40 pounds compost = ?? cubic feet

All of the compost I find is in 40 lb. bags and doesn't indicate how many cubic feet they are. I am not even sure how you can convert it properly since one is a measurement of weight and the other is a measurement of volume. Does anyone have a clue as to how much volume one of these 40 lb. bags of compost occupies?

that's about 1 cu foot . that's the size bag i found last year.

hth!

Interesting, I've only seen compost sold by volume, not weight. If a product isn't expandable like peat moss, a heaping 5 gallon bucket is a cubic foot. If you can visualize that, it will get you close.

Thanks that helps a lot. From my reading and a post I found on the forums I am going to shoot for 10 cubic feet per 4'x4' box to account for settling.

Couple of more questions... First, is the material in commercial bags of peat moss and compost debris-free enough to just use without sifting, or do you find it's still a good practice? Second, do you add 3" to each each board length (51" instead of 48") to account for the thickness of the boards themselves?...perhaps even more since the lattice used to make up the grid takes up some of that space as well?

My OCD is getting the best of me here I know

rob.emenaker wrote:Thanks that helps a lot. From my reading and a post I found on the forums I am going to shoot for 10 cubic feet per 4'x4' box to account for settling.

Couple of more questions... First, is the material in commercial bags of peat moss and compost debris-free enough to just use without sifting, or do you find it's still a good practice? Second, do you add 3" to each each board length (51" instead of 48") to account for the thickness of the boards themselves?...perhaps even more since the lattice used to make up the grid takes up some of that space as well?

My OCD is getting the best of me here I know

Rob,
I've never found it necessary to sift store-bought peat moss or compost. Just put it your raised beds and don't worry about it. Nature will soon handle any larger than average pieces. :-) As for adding three inches to your measurements, you're really splitting hairs IMHO. The ratios are rules of thumb and don't have to be exact to three decimal points. As Mel says, "You're not baking a cake." :-)
Best of luck.

Like Tim says, the little stuff doesn't matter. But I've purchased chicken compost by the bag that had chicken bones in it! I could identify a leg and thigh bone-I suggest removing those!

Mel himself states that 'close' is good enough. Give or take a little just doesn't matter in any part of SFG.

Most folks' 4x4 boxes end up being 48 inches on the outside because that's what you can get out of an 8 foot board. No reason to buy a 10 footer and have a foot and a half left over.

Very few of my boxes are the same size because I use whatever I have around when it's time to build a box.

I picked up 4 - 40lb bags myself... and not a hide-nor-hair mention of how many cubic feet the bag contained. Whereas the peat most clearly stated the cubic footage, as did the vermiculite.

I have some compost that's been going since last spring... but I need to sift it to keep the bigger stuff out, so that's why I got the bags.. so supplement my own compost (multiple sources, right?) Not sure if I got enough vermiculite to start, however, I only picked up one bag.. and am planning on starting with two 4'x8' (x6") boxes.

Multiple composts is a very good thing-no need to worry about ph and all that other stuff.

A 4x8 box is going to take 6ish cubic feet. Mel's mix can seem expensive when starting, but it's a lifetime investment-cheap in the long run.

Here's an online Cubic Volume Calculator...
just type in the length x's the Width x's the depth...

Cubic Volume Calculator

A 6 inch deep SFG bed would be 0.50 ft.
A 8 inch deep SFG bed would be 0.75 ft.
A 10 inch deep SFG bed would be 0.875 ft.
and so on and so on....

boffer wrote:Multiple composts is a very good thing-no need to worry about ph and all that other stuff.

A 4x8 box is going to take 6ish cubic feet. Mel's mix can seem expensive when starting, but it's a lifetime investment-cheap in the long run.

That's what I was figuring... almost shelled out the money for the Black Kow... but, decided a mix between my own compost and the cow manure compost should be a decent blend. I also picked up some 1/4" mesh (3'x36') do make a sifter with so I can keep the less composted material out. Of course, I haven't mowed the lawn since December, so...few additions in the past few months, but I started to add some leftover vegetable matter to the mix in the past couple of weeks.

I found out this weekend that the sifter is going to be required. I found a lot of matter that was not composted (sticks and a few pebbles) in my final mix. Good thing is I have several weeks until I put anything in the boxes yet so I have time to build a sifter and top everything off. Can't wait to get my own compost going!

Oh and check out my new blog for my SFG travels. I will be updating regularly with pics, things I have learned, and going-ons. There is an RSS feed at the top too so you can subscribe with Google Reader or whatever you use for feeds. Comments are welcome...

robssfg.com

Thanks...
Rob Emenaker

Link please Rob!

Happy Frog (Betty Ann) has a sweet garden blog you might want to look at too.

It didn't make a link did it. Let me retry...

http://robssfg.com

Wow, that is some coldframe!

I've been doing my SFG blogging in the Pacific Northwest regional forum....But yours is way kewl!

Thanks

Yeah that was not a cheap cold frame, but it's huge and really well built. Juwel 1000 I think is the brand and model. Trying to get off on the best foot I can

boffer wrote:Multiple composts is a very good thing-no need to worry about ph and all that other stuff.

A 4x8 box is going to take 6ish cubic feet. Mel's mix can seem expensive when starting, but it's a lifetime investment-cheap in the long run.

Indeed. I'm wondering now if I used too little compost or peat moss. I picked up a second bag of Vermiculite and mixed up what I had. I only had enough to fill one 4x8, and put down a small layer in my second 4x8 box (mostly to keep the weed fabric down.)

I used 2 bags of vermiculite, 4 bags of store bought compost, some of my own compost (maybe a bag worth), and 1 bale of peat moss. The vermiculite were 4cu/ft bags, the store bought compost were 40lb bags, and the compost was 3.0 cu/ft compressed, the largest my Home Depot carried. Again, no mention of actual volume, though the four were roughly the size of the compressed peat bale.

I had expected to fill one 4x8 and half of another... is it the extra area gained with the 4x8 vs the 4x4 boards?

So, should I just run with the full 4x8 and create another batch to fill up the second box, even the two out and add more compost to both boxes, or something else?

Hi Jeff,

You're confusing me with all your numbers!

I'm sure you're familiar with the acronym KISS ? Do it!

Lose the weight, work with volume, plan on having leftovers-I have a strong inkling you'll be making more boxes down the road to use them in. Yes, you could fill up the remaining space with compost. But, for your first two boxes, do it to spec. It will give you a baseline to compare to if you make changes down the road in other boxes.

I admit it took owning some gray hair before I acknowledged that it was silly to pay for professional advice if I wasn't going to use it. I don't take a pro's advice as gospel, but if I find myself discounting the advice because of cost, effort, inconvenience, and delay, I'm only fooling myself. After all, you did pay for a pro's advice when you bought the SFG book!

This is a 4x4 box filled with 10 cf; it will level out when saturated. That's 3 1/3 5 gallon bucket of each item in the mix. Just fill the buckets; it doesn't matter if there's air pockets or if it's heaping or slightly under.



It takes what it takes-you're committed now-do it right!

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crap, after all that, I re-read your post before I sent mine, and I didn't give you a very good answer! But I'm leaving it in cause you needed to hear it anyhow

Somehow you got too much vermiculite in the mix. I've filled multiple boxes at a time, and vermiculite usually measures out pretty close to what the fill volume of the bag is. Or was it too little peat and compost like you said. Or do both those sentences mean the same thing?! What I would do is make a proper batch, and mix it half and half with the batch you've made. Put a bucket of new in the empty bed, then a bucket of old. Repeat, stir as you go. I know how many buckets it will take, but I'm not gonna tell ya cause it doesn't matter. It's full when it's full!

Think volume!

Hi Just an FYI, a 4'x4'x6" box holds 8 cu ft. Mel's mix when available will be in 2 cu ft bags weighing 35-40 lbs. This info is from Mel at the class last wk. Seeya Phil

Mathematically it is 8cf. When it's dry. In real life, when it has been saturated, 10 cf doesn't quite make it to the top. But then, I'm not the pro, I'm just sharing my observations.