Ramial chipped wood

Ramial chipped wood (RCW), also called BRF (from the French name, bois raméal fragmenté, "chipped branch-wood"), is a type of woodchips made solely from small to medium-sized branches. The adjective "ramial" refers to branches (rami). RCW is a forest product used in agriculture for mulching and soil enrichment. It may be laid on top of the soil (as in mulching), mixed into it (as a green manure), or composted first and then applied.

RCW consists of the twigs and branches of trees and woody shrubs, preferably deciduous, including small limbs up to 7 cm (just under 3 inches) in diameter. It is processed into small pieces by chipping, and the resulting product has a relatively high ratio of cambium to cellulose compared to other chipped wood products. Thus, it is higher in nutrients and is an effective promoter of the growth of soil fungi and of soil-building in general. The goal is to develop an airy and spongy soil that holds an ideal amount of water and resists evaporation and compaction, while containing a long-term source of fertility. It can effectively serve as a panacea for depleted and eroded soils.

The raw material is primarily a byproduct of the hardwood logging industry, where it was traditionally regarded as a waste material. Research into forest soils and ecosystems at Laval University (Quebec, Canada) led to the recognition of the value of this material and to research into its uses.

The use of willow RCW mulch on mine waste rock can promote the spontaneous colonization of boreal tree seedlings. Moreover, the addition of RCW promotes bacterial diversity, particularly in the rhizosphere of pioneer trees and on waste rock substrates. It stimulates the development of microbial groups beneficial to plant growth, although its effect on fungal diversity is more variable. On heavily disturbed soils, particularly in boreal regions, RCW can thus play a key role in ecological restoration by facilitating the establishment of microbial and plant communities.