Green manures add short-lived fertility to your soil, but chipped branch wood is a much longer lasting source of organic matter. Combine the two and you’ll create incredibly rich soil!
What is Chipped Branch Wood?
Chipped branch wood is made from the twigs and stems of deciduous trees, with or without leaves, that have a diameter of 2.75in (7cm) or less. You can use wood from conifers if the proportion is less than 20%. The branch wood is chipped into pieces ¾ - 1 inches (2-3cm) wide and 1/10 inch (3mm) thick.
It’s important to recognise chipped branch wood is distinctly different from the types of wood chips that are made of trunk wood or bark. It’s special because nutrients and materials that convert into long lasting organic matter are concentrated in the smallest twigs and branches. This gives your soil good structure. Also, unlike other types of wood chips, “nitrogen robbery” isn’t a problem with chipped branch wood.
Sourcing the Wood Chips
The best source is closest to home. If you have deciduous trees on your property, use them first. If you don’t have your own source, you can ask a tree services company that clears brush or electrical lines.
Preparing the Wood Chips
On a small scale, use an axe or garden shredder with a chipping attachment to create the chips. For large quantities, it’s more economical to hire a tree services or landscaping company to chip it for you. After chipping, it’s best to apply it immediately or as soon as you can. If allowed to heat up in a pile it will begin to compost and lose energy. They can only be stored if kept dry.
Using the Wood Chips
Apply the chips in early Autumn or Winter, but before it snows, by hand or with a shovel. They must be in close contact with the soil so they can be decomposed quickly by micro-organisms. Apply at a rate of two pounds per ten square feet (1-2kg per square metre). Using a rake, mix the chips with the top 2in (5cm) of soil. Be careful not to bury them too deeply because the appropriate organisms need oxygen and are closest to the soil surface. For the same reason, don’t apply the wood chips to waterlogged soil or when the ground is expected to be too wet.
If your soil has been intensively cultivated, the required micro-organisms may not be present, or in very short supply. When applying the wood chips for the first time, it’s recommended to supplement the soil with these micro-organisms. To accomplish this, apply leaf mould at a rate of 0.35 – 0.7oz per 10 square feet (10g – 20g per square metre). Collect the ideal leaf mould from the ground of a deciduous forest at a depth of about 2 inches (5cm).
Combining Chipped Branch Wood with Green Manure
To get the best results, it’s recommended to follow the application of wood chips with a green manure. This will enhance the performance of both the chips and the green manure. Apply your chips first, then follow up with green manure a week or two later. Schedule your green manure during the fallow period of your crop rotation, or an overwinter green manure followed by a crop that has low nutrient requirements such as carrots.