The effect of different fertilizer treatments on water quality parameters in rice-cum-fish culture systems

Abstract

A rice-fish culture experiment was conducted to determine the effects of different fertilizer treatments on water quality parameters, i.e. dissolved oxygen, temperature, pH and conductivity, as well as the nutrients nitrogen, potassium and phosphorus. Data gathered were subjected to analysis of variance. Dissolved oxygen, nitrogen and potassium concentrations showed significant differences (P<0.5) among the various rice-cum-fish management systems, with the highest mean concentration in the fish-only management system. The insignificant difference (P>0.05) in the oxygen concentration between rice-only and rice-cum-fish management systems was probably due to the narrow spacing of rice cultivars (20 · 20 cm). Under different fertilizer treatments, dissolved oxygen, nitrogen and potassium concentrations were not significantly different (P>0.05), indicating that different fertilizer treatments had no effect on their concentrations. Mean temperature, pH, conductivity and phosphorus concentrations in all rice-cum-fish management systems and fertilizer treatments did not differ significantly (P>0.05) from each other. This might possibly be due to the hydrogeology and climatic conditions of the area. However, all levels of studied water quality parameters were tolerable to the fish (Oreochromis niloticus) in the rice-fish ecosystem. There was no significant difference (P>0.05) in rice yield between the rice-fish management system and the rice-only management system. However, there was a significant difference (P<0.05) under different fertilizer treatments, with nitrogen/phosphorus/potassium (NPK) (20 : 10 : 10) giving the highest production of an estimated 14.36 kg ha )1 year )1 , indicating that fertilizer treatments had an effect on the rice yield. Fish growth was not significantly different (P>0.05) under different rice-fish management systems, but was significant (P<0.05) under different fertilizer treatments. Chicken manure gave the best growth with 17.7±5.97 g; estimated fish yields were 343 and 602 kg ha )1 year )1 in fish monoculture and rice-fish culture respectively. It is recommended that farmers who are more inclined to fish or rice production in integrated rice-cum-fish management systems could use chicken manure and NPK (20 : 10 : 10) respectively.

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“…Fertilizer might positively or negatively affect the ecosystem quality to the benefit or detriment of live aquatic organisms including fish (Yaro By et al, 2005). These effects for aquatic organisms moved away from toxic effects of pollutant may be deadly or recover quickly (Kuma and Krishnamoorthi, 1983;Yaro By et al, 2005). In the present study, all the deaths were only 10% after transferring 96 h toxicity test survivors to flow through tanks, which is similar with previous reports (Xu and Oldham, 1997;Little et al, 2002).…”

“…The difference might be related to fertilizer composition, fish and physicochemical characteristics of the test water (Saha et al, 2002;Palanivelu et al, 2005). Fertilizer might positively or negatively affect the ecosystem quality to the benefit or detriment of live aquatic organisms including fish (Yaro By et al, 2005). These effects for aquatic organisms moved away from toxic effects of pollutant may be deadly or recover quickly (Kuma and Krishnamoorthi, 1983;Yaro By et al, 2005).…”

Impact of phased harvesting on population structure, feed intake pattern and growth performance of Macrobrachium rosenbergii DeMan (giant freshwater prawn) in polyculture with carps in concurrent rice–fish culture

“…Diatoms and green algae mainly dominated the phytoplankton population while the zooplankton population was dominated by copepods and rotifers. Plankton density always has a profound effect on water quality and is therefore directly relationship with fish production (Smith and Piedrahita 1988;Yaro et al 2005). In this experiment, a fluctuating trend in plankton density (7.3 9 10 3 -3.3 9 10 4 ) was recorded in the different treatments (Table 5), which ultimately reflected the fish and rice yield in T 1 and T 2 (Fig.…”

Acute Toxicity of NPK 20:10:10 to Fingerlings of Clarias Gariepinus

“…[WHO, 1994] Acute concentration of different toxicant differs with formulation and with environmental conditions. Fertilizers might positively or negatively affect the ecosystem quality to the benefit or detriment of live aquatic organisms including fish [YARO et al, 2005] .…”