| Author | Suditha, I Putu Hery |
| Call Number | AIT Thesis no. AS-98-23 |
| Subject(s) | Fish ponds--Fertilization
|
| 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 | Relationships between Secchi disc visibility and chlorophyll a, and the feasibility of
relating'timing of fertilization to Secchi disc depth were studied in the experiments I and II.
Weekly fertilization as a control and fe1tilization to maintain secchi disc depth of 20,
30 and 40 cm, respectively, were conducted in the experiment I by supplying Urea and TSP
fertilizers, at N:P ration of 4:1 and at a rate of 28 kg N/ha/day. The results showed increase in
secchi disc depth at the third week of experimental period, the concentration of chlorophyll a
for control, treatment at secchi depth of 20, 30 and 40 cm were 91.8, 92.6, 106.2 and 156.4
µg/L, respectively. The correlation between Secchi disc depth and chlorophyll a was weak (r
values ranging from 0.07 to 0.184).
Urea and TSP fertilizer (at N:P ratio of 4:1 and a rate of 28 kg N/ha/day), and urea,
TSP and NPK fertilizer (at N:P:K ratio of 4:2:1 and a rate 28 kg NI ha/day) were applied to
control, treatments of secchi disc depth 20 and 40 cm, respectively. Addition of potassium in
the NPK treatment of experiment II did not differ significantly in Secchi depth visibility and
chlorophyll a concentration from NP treatment. Instead, Secchi depth values increased at the
first week of experiment II, although the concentration of chlorophyll a at NPK treatments
was high at the range of 7.2 to 107 µg/L, while at NP treatment, it ranged from 3.4 to 101.7
µg/L. Accordingly, correlation between Secchi depth and chlorophyll a among treatments was
weak showing r values from 0.005 to 0.144.
Delaying fertilization resulted in the deficiency of nutrient and created high ratio of
NP, which might inhibit the phytoplankton growth of water column and increased the
dominance of buoyant blue green algae. The interference of scum alga contributed to the weak
correlation between secchi depth visibility and chlorophyll a in the experiment I and II. |
| Year | 1998 |
| 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 Aquatic Systems(AS) |
| Chairperson(s) | Yakupitiyage, Amararatne; |
| Examination Committee(s) | Lin, C. Kwei ;Edwards, Peter; |
| Scholarship Donor(s) | Asian Development Bank; |
| Degree | Thesis (M.Sc.) - Asian Institute of Technology, 1998 |