Cultural Weed Control Practices:
Several cultural practices like tillage, planting, fertilizer application, irrigation, etc., are employed for creating favorable conditions for the crop. These practices, if used properly, help in controlling weeds. Cultural methods alone cannot control weeds but help in reducing the weed population. They should, therefore, be used in combination with other methods. In cultural methods, tillage, fertilizer application, and irrigation are essential. In addition, aspects like selection of variety, time of sowing, cropping system, cleanliness of the farm, etc., are also helpful in controlling weeds.
1. Field preparation:
The field has to be kept weed-free. The flowering of weeds should not be allowed. This helps in the prevention of the build-up of the weed seed population.
2. Summer tillage:
The practice of summer tillage or off-season tillage is one of the effective cultural methods to check the growth of the perennial weed population in crop cultivation. Initial tillage before cropping should encourage clod formation. These clods, which have the weed propagules, upon drying desiccate the same. Subsequent tillage operations should break the clods into small units to expose the shriveled weeds to the hot sun.
3. Maintenance of optimum plant population:
Lack of adequate plant population is prone to heavy weed infestation, which becomes difficult to control later. Therefore practices like the selection of proper seed, suitable method of sowing, adequate seed rate protection of seed from soil-borne pests and diseases, etc., are essential to obtain a good and uniform crop stand capable of offering competition to the weeds.
4. Crop rotation:
The possibility of a specific weed species or group of species occurring is more significant if the same crop is grown year after year. In many instances, crop rotation can eliminate at least reduce difficult weed problems. The obnoxious weeds like Cyperus rotundus can be controlled effectively by including low-land rice in crop rotation.
5. Growing of inter-crops:
Inter-cropping suppresses weeds better than sole cropping and thus provides an opportunity to utilize crops themselves as weed management tools. Many short-duration pulses viz., green gram and soybean effectively smother weeds without causing the reduction in the yield of the main crop.
Mulch is a protective covering of material maintained on the soil surface. Mulching has a smothering effect on weed control by excluding light from the photosynthetic portions of a plant, thus inhibiting top growth. It is very effective against annual weeds and some perennial weeds like Cynodon dactylon. Mulching is done by dry or green crop residues, plastic sheets, or polythene film. To be effective, the mulch should be thick enough to prevent light transmission and eliminate photosynthesis.
This is another method of utilization of solar energy for the desiccation of weeds. In this method, the soil temperature is further raised by 5–10ºC by covering a pre-soaked fallow field with a thin transparent plastic sheet. The plastic sheet checks the long wave back radiation from the soil and prevents energy loss by hindering moisture evaporation.
8. Stale seedbed:
A stale seedbed is one where the initial one or two flushes of weeds are destroyed before planting a crop. This is achieved by soaking a well-prepared field with either irrigation or rain and allowing the weeds to germinate. At this stage, shallow tillage or non-residual herbicide like paraquat may be used to destroy the dense flush of young weed seedlings. This may be followed immediately by sowing. This technique allows the crop to germinate in an almost weed-free environment.
9. Blind tillage:
The tillage of the soil after sowing a crop before the crop plants emerge is blind tillage. It is extensively employed to minimize weed intensity in drill sowing crops where the emergence of crop seedling is hindered by soil crust formed on receipt of rain or irrigation immediately after sowing.
10. Crop management practices:
Good crop management practices that play an essential role in weed control are;
- Vigorous and fast-growing crop varieties are better competitors with weeds.
- Proper placement of fertilizers ensures greater nutrient availability to crop plants, thus keeping the weeds at a disadvantage.
- Better irrigation practices to have a good head start over the weeds
- The proper crop rotation program
- Higher plant population per unit area results in smothering effect on weed growth
Merits of Cultural Method
- Low cost for weed control
- Easy to adopt
- No residual Problem
- Technical skill is not involved
- No damage to crops
- Effective weed control
- Crop-weed ecosystem is maintained
Demerits of Cultural Method
- Immediate and quick weed control is not possible
- Weeds are kept under the suppressed condition
- Perennial and problematic weeds can not be controlled
- Practical difficulty in adoption