though the source water was same for all the tanks, after filling water the system
went through preparation phase for 1 week before stocking shrimp. Nutrient output
in the form of water represents nutrient contained in water on the harvest-day;
column water sample was taken to measure final nutrient concentration in water
prior to tank draining. Soil samples were collected by taking six cores from each
tank, and mixed in a composite sample for analysis; final soil sample was taken on
the harvest-day prior to tank draining. Nutrient concentration in the initial and final
soil sample was measured to calculate nutrient surplus in the soil over the study
period; the calculation was as follows: total nutrient content in sediment/nutrient
concentration in the sediment/total mass, total mass was calculated from mean