BRF is a common term in forestry and is derived from the French “Bois Raméal Fragmenté”, or Ramial Chipped Wood. It is mulch prepared from crushed and shredded green wood branches, which enriches and protects the garden soil.
While still under the radar of the public at large, BRF/RCW is a technique that is being pioneered by organic gardeners the world over. It was developed by Canadian scientists in the 1990s.
The basic concept is to cover the soil with a mulch of shredded and crushed young branches and sprigs freshly cut from trees. These branches, usually under 3 inches (7 cm) across, act to fertilize the soil, retain water to reduce watering, and eliminate the need for fertilizer and chemical treatments.
- The main difference with wood chip mulch is that ramial chipped wood is prepared from fresh branches. They’re still loaded with live buds, sap, and nutrients.
- Branches should be processed within a few weeks to still retain the specific RCW / BRF advantages.
- Older, drier wood isn’t as nutrient-rich, although it still has all the advantages of wood chips.
BRF, RCW, an organic solution
Indeed, like any other mulch, BRF (or RCW in English) protects soil from erosion, evaporation and inhibits weed growth. On top of that, it retains water very well. Young branches tend to contain a great many nutrients since buds are where leaves and flowers are produced. These nutrients are transformed by underground fauna and flora (worms, fungus, thrips…) and are made available as organic building blocks that enrich, aerate the soil and balance its pH.
Result: beautiful, healthy plants and more productive fruits and vegetables.
BRF / RCW is thus particularly well suited to poor soil, especially if clayish or chalky.
- Note that fungus is what breaks the wood bits down into healthy nutrients.
- These fungus require nitrogen to set up shop.
- Over the first few months, nitrogen-needing plants might have a tough time, but this is more than offset after a season has passed.
Ramial Chipped Wood, a practical solution
Best spread your BRF or RCW out at the end of winter or at the beginning of spring.
- Collect branches and shoots whenever you prune shrubs and trees in your garden.
- If you don’t have enough, check with your local municipality. Often, they will let you avail of pruning waste from various landscape and gardening companies in your area.
- Crush and shred this material in a chipper shredder.
- If possible, reduce the portion of conifer branches that tend to make the soil more acidic. Keep conifers to under 20% of the content (one part conifers for at least four parts deciduous).
Spread the mulch in a layer 1 to 2 inches (2 to 5 cm) thick atop your flower beds, future vegetable beds and fruit beds.
- BRF or RCW has been proven to be effective to increase harvests for tomato, zucchini and strawberry.
Lather it under your trees and shrubs – don’t cover the soil right around the trunk though, to keep the root crown free. Run the cultivator along the ground to stir in some of the ground bacteria. That’s all!
After that, simply sow and plant whatever you wish, as usual. Apply a new layer of BRF or RCW atop the previous one in fall of the following year. Wood chips from the first layer will already have been broken down and mingled with the soil.
Laure Hamann edited by Gaspard Lorthiois
Ramial Chipped wood, a new tool for forestry management
Considering the tree as a whole
Overall, hardwood deciduous trees make for the best Ramial Chipped Wood material. Their tips are loaded with nutrients all year long:
- in spring, new growth is bursting with rich sap
- in summer, tree crowns are where most of the photosynthesis occurs
- in fall and winter, buds form for the next season and contains many nutrients.
Ramial chipped wood is a great way to maximize forestry revenue. Just as a wheat farmer sets stalks aside as straw fodder for animals, tips of trees needn’t be discarded either.
When thinning rows of cultivated trees to maximize growth of the most promising specimens, a lot of extra material is left over. Wood is either sold or kept for firewood, but until recently, leafy fronds were simply left behind.
With ramial chipped wood mulching, this rich material can benefit fields in a completely organic and environment-friendly way.
- Note that a portion of the materials should still be left behind. This is important for the forest soil to keep improving.
Adapting soil for new species of wood and lumber
Ramial chipped wood has the capacity to enhance and increase the quality of forest soil, too. This is due to long, woody compounds called lignins that take several centuries before breaking down entirely.
- This is a form of long-lasting humus that is much richer than that derived from grassy plants and lawn trimmings.
RCW/BRF and soil pH
Plots of land that have long been planted with conifers tend to turn acidic. Conversely, soil that is above limestone bedrock tends to be rather alkaline.
Ramial Chipped Wood corrects these deviations and brings soil pH nearer to neutral.
- You can control soil pH with Ramial Chipped Wood.
- Actually, the resulting soil is very slightly acidic, at 6.8, which suits plants better than strictly neutral “ph 7”.
Applying RCW over a couple seasons will significantly impact the pH.
- Soil that was too acidic for higher-value wood can then be planted without fear in soil that is more neutral.
- Excessively alkaline soil can be brought to a more acidic pH.
This is very relevant in tropical island countries, where most of the soil is alkaline due to pH-raising coral bedrock.
Best tree varieties for Ramial Chipped Wood
Deciduous varieties that make for the richest RCW mulch
Deciduous trees such as birch, poplar, maple and hophornbeam are often used for RCW. They are fast-growing. When harvested at mature size, these trees can earn an extra amount from the very rich branch tips they leave behind.
Credits for images shared to Nature & Garden (all edits by Gaspard Lorthiois):
Ramial Chipped wood production by USDA Forest Service Research Operations, USDA Forest Service via Bugwood.org
RCW / BRF mulch lain down by Howard F. Schwartz, University of Colorado via Bugwood.org