Cover Crops for Weed Suppression in Tropical Plantations

Cover Crops for Weed Suppression in Tropical Plantations

Weeds compete with young palms and rubber for light, water, and nutrients, and clearing them by hand or herbicide is a recurring cost. A dense leguminous cover crop smothers weeds in the inter-row, including aggressive grasses like cogon (Imperata cylindrica), while fixing nitrogen and protecting the soil.

How cover crops suppress weeds

A vigorous legume forms a closed canopy and a thick surface mat that shades out germinating weed seedlings and denies them light. Once established, the cover competes directly with weeds for water and nutrients, so weed density and biomass fall sharply compared with bare or unweeded inter-rows. This reduces the number of herbicide passes and manual weeding rounds needed during the vulnerable establishment years.

94.7-99.9%Reduction in weed density and dry weight under a dense Mucuna bracteata mat versus unweeded oil palm inter-rows (CABI Digital Library).
Cogon grassA closed legume cover effectively suppresses Imperata cylindrica (lalang/cogon) and broadleaf competitors.

Best cover crops for weed suppression

  • Mucuna bracteata (MB): the most aggressive weed suppressor, forming a dense mat that smothers grasses and broadleaf weeds. Best for new plantings where weed pressure is high.
  • Pueraria javanica (PJ): vigorous, self-regenerating cover with strong, durable weed suppression under moderate shade.
  • Calopogonium mucunoides (CM): rapid pioneer that establishes early cover to beat weeds in young blocks, including on acidic soils.
  • Centrosema pubescens (CP): shade-tolerant, useful for holding ground and limiting weeds under a maturing or closed canopy.

Compare weed suppression alongside shade tolerance and biomass in the cover crop comparison guide.

Getting ahead of the weeds

The key is speed: establish the cover before weeds colonise the cleared inter-row. Sow into a clean seedbed ahead of the main rains, use an adequate seeding rate, and consider a mixture so a fast pioneer closes the gap while a persistent species holds it long term. Keep a weeded circle around young trees while the legume covers the inter-row. Outcomes depend on rainfall, soil, seed quality, and management. Work out the seed quantity you need with the Cover Crop Calculator.

Related resources

Cut your weeding costs with the right cover

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