Mulch
The job of building up your soil in planting areas (the subject of the previous post) will reward you with healthier plants. But the job isn’t finished until you apply mulch on top of that soil.
Mulch is a layer of relatively loose organic material, usually applied two to six inches deep in cultivated areas. There’s a whole literature on the best mulch material and when to apply it. Even the dynamics of mulch turn out to be complicated. But the benefits of mulching are easy to understand, and basic methods for using it equally so.
Probably the greatest benefit is the way mulch retains moisture in the soil beneath it. Even if you water a lot and frequently (never a good practice, really), evaporation will undo your work, particularly during our droughty summers. If you mulch, you don’t have to water as often or as much (definitely a good practice, for you and for the Island’s aquifer).
Next, consider mulch’s effect on soil temperature during the hot months. Even in a climate as moderate as ours, soil can become too warm, causing plant dehydration and slowing some kinds of beneficial soil activity. Mulch applied when soil temps have first warmed to summer levels can regulate soil temps when it’s hot out.
But don’t forget the equal benefits of winter mulching. Here the objective is using a layer of mulch to prevent the erosion of topsoils and the leaching out of minerals from the soil’s growing zone by winter rains.
Finally, think about how mulch feeds soil organisms, which, in turn, feed the soil. Much soil life depends on the presence of dead organic matter as food of the sort provided by mulch. In the process of feeding, these organisms break down that matter into nutrients for your plants.
As to the best kind of mulches, animal manures are hard to beat, whether mixed with animal bedding or not. Your supply must be aged somewhat, though, so that it’s not too hot from the decaying process that it burns plants adjacent to mulched areas. It also helps if the mulch is relatively small-particled, making uniform spreading easier and helping keep the mulch in place.
Just be sure the mulch isn’t too composted, since compost used as a mulching layer offers a perfect seedbed for weeds. Speaking of which, manures not composted enough may contain weed seeds that passed through livestock intact or blew in from nearby fields. (Composting done properly destroys seeds.) These may sprout once the mulch is spread out in planting areas.
Never use plastic films as mulch if you can avoid doing so. Plastic overheats the soil and kills much of the soil biome. If you need to use film to suppress invasive weeds or lawn grasses, remove it once it’s done the job. Better yet, use unbleached, unprinted cardboard for this purpose, topped with—you guessed it—organic mulch.
