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Food Security

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These Off Beat articles are about technology, science, and sometimes computer science, but they’re mostly unscripted adventures in online research. They also teach how to define and answer real world questions with online research.

Plus these Off Beat articles are meant to be fun: there will be detours.

The question I want to answer this month: How much physical space does one person, two people, or four people need to grow food to support themselves for one year? The ability to provide food for yourself on a consistent basis is called food security.

Food security, to start, triggers these questions in my mind:

  • How many calories does one person need each day?
  • What types of food does one person need to eat each day?
  • How much land or space is needed to feed one person enough calories from the right types of food?

Each of these questions, of course, lead to other questions. Let’s assume you have a mostly sunny backyard and a small home with window sill space. For now, let’s also assume you have a generous budget. Eventually we’ll want to look at the opposite case: can a person in an apartment or shared space with limited funds have enough room to provide their own food?

We’ll try to answer questions in order, starting with the basics: the minimum calories and types of food people need to consume then go off and look at how much land and space is required to meet those needs.

One quick aside: two hundred years ago, these questions were considered silly. And obvious. Most people either had farms, had a large garden, or lived in towns served by local farmers. Only an era and country where breakfast is Count Chocula plus milk in a carton would have to ask these questions. We’ve lost the everyday knowledge about food and what it takes to provide food to live.

How Many Calories Do You Consume?

Let’s start by trying to answer the most useful question: how many calories does one person need to eat each day? This answer we can use to figure out how much space they’ll need for a day, week, month, and year of food.

I typed the query, “how many calories do people consume in a day?” into the DuckDuckGo.com search engine. This appeared at the top of the page: 2,129 calories per person, on average, based on a sample size of 29,105 people in the US.

Wolfram Alpha search results for calorie count research
My Question Answered Neatly: 2,129 Calories

Sold! Next question?!

In the middle of the same search results page was a Discovery Health article that phrased my question more accurately, “how many calories does a person need daily?” This link led to an article clearly written for search engines. It’s a HowStuffWorks.com page sponsored by Discovery Health. But it still has good data to start with.

The article states the 2,000 calorie per person per day limit is a rough average. The amount of calories a person needs also depends on height, weight, activity level, basal metabolic rate, and the “thermic value of food.” Well, that last bit sounds important. Here is what they mean:

  • Your activity level is rather obvious: it’s the energy you burn while making your bed, or cleaning your room, walking to school or work, and generally moving around in the world.
  • Your basal metabolic rate, according to this article, is the amount of energy your body consumes at rest. Typically 60-70% of the energy you consume (as measured in calories) is burned at rest. This energy keeps your heart beating, eyes blinking, lungs expanding and contracting, and so on. Men apparently have a higher basal metabolic rate than women.
  • The “thermic value of food” turns out to be about the energy your body burns as it consumes food. Your body needs energy to convert food into energy and other elements needed to be healthy.

The search results page led to a number of other sites with calculators and more details about calories and how to calculate them. For the sake of argument, to move this article along, let’s assume 2,000 calories per person is needed.

If we want to research how much space an individual, two people, and four people need to feed themselves for a year, then we will assume one person will need 2,000 calories a day, two people will need 4,000 calories a day, and four people will need 8,000 calories a day.

What Kinds of Food Do People Need to Eat?

With a rough idea of calories each person needs to have a secure food supply, let’s tackle food types. For example, if beef is a key component of a person’s diet, it’s unlikely you can raise a cow in your apartment. Or your backyard. But beans, nuts, seeds, and other plant-based foods are definitely do-able sources of protein people might grow in their backyard.

Even more interesting, and not to pick on protein as a type of food people need to eat, but the amount of protein needed and the amount available in food is fairly even. An adult who eats a nine-ounce steak, for example, gets 63 grams of protein when their body only needs 56 grams a day. Many people eat more protein in a day, in other words, than their body needs.

In plain English, if you grow your own food, the amount of protein you would have to provide might be less than you think.

I then found a Centers for Disease Control (CDC) website with a nutrition basics page that lists these as the basic nutrition needs:

  • Food groups like vegetables, fruits, grains, dairy, and protein foods (e.g. peas, unsalted nuts, seeds)
  • Water through several glasses a day, as well as celery, tomatoes, oranges, and melons
  • Fat intake limited to 300 milligrams of dietary cholesterol a day
  • Carbohydrates to provide glucose sugar to your body, through fruits, vegetables, breads and cereals, milk, and processed foods with added sugar
  • Proteins found in dry beans, peas, nuts, seeds, grains, some vegetables, as well as meat, tofu, eggs, and milk.
  • Vitamins and minerals found naturally in food but also supplements

From this list, with an eye to what a person might be able to provide for themselves, everything but cows, chickens (eggs), and tofu sound possible for a backyard garden. The question is, how big would your garden have to be?

How Much Land Do You Need to Feed One Person?

Search results for this question got really interesting. One site, CookingGarden.com, posted this question and let people answer. Some of the “facts” (most of which I could not validate):

  • In England, in the Middle Ages, 40 acres could feed a family. Today it is much less.
  • The Irish could feed 10-12 people a year on half an acre of potatoes. Potato pancakes for breakfast, potato salad for lunch, potato soup for dinner! Recipes below, seriously.
  • The answer depends on the plant zone you’re in. A fertile zone grows more food. This person says 5 acres if you want grains (3 acres), fruit and nut trees (1/2 an acre), a garden (1 acre split equally between potatoes, corn, and other plants), a permanent garden (1/2 an acre for herbs, raspberries, mushrooms, etc.). This person also says she burns 5,000 calories a day planting, harvesting, and preserving.
  • Apparently traditional Victorian wisdom was that two acres would feed a person.
  • How much land also depends on animals: they need acreage to grow their feed. No animals, no extra acreage.
  • Hydroponics, aeroponics, and other technology can dramatically improve plant growth, reducing space needs, mostly by growing food in three dimensions (up or vertical is the third dimension) not two. Pumpkins apparently are 2-D biotechnology.

These answers also reminded me of something I had read awhile back, about the Three Sisters method of planting. If you don’t know, different plants draw different nutrients from soil; rotating crops, including a period of time where a bit of land has no crops, keeps soil healthy. Three Sisters is a technique Native Americans used, and other cultures around the world, to rotate plantings of corn, beans, and squash. These three plants grow well together. You might need less land if you use this growing technique. Plus your soil would be healthy longer.

I first heard of Three Sisters years ago, after researching another technique: terra preta. Apparently you can grow soil with charcoal, bone, and manure. One theory about the Amazon is that the natives figured out how to grow soil in otherwise stony ground and that, in turn, led to the vast Amazonian rain forests. So, if you were to grow food to feed yourself and others, techniques like Three Sisters and terra preta also help make the process sustainable over time. Terra preta also sounds a lot like compost, another technique to make agriculture sustainable.

The most interesting answer to the question of how much land you would need to feed one person, or more, is a Cornell University research project from 2007. They researched the impact on land use of different diets. A low-fat vegetarian diet, for example, only required .44 of an acre. However, adding meat made the diet and land-use more efficient. A vegetarian diet required better soil while adding meat required growing grains that grow in less-perfect soil. In New York state, most soil is useful but not high quality; as a result, adding a bit of meat to a vegetarian diet is the most efficient use of soil there.

The best answer I found, though, is from Mihail Kossev, an “edible landscaper,” one of the more fun job titles available. He’s based in Brooklyn, New York, a challenging place to support yourself with a garden. Kossev repeats the 5,000 calories a day burn data point from the earlier source, saying that is how much energy is expended during planting, harvesting, and preserving foods.

Kossev’s article also expands on the Three Sisters concept with a link to a Virgina Tech article about intensive gardening methods (with a schematic map to plan your seasonal gardens!).

Other options to answering this question — how much land do you need to support one person, two people, four people for a year — also include hydroponics and something called Consumer Supported Agriculture, or CSA.

Hydroponics will make the most of small spaces, for example, apartments or basements. You pay for the technology and supplies. If you've ever been to Disney’s Epcot Center in Orlando, Florida and taken The Land ride, you think of hydroponics as clean and white and neat technology with bright grow lights shining down on the plants (see photo above). The only down side to hydroponics is you might have to give tours to police who check on your purchases to inquire exactly what you're growing. If you act neighborly and offer them free vegetables, plus a $10 Dunkin Donuts card (hey, DD has healthy food besides coffee and donuts), perhaps they'll leave you alone.

More seriously, hydroponics involves using chemicals like Boric Acid as nutrients to grow plants. You can grow most anything but root vegetables (which require dirt) and grains apparently are not cost-effective grown this way. One of the issues to consider with hydroponic gardening is the cost of light. A setup in a light-filled greenhouse requires less energy than a dark basement with grow lights. And, wherever you set up, the constant use of water creates a risk of algae and similar infestations. Traditional farming, of course, has its own set of bugs, blights, and problems.

Unlike hydroponics or starting a farm in your backyard, Consumer Supported Agriculture (CSA) takes the hard work of growing food off your shoulders. I interviewed a friend, John Mitchell, who also happens to be a CSA farmer, for the details how CSA works. Here's what he said.

Instead of ten families growing their own food on their own properties, you have ten families who act as shareholders to buy some or all of a crop from a local farmer. You do have to show up periodically, at either the farm or a distribution point, and possibly wait around to sort out what you get from that round of crops. In many cases, people can buy specific crops for a set time period.

There are a few risks. One risk is a bad harvest but farmers might buy from another source. You have to trust your farmer to make the right choices when they buy from another farm. Another risk is too much food. You might find yourself sick of beans or squash with a large amount left in your fridge. In that case, you might want to sell or give away the food, perhaps to a local homeless shelter or food pantry.

Farmers use CSA to balance their income and ensure a stable market for what they grow. In some cases, they decide what to grow on their farm based on shareholders interests. Other cases CSA is only part of what the farmer grows.

I must mention CSA can also apply to dairy. You've probably heard of timeshares, buying a week or two a year at a swanky resort some place beautiful. Well, according to another friend, there is such a thing as a cow share. You buy in to get a portion of milk from a single cow. You show up at the dairy, twist a giant milk container a few times to loosen the cream, then pour out your share of milk into your own container. Usually people do this because they want raw milk, which is illegal unless you own the cow. Or a share of a cow.

What Have We Learned?

Total sustainability, complete food security, where every person has their own garden or small farm to feed themselves, appears, well, unsustainable. Most people don't have half an acre with lots of sunlight. And many people live in apartments. Hydroponics, growing food in nutrient-rich water, is extremely efficient but it also requires a bit of space, money, and time to work.

Then there is the calorie burn from farming, plus the daily distractions and must do work involved in planting, growing, and harvesting food. It's hard to work a job and grow your own food.

Plus you need a good amount of water. It probably would be inefficient for millions of people to have small farms in their backyard. Having lived a few years in a desert, people also might want to grow less thirsty plants to help reduce the need for water.

The best solution for food security appears to be community CSA farms where families and individuals contract with local farms to provide them with food each season. People get the benefit of fresh food without the hassles and distractions of farming. This is a throwback, of course, to an ancient model.

At the same time, people with a bit of space clearly can grow beans and other food to support their daily needs. But most people have to choose between the veggie aisle at the local supermarket and contracting with a local farm for fresh produce and meats.

A Bonus or Two, Maybe

For me, the best part of hours spent researching a topic are the offbeat details that pop up, like supporting 10-12 people on half an acre of potatoes (how many ways can you cook a potato before you repeat yourself and die of boredom?). Here are two more details that I stumbled on researching this article:

Perhaps the most odd result of all this research: many of the blog posts about food security and sustainability stop at 2007, 2009, 2012. It’s as if people ran out of gas, or something came up that makes the whole question moot? Perhaps I missed a memo sustainable agriculture is not longer viable?

Second, in researching Count Chocula cereal, for my comment at the start about modern day definitions of breakfast, turns out General Mills is releasing all of its monster themed cereals this fall in the US, around Halloween 2013. In addition to Count Chocula, there’s Franken Berry, Fruit Brute, Boo Berry, and Fruity Yummy Mummy. The Wikipedia link below also reveal Franken Berry used to turn your stool pink. Some kids would consider that a feature, however, not a bug.

Potato recipes included below, as well. Writing parts of this article made me hungry.

Learn More

How Many Calories Do People Consume?


What Types of Food Do People Need to Eat?


How Much Land Can Feed One Person?


Three Sisters


Terra Preta


Community Supported Agriculture (CSA)s




Disney’s Living with the Land Ride


Potato Recipes

Potato Pancakes
Potato Salad
Potato Soup

General Mills, Count Chocula, and Monster-Themed Cereals


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