There are four important reasons to mulch. The first, and probably the most important, is for water conservation. Mulch stops the top of the soil drying out, keeps the soil moist, and can reduce watering by about 60 per cent. Mulching also prevents weeds and weed seed germination, which compete with plants for moisture and nutrients. Mulching also keeps the soil temperature constant, and using an organic mulch means youre adding extra organic matter to the soil. So that's an added benefit.
Mulches can either be organic or inorganic, but I prefer organic mulches because they break down and add organic matter to the soil. This improves soil structure and drainage, and encourages earthworm and soil microbial activity.
so this means that a mulch for the good old outdoors grower to use
it does feed the plant with the slow breakdown of the mulch,it adds nitrogen from the broken down plant stuff