MATERIALS AND METHODS
Study area
The study area was located at the uncultivated field
behind „Ofrima‟ building within University of Port
Harcourt, Nigeria. The site (open field) was divided into
smaller plots (blocks) of 9m2 areas.
Herbicides
The herbicides used were purchased from a local
agricultural dealer store in Port Harcourt. The herbicides
are Gramoxone (designated “G” in this study) which
contains 276 g paraquat dichloride (200 g paraquat ion)
per litre and Multrazine (designated as “M”) which
contains 50% atrazine as the active ingredient.
Gramoxone is distributed by CG Biostadt Limited while
Multrazine is marketed by Multichem Industries Limited.
Soil treatments
The herbicides were applied at recommended rates (G1
= paraquat, M1 = atrazine) and half (0.5x) therecommended rates (G2 = paraquat, M2 = atrazine) to
know their effect on the soil bacterial population. The
treatments were carried out at recommended rates of 0.6
L/ha (at 30 ml in 10 L sprayer) for paraquat and 3 L/ha (at
150 ml in 10 L sprayer) for atrazine. Thereafter, two other
preparations were made which contained half the
recommended concentration of each herbicide. Soil
treatments were carried out in duplicates. The
preparations were made as described by Pal et al.
(1994)