DOING THE MATH: How much food to actually feed a community.

[zak]

This is an open question, but one I'm going to try (to some extent) to figure out. How much food can urban farms produce, and is it feasible to try to mostly feed a city's population with food grown within a certain distance? I'm trying to think of this purely in numbers. How many calories does a person consume a year? How much growing area would be needed to feed that one person? To feed 1000 people? Or a million?

I don't realistically think everything is going to be grown in immediate surrounding areas (besides things that are never going to be for most areas, like coffee, chocolate, etc. People will still want these but they're mostly non-essential.) -- at least not in the immediate future -- but it's a good equation to figure out.

To put it simply:
How much does a city/community eat in a year and how does that directly translate to square footage of food grown?

[Justin Boland]

Great contrarian perspective on home gardens from Alternet:
http://www.alternet.org/environment/86943

Suppose that half of the land on every one-acre-or-smaller urban/suburban home lot in the entire nation were devoted to food-growing. That would amount to a little over 5 million acres (pdf) sown to food plants, covering most of the space on each lot that’s not already covered by the house, a deck, a patio, or a driveway. (And in many places it couldn’t be done without cutting down shade trees and planting on unsuitably steep slopes).

That theoretical 5 million acres of potential home cropland compares with about 7 million acres of America’s commercial cropland currently in vegetables, fruits, and nuts, and 350 to 400 million acres of total farmland. The urban and suburban area to be brought into production would not approach the number of healthy acres of native grasses and other plants that are slated to be plowed up to make way for yet more corn, wheat, soybeans, and other grains under the newly passed federal Farm Bill.

A nationwide grow-your-own wave would send good vibes through society, ripples that could be greatly amplified by community and apartment-block gardening. But front- and backyard food, even if everyone grew it, would not cover the country’s produce needs, much less displace our huge volume of fresh-food imports.

The PDF being mentioned is available here and this is a goldmine:
http://www.ers.usda.gov/publications/EIB14/eib14g.pdf

[Justin Boland]

Can sustainable agriculture feed the world?
http://www.foodfirst.org/files/pdf/back ... 7final.pdf

Author discusses his findings here:
http://www.foodfirst.org/node/1778

From our food production estimate based on the 10 food categories and 160 cases in developed countries, we found that organic production could theoretically generate an amount of food equal to 92% of the current caloric availability (or a yield ratio of 0.92). This ratio is close to that found in a 1990 study by Gerald Stanhill of Israel's Agricultural Research Organization. However, looking at the 133 examples from the developing world, our team estimated food production equivalent to an overall yield ratio of 1.80—that is, 180% of current production in the developing world on a caloric basis.

From these regional results, researchers at the University of Michigan then constructed two models, a "conservative case" and a "realistic case." The "conservative case" applied the yield ratios of organic production to conventional production from the developed countries to worldwide agricultural production (production in both the developed and developing countries). As the yield ratios in the ten food categories were generally lower in the developed countries, applying them worldwide means that slightly fewer calories would be produced under a fully organic global system: 2,641 kcal/person/day instead of 2,786 kcal. However, this number is still above the suggested intake for healthy adults of 2200 to 2500 kcal/person/day, so even under this conservative estimate there would be sufficient food production for the current population. However, under more realistic assumptions—that a switch to organic agriculture would mean the relatively lower developed world yield ratios would apply to production in the developed world and the relatively higher developing world yield ratios would apply to production in the developing world—the result was an astounding 4,381 kcal/person/day, a caloric availability more than sufficient for today's population. Indeed, it would be more than enough to support an estimated population peak of around 10-11 billion people by the year 2100.

[jstorvick]

The data I keep coming across on the web and in gardening books suggests that, to provide an adequate, year-round vegetable diet (excluding grains) for a family of four using standardized organic gardening methods, you would need a garden plot about 4000-5000 square feet (which might be doable on a standard suburban lot). Using different methods, like John Jeavons' dynamic biointensive techniques, you could decrease that square footage considerably. Unfortunately, at this point, there is no reliable and consistent data regarding yields from permaculture/edible forest gardening techniques, though I would venture to guess that the yields could be quite high if designed correctly.

My vision of community food production would include a forest garden on every lot, and a community space reserved for the growing of grains using sustainable and renewable Fukuoka methods.

[Korey King]

huge list of warm climate fruits, including yields: http://www.hort.purdue.edu/newcrop/morton/index.html
think most data on average yields is pulled from commercial sources.

some common, and not-so-common-but-should-be ones:

Orange
On the average, a 'Washington Navel' orange tree may bear approximately 100 fruits in a season. It is said that very old, large orange trees in the Mediterranean area may bear 3,000 to 5,000 oranges each year.

Growers everywhere are testing high-density as a means of gaining higher yields. In Australia, 'Valencia' orange trees 6 years old, planted 1,011 to 2,023 trees per acre (2,500-5,000/ha), yielded 24 tons/acre (60 tons/ha). 'St. Ives Valencia' trees on P. trifoliata rootstock and inoculated in the nursery with mildly dwarfing exocortis, were planted in 1973 at densities ranging from 270 to 2,023 trees per acre (667-5,000 trees/ha). Those at 506 trees/ acre (1,250/ha) yielded 55 tons/acre (135 tons/ha). Those at 1,214 to 2,023 trees/acre (3,000-5,000/ha) yielded 105 tons/acre (260 tons/ha) until after the 4th crop, when productivity began to decline.


Lime
The yield from 7 ft (2.13 m) trees grafted on alemow rootstock has averaged 90 lbs (41 kg), while trees of the same size on rough lemon yielded 63 lbs (29 kg). Under advanced methods of management, Florida lime groves produce 600 bushels per acre (243 bu/ha) annually.


Mango
At 10 to 20 years, a good annual crop may be 200 to 300 fruits per tree. At twice that age and over, the crop will be doubled. In Java,, old trees have been known to bear 1,000 to 1,500 fruits in a season. Some cultivars in India bear 800 to 3,000 fruits in "on" years and, with good cultural attention, yields of 5,000 fruits have been reported. There is a famous mango, 'Pane Ka Aam' of Maharashtra and Khamgaon, India, with "paper-thin" skin and fiberless flesh. One of the oldest of these trees, well over 100 years of age, bears heavily 5 years out of 10 with 2 years of low yield. Average annual yield is 6,500 fruits; the highest record is 29,000.

Average mango yield in Florida is said to be about 30,000 lbs/acre. One leading commercial grower has reported his annual crop as 22,000 to 27,500 lbs/acre. One grower who has hedged and topped trees close-planted at the rate of 100 per acre (41/ha) averages 14,000 to 19.000 lbs/acre.


Mangosteen
Cropping is irregular and the yield varies from tree to tree and from season to season. The first crop may be 200 to 300 fruits. Average yield of a full-grown tree is about 500 fruits. The yield steadily increases up to the 30th year of bearing when crops of 1,000 to 2,000 fruits may be obtained. In Madras, individual trees between the ages of 20 and 45 years have borne 2,000 to 3,000 fruits. Productivity gradually declines thereafter, though the tree will still be fruiting at 100 years of age.


Lychee
The yield varies with the cultivar, age, weather, presence of pollinators, and cultural practices. In India, a 5-year-old tree may produce 500 fruits, a 20-year-old tree 4,000 to 5,000 fruits–160 to 330 lbs (72.5-149.6 kg). Exceptional trees have borne 1,000 lbs (455 kg) of fruit per year. One tree in Florida has borne 1,200 lbs (544 kg). In China, there are reports of 1,500 lb crops (680 kg). In South Africa, trees 25 years old have averaged 600 lbs (272 kg) each in good years; and an average yield per acre is approximately 10,000 lbs annually (roughly equivalent to 10,000 kg per hectare).


Passionfruit
Many factors influence the yield of passionfruit vines. In general, yields of commercial plantations range from 20,000 to 35,000 lbs per acre (roughly the same number of kg per ha). In Fiji, with hand pollination, 173 acres (70 ha) will yield 33 tons (30 MT) of fruits. Hybrids in Australia have raised yields far beyond those obtained with the purple passionfruit.

On the average, a bushel of passionfruits in Australia weighs 36 lbs (16 kg); yields 13 1/3 lbs (6 kg) of pulp from which is obtained 1 gal (3.785 liters)–that is 10.7 lbs (4.5 kg) of juice, and 2.6 lbs (1.18 kg) of seeds. With some strains, the juice yield is much higher.

-------

averaging out all food bearing trees, a mature tree will produce between 40-200kg (88-440 lbs) of fruit per year.

so, if this was the community standard and each lot had an average of 5 trees per (2front 3back), would produce around 150lbs/tree/year, or 750lbs of fruit or nuts, total. ten lots would produce 7500lbs, a hundred lots producing 75,000lbs of food from trees alone (once mature).

and last I heard the average american eats 5lbs a day, 1825lbs a year. high average 3 to a household, we'll say 5500lbs consumed per lot.

...we're gonna need more than trees. Or More Trees. whatever's clever.

[Korey King]

needs more specifics/hard figures:

could start in michigan. Detroit has 5,405,918 people total as of 2007, let's call it 5.4mil.
5.4 million people consuming 1825lbs per year, 9,855,000,000lbs of food needed to feed all of them.
or in a smaller city, say 300,000. 547,500,000lbs would be needed.
smaller still, population 20,000. 36,500,000lbs required.

ok. now How Do We Get There?

better case scenarios growing 6000lbs fruit+vegetables per year on 1/10th an acre, you would need:
164250 acres to feed all of Detroit
9125 acres to feed 300,000, and
608 acres to feed 20,000.

Detroit Metro covers 3,913 sq.mi, or 2,504,320 acres.

is this accurate?

[jstorvick]

I think in this case we're assuming that the totality of the average person's diet is going to consist solely of vegetables, which would be erroneous in my opinion. Also, a lot of this data is based on standardized farming methods, rather than on permaculture/forest garden methods. Utilizing forest gardens to basically pack many different species of edible plants into mutual-benefit guilds on as small a space as possible, I think it is possible to bring forth greater yields of much greater diversity. This doesn't even take into account the possibilities of meat production via livestock and poultry raised in the same spaces as plant production, and also possibilities of aquaculture/fish production in indoor or outdoor facilities. You can raise a shitload of tilapia in pretty small tanks, from what I understand. The possibilities are much greater, I think than what statistical data presents at this point since it relies on different food production technologies.

[zak]

You can raise a shitload of tilapia in pretty small tanks

I was watching a video with Will Allen of Growing Power in Milwaukee, and he said you need one gallon of water per fish. I think they were harvested after about six months. They had 5000 gallon tanks set up in their greenhouses (they have a full-on aquaculture cycle going) and the tanks did not seem that big at all. So you really can grow massive amounts of fish with the right setup, and directly benefit your whole system in the process.

Here are the videos; he mentions it in #3 I think:
1: http://www.youtube.com/watch?v=k39D2myzRFQ
2: http://www.youtube.com/watch?v=NutSMk2mpdM
3: http://www.youtube.com/watch?v=kENge18wIqg

[Xtal]

Farm-raised tilapia may not be very good for you, unfortunately. The article concludes by saying it makes a difference what the fish are fed on, but doesn't specifiy what feed would produce healthy or unhealthy fish.

http://news.health.com/2008/07/11/popul ... pia-heart/

[zak]

Farm-raised tilapia may not be very good for you, unfortunately. The article concludes by saying it makes a difference what the fish are fed on, but doesn't specifiy what feed would produce healthy or unhealthy fish.

http://news.health.com/2008/07/11/popul ... pia-heart/

Interesting article. Luckily there's seem to be a way to do it right, but yeah, it doesn't specify:

As for suppliers, “the industry needs to improve ways of farming fish,” said Katherine Tallmadge, a national spokeswoman for the American Dietetic Association. “The whole idea of farming is a great one, but they’re feeding the fish food that’s inexpensive, so they can keep the price down, and it’s having an adverse effect on the nutritional quality of the fish.”

Farmed trout and Atlantic salmon had relatively good concentrations of “good” omega-3 fatty acids compared with “bad” omega-6 fatty acids.

Farm-raised tilapia and catfish, on the other hand, had troubling ratios.

“In the 1970s, we lost the ability to feed the planet with fish we catch,” Chilton said. “Farm-raised fish has to be part of our future, but we must do it correctly. We must feed animals the correct foods. Animals become what we feed them, and we become what we eat as well. The food chain is fairly consistent.”

[Justin Boland]

Having seen a Tilapia farm up close, I came to the terms with the fact I don't want to eat Tilapia, like, ever. Not pleasant creatures. Salmon are beautiful, Tilapia are gila monsters.

That said, I'm still very interested in aquaculture, mostly because:
1. Tilapia will eat anything, to the point of cleaning the tanks they're in for food
2. Tilapia convert that food into biomass like nobody's business, and
3. Fish make great fertilizer.

Although I do have vague moral quibbles about raising aquatic animals in tight spaces in order to use their bodies as compost enhancement, I also see the potential for a simple, effective project that would look awesome and provide hours of stoned entertainment.



Some City Farmer datafeed about Tilapia Farming:
http://www.cityfarmer.info/tilapia-farming-at-home/

[Justin Boland]

...and I'm still trying to find that magical master list of THE BEST CROPS for high-speed high yields. I saw Vinay Gupta refer to this as "emergency permaculture," but he didn't find the magical master list yet, either.

The book "Gardening When it Counts: Growing Food in Hard Times" is on google books as a limited preview:
http://books.google.com/books?id=lbohaJ ... +it+counts

I know I've got a lot of random notes floating around two of my journals...I guess it's time to start gathering them up.

Oh, and here's Plants For A Future on their "best" picks:
http://www.pfaf.org/leaflets/top20.php

[zak]

...and I'm still trying to find that magical master list of THE BEST CROPS for high-speed high yields.

You might want to look into SPIN-farming (http://spinfarming.com). Since one of their main goals is turning a profit, they focus on high yield crops. I tried to find a list myself recently but I think it lies within their paid e-books. You can kind of get an idea from reading around on their web site.

From my limited experience, salad greens and peppers are. Berries aren't exactly high-speed, but once they get going they can be high-yield, especially if you're getting a lot of rain. Tomatillos have a high yield but I think take a little longer.

[Xtal]

We had salad greens in our balcony container garden last year. You can practically watch 'em grow.

[Justin Boland]

Some excellent John Robb material:
http://globalguerrillas.typepad.com/glo ... arden.html

"Victory gardens" are smart way to hedge against short term system failure and as a cost cutting measure. However, a longer term solution for decentralized agriculture needs to be much, much more productive than traditional gardening. Subscription plots/farming, low cost sensor networks (water, light, PH, etc.), high intensity plot plans, accelerated local composting systems, lawn garden entrepreneurs, tinkering networks, etc. will be needed to flesh out an innovative ecosystem that will drive the productivity curve. Given these innovations, its possible to see a situation were 80-90% of food consumption is locally derived and sold at a small fraction of current costs and at a much higher level of quality/freshness. Resilience needs to be productive/affordable to become dominant.

And a comment from Massachutsetts:

We've been building an alternative agricultural infrastructure and economic system since the 1970s in this state. It could very easily by maximized using many of the lessons that New Alchemy Institute pioneered during that time.

Gandhi said the heart of satyagraha was swadeshi, local production. Both the spinning of thread and, more famously, the salt march were economic as well as political acts and example of that local production, swadeshi principle. Gandhi's economics was based upon the revitalization of village (neighborhood) production and markets and its goal was full employment not larger GDP or more consumption.

I'm doing a directed reading on Gandhian economics and my raw notes are at
http://www.globalswadeshi.net/forum/top ... dations-of
http://www.globalswadeshi.net/forum/top ... j-swadeshi
http://www.globalswadeshi.net/forum/top ... ic-thought

[Justin Boland]

Source:
holy damn this was amazing

The need is:

15 litres water / day / person
2200 calories / day / person
2 million people (Lucas lives in the Canary Islands).

A Seawater Greenhouse setup for vegetable production produces 1.2 litres / m2 / day. Which is consumed by the vegetable production in the greenhouse. You should easily be able to get a yield of 30 kg / m2 / year from the greenhouse. (Some greenhouse growers, under less ideal conditions are able to double this yield, but lets use that for now.)

Eggplant, 0.25 calorie / g < http://caloriecount.about.com/calories-eggplant-i11209 >
Tomato, 0.18 calorie / g < http://caloriecount.about.com/calories- ... 529?size=4 >
Lettuce, 0.2 calorie / g < http://caloriecount.about.com/calories- ... ine-i11251 >
Green, snap beans, 0.3 calorie / g < http://caloriecount.about.com/calories- ... een-i11052 >

So for simplicity sake, lets assume 0.25 calorie / g vegetables. For 2200 calories then you need 8800 grams of vegetables / day to meet your calorie requirement. The so called Gorilla Diet.
http://www.beyondveg.com/billings-t/cal ... 1c.shtml...

Lets supplement it with a little bit of fish, we are talking about an island nation. Lets say one fillet of white fish (154g) / person / day, that is 265 calories. < http://caloriecount.about.com/calories- ... ies-i15223 >

Add two potatoes 2x 136 g / person / day, which is 236 calories. (Not sure of growing potatoes on the island, but I think we can use the cool air stream in the shade tent behind the greenhouse for colder climate to do that.)
< http://caloriecount.about.com/calories- ... ed-skin-... >

2200 - 265 - 236 = 1699 calories. If the remainder is vegetables then you need 6796 g vegatables. Lets say 6.8 kg / person / day.

Which shows that you probably will need to supplement with some avocados and nuts, maybe sundried tomatoes etc. but this is a “back of the envelope” calculation, so lets leave that for now.

For simplicity sake we will assume that all the vegetable yields are the same in the greenhouse for all vegetables. So one person needs 6.8 kg / person / day. 6.8 x 365 days = 2482 kg. Yield / m2 is 30 kg. Which gives 2482 kg / 30 kg/m2 = 82.7 m2 / person / year to grow the vegetables, lets say 83 m2 to make it easier.

1 hectare is 10 000 m2, so that feeds 120 people for one year with vegetables. So you need 2 million / 120 = 16 667 hectares of greenhouses, plus the space to grow the potatoes.

Lets do a sanity check on that. How much is that? Almeria in southern Spain has in the range of 25,000-30,000 hectares of greenhouses. According to one source (below) they only get about 9kg / m3 from their greenhouses (in 2000), but that is fairly typical for Almeria yield according to my sources.
http://www.schundler.com/spain.htm

Almeria is a huge exporter of vegetables. Think of it as about 1000 Euro / ton of vegetables. Do the math. It is a lot. Great income.

Ok, so the Canary Islands can become self sufficient in food if they want to, building a powerhouse of vegetable exports using only sustainable energy. The islands are pretty windy, so running window power stations for the power needed to drive the process in the greenhouse is possible. How much energy would be needed? Lets be conservative and assume 20 kW peak load per hectare for pumping power. 20 kW x 16700 = 334 000 kW = 334 MW. Which is 100 modern windpower stations at peak load. Not bad.

(The greenhouses perform a cooling function in the process of evaporative cooling which is about 250-400 kW / 1 kW of pumping power. That is a nice output, getting cooling power worth 250-400 times what you put in.)

Ok the water then?

A Seawater Greenhouse can output significantly more water than what the standard greenhouse will output, if we have access to cold water. The Las Palmas solution used deep water from nearby the island. < http://www.seawatergreenhouse.com/gran_canaria.htm >

Lets assume you have access to 1000 meter deep water within three, four km of the coast. Then you can build a pipeline there and go get the nice 6-8 C water. This type of cold water will improve the water output from the condensers in the greenhouse significantly. Lets assume we get 10x more water out this way. So you get 12 litres / m2 greenhouse / day. That is 10 litres extra, that the greenhouse won't need for the food crops you are growing.

10 litres x 10000 m2 (one hectare) = 100 000 litres or 100 m3 water per hectare. 16 700 hectares will then produce 1 670 000 m3 water. Or 1,7 million m3 water.

2 million people use according to our assumption above 15 litres /day / person = 2 million x 15 = 30 million litres or 30 000 m3.

So our setup would produce more water than we need. In fact this is probably quite a good idea, as the pipeline and pumping to bring up that water would cost quite a bit.

How much? A pipeline being build in Curacau where I have been looking at the business case a bit.
http://www.otecnews.org/articles/curacao-swac.html

That pipeline would cost about Euro 15 million to build. It is supposed to bring in water at about 500 litres / second. In one day that would be 43,200 m3. I am not sure, without having to take out the big calculator, how much that heat transfer that will give us the ability to condense. I would have to check that. But we are in the right ball park, I bet it is the right order of magnitude.

How much would the greenhouses cost to build? Well, the nice thing with them is that they are instantly profitable. As soon as you have one built it starts making money (ok so it takes a month or three for the vegetables to start maturing, but it is quick). So you can build something like this in stages and gradually prove the concept and be profitable at every step.

Did I say that it is easy to grow without using pesticides in he Seawater Greenhouse? Another synergistic effect. But that requires another story.

[sharqi]

I just read a couple of books by Jeavons. He says potatoes, followed by sweet potatoes and turnips are the most calorie-dense per space in the garden you can grow. For potatoes, it was something ridiculously small, like 1500 sf per person of potatoes (which is a huge patch, but not insurmountable). He advises also to grow beans in the summer, and plant wheat in the same spot to overwinter and harvest in the spring. Both beans and wheat provide good basic calories, and you can get two crops in the same space in time.

Jeavons claims his (labor) intensive gardening can yield 31 times what conventional vegetable ag can yield, three times what conventional grain ag can yield, and six times the nutrition per space as conventional ag. All that with drastically less water as well. I don't think labor intensive is going to be an issue, since only 65% of us are in the workforce anyway (and numbers dropping daily!). Maybe we'll get back to being a nation of farmers before long.

I was reading the do-it-ourselves guide by the rhizome collective, and last night's topic was aquaculture. I'm not sure I would eat tilapia either, having seen a working aquaponics gig. But, they said that duckweed is edible by humans and animals, and can be used as a green manure or as nitrogen in a compost pile. It grows like crazy, and it's very beneficial. Imagine that!

Don't forget edible weeds. Almost all the weeds growing freely without care in my yard are edible, medicinal, or both. It might not feed the masses, but it can provide for some easy calories.

I've also read that 30% of vegetables grown in the EU don't make it to market because of their odd shapes or colors, and 40% of food grown in America is not consumed. This is a ridiculous amount of waste, and local design, communication, and input could correct this issue.

I've read that a mature apple tree can provide 250 pounds of fruit per year. If one out of
every ten U.S. citizens planted two fruiting trees, we’d be richer by 12 billion pounds of fruit (given an average of 200 pounds per fruit per mature tree) each year. I don't know how much fresh fruit Americans consume, but we can up this to two or three citizens out of every ten, and I bet there would be "enough".

This is an issue to think about. Peak oil notwithstanding, worldwide food production has been plateauing, especially given the wacky climate factors. Soil is eroding fast and fierce. I grew up on a farm (not ours) that had thick black beautiful soil. Decades later, the soil is gray and dead. Not a weed grows on it, and the corn (every year corn!) wouldn't grow except for the inputs of irrigated water and fertilizer. It's going to take a lot of time and effort to recover fields like this--formerly one of the most fertile areas in the world.

But I do not give up hope that there is a better way to live than continuing to build landfills and deserts!

carey

[dlollard]

I think weeds might be better for vitamins, minerals, and medicine, more than straight calories. Though there's an abandoned lot near here with a LOT of burdock in it--I guess there are starchy weeds (kudzu)! Plus, for straight calories, fruit (berries, trees, vines) seems to me to have potential. We don't all necessarily have to have grainyards or potato hills to get our 2200/day.

Something I remembered someone linking to once upon a time, I didn't read it until today:

A Resilient Suburbia part 3: Weighing the Potential for Self-Sufficiency

Apparently, this was on The Oil Drum, so some of y'all might've already seen it. He's using John Jeavons' numbers, too.

Also, I read this ages ago, and my hard copy got swallowed into the yet-to-file file, but I finally found it online:

"Of course you couldn't feed the world with such a hippy-dippy, hunter-gatherer, landscape system like permaculture."

Wherein a practicing permaculturist explains just how much can be produced in a well-designed home-scale system:

On the subsistence agriculture level, we permies regularly have designed production systems around the world, which feed everyone living in a given house within a 50-foot radius of the house. This rule of thumb holds pretty well because the more folks who live there, the bigger the house, the larger the surface area, so no more than 50 feet is really necessary.

The math is easy. With a polyculture, yields of 3-10 pounds of food per square foot are easy to come up with in most climates. For comparison, commercial agriculture in California , which is way inefficient, routinely runs about 1.5-2.5 pounds per square foot per year across a wide variety of crops. People need to eat about two pounds of mixed food a day if active, or around 750 pounds a year. In a good but somewhat sloppy design, you need about 500 square feet per person MAXIMUM. In a very good design, 200 square feet will do the job. If your diet is heavy on grain you'll need more space but not an astronomical amount. Utilize a greenhouse to extend seasons and exchange air rich in carbon dioxide from chicken houses or human houses, which otherwise would go to waste, and yields ratchet up even more. Take a little more space and include ducks and aquaculture into the mix and the yields become quite diverse and substantial. This sort of system is typical in Vietnam now and there is no longer any measurable hunger there. Wouldn't it be nice if the US could do that with its "superior" first world agricultural system?

Now, how to do that in MY yard, THAT is the puzzle....

Don

[Justin Boland]

Some very interesting infographics from a Global Research article that's pure doomer apocalypse porn but nonetheless worth reading. Endless parade of bad news from around the world.

Stocks of foodstuff are dangerously low

Low stocks of foodstuff make the world's falling agriculture output particularly worrisome. The combined averaged of the ending stock levels of the major trading countries of Australia, Canada, United States, and the European Union have been declining steadily in the last few years:

2002-2005: 47.4 million tons
2007: 37.6 million tons
2008: 27.4 million tons

These inventory numbers are dangerously low, especially considering the horrifying possibility that China's 60 million tons of grain reserves doesn't actually exists .

California
California is facing its worst drought in recorded history . The drought is predicted to be the most severe in modern times, worse than those in 1977 and 1991. Thousands of acres of row crops already have been fallowed, with more to follow. The snowpack in the Northern Sierra, home to some of the state's most important reservoirs, proved to be just 49 percent of average. Water agencies throughout the state are scrambling to adopt conservation mandates.

[Justin Boland]

More data from the Microfarms Project:
http://www.microfarms.com/technical/mic ... ations.htm

http://www.microfarms.com/technical/mic ... mpage1.htm

[jstorvick]

Dude, this Micro Farms data is pure gold, thank you. I've got a bunch of related stuff that was handed out at the Permaculture Design Course this last weekend (I've got to talk to you about that as well at some point) that I really need to scan and put up here.

[Justin Boland]

More Numbers From Late-Night Research

The minimum amount of agricultural land necessary for sustainable food security, with a diversified diet similar to those of North America and Western Europe (hence including meat), is 0.5 of a hectare per person. This does not allow for any land degradation such as soil erosion, and it assumes adequate water supplies. Very few populous countries have more than an average of 0.25 of a hectare. It is realistic to suppose that the absolute minimum of arable land to support one person is a mere 0.07 of a hectare–and this assumes a largely vegetarian diet, no land degradation or water shortages, virtually no post-harvest waste, and farmers who know precisely when and how to plant, fertilize, irrigate, etc.

[FAO, 1993]

Now, 0.5 hectare is "civilized" talk for 1.23552 acres, which equals out to 53,819 square feet. Considering most people can't afford that much land, this is a problem...either in terms of faulty math in arriving at the figure, or in terms of overpopulation being a ravenous and life-destroying gaping maw, or something.

Also full of interesting points:
http://ask.metafilter.com/77287/How-muc ... erson-need

If you're interested in the maximum yield, you might look into the Biointensive method. This book, by John Jeavons, claims that less than half an acre (~ 0.2 hectares) can support a family of four, or about 0.05 hectares/person

...for more on Biointensive, here's the basic pitch: http://www.growbiointensive.org/grow_bio.html

AND HERE'S MOREfrom the Vegan Society, some of the palest experts available:
http://www.vegansociety.com/environment/land/

On the basis of these figures, a vegan diet can meet calorie and protein needs from just 300 square metres using mainly potatoes. A more varied diet with plenty of fruit and vegetables, grains and legumes would take about 700 square metres. Replacing a third of the calories in this diet with calories from milk and eggs would double the land requirements and a typical European omnivorous diet would require five times the amount of land required for a varied vegan diet.

...

Quite simply, we do not have enough land to feed everyone on an animal-based diet. So while 840 million people do not have enough food to live normal lives, we continue to waste two-thirds of agricultural land by obtaining only a small fraction of its potential calorific value.

Obviously access to food is an extremely complex issue and there are no easy answers. However, the fact remains that the world's population is increasing and viable agricultural land is diminishing. If we are to avoid future global food scarcity we must find sustainable ways of using our natural resource base. Industrial livestock production is unsustainable and unjustifiable.

[Justin Boland]

Source:
http://www.theglobaleducationproject.or ... d-soil.php

"Ninety percent of the world's food is derived from just 15 plant and 8 animal species." 2

"Biodiversity - and especially the maintenance of wild relatives of domesticated species - is essential to sustainable agriculture."1

75% of the genetic diversity of crop plants has been lost in the past century. 1

"Over the past 40 years, approximately 30% of the world's cropland has become unproductive."

"During the past 40 years nearly one-third of the world's cropland (1.5 billion hectares) has been abandoned because of soil erosion and degradation."

"About 2 million hectares of rainfed and irrigated agricultural lands are lost to production every year due to severe land degradation, among other factors."

"It takes approximately 500 years to replace 25 millimeters (1 inch) of topsoil lost to erosion. The minimal soil depth for agricultural production is 150 millimeters. From this perspective, productive fertile soil is a nonrenewable, endangered ecosystem."