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Starfish as compost ingredient or soil amendment

Posted by josko (My Page) on
Wed, Jun 23, 10 at 9:09

Came across a friend taking a load of starfish to the dump - they're a serious predator on his shellfish farm, and are reoutinely removed and destroyed. He must've had at least 500 lbs in his truck, and would have been glad to dump them in my driveway.
I was curious what (if any) value they would have as a compost ingredient or direct soil ammendment. They don't really 'rot' when left out, so I assume they're not nitrogen-heavy. There's probably some Calcium in their shell, or maybe even Phosphorus.
Does anybody have a clue what their nutritive contribution might be?

Follow-Up Postings:

RE: Starfish as compost ingredient or soil amendment

I'd bet they're a strong green---like most fish.

RE: Starfish as compost ingredient or soil amendment

They will stink to high Heaven. When I was a kid I put a starfish in a jar full of water and let it sit outside for a few days. When I finally opened it up the stink was overpowering, stunk up the area for hundreds of feet.

RE: Starfish as compost ingredient or soil amendment

I think if they are allowed to dry out, they do become very hard, like the ones you see in tourist shops. I notice that kelp that has been sun-dried becomes very hard and does not stink. But if put in compost pile it melts away like butter, and does stink if too much and not enough browns. I'm thinking that if you don't have enough browns to add to that whole 500 lbs to your compost, you might consider snaking a 'trench-composting'trough your garden. Once covered with enough soil, will not draw varmits and unless you forget where it is and dig into the uncomposted gunk, shouldn't bother you...but seems like it would cook down into very rich material for plants.

RE: Starfish as compost ingredient or soil amendment

If you buried them deep in an active heap or pile of wood chips, they wold be like fish or meat: high moisture and nitrogen. Potential for high stink.

Maybe trench composting would work.

Their skeleton is calcium carbonate, and it might need to be sifted out and bashed to dust if it doesn't degrade.

RE: Starfish as compost ingredient or soil amendment

I've tossed an occasional starfish in the compost, and found no trace of them later. The question here is whether it's really worth my while to compost a whole bin, given I can also get fish scrap. I've got three 4'x4'x5'bins with ~300 lb of fish scrap and 1 yd^3 of wood chips curing now. It makes great compost.
I'm wondering if it's worth my while to try a bin with starfish and wood chips, how to adjust from my usual fish+chips formula, and whether I'm likely to end up with some peculiar result owing to starfish biochemistry. In particular, I'm curious whether their calcium carbonate shells would have less phosphorus than fish bones, and whether mu usual 30 lb fish to 1 yd^3 woodchip ratio would need adjusting. Somehow, I think that 1 lb of starfish would have less N than a lb of fish, but I have no idea whether this is really correct.

RE: Starfish as compost ingredient or soil amendment

If I could get them I would use them in compost as I have done with fish and shell fish waste for years. One time I composted blue crab shells that did not get well covered with a brown and smelled up the pile a bit, all I did was add some grass clippings and the problem was instantly neutralized. FWIW: I would use them in compost.

RE: Starfish as compost ingredient or soil amendment

You have me thinking about saving the few I get each morning as I throw my cast net for my fishing charters. I tossed them back this morning but did bring home 15 or 20 pounds of threadfins (shiners) to bury where my next okra plant will go. Might be fun to see if the poor devil can out grow the rootknots.

RE: Starfish as compost ingredient or soil amendment

I have a friend who says starfish exoskeletons may have too much calcium. I found a list of NPK values for various compost ingredients including starfish on another site. The person who posted it there found it online but didn't give the source. She says at the bottom: "P.S. I just copied and pasted the entire list from the site onto MS word, then onto here. I didn't write any of the notes next to the compost ingredient."

Here is the link from my Google search: You'll need to scroll down in the post.

Here is the list:
Alfalfa Hay: 2.45/05/2.1
Apple Fruit: 0.05/0.02/0.1
Apple Leaves: 1.0/0.15/0.4
Apple Pomace: 0.2/0.02/0.15
Apple skins(ash) : 0/3.0/11/74
Banana Residues (ash): 1.75/0.75/0.5
Barley (grain): 0/0/0.5
Barley (straw): 0/0/1.0
Basalt Rock: 0/0/1.5
Bat Guano: 5.0-8.0/4.0-5.0/1.0
Beans, garden(seed and hull): 0.25/0.08/03
Beet Wastes: 0.4/0.4/0.7-4.1
Blood meal: 15.0/0/0
Bone Black: 1.5/0/0
Bonemeal (raw): 3.3-4.1/21.0/0.2
Bonemeal (steamed): 1.6-2.5/21.0/0.2
Brewery Wastes (wet): 1.0/0.5/0.05
Buckwheat straw: 0/0/2.0
Cantaloupe Rinds (ash): 0/9.77/12.0
Castor pomace: 4.0-6.6/1.0-2.0/1.0-2.0
Cattail reeds and water lily stems: 2.0/0.8/3.4
Cattail Seed: 0.98/0.25/0.1
Cattle Manure (fresh): 0.29/0.25/0.1
Cherry Leaves: 0.6/0/0.7
Chicken Manure (fresh): 1.6/1.0-1.5/0.6-1.0
Clover: 2/0/0/0 (also contains calcium)
Cocoa Shell Dust: 1.0/1.5/1.7
Coffee Grounds: 2.0/0.36/0.67
Corn (grain): 1.65/0.65/0.4
Corn (green forage): 0.4/0.13/0.33
Corn cobs: 0/0/2.0
Corn Silage: 0.42/0/0
Cornstalks: 0.75/0/0.8
Cottonseed hulls (ash): 0/8.7/23.9
Cottonseed Meal: 7.0/2.0-3.0/1.8
Cotton Wastes (factory): 1.32/0.45/0.36
Cowpea Hay: 3.0/0/2.3
Cowpeas (green forage): 0.45/0.12/0.45
Cowpeas (seed): 3.1/1.0/1.2
Crabgrass (green): 0.66/0.19/0.71
Crabs (dried, ground): 10.0/0/0 (I personally just crush the shells with my foot)
Crabs (fresh): 5.0/3.6/0.2
Cucumber Skins (ash): 0/11.28/27.2 ( WOW!!!! Who knew???)
Dried Blood: 10.0-14.0/1.0-5.0/0
Duck Manure (fresh): 1.12/1.44/0.6
Eggs: 2.25/0.4/0.15
Eggshells: 1.19/0.38/0.14
Feathers: 15.3/0/0
Felt Wastes: 14.0/0/1.0
Field Beans (seed): 4.0/1.2/1.3
Feild Beans (shells): 1.7/0.3/1.3
Fish (dried, ground): 8.0/7.0/0
Fish Scraps (fresh): 6.5/3.75/0
Gluten Meal: 6.4/0/0
Granite Dust: 0/0/3.0-5.5
Grapefruit Skins (ash): 0/3.6/30.6 (And people throw these things away? Wow!)
Grape Leaves: 0.45/0.1/0.4
Grape Pomace: 1.0/0.07/0.3
Grass (imature): 1.0/0/1.2
Greensand: 0/1.5/7.0
Hair: 14/0/0/0
Hoof and Horn Meal: 12.5/2.0/0
Horse Manure (fresh): 0.44/0.35/0.3
Incinerator Ash: 0.24/5.15/2.33
Jellyfish (dried): 4.6/0/0
Kentucky Bluegrass (green): 0.66/0.19/0.71
Kentucky Bluegrass (hay): 1.2/0.4/2.0
Leather Dust: 11.0/0/0
Lemon Culls: 0.15/0.06/0.26
Lemon Skins (ash): 06.33/1.0
Lobster Refuse: 4.5/3.5/0
Milk: 0.5/0.3/0.18
Millet Hay: 1.2/0/3.2
Molasses Residue
(From alcohol manufacture): 0.7/0/5.32
Molasses Waste
(From Sugar refining): 0/0/3.0-4.0
Mud (fresh water): 1.37/0.26/0.22
Mud (harbour): 0.99/0.77/0.05
Mud (salt): 0.4.0/0
Mussels: 1.0/0.12/0.13
Nutshells: 2.5/0/0
Oak Leaves: 0.8/0.35/0.2
Oats (grain): 2.0/0.8/0.6
Oats (green fodder): 0.49/0/0
Oat straw: 0/0/1.5
Olive Pomace: 1.15/0.78/1.3
Orange Culls: 0.2/0.13/0.21
Orange Skins: 0/3.0/27.0 (Right up there with Grapefruit. Note: both can attract fruit flies so, bury them in the compost)
Oyster Shells: 0.36/0/0
Peach Leaves: 0.9/0.15/0.6
Pea forage: 1.5-2.5/0/1.4
Peanuts (seed/kernals): 3.6/0.7/0.45
Peanut Shells: 3.6/0.15/0.5 (I grind them up in the food processor first)
Pea Pods (ash): 0/3.0/9.0 (I cut them up with a pair of scissors while shelling them)
Pea (vines): 0.25/0/0.7
Pear Leaves: 0.7/0/0.4
Pigeon manure (fresh): 4.19/2.24/1.0
Pigweed (rough): 0.6/0.1/0
Pine Needles: 0.5/0.12/0.03
Potato Skins (ash): 0/5.18/27.5
Potaote Tubers: 0.35/0.15/2.5
Potatoe Vines (dried): 0.6/0.16/1.6
Prune Refuse: 0.18/0.07/0.31
Pumpkins (fresh): 0.16/0.07/0.26
Rabbitbrush (ash): 0/0/13.04
Rabbit Manure: 2.4/1.4/0.6
Ragweed: 0.76/0.26/0
Rapeseed meal: 0/1.0=2.0/1.0=3.0
Raspberry leaves: 1.45/0/0.6
Red clover hay: 2.1/0.6/2.1
Redrop Hay: 1.2/0.35/1.0
Rock and Mussel Deposits
From Ocean: 0.22/0.09/1.78
Roses (flowers): 0.3/0.1/0.4
Rye Straw: 0/0/1.0
Salt March Hay: 1.1/0.25/0.75
Sardine Scrap: 8.0/7.1/0
Seaweed (dried): 1.1-1.5/0.75/4.9 (Seaweed is loaded with micronutrients including: Boron, Iodine, Magnesium and so on.)
Seaweed (fresh): 0.2-0.4/0/0
Sheep and Goat Manure (fresh): 0.55/0.6/0.3
Shoddy and Felt: 8.0/0/0
Shrimp Heads (dried): 7.8/4.2/0
Shrimp Wastes: 2.9/10.0/0
Siftings From Oyster Shell Mounds: 0.36/10.38/0.09
Silk Mill Wastes: 8.0/1.14/1.0
Silkworm Cocoons:10.0/1.82/1.08
Sludge: 2.0/1.9/0.3
Sludge (activated): 5.0/2.5-4.0/0.6
Smokehouse/Firepit Ash/0/4.96 (I put the ashes from my smoker in the pile)
Sorghum Straw/0/1.0
Soybean Hay: 1.5-3.0/0/1.2-2.3
Starfish: 1.8/0.2/0.25 (I'm not saying: "Go out and decimate starfish populations at our local beaches" but, the odd starfish would be okay. Incidentally, the edndoskeletons of starfish are made of Calcium Carbonate which, is slow to break down.)
String Beans (strings and stems, ash): 0/4.99/18.0 (Why we throw this stuff away? I have no idea. Look at all that potash!)
Sugar Wastes (raw): 2.0/8.0/0
Sweet Potatoes: 0.25/0.1/0.5
Swine Manure (fresh): 0.6/0.45/0.5
Tanbark Ash: 0/0.34/3.8
Tanbark Ash (spent): 0/1.75/2.0
Tankage: 3.0-11.0/2.0-5.0/0
Tea Grounds: 4.15/0.62/0.4
Timothy Hay: 1.2/0.55/1.4
Tobacco Leaves: 4.0/0.5/6.0
Tobacco Stems: 2.5-3.7/0.6-0.9/4.5-7.0
Tomatoe Fruit: 0.2/0.07/0.35 (A note on tomatoe fruit: These should be hot composted. I just let any rotted or insect eaten tomatoes compost in the soil beneath the plants and have "freebees" come back each consecutive year. Hot composting will kill the seeds.)
Tomatoe Leaves: 0.35/0.1/0.4
Tomatoe Stalks: 0.35/0.1/0.5
Tung Oil Pumace: 6.1/0/0
Vetch Hay: 2.8/0/2.3
Waste Silt: 9.5/0/0
Wheat Bran: 2.4/2.9/1.6
Wheat (grain): 2.0/0.85/0.5
Wheat Straw: 0.5/0.15/0.8
White Clover (Green): 0.5/0.2/0.3
Winter Rye Hay: 0/0/1.0
Wood Ash: 0/1.0-2.0/6.0-10.0 (A note on Wood ash: Wood Ash can contain chemicals that could harm plants and also carcinogens so, they should be composted in moderation)
Wool Wastes: 3.5-6.0/2.0-4.0/1.0-3

Read more: Making Compost at Home : Composting

RE: Starfish as compost ingredient or soil amendment

You might be a comopst wacko posting on an entire forum of compost wackos if you include the phrase

"my usual fish+chips formula"

& nobody makes a wisecrack.

RE: Starfish as compost ingredient or soil amendment

Well. I did try a pile with 4 totes of starfish and enough woodchips to fill out a pallet bin. It didn't stink, heated right up to 150-160 for a good month, dropped by about a third. I opened it up a few weeks back, and it looked great: one could see miniscule white starfish skeleton 'bits', but the end product sifted through a 1/2" mesh no problem. I ended up using it as lawn top dressing, with the reasoning that the starfish calcium might work as lime.
It was a very painless and worthwhile compost batch. I told my friend I'd be glad to take another load when he's getting them off his shellfish farm.

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