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I'm vegetarian but I need a high-protein diet. I was eating a lot of beans but they're not so great for my digestion. My belly really prefers nuts instead.

I know a lot of veggies eat cashews, but after being in Costa Rica and seeing how they are grown, I'm a little concerned about how eco-friendly they are. (Basically, there is a fruit the size of your hand, and there is one cashew that grows on the end of it. In other words, for each cashew, you need to grow an entire fruit).

Can anyone comment on what kinds of nuts are sustainable or not?

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    Growing a fruit does not make it unsustainable. Chances are that fruit is at least biodegradable and usable in compost. – user141 Apr 4 '13 at 20:39
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    Cashew juice is a delicacy, so the fruit is being used. – Earthliŋ Apr 12 '13 at 0:11
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    One thing to keep in mind is where the commercial nut is actually grown and water use. It takes one gallon of water to produce one almond in California (where 60% of the world's almonds are grown), so I'm looking for an alternative to that diet-friendly nut. – user2289 Jun 7 '15 at 21:22
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    Even if human ignore the fruit, something will eat it. If we follow your logic, we have to cut down all the forest because tons of fruits grow there without being eaten by humans – Madlozoz Jun 23 '15 at 19:44
  • @user2289 Assuming grown organically, and the water isn't getting polluted, that "one gallon of water" will be 100% recycled. So from a long-term sustainable point of view, water required per nut is not an issue. (Of course, I imagine your comment was also that California is currently in a drought, and burning fossil fuels to import water, etc. But apparently an ounce of red meat uses 106 gallons, compared to 23 for an ounce of almonds, and with the same protein %. ) (See uk.businessinsider.com/…) – Darren Cook Jun 25 '15 at 20:47
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Interestingly the cashew fruits are edible and some people do cook them. Permaculturalists also eat the young leaves cooked.

I don't think yield of nuts is the only issue. The other issues must include long-term soil issues and the like. While higher yields can in theory support larger populations, that's only one long-term variable.

In general, nuts are probably more sustainable as a class than beans because beans are typically grown as pioneer species on disturbed soil while nuts are grown as longish term trees. While beans fix nitrogen, the fact that they are pioneer species works against them in the long run.

The reason why permaculturalists disfavor pioneer species for long-term sustainability is that they grow in disturbed soil, which requires ploughing, and this leads to both depletion of nutrients and erosion of soil. This requires strategies for mitigating both pests and nutrient depletion. Trees are considered more sustainable because they represent an ecological niche closer to the apex of ecological succession and are thus can be grown in ways which require, long term, far fewer inputs. Of course this is only one factor and how the trees are grown is critically important too. For more on this, see Toby Hemenway's Gaia's Garden.

In short there are a very large number of variables. Some that I think you should consider are:

  1. How useful are the rest of the parts of the tree? With cashews, the "apples" can be cooked and eaten (mildly astringent fruit resembling the Indonesian jambu air). With walnuts, the wood is useful. We don't use as much hazelwood as we used to (it's good for bows and for tally sticks). And so forth.

  2. What is the impact long-term on the soil as it is typically grown? How much fertilizer goes in? How much in the way of pesticides? This is a real issue and it may differ so much from region to region that it makes a clear comparison difficult. In general organically grown nuts as a class will do better than non-organic.

  3. What is the embodied energy of the labor? Does it require a lot of migrant labor which comes in via car and moves around (in small groups by car) around a large area every year? Or does it support more sendantary labor? Tropical nuts will do better than temperate nuts in this regard, but....

  4. Are you growing them yourself? There is no more sustainable food than the food you grow and harvest yourself without chemical fertilizers or pesticides.

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I question your basic premise that a plant's edible yield density necessarily equates to "eco-friendly." That may turn out to be the case, but it would have much more to do with the conventional farming and production practices used, offset by any possible other sustainable uses for these disposable byproducts.

Consider that most nuts come from trees that are huge — dozens of feet tall — and often live for hundreds of years. Barring other external factors (like clearing rainforests to create farmlands, or indiscriminate use of fertilizers or pesticides that may destroy eco systems), harvesting fruits from long-lived tress seems eminently more eco-friendly than a conventional "instant crops" like beans, peanuts, etc.

But to answer the crux of your question, cashew trees produce on average about 817 pounds per acre (916 kg/hectare) (source). Compare that to other commercially-grown nuts —

From Profitable Plants:

  • Almonds — 1,500 to 3,000 shelled pounds per acre per year
  • Chestnuts — 2,000 to 3,000 pounds per acre
  • Filberts — 1,500 pounds of dried nuts per acre
  • Pecans — 1,200 to 2,000 pounds of nuts per acre
  • Walnuts — 6,000 pounds per acre
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    For Almonds you said 1,500 to 3,000 shelled pounds. What about the figures for the other nuts - are they also shelled or unshelled? – user439 Jan 20 '16 at 14:01
  • Do you think you could respond to the question in @user439’s comment? – PJTraill May 17 '18 at 9:24
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Building on Chris' answer: think about transportation.
For example, California produces a huge percentage of almonds and other nuts, and they are exported everywhere: I live in Italy and for example it's much easier and cheaper to buy walnuts from California than from any other country (Italy included).

Probably buying local nuts it's the primary factor. Given that, you can think about the rest.

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    In the case of nut, this argument is... nut Only 1 container(30 tons) of cashew nut is 165 million freaking calories. This is the ration of 1 man for 200 year. If you bring it from the other side of the world, it burns about 1 ton of fuel, which is obscene for any wares but cashew nuts – Madlozoz Jun 23 '15 at 19:41
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TLDR: Regarding water consumption and plain land use, Brazil nuts are the winners, and by far -- at least from the numbers in this old report.

I think the current answers ignore an important factor: Water consumption. (The question also already is a bit old.) I also included land use data further down, both from here.

According to around page 14 of the report, green + blue water consumption (from rain and from lakes, rivers, tab water and the like) was on global average, between 1996 and 2005: (in m³ / ton)

Shelled:

  • Almonds: 13'080
  • Hazelnuts: 9'810
  • Ground-nuts*: 3'740
  • Walnuts: 7'740

Unshelled:

  • Almonds: 6'540
  • Brazil nuts: 250 (!)
  • Ground-nuts*: 2'620
  • Hazelnuts: 4'900
  • Walnuts: 4'100

* Ground-nuts = peanuts?

Don't know/same:

  • Cashew nuts: 13'770
  • Pistachios: 10'700
  • Shea nut: 3'360
  • Sunflower Seeds: 3'170

(I couldn't find information on Pecans, Macadamia, Mongongo, ...)

Of course, there could have been big changes in production since 2005.

This is water consumption per weight, but I would guess that most nuts have similar calorie-per-weight ratios, so a comparison of these values should make sense. The couple I checked had between 560 to 620 kcal/100g.

Of course, water is only one aspect. Transport and pesticide use would be others. This article covers other aspects, with lots of sources. For example, growing Brazil nuts apparently doesn't destroy but protect the Amazon rainforest[3] (but see this paper, as pointed out by THelper). And Peanuts require few to no pesticides, they say.

Production per area, also from [1], in ton/(yr*hr) - higher is better:

  • Cashew nuts: 1.99 / 3.24 = 0.6
  • Almonds: 1.57 / 1.63 = 0.96
  • Pistachios: 0.47 / 0.45 = 1.0
  • Sunflower seed: 25.8 / 21.0 = 1.2
  • Ground-nuts: 35.5 / 23.1 = 1.5
  • Hazelnuts: 0.74 / 0.51 = 1.5
  • Walnuts: 1.35 / 0.61 = 2.2
  • Brazil nuts: (No land use, so = infinity. - they apparently grow inside of intact rainforest only )

To make this post even longer, here's a comparison of water consumption, nuts vs. meat. Numbers are based on the report, 5. below, and other calorie-listing websites which I'd post if this were not beyond my link-posting limit: (in gallons / kcal)


Edit: Title of the report:
Mekonnen, Hoekstra, 2010: "The green, blue and grey water footprint of crops and derived crop products. Volume 2: Appendices. Value of Water Research Report Series No. 47 "

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    Welcome to Sustainable Living! Nice first answer. I think that Brazil nuts can be grown sustainably, but there is always a danger of overexploitation (see this paper for example) – THelper Sep 15 '18 at 17:03
  • "Ground nuts" may refer to apios americana, not a nut at all. – Jean-Paul Calderone Sep 16 '18 at 0:04
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    Great answer! It would be helpful if you could include the titles and possibly authors of the referenced studies/articles, in case the links break in the future. – LShaver Sep 16 '18 at 3:18
  • @Jean-PaulCalderone certainly not a nut from a biology viewpoint, but included with nuts from a culinary viewpoint. – LShaver Sep 16 '18 at 3:20
  • @THelper Thanks, that's useful information, so there are issues with Brazil nuts as well. It is probably not possible to scale up production anyway, to replace any of the other nuts. (The report lists a production of 0.06 mio tons/yr, compared to 0.5 for only pistachios, or 35 for 'groundnuts'.) – dasWesen Sep 16 '18 at 15:49

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