Can Pistachio nut shells be added to the compost bin? - Knowledgebase Question

Massapequa Park, Ne
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Question by ndpettit46
July 12, 2010
Can Pistachio nut shells be added to the compost bin?

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A comment from 2016NGA20e
February 3, 2018
The answer like most things with compost is "it depends." It depends on your setup, where your compost bin is, what you're using the compost for, and how long you're composting.

I generally agree with NGA that seedy weeds are about the only thing I DON'T put in my compost, but only because I don't put time and work into creating well-mixed, frequently-turned, HOT compost.

With respect to break-down of nut shells, I don't care. The surface of my garden is littered with pieces of composted eggshell, chicken and beef bones, and nut shells. It doesn't hurt anything and finishes breaking down slowly over a period of years. I'm not trying to win an award for manicured garden.

With respect to salt, it depends on relative volume. A 1/2 gallon of salty pistachio shells (that's a lot of shells) in a 64 cuft compost pile (4x4x4) is NOT a problem. A 50-lb sack of salty nuts...that might be a problem, but it might not be. When I have a bag of salty peanut shells from a restaurant, I usually use them as surface mulch around my asparagus, because asparagus doesn't mind a little salt.

With respect to vermin and smells, it depends on where you are and what type of compost bin you have. If your compost bin is on an apartment balcony, you may need to be more conservative in what you put in the bin. I have a large plastic-walled bin with plastic and wire mesh on top. I have to use the mesh because of dogs and racoons. Now I compost raw meat, cooked meat, fat, oil, nut shells, eggshells, paper plates, napkins, qtips, paper towels, and the rest of the kitchen and garden waste. It helps to have a lot of carbonaceous material (the browns) to mix with the above materials since they're high in water and nitrogen. Covering with lot of carbon material helps to eliminate flies, other bugs, smells, and 4-legged pests.

In warm climates or in the summer, you are likely to attract soldier flies if you compost kitchen scraps. I'm trying to make compost - not fat larvae. So in the summer, I usually bury my compost in wide trenches in an unused garden bed...covered with wire and plastic mesh to keep dogs from digging it up.

I leave compost in the bin for 6 - 12 months, and usually only turn it a few times. When I use my compost in the garden, I sometimes shake it through a homemade 1/2 inch mesh screening box. And then sometimes after picking out the occasional pieces of plastic and foil, I'll just throw all the larger pieces onto the garden surface anyway or maybe back into the compost bin.

Hope this helps a bit. Keep on gardening!!

Name: J.R. Baca
Pueblo West Co. ( High Dessert (Zone 6a)
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Answer from josebaca
September 2, 2017
Working for the local school district, we must use 'safe' alternatives, one such is walnut shells to sand blast graffiti. After a serious rainstorm some bags were 'damaged' and had to be discarded. Needless to say they are now servicing as a soil loosener ( is that a word? ) right alongside the perlite.
If your soil is light enough then maybe you could make biochar with them.

Answer from NGA
July 12, 2010
Stay away from greasy kitchen scraps, meat, fish, bones, etc. They will decompose, but they may also attract rodents and that's probably not something you really want to have. I'd also keep weeds that have gone to seed out of the compost bin. Chances are the heat generated by the decomposition process will kill the seeds, but it's happened that weeds, squash, melons and tomato plants popped up in the finished compost. 

As for the pistachio shells, like walnut shells, they are very hard and won't readily decompose even in a well managed batch of compost. You can crush them prior to adding them, but they will still take years and years to break down. They will add bulk to the compost, though, so they are not harmful to add, they just won't decompose for a few years.

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A comment from BonniePega
February 3, 2018
I would be sure the pistachio shells are not dyed and not salted.

Name: Phillip williams
(Zone 7b)
A comment from phillipawill
February 3, 2018

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