3.3. Nutrient budget
Table 3 shows the nutrient budget for all the treatments over the experimental
period. Nutrient budget revealed that shrimp feed was the major input of nitrogen
and phosphorous. Nitrogen inputs in the form of feed ranged from 76.4 to 92.4%,
and phosphorous input through feed ranged from 69.8 to 90.6% of the total inputs.
In addition, nitrogen and phosphorous inputs through feed were significantly higher
in the treatments with higher stocking density (Table 1). Nutrient budget showed
that the major portion of the nutrient inputs were deposited in the sediment followed
by nutrient contained in discharge water at harvest, and relatively smaller fraction
was retained by the shrimp. Percentage nitrogen accumulated into sediments ranged
from 14.1 to 52.8% and was significantly higher in the treatments with soil bottom
substrate. Percentage phosphorous accumulated into sediment ranged from 38.8 to
66.7% and was also significantly higher in the treatments with soil bottom substrate.
However, nitrogen and phosphorous accumulated into sediment were not significantly
affected by stocking density. Nitrogen and phosphorous retained in the
shrimp ranged from 22.8 to 30.7 and 10.5/12.8% of the total inputs, and were not
significantly different among the treatments either stocking density or bottom
substrate. Nitrogen output in the discharged water during harvest ranged from 14.1
to 28.4%, and was significantly higher in the treatments with lower stocking density,
although no significant effect of bottom substrate was observed. Phosphorus output
in the discharged water during harvest ranged from 12.4 to 28.9% and was not
significantly different among the treatments with factor either stocking density or
bottom substrate. In addition, nutrient budgets revealed that during the rearing cycle
some of the nitrogen and phosphorous went unaccounted. Unaccounted nitrogen
ranged from 5.2 to 36.0% of the total inputs, and was significantly higher for the
treatments with concrete bottom substrate. Unaccounted phosphorous ranged from
5.3 to 19.7%, and was also significantly higher for the treatments with concrete
bottom substrate.
3.3. Nutrient budgetTable 3 shows the nutrient budget for all the treatments over the experimentalperiod. Nutrient budget revealed that shrimp feed was the major input of nitrogenand phosphorous. Nitrogen inputs in the form of feed ranged from 76.4 to 92.4%,and phosphorous input through feed ranged from 69.8 to 90.6% of the total inputs.In addition, nitrogen and phosphorous inputs through feed were significantly higherin the treatments with higher stocking density (Table 1). Nutrient budget showedthat the major portion of the nutrient inputs were deposited in the sediment followedby nutrient contained in discharge water at harvest, and relatively smaller fractionwas retained by the shrimp. Percentage nitrogen accumulated into sediments rangedfrom 14.1 to 52.8% and was significantly higher in the treatments with soil bottomsubstrate. Percentage phosphorous accumulated into sediment ranged from 38.8 to66.7% and was also significantly higher in the treatments with soil bottom substrate.However, nitrogen and phosphorous accumulated into sediment were not significantlyaffected by stocking density. Nitrogen and phosphorous retained in theshrimp ranged from 22.8 to 30.7 and 10.5/12.8% of the total inputs, and were notsignificantly different among the treatments either stocking density or bottomsubstrate. Nitrogen output in the discharged water during harvest ranged from 14.1to 28.4%, and was significantly higher in the treatments with lower stocking density,although no significant effect of bottom substrate was observed. Phosphorus outputin the discharged water during harvest ranged from 12.4 to 28.9% and was notsignificantly different among the treatments with factor either stocking density orbottom substrate. In addition, nutrient budgets revealed that during the rearing cyclesome of the nitrogen and phosphorous went unaccounted. Unaccounted nitrogenranged from 5.2 to 36.0% of the total inputs, and was significantly higher for thetreatments with concrete bottom substrate. Unaccounted phosphorous ranged from5.3 to 19.7%, and was also significantly higher for the treatments with concretebottom substrate.
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