Improving Agricultural Productivity

Population grew at the fastest rate in human history during the second half of the twentieth century, as discussed in Chapter 2. With the amount of land devoted to agriculture not increasing, many experts forecast massive global famine. But these dire predictions did not come true. Instead, increased productivity has resulted in an expansion of food supply. New agricultural practices have permitted farmers worldwide to achieve much greater yields from the same amount of land.

Increased Productivity: Commercial Farmers

The second agricultural revolution, which began in the United Kingdom in the seventeenth century, increased productivity through improvement of crop rotation and breeding of livestock. Increased agricultural productivity helped to feed the rapidly growing population in countries in stage 2 of the demographic transition during the nineteenth century.

Productivity has also increased among commercial farmers in recent years. New seeds, fertilizers, pesticides, mechanical equipment, and management practices have enabled commercial farmers to obtain greatly increased yields per area of land.

The experience of dairy farming in the United States demonstrates the growth in productivity. The number of dairy cows in the United States decreased from 10.8 million to 9.4 million between 1980 and 2017. But milk production increased from 58 to 98 million metric tons. Thus, yield per cow increased 93 percent during this 37-year period, from 5.4 to 10.4 metric tons per cow.

U.S. Dairy Productivity

The amount of milk produced per cow has increased rapidly in the United States, especially since the 1980s.

Intensification by Subsistence Farmers

For hundreds if not thousands of years, subsistence farming in developing countries yielded enough food for people living in rural villages to survive, assuming that no drought, flood, or other natural disaster occurred. Suddenly in the late twentieth century, subsistence farming practices needed to provide enough food for a rapidly increasing population as well as for the growing number of urban residents who cannot grow their own food.

Population growth influences the distribution of types of subsistence farming, according to economist Ester Boserup. It compels subsistence farmers to consider new farming approaches that produce enough food to take care of the additional people.

According to Boserup, subsistence farmers increase the supply of food through intensification of production, achieved in two ways. First, new farming methods are adopted. Plows replace axes and sticks. More weeding is done, more manure is applied, more terraces are carved out of hillsides, and more irrigation ditches are dug. The additional labor needed to perform these operations comes from the population growth. The farmland yields more food per area of land, but with the growing population, output per person remains about the same.

Second, land is left fallow for shorter periods. This expands the amount of land area devoted to growing crops at any given time. Boserup identified five basic stages in the reduction of fallow farmland:

1. Forest fallow. Fields are cleared and utilized for up to 2 years and left fallow for more than 20 years, long enough for the forest to grow back.

2. Bush fallow. Fields are cleared and utilized for up to 8 years and left fallow for up to 10 years, long enough for small trees and bushes to grow back.

3. Short fallow. Fields are cleared and utilized for perhaps 2 years (Boserup was uncertain) and left fallow for up to 2 years, long enough for wild grasses to grow back.

4. Annual cropping. Fields are used every year and rotated between legumes and roots.

5. Multi-cropping. Fields are used several times a year and never left fallow.

Contrast shifting cultivation, practiced in regions of low population density such as sub-Saharan Africa, with intensive subsistence agriculture, practiced in regions of high population density such as East Asia. Under shifting cultivation, cleared fields are utilized for a couple years and then left fallow for 20 years or more. This type of agriculture supports a small population living at low density.

As the number of people living in an area increases (that is, as the population density increases) and more food must be grown, fields will be left fallow for shorter periods of time. Eventually, farmers achieve the very intensive use of farmland characteristic of areas of high population density.

The Green Revolution

The invention and rapid diffusion of more productive agricultural techniques during the 1970s and 1980s is called the green revolution. The green revolution involves two main practices: the introduction of new higher-yield seeds and the expanded use of fertilizers. Because of the green revolution, agricultural productivity at a global scale has increased faster than population growth. Scientists began an intensive series of experiments during the 1950s to develop a higher-yield form of wheat. A decade later, the “miracle wheat seed” was ready. Shorter and stiffer than traditional breeds, the new wheat was less sensitive to variation in day length, responded better to fertilizers, and matured faster. The Rockefeller and Ford foundations sponsored many of the studies, and the program’s director, Dr. Norman Borlaug, won the Nobel Peace Prize in 1970.

The International Rice Research Institute, established in the Philippines by the Rockefeller and Ford foundations, worked to create a miracle rice seed (Figure 9-60). During the 1960s, their scientists introduced a hybrid of Indonesian rice and Taiwan dwarf rice that was hardier and that increased yields. More recently, scientists have developed new high-yield maize (corn).

Testing New Varieties of Rice

“Miracle” high-yield seeds have been produced through laboratory experiments at the International Rice Research Institute (IRRI). The IRRI is testing varieties in the Philippines.

The new miracle seeds were diffused rapidly around the world. India’s wheat production, for example, more than doubled in five years. After importing 10 million tons of wheat annually in the mid-1960s, India had a surplus of several million tons by 1971. Other Asian and Latin American countries recorded similar productivity increases. The green revolution was largely responsible for preventing a food crisis in these regions during the 1970s and 1980s. But will these scientific breakthroughs continue in the twenty-first century?

To take full advantage of the new miracle seeds, farmers must use more fertilizer and machinery. Farmers have known for thousands of years that application of manure, bones, and ashes somehow increases, or at least maintains, the fertility of the land. Not until the nineteenth century did scientists identify nitrogen, phosphorus, and potassium (potash) as the critical elements in these substances that improve fertility. Today these three elements form the basis for fertilizers—products that farmers apply to their fields to enrich the soil by restoring lost nutrients.

Nitrogen, the most important fertilizer, is a ubiquitous substance. China is the leading producer of nitrogen fertilizer. Europeans most commonly produce a fertilizer known as urea, which contains 46 percent nitrogen. In North America, nitrogen is available as ammonia gas, which is 82 percent nitrogen but more awkward than urea to transport and store. Both urea and ammonia gas combine nitrogen and hydrogen. The problem is that the cheapest way to produce both types of nitrogen-based fertilizers is to obtain hydrogen from natural gas or petroleum. When fossil fuel prices increase, so do the prices for nitrogen-based fertilizers, which then become too expensive for many farmers in developing countries.

In contrast to nitrogen, phosphorus and potash reserves are not distributed uniformly across Earth’s surface. Phosphate rock reserves are clustered in China, Morocco, and the United States. Proven potash reserves are concentrated in Canada, Russia, and Ukraine.

Farmers need tractors, irrigation pumps, and other machinery to make the most effective use of the new miracle seeds. In developing countries, farmers cannot afford such equipment and cannot, in view of high energy costs, buy fuel to operate the equipment. To maintain the green revolution, governments in developing countries must allocate scarce funds to subsidize the cost of seeds, fertilizers, and machinery.

Pause & Reflect 9.4.3

What would be the impact on the green revolution of a decline in energy prices?