The other day I was driving through my neighborhood and I noticed something quite dramatic. At the end of last fall, I saw someone spreading mulch beneath some Norfolk Pines, presumably as a sheet mulch to kill the grass beneath the trees in an effort to respect drought restrictions. Unfortunately, the mulch only covered the ground beneath two out of three of the trees. I guess they never got their project done. When I drove by recently, I noticed that the two trees that had mulch spread beneath them were alive and well while the third tree, surrounded by dead grass, had itself died.
The mulch held moisture in and prevented evaporation over the summer. The area with no mulch did not get enough moisture to keep the tree hydrated during the dry periods.
This is a perfect testament to Mulch, which doesn't get a lot of glory in this day and age of trending green technology. Forests have known the secret of mulching for time immortal, so there's nothing new and innovative to capitalize on here. In fact, we seem to disregard the lessons that the natural world has taught us because we want to believe that we can innovate something more clever and sophisticated. Mostly, we can't. Nature has far more elegant solutions than anything we can come up with. If we can pay attention long enough, we'll learn her magic and get farther down the road of efficiency than anything we can buy will get us.
No rainwater collection is complete without a layer of mulch covering bare dirt around plantings. Mulch is like a giant sponge. It soaks up any standing water and holds it in place rather than allowing it to flow away from plantings. Brad Lancaster has a great video demonstrating this.
But there is a difference between mulch and wood chips. Wood chips are great aesthetically, but can rob the soil of nitrogen. So if you are trying to grown plants that need nitrogen for fertility, you might notice them struggling. Applying nitrogen rich fertilizer, or using more broken down mulch will help. Here is a great article from Rodale's Organic Life on mulch basics. Be sure to click around on the image or advance pages to learn about each mulch option.