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The Benefits of Mulching

  • Conserves soil moisture

  • Moderates soil temperature

  • Reduces soil erosion and water runoff

  • Increase in soil fertility by nutrient leaching or decomposition

  • Soil microorganism activity is enhanced

  • Protects surface soil from compaction

  • Coarse mulches reduce heat radiation and reflection

  • Suppresses weed growth

  • Improves soil structure and soil pore space

  • Recycling of organic waste

Avoiding Possible Problems With Mulches

  • Plants may develop nitrogen deficiency 

    • Use composted mulch materials with a C:N (Carbon:Nitrogen) ratio of 25:1 or less.​

  • Excessive moisture in fine-textured or poorly drained soils​

    • Apply treatments to improve drainage; use of mulch ​may not be appropriate.

  • Air temperatures in the winter are colder above a mulch​

    • Remove mulch before cold weather so the heat capacity of the soil can moderate air temperatures​

  • Air temperatures are hotter in summer above a mulch

    • Avoid using mulches where heat-sensitive plants could be damaged during high summer temperatures​

  • Mulched plants may be delayed in developing hardiness ​because they usually grow later into the summer

    • Remove mulch in late summer; this is not a common problem and has been reported only on species that were marginally ​hardy for the area (Whitcomb 1980)

  • Mulch may delay growth in spring because the soil warms more slowly than without mulch​

    • Remove mulch around plants to expose soil to sun in the spring; it is unusual that this would be a problem for woody plants​

  • Some diseases, such as collar rot and Armillaria root rot may be more likely​

    • Do not place mulch against the trunk and root collar​

  • Rodent damage to root collars and trunks may be increased​

    • Keep mulch away from the trunk and root collar will discourage rodent feeding because it removes their cover for activity​

  • Some mulches increase fire hazard​

    • Avoid using loose mulch of straw or other dry, lightweight materials where fire is of concern​

  • Some mulches may be phytotoxic​

    • Use mature composted mulch​

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