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Mulches of Many Colours

Author:

Janice LeBoeuf - Vegetable Crop Specialist/OMAFRA
Creation Date: 11 May 2006
Last Reviewed: 11 May 2006


Whether you want to modify soil temperature, control weeds, conserve moisture, keep the produce clean, influence plant growth, or modify insect behavior, there is a mulch for the job. Degradable mulches are also available for growers hoping to minimize the labour and disposal costs of removing plastic at the end of the season. Since no mulch will do all of these tricks, and some features cost more than others, growers must consider the costs and benefits before making a decision. The following chart summarizes some of the key attributes of a number of plastic mulches.

Type of plastic mulch

Properties

Features

Clear
  • transmits most incoming light
  • maximum increase in soil temperatures
  • weeds grow under the plastic

Black
  • absorbs most incoming light; some heat transferred to soil but much lost to atmosphere
  • minimal increase in soil temperatures, however the plastic can get hot enough to damage plant or fruit
  • controls weeds

White
  • reflects most incoming light; remaining light transmitted through mulch
  • generally decreases soil temperature
  • weed growth depends on how much light the mulch transmits

White on black
  • reflects most incoming light (white layer)
  • blocks transmission of light (black layer)
  • generally decreases soil temperature
  • controls weeds

IRT (infrared transmitting) (several colours)
  • absorbs photosynthetically active wavelengths
  • transmits infrared & near-infrared wavelengths
  • increases soil temperatures (less than clear, more than black), but the plastic stays cooler than black
  • suppresses weed growth

Reflective (silver, aluminum, striped)
  • reflects most incoming light
  • generally decreases soil temperature
  • controls weeds
  • used for management of specific pests

Coloured (red, yellow, blue…)
  • reflect specific wave-lengths back to the crop
  • light transmission (amount & wavelength) varies with product
  • may influence growth & development of certain crops & varieties
  • soil warming effect & weed growth or suppression depends on light transmission properties of the product

Photodegradable*
  • broken down by sunlight, but buried edges unaffected
  • reduces removal & disposal costs, but buried edges remain
  • other features depend on colour, optical properties

Biodegradable*
  • broken down by heat, light, soil organisms, wear & tear
  • reduces removal & disposal costs
  • other features depend on colour, optical properties

* With degradable mulches, the timing of breakdown must suit the cropping system. It is best to try them on a small scale, initially, to ensure they suit your production system.

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