Green organic farming: Weed management

Green organic farming - 

Method 2: Weed management

Organic weed management promotes weed suppression, rather than weed elimination, by enhancing crop competition and effects on weeds. Organic farmers integrate cultural, biological, mechanical, physical and chemical tactics to manage weeds without synthetic herbicides. 

Organic standards require rotation of annual crops, meaning that a single crop cannot be grown in the same location without a different, intervening crop. Organic crop rotations frequently include weed-suppressive cover crops and crops with dissimilar life cycles to discourage weeds associated with a particular crop. Organic farmers strive to increase soil organic matter content, which can support microorganisms that destroy common weed seeds. 

Other cultural practices used to enhance crop competitiveness and reduce weed pressure include selection of competitive crop varieties, high-density planting, tight row spacing, and late planting into warm soil to encourage rapid crop germination. Mechanical and physical weed control practices used on organic farms can be broadly grouped as: 

• Tillage - Turning the soil between crops to incorporate crop residues and soil amendments; remove existing weed growth and prepare a seedbed for planting; 
• Cultivation - Disturbing the soil after seeding; 
• Mowing and cutting - Removing top growth of weeds; 
• Flame weeding and thermal weeding - Using heat to kill weeds; and 
• Mulching - Blocking weed emergence with organic materials, plastic films, or landscape fabric. 

Some naturally sourced chemicals are allowed for herbicidal use. These include certain formulations of acetic acid, corn gluten meal, and essential oils. Weeds can be controlled by grazing. For example, geese have been used successfully to weed a range of organic crops including cotton, strawberries, tobacco, and corn, reviving the practice of keeping cotton patch geese, common in the southern U.S. before the 1950s. Similarly, some rice farmers introduce ducks and fish to wet paddy fields to eat both weeds and insects.

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