There are numerous reasons to mulch. The most important is to conserve water. Mulch stops the top of the soil drying out, keeps the soil moist and can reduce watering by about 60 to 70 percent. Mulching prevents weeds and weed seed germination, which competes with plants for moisture and nutrients. Mulching also keeps the soil temperature constant, and using an organic mulch means you’re adding extra organic matter to the soil.
You don’t need to be a green thumb to create or use your own mulch. There is everything to gain from mulching and nothing to lose. Here is some valuable advice from www.mulchnet.com.
Not all mulches are equal and not all save water. To understand why some mulches are better than others, it is necessary to explain what makes a good mulch work. You need to imagine or have on hand a glass of water with a clear drinking straw in it.
When the sun shines on the soil, surface water is evaporated. If that is all that happened, there would be no need for mulches, but it is not. The structure of soil is such that a series of tubes are formed by spaces between soil particles. The water in the soil is “sucked up” through these tubes by capillary action, in the same way that water rises to a higher level in the straw than in the rest of the water in the glass.
By this action, water is brought up from within the soil to the surface where it is evaporated. The process continues until gravity overpowers the capillary pull. In the meantime, the soil has been dried to several centimetres deep.
If the tubes can be “broken” by making the holes much bigger, as in the surface of the glass, capillary action ceases and the moisture stays in the soil. In order to do this, the mulch should consist of large coarse particles of irregular shape which have big gaps between.
The mulch will be even better at saving water if it is non-absorbent and allows water to pass straight through and into the soil below. The mulch itself will then quickly dry off which discourages bacterial action that may otherwise result in nitrogen being taken from the soil.
Mulches that have lots of fine particles and therefore a similar structure to the soil, do not stop the capillary action. Even worse, when mulches such as rotted organic material, manure, compost or crushed plant material with added peat or straw are used, they will absorb water rather than let it through to the plant’s roots below. This simply allows the water to evaporate through the surface by capillary action.
The retained moisture in these mulches also encourages bacterial action which may pull nitrogen from the soil, will allow weeds seeds to germinate and increase the risk of collar rot when material is placed against the stem of plants.
If you’re unsure, ask your local gardening store expert. They can advise you on the best mulch to buy or, if you’re really keen, how to make your own mulch.