Preparing the Soil for Garden Mulching
A surface dressing of a bulky organic or inorganic material reduces moisture loss from the, keeps roots cool in summer and suppresses weed growth.
Soil is a natural reservoir for water, which is needed to a greater or lesser extent by all plants. The only natural source of water in most gardens is rain — and to a lesser extent snow — though moisture can seep in from adjacent streams and permanently boggy soil, especially in low-lying sites.
Apart from surplus rain-water whichaway, soil loses moisture in two ways — by direct evaporation from the surface and through the action of plants, which take up water in their roots and keep cool by transpiring it through their leaves.
In hot, dry spells the moisture content of soil needs to be supplemented by watering, but it can also be conserved by garden mulching. This entails placing a physical barrier between the moisture-holding soil and the air.
Garden mulches can be made from many materials — both organic and inorganic — but wood bark chippings,, well-rotted stable manure and black polythene are the most commonly used types nowadays.
In some regions, other organic materials may be readily available for use as a garden mulch — such as spent mushroom compost from mushroom farms, spent hops and brewery waste, seaweed, straw, shoddy waste from woollen mills and sawdust or wood shavings from saw mills.
In the long term, garden mulches of organic material, such as manure or compost, have an additional value — they ultimately add to the humus content of the soil.
Preparing the Soil
The addition of a mulch to the surface of the soil will impede subsequent cultivation of the ground, so it is important to prepare the site thoroughly beforehand.
Dig over the soil and eliminate all perennial weeds, either by hand-weeding or with chemical herbicides, since even broken segments of root can often grow into new plants and penetrate the garden mulch. At the same time, remove as many annual weeds as possible.
Rake in a general purpose slow-release fertilizer which will feed your plants for several months after laying the mulch. Later feeding can be achieved by using liquid fertilizers applied to the foliage or to the ground, but it will be impossible to mix granular types with the soil.
If you plan to use straw, wood bark, wood shavings or sawdust as a garden mulch — organic materials which have not been composted and will therefore use up nitrogen from the soil as they decompose — rake in an extra dressing of nitrogenous fertilizer at the rate of about a handful per sq m/yd before mulching.
If the reason for laying a garden mulch is to conserve moisture, ensure that the soil is saturated before covering it. Either wait for a heavy downpour of rain or water the site by hand. The water in the soil will still be depleted by the plants and by evaporation, and you will need to water during dry periods, but not as often as you would if the soil had no garden mulch at all.