Ysgol Arlwyo, Lletygarwch ac Amaethyddiaeth
School of Catering, Hospitality and Agriculture
Organic mulches
&
composting
Neil Barry
Adran garddwriaeth
Horticulture Department
Organic Mulches - benefits
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Applied to the soil to reduce weed growth
and retain water.
Can prevent soil capping on silty soils
Retains warmth in the soil, producing a
more steady temperature
Can be used to protect more tender
perennials from frost.
Can be decorative and protect plants
from splashes of soil
Adran garddwriaeth
Horticulture Department
Organic mulches - limitations
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Slow to break down so do not
significantly increase soil organic
matter on their own.
Need to be thick to supress weeds –
10cm at least.
Can rob the soil of nitrogen whilst
decomposing
Must not touch the stems of woody
plants or fungal diseases will enter.
Adran garddwriaeth
Horticulture Department
Types of Organic Mulch
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Chipped bark – forestry byproduct. Comes in a number of
different grades
Easily available and a good weed
suppressant
However it can rob the soil of
nitrogen and can be easily blown
about. Some risk of introduction
of honey fungus in wood chip
products.
Adran garddwriaeth
Horticulture Department
Types of organic mulch –
Leaf mould
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Essentially free if you make your
own; recycles waste. A good soil
improver if dug in before being
replaced.
Difficult to obtain in any quantity.
Composted pine needles produce
acidic leaf mould that is good for
acid loving plants.
Adran garddwriaeth
Horticulture Department
Types of organic mulch –
composted straw
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Either produced in the garden or
purchased as mineralised
composted straw (‘Strulch’).
If mineralised, long lasting and a
good soil improver. However,
expensive to buy.
Home made will need storage
space (takes up to two years); can
rob the soil of nitrogen and can
be messy.
Adran garddwriaeth
Horticulture Department
Types of organic mulch –
cocoa shell
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By-product of the chocolate industry so
recycles waste.
Benefits – long life; pleasant smell; easy
to handle; Contains nitrogen so does not
rob the soil; good weed suppressant.
Limitations – toxic to dogs when fresh;
shipped to the UK so not necessarily
‘green’. Forms a hard crust which may
reduce water penetration.
Adran garddwriaeth
Horticulture Department
Making compost
Options
• Hot heaps/bed method
• Cold heaps
• Leaf mould
• Wormeries
• Comfrey & nettle teas.
Adran garddwriaeth
Horticulture Department
Composting - organisms
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Bacteria – the main agents of
decomposition; come in two sorts, aerobic
and anaerobic. Use nitrogen to digest
carbon and then release the nitrogen
when they die.
Worms – consume soft, partially
decomposed organic matter, reduce it to
a fine texture and excrete what they do
not need (including a lot of the carbon
and plant nutrients like phosphates)
Fungi – break down organic matter to
release nutrients and energy.
Adran garddwriaeth
Horticulture Department
Composting – garden
compost
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Hot Heap method (aerobic
composting)– careful balance of carbon
and nitrogen and regular aeration.
Benefits– kills weed seeds and (some)
fungal spores;
Quick method (3-6 months).
Limitation – need to store materials
(browns and greens) to get the right
mix; effort of turning; volume needed.
Adran garddwriaeth
Horticulture Department
Composting – garden
compost
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Cool Heap method (anaerobic
composting)- less care with carbon –
nitrogen balance, no turning.
Benefits – less effort than a Hot
Heap; requires less volume of material.
Limitations – much slower than aerobic
composting (at least a year); does not
kill weed seeds or fungal spores; can
produce smelly, slimy compost if too
wet/too much nitrogen.
Adran garddwriaeth
Horticulture Department
Composting – leaf mould
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Fallen autumn leaves are allowed
to rot in either a chicken wire
frame or punctured plastic bags.
Benefits – produces an excellent
soil conditioner.
Limitations – hard to get enough
leaves to make a significant
amount; slow process (1-2 years).
Adran garddwriaeth
Horticulture Department
Composting - Wormeries
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A small scale method for composting
kitchen scraps and some card or paper
using brandling worms.
Benefits – Wormeries can be used
inside the house in the kitchen or
garage etc. Produces a high nutrient
compost and a liquid feed (must be
diluted)
Limitations – care needed to keep the
conditions right (not too wet or too
acidic); regular care and inspection
required. Small scale only for
domestic use.
Ysgol Arlwyo, Lletygarwch ac Amaethyddiaeth
School of Catering, Hospitality and Agriculture
Tea anyone?
Making comfrey tea (3.5 mins):
http://www.youtube.com/watch?v=FZ-LeldFwVk
Neil Barry
Ysgol Arlwyo, Lletygarwch ac Amaethyddiaeth
School of Catering, Hospitality and Agriculture
Homework activity:
Research different types
of composting & feed back
to class next week
Ysgol Arlwyo, Lletygarwch ac Amaethyddiaeth
School of Catering, Hospitality and Agriculture
Oes cwestinau gyda chi?
Neil Barry