|Mechanical/Physical methods of weed control with Merits and Demerits
Mechanical methods of weed control
Mechanical/Cultural/Physical method of weed control are being employed ever since man began to grow crops. Many agricultural practices are dictated by the need for weed control. Although herbicides are fast replacing the traditional methods of weed control, mechanical methods are very much needed to make weed control more effective and economical. The mechanical methods include tillage, sickling, hoeing, hand weeding, digging, mowing, burning, flooding, mulching etc.
Tillage removes weeds from the soil, resulting in their death. It may weaken plants through injury or root and stem pruning, reducing their competitiveness or regenerative capacity. Tillage also buries weeds. Besides controlling weeds, tillage affects the physical condition of the soil.
Simple ploughing helps I buried of annual, biennial and many perennial weeds.
The important tillage implements are the plough, harrow etc. The type of implement needed for most effective weed control depends upon the weed species, underground root system, age of the weed etc.
Hoe has been the most appropriate and widely used weeding tool for centuries. “The man with the hoe” which symbolized weed control centuries is being replaced by “The man with sprayer”. Hoe, however is still a very useful implement to obtain results effective and cheaply. Hoeing is particularly more effective on annuals and biennials as weed growth can be completely destroyed.
Hand weeding is done by physical removal or pulling out of weeds by hand or removal by implement called khurpi, which resembles sickle. It is probably the oldest method controlling weeds and it is still a practical and efficient method of elimination weeds in cropped and non – cropped lands.
Digging is very useful in the case of perennial weeds to remove the underground propagating parts of weeds from the deeper layers of the soil. This practices is more effective than hand pulling. Digging is accompanied by hand pulling of the plant. Hand pulling without proper digging results in the removal of top growth only, allowing regrowth from the left over plant parts.
Sickling and mowing:
Sickling is also done by hand with the help of a sickle, to remove the top growth of weeds, to prevent seed production and to starve the underground parts. Sickling is also done to reduce the mature perennial weed growth.
Mowing is a machine operated process mostly done along roadside and on lawns. It’s objectives is same as that of sickling.
Burning or fire is often an economical and practical means of controlling weeds. It is used to
1. Dispose of accumulated vegetation
2. Destroy dry tops of weeds that have matured.
3. Kill green weed growth.
4. To destroy the buried weed seeds
Fire is used to burn crop residues in cotton, sugarcane, potatoes, corn, soybean, sorghum, castor etc.
Flooding is sometimes used for weed control in rice. Which is able to grow under flooded conditions. Flooding kills plants by reducing oxygen availability for plant growth. The success of flooding treatment depends upon complete submergence of weeds for long periods.
Mulching is the method of covering the soil with some organic or inert materials such as straw, saw dust, bark dust and other plant parts of various sizes. It is also done by paper, plastic sheets or polythene. So mulching is the practical on small scale in some areas to check the growth of weed.
Merits of Mechanical Method
1) Oldest, effective and economical method
2) Large area can be covered in shorter time
3) Safe method for environment
4) Does not involve any skill
5) Weeding is possible in between plants
6) Deep rooted weeds can be controlled effectively
Demerits of Mechanical Method
1) Labor consuming
2) Possibility of damaging crop
3) Requires ideal and optimum specific condition
Useful Agricultural Websites
Online Agricultural Study
Food and Agricultural Organization