Q. I’m setting up some raised beds for planting this spring
and wondered about water evaporation from the soil. Since water retention in
the soils here in Vegas is an issue due to the heat would it make sense to put
a liner in the beds to help keep the moisture from draining out so quickly?
A. No, I would not do that. Water will drain to the liner
and begin to puddle or “perch”. You need continuous movement of water through
the soil to prevent your raised bed from staying too wet above the liner.
and begin to puddle or “perch”. You need continuous movement of water through
the soil to prevent your raised bed from staying too wet above the liner.
.JPG) |
| Raised bed under construction with cement side walls against a block wall. |
In the Las
Vegas Valley, water originating from the Colorado River carries significant
amounts of salt. Our soils also contain large amounts of salts. Some are good
salts and some are not but regardless we must keep these salts moving through
our soils.
Vegas Valley, water originating from the Colorado River carries significant
amounts of salt. Our soils also contain large amounts of salts. Some are good
salts and some are not but regardless we must keep these salts moving through
our soils.
The best
way to do this is to “overwater” our soils to flush salts through the soil. The
overwatering does not have to be much, maybe 15 to 20%. But this 15 to 20% has
to go somewhere.
way to do this is to “overwater” our soils to flush salts through the soil. The
overwatering does not have to be much, maybe 15 to 20%. But this 15 to 20% has
to go somewhere.
To keep
these salts moving or eliminated from our soils we have to make sure water
leaves raised beds and goes somewhere. A liner at the bottom of the bed slows
down this “flushing” action.
these salts moving or eliminated from our soils we have to make sure water
leaves raised beds and goes somewhere. A liner at the bottom of the bed slows
down this “flushing” action.
If you are
going to put some sort of barrier at the bottom make it porous so water can
move through it.
going to put some sort of barrier at the bottom make it porous so water can
move through it.
Any thought to the soil load going up on the non-retaining site wall? Liability lurks! Especially with the waterproofing issue.