|Title:||Use of Tobacco Dust Plus as botanical pond toxicant in freshwater|
The Tobacco Dust Plus (TDP), a specially formulated mixture of finely ground sundried tobacco leaves and packaged commercially as an organic fertilizer for algal growth in fishponds, was evaluated as pond toxicant on the polyculture of Vannamei (white shrimp) and tilapia and in the monoculture of Vannamei in freshwater pond in comparison with Tea Seed (TS) in Calumpit, Bulacan. The trial was conducted to 1) develop a protocol on the use of TDP to control fishpond snails and other fish predators in freshwater polyculture systems; 2) formulate location-specific technology recommendations on the use of tobacco dust as botanical pond toxicant and fishpond fertilizer and; 3) generate data to support the registration of TDP as botanical toxicant for fishponds to the Fertilizer and Pesticide Authority (FPA).
TDP was applied at two rates, 400 kg and 500 kg/ha, and TS at 200 kg/ha. Two ponds per treatment were used which also served as replication.
Results from both monoculture and polyculture systems showed that snails were effectively controlled by TDP at 400- 500 kg/ha (95 - 100%) and 200 kg/ha of TS (92- 99%). On the other hand, different species of fish predators were effectively eliminated 30 minutes to 48 hours after application of both the TDPat 400- 500 kg/ha and TS at the rate of 200 kg/ha.
In the monoculture system, soil properties such as pH, percent of organic matter, total available nitrogen, available phosphorus, and the exchangeable potassium was improved slightly by the application of TDP and TS, but was not within the desired level for optimum growth of fishes and shrimps as set by the Bureau of Fisheries and Aquatic Resources (BFAR). During the culture period, water depth was only 0.5 – 0.6 m which was lower than the desired range of 1.0 – 1.5 m. This was due to the El Niño phenomenon that existed during that year. As a result, the average temperature in ponds with TDP was much higher (33.50 -34.40 °C) than the desirable range (23 -30 °C) for vannamei culture. However, the dissolved oxygen level was within the desirable range at 3 mg/lit.
Results further showed that ponds treated with 400 kg/ha of TDP consistently gave the highest average weight (8.0 - 28 g) and length (10.5 - 15.5 cm) of vannamei from 30 - 105 days after stocking (DAS) followed by ponds treated with 500 kg/ha of TDP in the polyculture system. The highest kilogram (667.6 and 660 kg) and total sales (P43390 and P42,900.00) of tilapia harvested was obtained from ponds treated with 500 and 400 kg/ha, respectively. There was a difference of P41,808 (500 kg/ha) and P41,314 (400 kg/ha) in the total sales of tilapia compared with the control. On the other hand, the highest total kilograms of vannamei harvested was obtained from ponds treated with 500 kg/ha (222.2 kg) valued at P57,772 with a difference of P54,704 if compared to the sales from the control. The lowest total sales of tilapia (P3,237) and vannamei (P19,449) came from the TS fishponds. The highest total sales of both tilapia and vannamei (P101,176) was obtained from ponds treated with 500 kg/ha of TDP.
In the monoculture of vannamei, ponds treated with TDP at the rate of 500 kg/ha produced the heaviest (8.30 g) vannamei after 60 days of culturing. On a per hectare basis, pond applied with 500 kg TDP had a computed sales of P81,885 on vannamei with a net income of P10,670 and 14.98% ROI per hectare. Ponds applied with 400 kg/ha of TDP and TS with 200kg/ha, recorded a total sales of P9,319 and P66,784 respectively. Thus, incurred a negative net income and ROI for both treatments.
However, economic analysis was not performed under the polyculture system because harvesting of the cultured species was not completed due to typhoons Ondoy & Pepeng which totally flooded the ponds.