Brown waste

Brown waste is any biodegradable waste that is predominantly carbon based. The term includes such items as grass cuttings, dry leaves, twigs, hay, paper, sawdust, corn cobs, cardboard, pine needles or cones, etc. Carbon is necessary to composting, which uses a combination of green waste and brown waste to promote the microbial processes involved in the decomposition process. The composting of brown waste sustainably returns the carbon to the carbon cycle.

...
Wikipedia