-1. The size
ranges were 8-15 g for fishes and 10-12-mm/10 mg for prawns. The carp species
stocked were Silver carp (Hypophthalmichthys molitrix) -10%, Catla (Catla
Catla ) -20%, Rohu (Labeo rohita ) -25%, Common carp (Cyprinus
carpio) -5%, Puntius (Puntius Javanicus) -25%, Grass carp ( Ctenopharyngodon
idella) -10% and Mrigal (Cirrhinus mrigala)-5%. Supplementary formulated
feed with crude protein level of 35% was given at the rate of 2-3% of body weight
twice in a day at 10:00 and 15:00 h. The feeding quantity was adjusted at monthly
intervals after estimating the biomass increase through intermittent sampling.
Fish production was assessed for both the ponds at the end of culture period.
Energy use in the production of fish was calculated per m2 basis.
During rearing period, various operations were involved for greenhouse fish
production viz., water filling, weed control, fertilizer and cow dung application,
aeration, feeding of fish, monitoring of water quality, sampling of fish and
finally harvesting of fish. In this experimental study, input-output ratio,
specific energy and energy productivity for the greenhouse fish production were
calculated using the following relations (Tiwari and Sarkar, 2007):
RESULTS AND DISCUSSION
The energy consumption and its sources for open pond are presented in Table
4. The total energy used in various farm inputs was 584.99 MJ/50 m2
in open pond. Diesel energy had the biggest share in the total energy
with 43.32% followed by human (30.49%), feed (9.90%), chemicals (6.92%), lime
(6.15%), manure (2.59%) and phosphate P2O5 (0.63%). The
energy inputs for human included water filling, lime application, weed control,
fertilizer application, cow dung application, feeding of fish, testing of water
quality parameters, sampling of fish and finally harvesting. The diesel energy
was mainly used for operating the pump set for water filling and compensation
of seepage and evaporation. Feed energy was used for providing artificial feeding
to the fish. Lime, manure and P2O5 were mainly used for
pond fertilization and to provide natural food organisms to the fish. Chemicals
were used for testing of water quality parameters. Embodied energy used for
pond construction could not be considered, for evaluating energy input-output
analysis, since both the values were same and ponds are permanent in nature.
Table 5 shows the energy consumption and its sources for greenhouse
fish production. The total energy used in various farm inputs was 1027.22 MJ/50
m2 for five months operation in greenhouse pond.
||Energy inputs-output ratio, specific energy and energy productivity in
|| Energy inputs-output ratio, specific energy and energy productivity in
Of all the inputs, greenhouse structure had the highest share of 37.23%. This was attributed to the high-energy value that was used for constructing the greenhouse structure. The second highest was the diesel oil with share of 22.65%. However, diesel energy consumption was slightly less due to increase in humidity inside greenhouse. The others were human energy (17.36%), feed energy (12.32%), fertilizer and lime (4.67%), manure (1.47%) and P2O5 (0.36%). Feed energy consumption was more in greenhouse due to increase in yield.
After five months of culture, fish yield was 8.8 and 16.15 kg/50 m2 in open and greenhouse ponds, respectively. The higher yield was obtained in greenhouse due to stable water temperature and higher feed intake. The total energy output was calculated multiplying by the equivalent energy input and output coefficients.
Output-input ratio is one of the essential indicators, which provide the efficiency of the farming system. Among both the investigations, greenhouse had the highest energy output-input ratio. The lowest energy ratio was observed in open condition, mainly because of lower water temperature and poor feed intake by fish. These energy ratios were quite low, in general, when compared with to the values of agricultural crops. The average input-output ratio was calculated as 0.070 and 0.079 in case of open and greenhouse ponds, respectively. The results indicated that specific energy and energy productivity were 71.55 MJ kg-1 and 0.014 kg MJ-1 incase of open pond, whereas, 63.60 MJ kg-1 and 0.015 kg MJ-1for greenhouse pond. In the greenhouse, the energy ratio was higher due to lower inputs and the specific energy showed lower value due to the higher yield. Thus, efficient use of these energy sources helped to achieve increased production, productivity and higher profitability of greenhouse aquaculture. In comparison with the previous studies, Tiwari and Sarkar (2006) reported that the energy input- output ratios of Labeo rohita, in open and greenhouse ponds are 0.078 and 0.090, respectively for five months culture operation. Singh and Pannu (1998) from a case study reported the energy ratio of 0.15 in a village pond for more than one-year culture period. The results of Singh and Pannu are obtained from the culture of fish from larger water body. But, in the present case, the ratio is quite lower than that were reported by Singh and Pannu (1998) and Tiwari and Sarkar (2006). The main reason for this difference may be attributed to the different species used having different energy content, which is directly influence the output of fish.
The following conclusions are drawn from the present study:
||Fish culture in greenhouse has low specific energy use (63.60
MJ kg-1) and higher energy ratio (0.079). Rearing of fish was
economical in terms of energy in greenhouse pond.
||Use of greenhouse structure in term of energy for fish rearing was the
maximum (382.41MJ). It is because of high energy value material was used
for constructing the structure.
||In the research area for greenhouse operations the amount of inputs used
in fish production are still increasing. It is expected that the yield will
go up with the advancement of fish technology and use of larger pond, and
will become more profitable in the near future.
This research was supported by the AICRP on Application of Plastics in Agriculture, Indian Council of Agricultural Research, New Delhi. The authors are thankful to the Director, CIFA and Project Coordinator of APA Project, CIPHET, Ludhiana for their encouragement and making the facilities available.