Sawdust is the dust left behind by the process of cutting wood or timber. Other machining processes like grinding, drilling, shaping etc. also leaves behind sawdust. Sawdust can be fine or coarse depending on the process that was carried out. Some animals and birds too leave behind sawdust in nature.
Following natural patterns is definitely good. Nature depends a lot on leaves, limbs, seeds, broken branches etc. to enrich the soil. The same strategy can be used in gardening- enriching the garden soil by the use of sawdust and other woody elements for long term gains. Bits of wood remain in the soil for a considerably long time improving the ability of the soil to retain moisture and other nutrients, thereby providing better crops.
However, caution needs to be exercised before straight away using sawdust as mulch. Since wood is slow to decompose it tends to use up a lot of nitrogen in the process. This is natural because wood is high in carbon and cellulose. Thus, if sawdust is used directly in the soil, it would render the soil rather useless because all the nitrogen will be consumed by the sawdust. So ideally, the sawdust needs to be left to rot for at least two seasons.
It would be of interest to note however, that sawdust makes remarkable mulch for perennial crops when mixed with other organic fertilizer like poultry manure. Sawdust contributes tremendously to the soil’s quality after it has rotted, because of the spongy material remaining in the soil for a longer period of time. Wood is a natural material and it will become a soil-like eventually. So generally, sawdust is good for soil in the longer run.
The worth of sawdust as a basis of plant food is quite unmistakable when it is realized that it has the same minerals used to build the tree from which it came. For trees and shrubs, sawdust that is quite old is pretty good when mixed in the soil. It naturally keeps the roots cool by retaining moisture for long periods of time. Sawdust that has rotted in the open for a few years and turned black or dark brown is the best for this use.
Uses of Sawdust
Sawdust retains moisture around the plant roots and it can be spread shrubs as mulch. Care should be taken to spread the sawdust around the plants not pile it up against the stem.
On the farm
Sawdust can be used as litter in barns, rabbit houses and poultry sheds. The resultant mixture is a very good fertilizer.
Sawdust can be used to mix with the existing soil when a new lawn is being prepared, as a lot of humus material is required.
Old sawdust mixed in compost greatly enhances its value as well as its bulk. Fresh sawdust however needs to be used sparingly.
Decomposition of sawdust is fastest when mixed with soil and kept wet. The process is slower when it is used as mulch.