|PD/A CRSP Twentieth Annual Administrative Report
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Subcontract No. RD010E-07
Auburn University, Alabama
|Claude E. Boyd||US Principal Investigator|
|C. Wesley Wood||US Principal Investigator|
|Taworn Thunjai||Ph.D. Student (Thailand; CRSP funded)|
|Kom Silapajarn||Ph.D. Student (Thailand; partially CRSP funded)|
|Orawan Silapajarn||Ph.D. Student (Thailand; partially CRSP funded)|
|Danie Brink||Host Country Principal Investigator|
|Khalid Salie||Research Assistant|
|Mali Boonyaratpalin||Host Country Principal Investigator|
|Julio Queiroz||Host Country Principal Investigator|
This subcontract was awarded funding to conduct the following Tenth Work Plan investigations:
Boyd, C.E., 2002. Management of bottom soil condition and pond water and effluent quality. In: C. Lim and C.D. Webster (Editors), Tilapias: Culture, Nutrition, and Feeding. The Haworth Press, Binghamton, New York. (in press)
Boyd, C.E., T. Thunjai, and M. Boonyaratpalin, 2002. Dissolved salts in water for inland, low-salinity shrimp culture. Global Aquaculture Advocate, 5(2).
Boyd, C.E., C.W. Wood, and T. Thunjai, 2002. Aquaculture pond bottom soil quality management. Pond Dynamics/Aquaculture CRSP, Corvallis, Oregon, 41 pp.
Boyd, C.E., C.W. Wood, and T. Thunjai, 2001. On-the-ground uses of CRSP pond soil research results. Aquanews, 16(4):13.
Rowan, M., 2001. Chemical phosphorus removal from aquaculture pond water and effluent. Ph.D. dissertation, Auburn University, Alabama.
Aquaculture America 2002 at San Diego, California, 2730 January 2002. (Boyd, Wood, Thunjai)
PD/A CRSP Annual Meeting at San Diego, California, 31 January 2002. (Boyd, Wood)
Latin American and the Caribbean Region Expert Panel Meeting at San Diego, California, 1 February 2002. (Queiroz)
World Aquaculture 2002 at Beijing, China, 2327 April 2002. (Boyd)
Asia Region Expert Panel Meeting at Beijing, China, 23 April 2002. (Bolivar, Boyd)
Africa Regional Expert Panel Meeting at Nairobi, Kenya, 8 July 2002. (Brink)
Pond water and bottom soil samples were collected from 35 tilapia ponds near Samutprakarn, Thailand, and from 17 tilapia ponds near Chiangrai, Thailand. The ponds ranged in age from 3 to 38 years. Ponds had been treated with large amounts of liming materials, and soils usually had pH above 7. Total alkalinity and total hardness concentrations in pond water usually exceeded 100 mg l-1. Total carbon concentrations in pond soils were mostly between 1 and 3%. About two-thirds of the carbon was in organic form and the remainder was bound in carbonate. Soil carbon concentrations in ponds at Samutprakarn were similar to those in ponds at Chiangrai. The source of the inorganic carbon was liming materials. Although large inputs of liming materials originally were necessary to increase the pH of the naturally acidic soils, the pond soils now have rather high pH. Thus, liming is no longer necessary, and it is possibly counterproductive in some ponds. Soil respiration rates averaged higher in ponds at Samutprakarn than those at Chiangrai. The reason for this difference has not yet been determined because all analyses have not been completed. There is a weak tendency for soil organic carbon to increase with increasing pond age. Sediment had been removed one or more times from some of the ponds at Samutprakarn. Nevertheless, soil quality was not different between ponds as a result of sediment removal.
Samples of liming materials used in Thai aquaculture were analyzed. About half of the brands had mislabeled liming compounds or were of low quality. Farmers should insist that vendors analyze liming materials and report results of analyzed labels.
The ponds for this research were acquired on a private farm in Brazil, and the study was initiated in December 2001. The treatments are as follows: 1) agricultural limestone was applied over pond water surface after filling (3 ponds); 2) agricultural limestone was applied over pond bottom before filling (3 ponds); 3) agricultural limestone was applied over pond bottom followed by tilling of soil before filling (3 ponds); and 4) control (no agricultural limestone was applied).
Water samples are being collected weekly for analyses of total alkalinity and total hardness concentrations. Soil cores are being collected monthly and divided into 2 cm segments that are being analyzed for pH and exchangeable acidity. Pond aspects of the study will be completed in October 2002, but analyses of soil will not be completed until early 2003. Preliminary analyses reveal that all methods of liming increased the alkalinity and hardness of water in roughly equal amounts. Furthermore, there does not appear to be large differences in rates and depths of reaction in bottom soils related to method of application of agricultural limestone.
Ponds for this research were arranged by the University of Stellenbosch. The treatments are as follows: 1) agricultural limestone was applied over pond water surface after filling (3 ponds); 2) agricultural limestone was applied over pond bottom before filling (3 ponds); 3) agricultural limestone was applied over pond bottom followed by tilling of soil before filling (3 ponds); and 4) control (no agricultural limestone was applied).
Water samples are being collected weekly for analyses of total alkalinity and total hardness concentrations. Soil cores are being collected monthly and divided into 2 cm-long segments, that are being analyzed for pH and exchangeable acidity. The experiment was initiated in July 2002, and the pond sampling will be completed in February 2003. The study has not progressed far enough to have preliminary information on the performance of the different treatments.
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