The former prejudice against the use of sawdust in the garden is dying out, and rightly so, as properly used it has a definite value. Fresh sawdust is best added to theheap and not dug into the soil. Decomposing sawdust is attacked by bacteria which on the cellulose. These bacteria also require nitrogen and by absorbing this from the soil they reduce (albeit temporarily) its fertility. This may affect the growth of plants. When mixed with the various materials on the compost heap it is advisable to hasten decomposition by giving a sprinkling of sulphate of ammonia or a proprietary compost maker. Sawdust that has been mixed with straw, peat etc. as bedding for poultry is particularly valuable, as it has the property of absorbing ammonia. It should also be added to the compost heap. Although composted sawdust can be dug into the soil it is better to use it as a mulch in spring after the soil has warmed up. Annual weeds like groundsel and chickwced will be suppressed. Raspberries, strawberries and roses respond well to sawdust mulches. Always apply a nitrogenous fertiliser at the same time e.g. sulphate of ammonia, ‘Nitro-Chalk’ or dried blood. The sawdust can be dug in early autumn or winter. It will improve the moisture-holding capacity of sandy soil and probably help to open up heavy land. Sawdust has very little and it is thought that when used as a mulch as long as 5 years may elapse before decomposition is complete. Although fresh sawdust often produces fungus growths when worked into the soil, this does not matter, as such fungi do not attack living plants.
Seldom seen, these have several advantages: they drain freely, have a firm surface on which slipping is virtually impossible and discourage weed growth. The sawdust should be sprinkled evenly over the surface about 4 in. thick. To consolidate, roll in the usual way. Add further layers of sawdust in future years as some sinking is inevitable.