See the related chart: World Staple Crops Compared - Expanded Chart
Calories per Person
Suppose the world, in the not too distant future, will have a population of 10 billion people. The average number of calories needed per person varies greatly based on age, gender, height and weight, level of activity, etc. Suppose a generous estimate of 4,000 calories per person per day. This allows for a significant loss of calories from the field to the table. Data for calories produced per crop is field weight data; most crops are processed post harvest, reducing calories available for consumption significantly. Multiply 10 billion times 4 thousand times 365 days a year, and the result is exactly 1.46 x 10^16. Now consider the number of calories produced by the 44 crops listed in this chart: 1.4841E+16. That number is 104 percent of the generous estimate of the calories needed to feed 10 billion people. And those 44 crops do not include many fruit and vegetable crops, fish harvested in the wild, and various minor crops. So the total food calories produced worldwide already exceeds the amount needed to feed 10 billion persons.
Adding the calories from only the top 34 crops (neglecting those that have a value of E+12 or less) results in total calories of 1.4800E+16. Adding the calories from only the top 25 crops, results in total calories of 1.46022E+16, which again is still sufficient to feed 10 billion persons. Only the top 25 staple crops, grown at 2008 levels, are needed to provide enough calories for 10 billion persons. And yet, in a world of less than 7 billion persons, 1 billion go hungry every year. The top 25 staple crops, in order by total calories produced by that crop worldwide (based on FAOSTAT 2008 world data and the USDA Nutrient Database, are:
Crop CaloriesFor the full list, see this chart (tab delimited, plain text).
The top five world staple crops provide over 75% percent (76.62%) of the calories needed for 10 billion persons. Those same five crops provide sufficient calories (not sufficient total nutrition) for over 7.5 billion persons. Only the top four crops are needed to provide sufficient calories for the current world population. Yet in a world of about 6.8 billion persons, about one billion suffer from hunger (to varying extents).
But the above calculation does not include animal food products, such as meat, poultry, farm-raised fish, eggs, and dairy, which together constitute about 13.5% of the world average diet (FAO.org). And that is the problem. The world produces about enough calories for 10 billion persons, except that a significant portion of the calories from our staple crops are used to feed animals. We receive calories from animal food products, but the output of calories is far less than the input. (http://www.news.cornell.edu/releases/aug97/livestock.hrs.html) Therefore, any sudden reduction in the world food supply will require a sudden reduction in the percent of calories that the world obtains from animal food products. The staple crops used to feed animals will be needed for direct human consumption.
Then too, if we are to meet the nutritional needs of the world's growing population, the amount of land used to grow crops must increase faster than the population, or we must stop feeding high-quality grains and soy to animals. Animals should be fed from grazing land, from forage grown between plantings of food crops (e.g. alfalfa, which also improves the soil for the next staple crop), and from by-products of human food preparation (e.g. press cake from oil crops). And the average diet in developed nations should have less animal sources, and more plant sources. With this change in approach, the world could feed 10 billion people or more, with little or no increase in the land used for agriculture. Then the food from animal products would supplement, not detract from, the world food supply. But animals fed in this way would grow to maturity slower, would produce less meat or by-products, and would not be not competitive in current market conditions. The demands of the marketplace pressure farmers to use high-quality grains as animal feed, reducing the amount of food calories and macronutrients (protein, fat, carbs) available to the world population.
Hectares Needed for Calories
The 25 top calorie staple crops listed above, according to 2008 FAOSTAT data, required 1.02056e+9 hectares to grow. In terms of calories, then, approximately 1 billion hectares can feed 10 billion persons, and one hectare can feed about 10 persons. However, local growing conditions can be unpredictable. Using a world average allows for some poor crops in one area and some better crops in other areas. For food security in a local area, one hectare might not be sufficient to feed 10 persons. Factors such as unfavorable weather conditions, poor choice of crops or varieties, plant diseases and pests, mishandling of the crop at any stage, etc. can cause a hectare of land to produce fewer calories than anticipated. Also, in some regions, crops cannot be grown in winter, reducing the total produce from each hectare per year. So a subsistence farmer must plan on feeding fewer persons per hectare. Then if his crop produces more food than needed, he can sell the excess. Prudent planning might allow for only 5 persons (or less) to be fed with each hectare, which is 2 persons per acre.
Protein per Person
If we analyze world staple crops in terms of protein, rather than calories, a similar result occurs, albeit with a somewhat different list of crops. As with calories, we should over-estimate the amount of protein needed per person, in case of loss from the field to the table, and to account for uneven distribution and possible variations in crop output from year to year. The average minimum requirement of protein is only 0.6 grams of protein per kilogram of body weight. Average adult body weight is considered to be 70 kilograms (154 pounds). So the average adult needs a minimum of 42 grams of protein per day. The U.S. Recommended Daily Allowance of protein is 0.8 gram per kilogram of ideal body weight for the adult, which is 56 grams for a 70 kg adult. But if a person is 50 pounds overweight, his protein needs are not substantially increased, because the excess weight is fat, not muscle. So a population with many overweight persons would not necessarily need more than 0.8 g/kg. Recommendations on amounts of protein also vary depending on age, gender, height and frame size (i.e. ideal weight), and level of daily activity. But 100 grams of protein per day should significantly exceed the needs of the vast majority of any population. So rather than use a minimum or an average amount of protein per day, as with calories, a surfeit is better, so that the nutritional needs of the world are not underestimated in any case.
Supposing a world of 10 billion persons, and a daily protein allotment of 100 grams per person, the total protein per year is exactly 3.65e+8 metric tonnes of protein. This was calculated as 100 grams of protein per day x 365 days x 10 billion persons divided by one million to convert grams to metric tonnes, yielding 3.65e+8 tonnes. We could also calculate for a lesser protein requirement, or a lesser population, or both.
(70 g protein per day x 365 days x 7 billion persons)/1e+6 =
(100 g protein per day x 365 days x 7 billion persons)/1e+6 =
(70 g protein per day x 365 days x 10 billion persons)/1e+6 =
(100 g protein per day x 365 days x 10 billion persons)/1e+6 =
How do the top staple crops of the world, ordered by total protein produced each year, compare to the protein needs of the world? Again we find that the world already produces more than enough protein for a population of 10 billion, even when we over-estimate the daily protein needs per person. The 44 crop sum of protein is 3.7680e+8 tonnes; the 25 crop sum is 3.7513e+8 tonnes. The 16 top protein crops yield 3.6580e+8 tonnes, which is sufficient for 100 g per day for 10 billion persons. The top 10 crops yield 3.4857e+8 tonnes; the top 5 protein crops yield 3.1313e+8 tonnes; the top 4 crops yield 2.9346e+8. But the top 3 crops still give us 2.4461e+8 metric tonnes of protein per year, which substantially exceeds 70 grams per day for 7 billion persons.
1. Wheat 94522563For the full list, see this chart (tab delimited, plain text).
How many hectares of land is needed for these 25 top crops? 9.7185e+8 hectares, which is just under one billion hectares. But only the top 16 crops are needed to provide 100 grams of protein per day to 10 billion persons, and that area of land is 9.2468e+8 hectares.
Fat per Person
The same type of calculation can be made for fat, an essential macronutrient, as for protein and calories. And just as 100 grams of protein per day is a surfeit, 100 grams of fat per day more than is needed. The US RDA for fat, for a 2000 calorie diet is 65 grams, which is about 30% of calories from fat. For a 3000 calorie diet, 30% is 900 calories, and about 100 grams of fat. If we again wanted to choose a number that was in excess of world nutritional needs, in order to account for losses from field to table, and for yearly crop variations and inequitable distribution, 130 grams of fat would be suitable as about 30% of a 4000 calorie diet (the surfeit of calories used above).
(63.5 g fat per day x 365 days x 10 billion persons)/1e+6 = 2.31775e+8 tonnes of fat
(65 g fat per day x 365 days x 10 billion persons)/1e+6 = 2.3725e+8 tonnes of fat
(100 g fat per day x 365 days x 10 billion persons)/1e+6 = 3.650e+8 tonnes of fat
(130 g fat per day x 365 days x 10 billion persons)/1e+6 = 4.745e+8 tonnes of fat
(65 g fat per day x 365 days x 7 billion persons)/1e+6 = 1.661e+8 tonnes of fat
(100 g fat per day x 365 days x 7 billion persons)/1e+6 = 2.555e+8 tonnes of fat
(130 g fat per day x 365 days x 7 billion persons)/1e+6 = 3.3215e+8 tonnes of fat
But when we compare the world staple crop production of oil to the above calculated needs, there is a substantial deficit.
The 44 world staple crops listed in the chart produce only 2.3313e+8 tonnes of fat per year. The top 25 crops, ordered by total amount of fat produced, provide 2.3196e+8 tonnes of fat, and the top 20 provide 2.3020e+8 tonnes of fat. The top 15 crops provide 2.2383e+8 tonnes, and the top ten provide 2.0688e+8 tonnes of fat. Only the top 6 fat crops are needed to exceed the 1.661e+8 tonnes of fat needed for 65 grams per person at a population of 7 billion. The top 5 fat crops provide only 1.5879e+8 tonnes of fat.
So, unlike protein and calories, the current world agricultural system does not provide enough fat for 10 billion persons. If we reduce the amount of fat per person to 63.5 grams, the top 25 fat crops would seem to produce enough fat for 10 billion persons. But this analysis fails to take into account the losses from field to table, from diversion of crops for animal feed, and from inequitable distribution. Given these well-known inefficiencies and inequities in the worldwide food economy, the amount of fat produced today is not even sufficient for 7 billion persons, and would be far short of what is needed for 10 billion persons. Why are one billion persons undernourished each year? One major contributor to that problem is the lack of fat produced by the world agricultural system.
How much more land must be devoted to agriculture to feed a population of 10 billion? For caloric and protein needs, no additional land is needed, provided that high quality grain and soy are used for human consumption, rather than as feed for cattle, poultry, and fish. For the macronutrient of fat, more land must be devoted to crops that produce vegetable fat for human consumption. If we use 130 grams of fat per day per person as our goal, again choosing a surfeit as a bulwark against various losses, inefficiencies and inequities, the results are as follows.
The current top 20 fat crops require 9.50470972e+8 hectares of land to produce 2.3020e+8 tonnes of fat. The average fat per hectare is 0.242 tonnes. At 130 grams and 10 billion persons, the world needs 4.745e+8 tonnes of fat. The difference lacking is 2.443e+8 tonnes. At 0.242 tonnes per hectare, the world would seem to need 1.0095e+9 additional hectares of land for the fat needs of 10 billion. However, if those additional hectares are used exclusively for the highest producing fat crops (see the Oil Crops chart), the average fat per hectare is 0.903 tonnes. In this case, the additional hectares needed would be less at about 2.705e+8 hectares. This area of land is equivalent to just over 1 million square miles, or about 2.6 million square kilometers, which is about 6.3% of the arable land in the world (World Soil Resources Report, Table 15, p. 39). But this additional area is still a substantial increase in the total land needed for agriculture in the world.
The 9 crops recommended for the above additional hectares of land for oil are (crop, yield in kg/ha) as follows:
1. Flaxseed, 1450 - high production per hectare; high in omega-3; best use as an oil crop.
2. Camelina, 1340 - high production; high in omega-3; stores well without refrigeration and with little refining; best use as an oil crop, but possible use as a whole food.
3. Chufa oil, 1308 - also called 'tiger nut'; high production per hectare; low in essential fatty acids; oil stores well; can be used for oil or whole food.
4. Canola, 764 - moderate production; well established crop; stores well when refined; best use as an oil crop.
5. Peanut, 760 - moderate production; well established crop; stores well when refined; can be used for oil or whole food.
6. Pumpkin seed, 672 - moderate production; needs further research and development; can be used for oil or food
7. Safflower seed, 662 - moderate production; established crop; very high in omega-6; best use for oil, possible food use
8. Hempseed, 600 - moderate production; illegal to grow in some nations; good balance of omega-6 and omega-3 fats; can be pressed for oil or eaten as a whole food.
9. Sunflower seed, 570 - moderate production; well established crop; stores well when refined; can be used for oil or whole food.
Certain other oil crops were omitted for various reasons. Palm oil was omitted because the current world reliance on this one oil crop is excessive. Palm oil is the second highest producing oil crop, after soybean, in the world. However, the world devotes too much of its land to soybean, and much of that nutrition is diverted to animal feed. Palm oil and other tree oil crops (coconut, olive, palm kernel) require a much greater length of time to increase the area of land planted. Other oil crops can be planted and harvested in less than 12 months; tree oil crops require years to be ready for the first substantial harvest.
Certain oil crops were included in the above list, despite not currently providing substantial oil for the world food system. Pumpkin seed could be developed further into a major oil crop, with the advantage of providing protein and carbs from the seed and flesh, along with the oil. The area of land devoted to hempseed should be increased because hemp also provides protein and carbs, and its fatty acid profile has an ideal balance of omega-6 and omega-3 fats. Camelina sativa oil is also high in omega-3 fat, and it stores well without refrigeration. Among high omega-3 fat sources, camelina is the oil with the best storage properties. Flaxseed and peanut are both good producers of fat; the former grows well in cool climates and the latter grows well in hot climates. Safflower is very high in omega-6 fats, and therefore deserves more area of land devoted to it. Chufa oil has the potential for high production per hectare; further research and development is needed.
Sacha inchi seeds produce a high quantity of oil per hectare per year, but the plant is a perennial, growing only in climates with hot temperatures and much rainfall throughout the year. The crop must be harvested by manual labor, but the seeds provide a good source of protein as well as fat. This crop should be developed further, and could be used as a cash crop in suitable areas of the world. Sacha inchi would be a fitting auxiliary source of fat for the world's nutritional needs. But climate restrictions and the need for manual harvesting prevent it from being a major world source of fat.
World Agriculture: Proportions of Macronutrients
Now lets consider the proportions of the macronutrients produced by the world agricultural system. We can use this chart to estimate the total macronutrients produced worldwide, even though the chart has relatively few crops.
We don't need to add all calories produced by all crops because of the immense imbalance in the production quantities of different crops. Only a few crops in the world are grown in the immense quantities of hundreds of millions of metric tonnes per year, yielding in the range 10^15 total kilocalories. The next few crops, in order by total kilocalories of world production, are an order of magnitude less at about 10^14 kcal. Then again there are only a few crops another order of magnitude less at about 10^13 kcal. Only about 20 or 30 crops worldwide are grown in a large enough quantity to have much of an effect on the total protein, fat, carbohydrates, and calories produced by the world agricultural system. All the hundreds of other crops together have little effect on these numbers. There are thousands of food crops, but only a few dozen have a major impact on the world population's total macronutrient intake.
3.7680e+8 metric tonnes
Calories from protein:
3.8 calories/gram * 3.7680e+8 metric tonnes * 1.0e+6 grams/tonne = 1.43184e+15 calories
Protein calories as a percent of total calories:
2.3313e+8 metric tonnes
Calories from fat:
8.8 calories/gram * 2.3313e+8 tonnes * 1.0e+6 grams/tonne = 2.051544e+15 calories
Fat calories as a percent of total calories:
Calories from carbs:
3.89 calories/gram * 2.4422e+9 tonnes * 1.0e+6 grams/tonne = 9.500158e+15 calories
Carbohydrate calories as a percent of total calories:
Total calories used to calculate percents: 1.2983542e+16
The world agricultural system produces enough food for a diet that has
11.0% of its calories from protein,
15.8% of its calories from fat, and
73.2% of its calories from carbohydrates.
However, the recommend intake of macronutrients as a percent of total calories is substantially different from the above proportions.
Acceptable Macronutrient Distribution Range (AMDR)
Protein: 10 to 35% of total calories
Fat: 25 to 35% of total calories
Carbohydrate: 45 to 65% of total calories
[Source: Dietary Reference Intakes for Energy, Carbohydrate. Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids (2002/2005). PDF Chart based on this book | ]
The world agricultural system does not produce sufficient fat for a healthy diet for the world population. The world agricultural system also produces barely enough protein, and too many carbohydrates.
Conversion of some agricultural land from carbs (grains, tubers) to fat and protein (seeds, nuts, oil crops) would benefit the world population. Adding new arable land to the world agricultural system, to be used for protein and fat, would also be beneficial. With the current trend in world population growth, the health of the world requires these changes to be made as soon as possible.
Summary and Conclusions
The world agricultural system already produces sufficient calories and protein to feed 10 billion persons. However, a large percentage of these calories and protein are used for animal feed, instead of human nutrition. The resulting animal food products contain far less macronutrients than required to feed the animals. The result is a substantial reduction in calories and protein available to feed the world. In order to feed 10 billion human persons, we must no longer feed grain and soy to domesticated animals. They should be fed from by-products of food grown for human use, such as canola press cakes (left over from oil production) and the stalks and husks of rice, corn, and wheat, rather than the grains.
Worse still, current production of fat is sufficient to meet the dietary needs of the current world population (of about 6.8 billion), only if little or no vegetable fat is diverted to feed animals. World production of vegetable oil must increase substantially merely in order to feed the current population. And since the world population is growing steadily, we should set as our goal the development of an additional 1 million square miles of new agricultural land for use in growing oil crops -- the amount of new agricultural land needed to meet the goal of feeding 10 billion persons.
Problems of unfair distribution of food can be best addressed by having as much food as possible grown as locally as possible. Emphasis should be placed on oil staple crops first, then secondly on staple crops that provide carbs and protein, such as grains and tubers.
There is a severe imbalance in the production quantities of carbohydrate, protein, and oil staple crops, such that very few crops provide most of the macronutrients needed by the world. Often these few crops consist of very few cultivars grown very extensively. If any one cultivar experiences a problem with a particular plant disease or pest, the result would be a devastating loss of the macronutrients available to the world.
To address this problem, the world agricultural system must increase the number of different types of plants grown as staples, and increase the number of different cultivars within each type. In particular, the world should grow less maize, which is particularly low in protein and lysine compared to other grains, and less rice, wheat, soybean, sugar cane, and more of many other sources of macronutrients. Among the top staple crops, cassava is particularly problematic as it is poor in protein, and contains toxic cyanogenic glucosides. This staple should be developed further to address these problems, or be replaced by better sources of protein and carbs.
Additional plant types suitable for development and use as staple crops include: amaranth, quinoa, fonio, teff, kaniwa (canihua), millet, and other grains; oca, ulluco, maca, sweet potato, and other tubers; pumpkin seed, sacha inchi, hemp, safflower, chia, chufa, camelina, and other oil sources.