Soil application of herbicides

a. Surface application

• Soil active herbicides are applied uniformly on the surface of the soil either by spraying or by broadcasting. The applied herbicides are either left undisturbed or incorporated in to the soil.
• Incorporation is done to prevent the volatilization and photo-decomposition of the herbicides. Eg. Fluchoralin – Left undisturbed under irrigated condition- Incorporated under rainfed condition

b. Subsurface application

• It is the application of herbicides in a concentrated band, about 7-10 cm below the soil surface for controlling perennial weeds.
• For this special type of nozzle is introduced below the soil under the cover of a sweep hood.
• Carbamate herbicides to control Cyperus rotundusNitralin herbicides to control Convolvulus arvensisc.

c. Band application

• Application to a restricted band along the crop rows leaving an untreated band in the inter-rows. Later inter-rows are cultivated to remove the weeds.
• Saving in cost is possible here. For example when a 30 cm wide band of a herbicide applied over a crop rows that were spaced 90 cm apart, then two-third cost is saved.

d. Fumigation

• Application of volatile chemicals in to confined spaces or in to the soil to produce gas that will destroy weed seeds is called fumigation.
• Herbicides used for fumigation are called as fumigants. These are good for killing perennial weeds and as well for eliminating weed seeds
• Methyl bromide, Metham

e. Herbigation

• It is the application of herbicides with irigation water both by surface and sprinkler systems