1. Organic mulches
&
composting
Neil Barry

2. Organic Mulches - benefits
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

3. Organic mulches - limitations
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.

4. Types of Organic Mulch
Chipped bark – forestry by-product. 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.

5. Types of organic mulch – Leaf mould
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.

6. Types of organic mulch – composted straw
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.

7. Types of organic mulch – cocoa shell
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.

8. Making compost Options Hot heaps/bed method Cold heaps Leaf mould
Wormeries
Comfrey & nettle teas.

9. Composting - organisms
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.

10. Composting – garden compost
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.

11. Composting – garden compost
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.

12. Composting – leaf mould
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).

13. Composting - Wormeries
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.

14. Tea anyone? Making comfrey tea (3.5 mins):
Neil Barry

15. Homework activity:
Research different types of composting & feed back to class next week

16. Oes cwestinau gyda chi?
Neil Barry