Something gardeners need to think more and more about each year is water. How do we use water more efficiently and how do we not waste water?
Eric explains how he sets his garden up each year for maximum water efficiency. Black plastic does a lot of wonderful things for plants. First it heats the soil so roots grow well. Also most of the water that comes via rain or irrigation evaporates off before plants get to use it. It's estimated that 40%-50% of all water we put on plants is lost due to evaporation. That's water the plant never gets to see.
He has cut a little triangle around each plant and can hand water into that little hole. There it is trapped, holding the majority of the moisture, and holding the moisture there for a long time. Remember in your backyard, pulling up a plastic bag or tarp that had been lying on the ground, even in the middle of a drought it's moist under that tarp. It protects the soil from evaporating moisture. Thus a very efficient use of water.
In another location Eric has put down a pine mulch. Primarily he put the mulch down rather than the black plastic because he has planted a bunch of little bean seeds, thus impractical to punch a lot of little holes every 4 to 6 inches in the black poly. The mulch accomplishes many of the same things. The mulch, pine bark, and black poly both prevent weeds from popping up. Those weds would compete for water with the plants. And, both trap a lot of water underneath.
Another consideration, if you don't put down mulch or poly, rain will compact the soil. That will leave less air space for the roots to grow into, meaning less performance from your plants. Thus these coverings keep the soil nice and soft so the roots can grow in easier and can go deeper in soil when not compacted.
So when setting your garden up for maximum water efficiency, look for different ways to mulch. Black plastic and ground pine bark both prevent weeds from competing for water with your plants.