Two of the experiments used for the study took
place in the wet season (1998 and 1999); the other
took place in the dry season (1998±99).
Experiments in the wet season included a rice crop
(beginning of wet season) followed by a rice ratoon
crop (middle of wet season). The experiment in the
dry season included a rice crop followed by a period
during which fish remained in the trench without
any access to the field. In all experiments IR62032
rice was hand-seeded at a rate of 150 kg ha±1, or
row-seeded at a rate of 80 kg ha±1. Hand or row
seeding did not show any effect on fish production
parameters (N Vromant, unpublished data). While
we applied inorganic fertilizer to the rice at normal
rates, we did not apply organic manure. All fields
were thoroughly hand-weeded and, when necessary,
insecticides or fungicides were applied.