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If one makes coffee in the backcountry, there will be used grounds. Coffee grounds are biodegradable, but should one instead pack them out completely?

What is the Leave No Trace way to deal with used coffee grounds in the backcountry?

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The material in Owlcation, Can Caffeine Kill? How It Impacts Animals, Plants, and the Environment, updated June 23, 2018, suggests that the safest thing to do with coffee grounds, relative to the environment, is to pack them out.

Caffeine has a stimulating and apparently not harmful effect on horses, birds, and bees. Caffeine is banned in horse racing and in competitions involving pigeons. Bees naturally get caffeine from citrus plants.

However, it can kill other animals and can kill plants. In its natural plant-produced form caffeine functions as a pesticide and inhibits enzymes in herbivorous insects’ nervous systems, triggering paralysis and death in the more susceptible bugs. Others show enduring reproductive harm.

Since many bugs are essential parts of many ecosystems, this can be an adverse effect on the environment if you bury coffee grounds. For example, caffeine kills or harms mosquito larvae (maybe not bad, although fish eat them), spiders, snails and frogs. Caffeine can kill dogs and cats.

Caffeine in the soil destroys organisms that prey on coffee plants, but

..... despite its protection against predators, whether insect, fungal, or bacterial, and despite its ability to prevent weeds and competing growth, caffeinated soil eventually destroys the very plants which produce it and at first thrive because of its production.

As for use in agriculture

The Hawaiian government wanted to spray caffeine on frogs as a form of pest control.

However, the permit that had legalized caffeine-based pesticide use and development was suspended after the EPA, spurred by an angry public, stated a need for more information on how non-targeted insects and animals would be affected should the plan be carried out.

The final point to check is if used coffee grounds contain a significant amount of caffeine. According to Caffeine Informer, the answer is Yes, they do.. The article states further:

Care should be used when disposing of spent coffee grounds as caffeine has been detected by some municipalities in our waterways and reservoirs.

What all this adds up to, even if you are not hiking near a coffee plantation, and even if you applaud killing mosquito larvae, is that the caffeine presents enough dangers to animals and plants that, in the spirit of caution and Leave No Trace, packing coffee grounds out instead of scattering them or burying them is the way to go.

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    ‘Pack them out” - what does that mean? It’s not an idiom with which I’m familiar. Do you mean, pack them up and take them with you? Or do you mean, pack (squeeze) them into some cavity somewhere? ‘Pack.... out” is an unfamiliar use of English, and your answer contains no other context explaining it. – Chris Melville Jun 9 at 8:15
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    @Chris it means take it home with you. backpacker.com/trips/packing-out-waste-you-can-take-it-with-you – Richard Tingle Jun 9 at 8:21
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    Don't know. Tea has less caffeine than coffee. Don't know whether used tea leaves retain proportionally less than used coffee grounds. It is a separate Q. Tea leaves are often reused by people who don't mind weak tea. – ab2 ReinstateMonicaNow Jun 9 at 18:39
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    "Caffeine can kill dogs and cats." So can water, if it comes in faster than they can handle. It's all about when it's lethal, not about if. Everything is potentially lethal. – Mast Jun 10 at 8:21
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    @Mast Why is it that, any time somebody points out that something is poisonous to something else, somebody feels the need to point out that dose is important? When people say things like "Caffeine can kill dogs and cats", they are saying "Caffeine can kill dogs and cats in doses that a dog or cat could conceivably accidentally eat", not making the vacuous statement "Pretty much any substance can kill a dog or a cat if administered in sufficiently high doses. Caffeine is an example of a substance." – David Richerby Jun 10 at 11:12
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The Leave No Trace approach to coffee grounds is to bring them in carefully without spilling them, use them responsibly without making a mess, and take them with you when you leave, together with all your other biodegradable materials. Don't scatter, bury or burn them.

In June, 2019, Popular Science magazine published an article based on an interview with Ben Lawhon, the Education Director at Leave No Trace Center for Outdoor Ethics. It's entitled "How to leave the great outdoors exactly how you found it. No, you can't just throw food in the woods."

The summary comes down to one main idea, that if humans bring in anything that would not have been there without us, we must not leave it behind. Used coffee grounds are not found in nature, so they should be taken out, whether or not they'd biodegrade eventually.

To best put the principles into practice, ask yourself, “Would this item be here or would this area look like this if I had never come through?” Answering that will ensure you’re minimizing your effect on nature.

Used coffee grounds belong in the category of Rule 3, Dispose of Waste Properly.

“Pack it in, Pack it out” is a familiar mantra to seasoned wildland visitors. Any user of recreation lands has a responsibility to clean up before he or she leaves. Inspect your campsite and rest areas for trash or spilled foods. Pack out all trash and garbage.

The United States Government has a 26-page manual on how to train leaders in the principles of Leave No Trace before taking groups out. It's mostly focused on Alaska, but the Principles are the same. The part that addresses your question about coffee grounds begins on page 10, and is based on the same Leave No Trace Principle #3 as other sources. It includes coffee grounds in the list of things that should be taken when you leave.

Ensure everyone understands what qualifies as trash and how it must be secured. “Pack it in, pack it out” is the simple mantra to follow.

  • Biodegradable trash, such as orange peels, apple cores, coffee grounds and onion skins, must be packed out.
  • Trash must be secured with food to prevent conditioning of bears, rodents, birds and other animals.
  • Separating trash into dry and wet containments allows dry trash to be compressed tightly and wet trash to be doubly- or triply-secured.

Orange peels and other biodegradable foods are number one in the Leave No Trace Five most common litter sightings. While coffee grounds aren't specifically listed here, the related foods mentioned elsewhere are. From this I infer that coffee grounds should not be left behind.

  1. Orange Peels
    Orange peels can take as long as two years to decompose. There is a common misconception that “natural trash” such as orange peels, banana peels, apple cores, and shells from nuts and seeds are okay to leave behind on the trail, in campgrounds, or in other outdoor spaces. While these things are natural, they are not natural to the places they are being left. These types of trash attract wildlife to areas with human activity, affecting their health and habits.

An author of The Adventure Journal has studied Leave No Trace for years, and has given himself a Leave No Trace Black Belt. He calls it the "highest order of LNT."

I have abided by these guidelines for years, and along the way utilized some ideas that go a little above and beyond Leave No Trace’s basic guidelines, which I have half-jokingly called “The Leave No Trace Black Belt,” as if it is the highest order of LNT, the practices of true masters of the craft.

One of his litmus tests is to consider animals, and how we attract them to the site. If a bear can smell coffee grounds, we've upset the order of things in the bear's world. (This is true for all animals, and is mentioned in many articles.)

He challenges us to examine our dedication to leaving no trace in a simple question: Did we really do everything we could to leave no trace of our passage?

When considering the Leave No Trace Black Belt, imagine a fierce, hypersensitive bear who will kill you if it detects the slightest ripple in its environment-minute food scraps scattered into the woods, coffee grounds buried under a rock, wildflowers smashed by a tent. Did you really do everything you could to leave no trace of your passage here?

The excellent answer you received about caffeine is very important. I had no idea how much damage caffeine does to our world! Nothing written I found based on, or implied by, Leave No Trace, mentioned caffeine at all. Perhaps it's to make sure people don't feel that it's okay to leave decaffeinated coffee.

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Used (spent) coffee grounds contain little to no caffeine (after all, its been extracted into the cup you drank). Depending on the situation, either pack it out, bury, or spread diffusely over a wide area.

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    Do you have a citation for the claim that there's little to no caffeine? Is coffee brewing really that efficient at extracting "coffeeness" from the grounds? If you use the same grounds a second time, the result is yucky weak coffee, not water. – David Richerby Jun 10 at 11:08
  • So this guys says there's a fair bit of caffeine left in the used coffee grounds: caffeineinformer.com/caffeine-content/coffee-grounds and yet coffee grounds are good for a compost bin: today.oregonstate.edu/archives/2008/jul/… – timmmay Jun 10 at 20:25
  • @timmmay - I moved this over for you as per Sue's comment. Once you have more rep you will be able to leave comments, and with just a little more rep, you can edit things like this in to other people's posts to help improve them. Welcome :-) – Rory Alsop Jun 13 at 19:26

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