small levees were raised around each treatment plot.
Marl was broadcast 15 to 30 days in dry soil before transplanting and fertilizers were applied within one to three days before transplanting.
Three 30-day-old seedlings per h i l l were planted 25 by 25 cm apart in straight rows in
puddled soil at all sites.
Water was applied to the experimental plots about one week before planting.
This was followed by rainfed surface flooding through the cropping season.
Top-dressing with ammonium sulfate was done at the panicle initiation
stage. Weeding and pest control were practiced.
Yield components at harvest were recorded for statistical analysis. Grain yield was measured
by sampling 8 m2 of each 12 m2 plot.
The economic aspects were also evaluated.
Production costs and returns were calculated by recording all variable and fixedcosts at each site.
The profit could then be calculated by deducting total costs from the
gross crop value.