EXPERIMENTAL STUDIES ON NITROGEN AND PHOSPHORUS BUDGETS OF SHRIMP CULTURE POND

Nit ro gen a nd phosphorus budget s of shr imp culture pond wer e studied in six enclo sures stocked w ith Penaeus chinensis a t three lev els, i. e, 52 000 ind. / hm2, 60 000 ind. / hm 2 and 75 200 ind. / hm 2 , respect ively. The main results w ere as fo llow s: The largest per centages of N a nd P input w ere feed and fert ilizer, 49. 7% ~ 54. 5% and 47. 5% ~ 50. 1% for N, 30. 0%~ 34. 7% and 65. 1%~ 69. 9% fo r P. Among the items of N and P outputs, the shr imp ha rvest compr ising 9. 06%~ 11. 05% o f total N input and 3. 02% ~ 3. 94% of to ta l P inputs. Uptake by muds r epr esented the majo r lo ss of N and P, comprising 19. 4% ~ 64. 6% of N input and 21. 7% ~ 95. 9% o f P input, w hile the loss thro ugh seepage only compr ising small percentage of the total input s of N and P, i. e, 5. 0% for N and 0. 5% f