PYRENEES QUARRIES PTY. LTD.
Pyrenees Quarries – Your One Stop Stone Suppliers

Primary website at:
 www.pyreneesquarries.com.au

 

STONE MULCH

 

PROPERTIES OF  SHALE  MULCH:
Shale is a lightly metamorphosed form of mudstone.  The light colour helps to reflect light and heat, keeping the soil cooler.  This shale is very micromicaceous, containing  thousands of microscopic sized grains of clear muscovite mica which act like thousands of tiny mirrors in the stone.  This reflects the heat, and keeps the ground cooler. 
Shale is a clay based rock. At night, the clay platelets absorb atmospheric moisture which  then evaporate during the heat of the day, further cooling the stone.  
The shale is composed of flat stone pieces, not rounded as in conventional pebbles.  The flat stone pieces limit air circulation and hence water evaporation.  This can be compared with a board or piece of tin left on a lawn overnight.  It will be damp underneath next morning, whereas a ball left on the lawn overnight will only leave a very small damp area. 
The shale mulch contains 2-5% silty clay.  This washes off readily, bonding together the bottom layer of stone.  This adds an additional barrier to air circulation on top of the soil, while still allowing water to readily penetrate and for the soil to breathe naturally.

• BENEFITS OF SHALE MULCH:
  Maximum benefit from shale mulch is obtained where low or no garden watering is required, or where a fire risk is present.  Unlike conventional organic mulches, shale and stone do not absorb significant water during rainfall events.  Most rainfall events in summer are either low rainfall, ie, less than10mm, or heavy thunderstorm events, where the rainfall is more than 10mm occurring in less than an hour.
  With organic mulches, low rainfall is absorbed into the mulch layer with little or no water penetrating to the plant roots.  With heavy thunderstorm events, the rain water sheets off, which causes conventional organic mulches to float off.  With stone mulch, this will only occur in extreme cases, with the stone “trapping” the water long enough for most to soak in, thus, the water becomes available to the tree roots.  Additionally, stone mulches do not add plant oils and resins to the soil.  These oils and resins cause the water to “bead” on top of the soil and not soak in, whereas the silty clay from the shale aids water absorption.  Additionally, as organic mulches begin to decompose, they become dark coloured, thus absorbing more heat from the sun.  With increased soil heat, water evaporation and water loss from the soil occurs more rapidly.
  Unlike other stone mulches, metamorphic shales and slates are “flat” in shape, thus reducing air circulation – hence water evaporation is also reduced.  As an additional benefit, the flat shaped stone pieces improve weed suppression. Flat shaped stones are less prone to “roll and scatter” and are more easily maintained than rounded pebbles.
  Slate/shale mulches are naturally occurring quarried stones, hence “recycled” chemicals (present in some organic mulches) should not be present.
  Stones are less prone to be wind blown, bird scratched, water washed etc than organic mulches.  Stone mulches are not flammable so will not burn.
  With shale mulch, the soil temperature remains lower and, as it is a permanent capping material, plant feeder roots are able to permanently exist closer the soil surface, thus permitting nutrient and moisture capture by the plant from smaller rainfall events.

• ADDITONAL TIPS:
  Shale mulch can be used on top of conventional mulches.
  For low or no water gardening, do not over fertilize.  Use only sufficient compost/fertilizer to maintain slow but healthy growth through the wetter months.   Excessive growth and foliage causes the plant to require more water to survive (water is lost through the plant leaves and stems) - the less foliage, the less water required for the plant to remain alive and healthy through dryer periods.
  When watering is required through plant stress, water more deeply but less often.
  Do not use dark coloured stones or materials except where additional “heating” of the ground is required.
  Use a light coloured micromicaceous clay based stone for increased ground cooling effects (shale, slate or schist are normally best).
  Use a stone which is flat shaped to reduce air circulation and hence water loss.  Flat shaped stones are also better for increased weed suppression and less prone to “scatter”.
  Consider using stone mulches to reduce fire risk where this may be a problem.
  An air blower can be effectively used to remove leaf litter.
  Stone mulches do not supply any significant nutrients to the soil, but do supply some natural minerals.
  DO NOT use slate or shale for driveways or high traffic pathways as these will crush more readily than other harder pebbles.

•  OTHER BENEFITS OF STONE MULCH:
  1:    Long lasting.
  2:    Helps retain soil moisture.
  3:    Helps keep soil warm in winter, cool in summer.
  4:    Lasting attractive colour.
  5:    Low maintenance.
  6:    Fire resistant.
  7:    Insect and mould resistant.
  8:    Little compaction with time.
  9:    Easy water penetration.
  10:  Not easily wind blown.
  11:  Pet and plant friendly.
  12:  Lower long term cost than conventional mulches

• STONE TYPE: 
  The shale mulch produced by Pyrenees Quarries is a lightly metamorphosed slaty silty shale, pastel beige pink to beige green in colour, flaky, soft and very micromicaceous.

SLATE MULCH SIZES:
1:  Fine: shale flakes approximately 10-30 mm in diameter.
2:  Medium:  shale pieces approximately 30-70 mm in diameter.
3:  Large:  shale plates approximately 70-200 mm in diameter.

RECOMMENDED USAGE:
Fine shale mulch for pots, planters and small garden beds.
Medium shale mulch for larger garden beds, and over the root areas of shrubs, bushes and trees.
Coarse shale mulch for rock gardens and dry creek beds or where a more rustic appearance is required – may be mixed with medium grade as required.
Better water retention if applied over a thin layer of organic mulch.
NOTE:  Product NOT suitable for high traffic areas.

RECOMMENDED APPLICATION RATES:
Fine shale mulch; recommended minimum application depth 50mm.
Medium shale mulch; recommended application depth 50-100mm.
Coarse shale mulch; recommended application depth 100mm plus.
Thicker application rates improve moisture retention and weed suppression.

COVERAGE CALCULATIONS:
Calculate the square meters of area to be covered (eg. An area 2 meters long by 3 meters wide is 2x3=6 square meters.  For shale mulch applied at 50mm thick, this would be a cubic meter volume of 6x0.05= 0.3 of a cubic meter).
OR:  1 cubic meter will cover an area of 40 square meters at 25mm thick.
OR:  1 cubic meter will cover an area of 20 square meters at 50mm thick.
OR:  1 cubic meter will cover an area of 10 square meters at 100mm thick.
A full load on a conventional 6ftx4ft trailer is 0.5 or half a cubic meter.
Weight is approximately 1.5 tonne per cubic meter.

PRICE: 
Calculated on a cubic meter basis or part thereof.

"Urban Landscape in the Suburban Jungle"
The Garden Design and labour completed by the owners Ken Johnstone
& Mark De Wacht, who wanted to keep the garden low maintenance with
visual impact & style.  All the Retaining Walls and Decking by Hans Van Den Hengel.  Shale mulch supplied by Pyrenees Quarries.

OTHER NATURAL STONE PRODUCTS:
For all your stone requirements please visit our main website at: www.pyreneesquarries.com.au

Pyrenees Quarries is a Member of the
*CASTLEMAINE SLATE SANDSTONE AND GRANITE SUPPLIERS.