Who likes a mystery?
Okay for me this is a mystery, hopefully, some of you more seasoned gardeners and wise sages have some clues or even answers for me.
I live on the south side of a hill. There is a fairly steep drop, but the garden is the "flattest" of the slope. It drops about 4-6" in a three foot wide width of a raised bed.
We double dug the beds down to a depth of about 3'. We removed the larger rocks, and then we invented a sift for the rest of the soil, using 1" chicken wire. Which took out several 5 gallon buckets of rocks per 3x6 bed.
When the soil was returned to the bed it was layered with purchased bags of soil. The soil was built back up to level with the garden tiles (4" treated timbers). After each rain, the soil was back down to a 'sunken garden' status.
Okay, air pockets were cleared and filled with dirt. The compost in the bags of soil likely continued to break down... I explained all this to myself, and added more bags of soil to the beds. Then I added manure and mulch, planted and enjoyed a season.
By spring, I removed all the mulch, and I had sunken beds again. I went to the gravel quarry and got a pick up load of topsoil, which I just placed on top of the beds... topsoil goes on top right? I then, added aged manure, planted it and mulched. enjoyed a season again. But again, midseason, I had sunken beds! In beds that were not all season, I added more soil, the others I just kept building the mulch up to keep all well covered.
About the third year, the rocks were too bad to continue, so the beds had to be double dug and rocks removed again. Not quite as large of rocks and not quite as many of them as when dealing with virgin soil. More soil was added, when refilling the beds. Again, soil had to be topped up at midseason, and was a sunken garden by fall.
This has gone on for nearly 20 years. I look all around the beds, no signs of the soil. No deep compost, so shouldn't be that it just broke down. In most years no double digging, so shouldn't be air pockets. I even tried no till, thinking all that digging was making smaller soil particles and causing the beds to sink. Still mid season sunken bed. It is not blowing away, the beds are only uncovered for 3-4 days and then it has plastic over it to kill pests with solar power. The plastic steams nicely, so soil can't be escaping then.
There are about 1-2 earthworms per foot... but still a lot of grubs, are there.
Lizards, snakes, toads and treefrogs are plentiful, so it is a healthy area.
The beds are covered with chicken wire cages shaped like hoop houses to keep the chickens, ducks, and geese out of the plants. I want the poultry in the paths to eat the slugs and other bugs. I had a tick on me yesterday, February 22 with an ice storm! I know likely off of my goats. But, no time of the year is safe from bugs.
Rocks continue to work to the surface and soil continues to disappear.
Any ideas or suggestions as to where it is going?