A study was
conducted in a split-plot design to evaluate the effect of fertilizer placement
method on weed growth and grain yield in a dry-seeded rice (DSR) system.
Main-plot treatments were four fertilizer placement methods: between narrow
rows (between 15-cm-wide rows of the pattern 25-15-25 cm), between uniform rows
(between 20-cm-wide rows), within uniform rows, and surface broadcast. Subplot
treatments were three weed control methods: herbicide-treated, nontreated, and
weed-free. Weed biomass was greater in the nontreated plots than in the
herbicide-treated plots. Herbicide application reduced weed biomass by 89% to 99% compared with the
nontreated control. Fertilizer placement did not influence weed biomass in the
herbicide-treated plots; however, it greatly influenced biomass in the
nontreated plots. Fertilizer placement on the surface increased weed biomass (69 -71 g·m–2)
compared with the placement of fertilizer below the soil surface (37 -57 g·m–2).
Fertilizer placement did not influence weed density and biomass at 60
days after planting. Nontreated plots yielded 700 to 2080 kg·ha–1.
Grain yield was similar between the herbicide-treated (2660-3250 kg