Should waste be chopped or shredded?

Wednesday, 16 July 2014  |  HOTBIN Composting

 

Should waste be chopped or shredded before adding to my HOTBIN?

Chopping Waste Increases the Speed of Breakdown

 

Ideally yes, chopping and shredding waste will help decrease the time taken for waste to compost and ensure a more consistent finer texture in the end compost you achieve.

 

Why Consider Chopping / Shredding Waste?

  1. Greater Surface Area - When you chop and shred waste you increase the surface area. Bacteria eat at the surface – the more surface to attack the faster the rate of eating. Although the maths does vary, one can approximate each cut to doubling the surface area – and doubling the speed.
  2. Breaks Through Protective Layers - Chopping cuts through the outer protect layers such as barks, shells, peels and skins. These layers are designed to be more resistant to bacterial attack. If we cut through them, bacteria can attack the easier to digest material behind. This tends to generate heat faster and higher temperature increases the rate of further decay.
  3. Finer Compost – Chopping/Shredding helps to ensure a finer and more consistent texture in the final product.
  4. Food Waste – This may need to be chopped to increase the surface area of the waste for bacteria to eat.

 

Tools and Techniques


Tool
 

Positives

Negatives

Knife / Secateurs

Cheap
Easy

Time consuming.
Hard for large volume waste

Machete, Axe

Easy/Medium

Safety – Be careful

Shredder

Good for high volume.

They can be expensive and take up storage room.
Essential no stones are added – wreck blades in seconds.

Hedge Trimmer

Pile up hedge trimming and then cross cut pile.
Little time needed to reduce a big pile of branches to a small pile of leaves and chippings.

Will only work on small branches.

Rotary Lawn Mower

Great for autumn leaves.
Can shred and collect at same time.

Essential no stones are in the leaf pile.
Works for other non-woody garden waste.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Things to Chop!

  • NOTE: Aim for all waste to be less 4cm, and preferably less than 2 cm.
  • Broccoli, cut along length so bacteria can get to softer inside.
  • Rose stems (small diameter, less than 0.5 cm) chop into 4 cm long bits.
  • Bones – e.g. chop chicken bones in half so bacteria can get inside.
  • Woody stalks (less than 1 cm diameter), chop 4cm length.
  • Woody stems (greater than 1 cm diameter) – pass through a shredder.
  • Tree branches – need to shred.