Rainfed rice - IRRI books - International Rice Research Institute

RAINFED RICE A SOURCEBOOK OF BEST PRACTICES AND STRATEGIES IN EASTERN INDIA
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If a herbicide is to be used and if the soil is dry, apply only the liquid form. If
there is standing water, farmers can use either the granular or liquid form as
described for transplanted lowlands.
First weeding
In chemical weed control, use herbicides one to two days after rice
emergence. If farmers adopt manual or mechanical weeding, it should be
completed within three weeks of sowing. Where applicable, first weeding
can be achieved by beushening.
Second weeding
Do manual and/or mechanical weeding after four weeks of herbicide spray
or three weeks after manual weeding, whichever is required.
Nursery for transplanting
If the weed population is not very high, one hand weeding at 15 to 20 days
after seeding is adequate. Where weeds are expected to be prolific, use a
herbicide as recommended for upland rice.
Transplanted lowland
Method
Do two to three hand weedings at three-week intervals after transplanting
or use a combination of chemicals and hand weeding like in upland rice
farming. In transplanted conditions, apply herbicides preferably in the
granular form. If the granular form is not available, mix the liquid form with
sand as a carrier and apply in a thin film of water, six to seven days after
transplanting. The liquid form of herbicide may also be sprayed if there is no
standing water. After seven to 10 days of herbicide application, flood the
field to check the further growth of weeds.
Wet-seeded lowland
This type of rice culture replaces transplanting. This rice ecosystem is
becoming important due to increased labour wages and water scarcity. In
this ecosystem, the problems of weeds and weed management costs are
more than with transplanting. However, the reduced cost of establishing the
crop due to savings in water more than compensates for the problem.
Method
Use a herbicide in a granular form (more economical than manual weeding)
one to two days after rice emergence, followed by hand weeding 15 to 30
days after sowing.