Claim: Three Acre Urban Farm Produces Million Pounds of Food in a Year


Senior Member.

Urban Farmer, Will Allen Grows One Million Pounds of Food in the Dead of Winter

The article clarifies that the entire growing season is the entire year, not just the winter.

On just 3 acres they are producing 1,000,000 pounds of food each
year! How are they doing this?

-10,000 fish

-300-500 yards worm compost

-3 acres of land in green houses

-Growing all year using heat from compost piles

-Using vertical space
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The author walks the reader through a quick survey of “bio intensive” farming.

Think of it this way, the standard planted row may have 2 or 3 rows of veggies. Bio intensive will plant 12 rows; thats already 4 times the produce. Now add in onions, for example, that grow vertically above sweet potato vines, this increases production a lot. Now add to that 4 harvest per year vs the standard one season growing season. Now you have 4x more productivity. This brings us to 4×4 or 16 times the productivity of the standard growing methods.

If you add to that hanging pots to add more growing space you have again increased productivity. I personally have not used vertical space in that way. A snap shot of my experience is growing one sweet potato per 1.5′ x 1.5′ area (2.25 square feet.) This one plant produces on average 12 pounds of root per plant and in that space I grow 4 to 6 leeks adding a pond of produce.

Now, the vines grow all over the place, and I tie some up, are not confined to that 2.25 square feet of soil space. From each plant you can easily average 3 pounds of delicious edible leaves as you pick them over the growing season. At this point alone I am averaging 16 pounds of eatable food in 2.25 square feet or 16/2.25 about 7 pounds of food per square foot.
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Finally, the author engages in some back of the envelope math and comes up with the million pound figure. [my emphasis]

Now that is in ONE GROWING SEASON. As I also grow fava beans, wheat, and fodder greens for two more seasons so my yelid is averaging 8 to 10 pounds in a year. IF I did this on 3 acres of growing space, excluding foot paths and green house walls etc. then my production would be 8 pounds per square foot * 43560 feet acre * 3 = 1,045,440 pounds of food. It is possible to get even more by choosing the right crops and getting 4 harvest per year. I have settled on 4000 square feet of growing space per person for providing pretty much all the food a person needs. I suggest anyone starting out begin with a very small garden and do it well. Something like a 5′ by 20′ growing bed would be the most you would start with.
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Neither accompanying video mentions crop yields on Will Allen’s small farm.

I am an amateur gardener with limited knowledge of the topic.

Is any of this even close to possible?


Senior Member.
High density gardening isn't really a new thing - he's using some clever tricks to be able to do it year round in an environment where it's usually not feasible, but those also aren't exactly new tricks, either.

I like the pond trick. My grandfather does the same thing, he filters his pond water through soil and grows tomatoes in it, getting a very impressive yield for his effort. He doesn't harvest fish for food, since it's a koi pond, but you could easily switch it for something like tilapia for similar results on the plant side and edible product on the fish side.

Growing like that is labor intensive. Farming works because plants grow by themselves if you work with their nature. This kind of growing is against that nature. Not impossible, but left to their own devices the plants won't thrive, it takes ongoing work to make them. Makes a great hobby, but not such a great industry.


Senior Member.
According to the University of Missouri:

A hill of sweet potatoes will yield about 2 pounds of marketable sweet potatoes and an average yield per acre of 400 bushels (50 pounds) is attainable. Sweet potatoes should be harvested before the first frost in the fall. Frost will kill the vines but should not damage the sweet potatoes.
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So, 20,000 pounds of sweet potatoes per acre is pretty impressive, but not close to the figure cited in the article. It is also far less than the yield cited in the article.

Okay, so now I officially know more about sweet potatoes than I ever expected to in my entire life.


Senior Member.

That information is for farming, not gardening. The difference basically comes down to labor - gardening can vastly increase yields per square foot by constant effort, every plant gets regular hands-on attention and care adjusted for its individual needs, soil is always kept fresh and fertile, invasive plants are manually removed on a regular basis, and so forth. None of these things happen on a farm because can you imagine how much labor that would take?

From the information in this link and some of the discussions, with only one growing season outdoors instead of four in a climate controlled greenhouse, a pound per square foot or better is possible, which translates to four pounds per square foot with a year-round growing cycle. And that doesn't count that you can plant other things between rows of potatoes and the hanging baskets this super-garden uses to improve output.

This still comes out a couple pounds short of his 8 pounds per square foot, but he does seem to be counting technically edible greens that nobody ever actually eats.

It all comes down to labor, though. His 3 acre garden is going to involve more hands-on labor than a farm that produces a hundred times the food.


Senior Member.
Be also interesting to work out the labour costs to farm that intensively. Would the yield to cost factor price the produce out of the market?


Senior Member.
I’m interested to see just how soil handles additives like phosphorus, potassium, and nitrogen during intensive farming.

Sweet potatoes tolerate acidic soils and the soil pH can be 5.0 to 6.5 for successful growth. Before planting, phosphorus and potassium should be applied based on a soil test. Nitrogen should be applied three weeks after transplanting (11 ounces per 1,000 square feet). An additional side-dress application of 11 to 12 ounces per 1,000 square feet of nitrogen can be applied when the vines begin "running" off the beds. Avoid applying too much nitrogen to sweet potatoes. Excessive nitrogen results in extensive vine growth, but few sweet potatoes.
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I contacted a good friend who is a plant biologist to find out.


Senior Member.
This is my standard response to this type of a post. It is from several sources.

Farming vs Gardening

I hear pretty frequently about how gardens (that people erroneously call farms) are the future of food production.

One family of 4 produces 6,000 pounds of food per year!

Another one, covering 2 rooftops produces 50,000 pounds of food per year!

There are a few realities that people need to understand.

Food and Farm Discussion Lab covered it well.

Let’s Be Honest. It’s an Acre.

The average person consumes 3-5 lbs of food per day. That puts a good average at around 2,000 lbs of food per year, or about a million calories.

That means the family of four doesn’t produce enough to feed themselves. The two rooftops might be able to feed 25 people. This is not sustainable farming.

100 hectares, or 1 sq. km, feeds about 3000 people for a year. now, let’s suppose we convert all the rooftops in New York City to rooftop gardens. NYC is about 304 square miles. Even if the entirety of those sq miles were rooftops, it would equate to 787 sq km. That would produce, if they were actual farms, enough food to feed 2,361,000 people.

There are 8.4 million people in New York City.

This doesn’t even take into effect the fact that most people don’t have the time or space to garden, and most of the world doesn’t have the climate. So, let’s dismiss the idea that gardening is any sort of solution for food production.


Senior Member.
Be also interesting to work out the labour costs to farm that intensively. Would the yield to cost factor price the produce out of the market?
Probably by a long shot.

My wife's garden is nowhere near as intensive, and I've never tried to work out the pounds per square foot it puts out (it's a strip probably 20'x3'), but for about $50 a year in various supplies it gives us a good $500 worth of produce - enough carrots, green onions, cucumbers, tomatoes, and rhubarb for ourselves, the neighbors, and some friends, plus some sunflower seeds, usually a couple watermelons and pumpkins, and in a good year a few ears of corn. Plus almost every year we experiment with something or other, some years that pays off, like enough zucchini to make bread for everyone we knew a few years ago, but others it didn't, like a walnut tree that gives us nothing but squirrels everywhere and a quince bush that serves as a life lesson in research because no fruit is worth those inch long razor sharp thorns everywhere.

To get that kind of output, we're both out there at least an hour a day for three or four months. If we paid ourselves Michigan's minimum wage for that time, that's $1530 a year - even if we bought the most expensive organic food the entire crop is worth maybe $750.
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Senior Member.
I live in Dallas, heavy black clay. It is great for cotton and for okra. It is horrible for any root crop (our soils expands and contracts and when dried, it is HARD--lot of lime in it) With the heat here, crops like tomatoes have to be planted in the spring, then ripped out and replanted in July. Climate and soils limit one's crops. Most of these stories end up coming from southern Cal, where the climate is mild and soils are fertile.

Peaches grow in some nearby areas and they did not get enough cold this winter to produce real well. The growers are afraid of a late freeze. It was 89 today.


there is a quote in the book of the martain witch I will look up when I am not at work. but in it he basicley says that it is amazing how well potatos grow on Mars when you have sevral billion dollars of life support equipment to make the perfect environment. he also says that he is ruining his soil doing this but he only needs them for 1 year.

sof if you have the time and mony of spend of expencive things (soil heat water fertiliser etc) I am sure you can get a lot of food. but dose that make it a effective thing to do.