Efficacy of Hercides for weed control in soyabean(glycine max)under a no-Tillage cultivation system in Zambia

A study was conducted at Lilayi farm in a no-tillage crop production system.
The objective of the study was to assess the efficacy of new herbicides in a
no-tillage soybean cultivation system in Zambia. Eleven treatments were used
in this study. These include four preemergence, five postemergence and
combinations of these herbicides. They were compared with hand hoe weeding (14
and 28 days after planting) and no weeding.
The seedbed was prepared by two applications of 0.6 kg a.i/ha paraquat before
planting and this effectively controlled the first and second flush of weeds
respectively. However, Euphorbia heterophylla recovered from the application
of paraquat whereby the new shoots emerged from the lower nodes. All
preemergence herbicides gave a season-long control of Nicandra physalodes. The
infestation of other weeds was very low that their presence was considered to
be negligible. The ability of Euphorbia heterophylla to recover from the
application of paraquat made postemergence herbicides unable to control this
weed effectively.
Weed cover relative to crop cover was low throughout the season. Whereas the
no weeding treatment had significantly the highest weed biomass, other
treatments did not differ significantly from each other in weed biomass.
Preemergence application of oxadiazon resulted in highest soybean seed yield
and the no weeding treatment gave the lowest seed yield.