In my last couple videos,
you saw me carrying dozens of bags of leaves and pale after pale of compost.
This prompted a few of you to wonder if I might be adding too much organic matter to the garden,
and ,in retrospect,
I can see how these images might have given that impression.
So, today I thought I’d talk about how much mulch and compost we add to the garden,
and begin to address the question “is it too much?”
Let’s start with compost.
We added more compost this year than ever before,
and based on the dimensions of our five compost bins,
I can provide a fairly accurate estimate of how much.
Our largest bin provided about 1 cubic yard of compost.
We emptied all 0.9 cubic yards from this bin.
This temporary bin yielded about 0.7 cubic yards.
0.5 cubic yards were harvested from this bin.
And, finally, though this bin holds 1.25 cubic yards,
we only harvested, at most, a quarter of that, or about 0.3 cubic yards.
That gives us a total of 3.4 cubic yards of compost.
But wait a minute.
We added quite a bit of vermicompost to the garden too,
so let’s make sure to add that to the total.
Here more guesswork is involved because we usually harvest castings a little at a time, as they’re needed,
which makes the quantity harder to gauge.
My best guess, though,
is that we added about 0.33 cubic yards of vermicompost to the garden this year,
bringing our total to 3.73 cubic yards.
Now let’s use a landscape calculator
to figure out how much compost we’d need to add 2 inches of compost
to our 580 square feet of growing space.
I chose 2 inches based on horticulturist Jeff Gillman’s recommendation
to amend garden beds with 2 to 3 inches of compost per year.
I enter a length and width that will give the desired 580 square feet;
and enter a depth of 2 inches.
It turns out we’d need 3.6 cubic yards to add 2 inches of compost.
So, the 3.73 cubic yards we harvested was just enough!
If we wanted to add 3 inches,
we’d need 5.4 cubic yards.
As I mentioned earlier,
we added more compost this year than ever before.
For example, in prior years
we didn’t harvest compost from this compost bin.
So, subtracting the one cubic yard of compost it produced,
leaves us with 1 ½ inches of compost.
And two years ago,
we also didn’t harvest from this bin.
Subtracting the 0.5 cubic yards it provided
leaves us with only 1 1/4 inches of compost applied to the garden.
So, at least by the standard of 2 to 3 inches per year,
we’re not applying too much compost to the garden.
In fact, most years
we apply considerably less than 2 inches.
Now let’s talk mulch.
As with compost, Gillman recommends adding as much as 2 to 3 inches of mulch per year
to perennial and no-till garden beds.
While it was pretty straight forward estimating how much compost we use,
it’s more difficult to do with mulch.
We chop and drop comfrey and garden waste during the spring and summer,
and mulch with leaves and used coffee grounds in the fall.
We also mulch our blackberries, raspberries, and grapes with wood chips.
Last year we mulched our vegetables with aged wood chips as well
but didn’t this year
because we had a lot of rain
and didn’t want the soil to hold too much moisture.
Like I said, it’s difficult to estimate,
but if I had to guess, I’d say we probably mulch somewhere in the ballpark of 2 to 3 inches per year.
So, at least based on Gillman’s recommendations,
I don’t think we’re adding too much organic matter to the soil,
and I’ve seen no evidence of it in terms of the health of our plants.
Even so,
I plan to have the soil tested in the spring
to get a clearer picture of organic matter and nutrient levels.
I’ll pay particular attention to the level of phosphorus,
because too much organic matter in the soil
can lead to elevated phosphorus levels.
So, if the nutrient levels are high,
especially the phosphorus,
that will be a good indication that we can reduce the amount of compost and mulch that we’re adding to the garden.
Well, that's all for now.
Thank you very much for watching,
and until next time remember
you can change the world one yard at a time.