A comparative of constant and variable loading rates of organic manure in fish culture | |
| Author | Villacorta, Lyndo Gamboa |
| Call Number | AIT Thesis no. AE-89-29 |
| Subject(s) | Fishes--Feeding and feeds Fish-culture |
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science, School of Environment, Resources and Development |
| Publisher | Asian Institute of Technology |
| Abstract | The optimum loading rates of septage that led to a balanced production of natural food organisms and the maintenance of suitable environment for optimal growth of Nile tilapia (Oreochromis niloticus) were quantif_ied. The study consisted of two experiments, Experiment 1 with constant loading rates and Experiment 2 with variable loading rates. The former included six treatments with 50 kg dry matter(DM)/ha/day increments: Treatments I-0 (control); II- 50; .III-100; IV-150; V-200; and VI250 kg DM/ha/day. The latter involved varying organic inputs based on fish growth and water quality: Treatment I-100 to 75 to 100 kg DM/ha/day ; and Treatment II-150 to 125 to 100 kg DM/ha/day. High organic .inputs were needed to produce adequate suppl.ies of natural fish food but a manure input greater than 200 kg DM/ha/day created water quality problems such as wide dissolved oxygen fluctuations and high concentrations of ammonia and nitrite. A maximum extrapolated net yield of 5.7 tons/ha/year was attained by a constant septage loading of 150 kg DM/ha/day although yields of 4 . 7 from 200 and 4.1 tons/ha/year from 100 kg DM/ha/day were not significantly different. Higher :fish growth was attained in fluctuating rates of organic fertilization than with constant organ.ic loading rates. Net extrapolated yields greater than 6. 7 tons/ha/year was obtained by varying loading rates from 150 to 125 to 100 kg DM/ha/day. Using a high loading rate at the start of the culture period and reducing it with time could maintain a more balance aquatic environment for sustaining high primary productivity with optimization of fish growth. |
| Year | 1989 |
| Type | Thesis |
| School | School of Environment, Resources, and Development |
| Department | Department of Food, Agriculture and Natural Resources (Former title: Department of Food Agriculture, and BioResources (DFAB)) |
| Academic Program/FoS | Agricultural and Food Engineering (AE) |
| Chairperson(s) | Edwards, Peter ; |
| Examination Committee(s) | Lin, Chang Kwei ;Knud-Hansen, Christopher F. ; |
| Scholarship Donor(s) | The Government of Switzerland ; |
| Degree | Thesis (M.Sc.) - Asian Institute of Technology, 1989 |