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How Much Fertilizer would be needed to End World Hunger?

Crop yields vary greatly from one nation to another. The developed nations generally have much higher crop yields than the developing nations. Many factors are responsible for this disparity. But one of the principle factors is fertilizer, or the lack thereof. A vast quantity of Fertilizerarable land, currently being used to grow food for the world, is unfertilized and therefore much less productive than it could be.

How much cropland, not currently fertilized, would need to be fertilized to fulfill the unmet needs of the hungry of the world for protein, fat, and carbohydrates?

Crop yields affect the amount of food produced in any nation. A number of studies have shown that simply adding a basic N-P-K fertilizer to a formerly unfertilized field will more than double yields. In the developed world, using fertilizer is the norm. But in the developing world, much of the agricultural land does not use fertilizer at all. Sometimes the farmer uses a technique of leaving the land fallow for a time. Another approach is to use manure as a natural fertilizer. However, manure is not nearly as effective as N-P-K.

In the U.S., one study found that 46% of the wheat yield (1989 to 1998) is attributable to fertilizer (nutrient inputs). In other words, a fertilized field produces 85% more wheat than an unfertilized field (100/54 = 1.85). The same study found that, in an earlier period, 1979 to 1998, as much as 77% of the wheat yield was attributable to fertilizer, representing an increase of over 4 times (100/23 = 4.35).

Another U.S. study found that 67% of the corn yield (1995 to 2000) is attributable to fertilizer. In other words, yields triple with fertilizer, compared to without fertilizer (100/33 = 3.0). A U.K. study found that 76 to 82% of the wheat yield is due to nitrogen in the fertilizer. This translates to an increase in yield of more than 5 times (100/18 = 5.55).

Studies in Brazil and Peru found that new agricultural land had an even heavier dependency on fertilizer. From 80 to over 90% of crop yields, for several different staple crops (rice, soybean, cowpea, and corn), were attributed to fertilizer. This implies a 5- to 10-fold increase in yield (100/20 = 5 and 100/10 = 10). [W. M. Stewart, et al., “The Contribution of Commercial Fertilizer Nutrients to Food Production”, Agronomy Journal, vol. 97, Jan-Feb, 2005, n. 1.]

But let’s use a conservative estimate of double yields with fertilizer. How much crop land would need to be fertilized to produced enough protein, fat, and carbohydrates to fill the unmet needs of the hungry of the world? The calculations in detail are found in my book, Hunger Math. The conclusion is as follows:

The total area is therefore about 146 million hectares. But since these figure are all rough estimates, let’s use a slightly more conservative figure of 150 million ha. That is the amount of agricultural land, used to grow staple crops for the production of protein, fat, and carbohydrates, that would need to be fertilized to obtain enough of an increase in yield to meet the unmet needs of the one billion hungry of the world for macronutrients.

However, that figure is for one crop per year. If the same land grows 2 staple crops per year, then we only need to fertilize 75 million ha of land that was not previously fertilized in the developing world. If we could grow 3 staples crops per year on that land, only 50 million ha would need fertilizer. (Of course, each crop must be fertilized each time, so the amount of land is decreased, but not the amount of fertilizer.)

How does this compare to the total amount of agricultural land in the world? The FAOSTAT database estimates the world’s “arable land” at just over 1.387 billion hectares, and land under “permanent crops” at 0.1505 billion ha. The total is 1.5375 billion ha. My own analysis of the top 50 staple crops (2009 FAOSTAT data) found 1.136 billion ha devoted to those 50 crops, producing a total of about 1016 kcal per year — enough kcal to feed 10 billion persons. So the FAO total of about 1.5 billion ha is a good estimate of the land area that is needed to feed 7 billion persons, the current world population. A lesser amount of land, used more efficiently would certainly suffice. But let’s be conservative and choose the higher estimate.

The 150 million ha that would need to be fertilized, for one crop only per year, to end world hunger, is only about 10% of the total agricultural land. If we could obtain 2 fertilized crops per year from that land, we would only need to fertilize 5% of the agricultural land.

According to the FAO, the 50 least developed nations have about 167.2 million ha of arable land. So if we were to move about half that land toward modern methods of agriculture, simply by adding fertilizer, perhaps also by making better choices of crops, cultivars, planting dates, etc., there would be enough additional food to end hunger. And that list of the 50 least developed nations does not include India or China. India has over 157 million ha of arable land. China has over 111 million ha of arable land. So there certainly is sufficient land in the developing nations, in those nations where hunger is worst, to grow the food needed by all the hungry of the world.

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