Day 4: It’s a Hole!
The next site test is about drainage, and the procedure is as follows: dig a 5-gallon hole, fill it with water. After an hour or two, top it up. Wait 24 hours. If the water is not gone, choose somewhere else to plant, because whatever you plant in this spot will drown.
So I finished my hole. It’s about 1′ diameter and about 1′ deep. I decided that was the right size, based on a number that got stuck in my head when I was in my 20s. As follows: I used to work with somebody who really exercised my brain, by engaging me in random speculations on science topics. One day, during the course of replacing one of those old 5 gallon jugs of water in the water cooler, the question came up “What does a cubic foot of water weigh?” So we got out our CRC Handbook of Chemistry and Physics (this was in the days of “books”) and looked up the specific mass of water and did the metric-to-English conversion, and came up with this: a cubic foot of water is about 7 gallons, and weighs about 62 pounds. So our 5 gallon water jugs weighed about 50 pounds. This calculation came in handy later, for the question “What does your waterbed weigh?” Easy!
And again today I got to use this number! My hole is a foot deep and a bit more than a foot in diameter. So the volume calculation gives me about .785 cubic feet, times 7 gallons/cubic foot, gives me 5.5 gallons! Done!
I’m sure my dirt will pass the drainage test with flying colors. I was thinking I’d have to cover the hole with something heavy so the critters don’t just drink the water and mess up my results, but I did the first filling about two hours ago, and the water is almost gone, even in the shade. I topped it up, but I expect the water will be completely gone by bedtime.
I noticed while I was
hacking digging the hole that the structure of the subsoil is what our Master Gardener calls “platy”, meaning thin horizontal clumps, stacked up. The preferred structure is “blocky”, and this all makes sense of the fact that the local plants tend to have wide-ranging but shallow root systems. I can attest to the difficulty of getting through those horizontal soil layers!
I don’t know what was done to this plot of dirt while they were building the house, but I can guess. See the big rocks at the far left of the first picture? There’s a small (4′) hill there. I’m guessing they scraped this area flat for the lawn, which means I’m actually looking at the original substructure of the dirt below, and that means all the nearby dirt will be similar. Oh yay. 🙄