AGRICULTURE

The earliest human inhabitants of the earth were hunters and gatherers. Under favorable conditions they required at least 1.5 square kilometers to provide food for one person, and in harsher environments as much as 80 to 100 square kilometers. Population pressure eventually led humans to raise plants and animals.

With the introduction of agriculture, humans began to use energy to control the growth of plants and animals, to make more efficient use of the solar energy stored in plants by photosynthesis. However, for many thousands of years, the only energy used for this purpose was human energy. The energy drawn from the biosphere was limited to the dietary energy provided by plant food and meat, and to the use of wood and grasses as fuel for heating and cooking. Later, humans learned to use animal, water, and wind energy to obtain power for transport and for simple agricultural and industrial processes. As population grew, the use of energy increased steadily, but all of it came from renewable resources.

Shifting cultivation, one of the first agricultural practices developed, is still widely used. In the early 1970s, about 36 million square kilometers of land were farmed under this system, producing food for about 250 million people. Each hectare (2.47 acres or 10,000 square meters) under shifting cultivation can provide adequate food for one person. Degradation of soil and vegetation usually occurs when the population density exceeds one person per four hectares. At higher population densities, shorter fallow periods and eventually annual cropping become necessary.

Annual cropping by traditional methods requires more labor, and yields are generally lower. Although animal power can help reduce human labor and provide manure for fertilizer, draught animals must be either fed by some of the crop or pastured, thereby increasing the land area required per person unless yields per unit of land increase accordingly. Average livestock ate one-fourth of the yield in the early nineteenth century.

This land per person dynamic has changed in the past one hundred years as humans moved beyond the limitations of human and animal power by drawing upon nonrenewable sources of energy in the form of fossil fuels—coal, oil, and natural gas. Rapid improvements in technology made it possible to locate and extract increasing quantities of fossil fuels with little or no increase in cost. By the 1950s and 1960s the world had come to take advantage of the large supply of fossil fuels to dramatically and economically boost agricultural production.

Energy dense fossil fuels can be converted very efficiently to heat and/or power. Use of energy for power has spread rapidly in both the industrial and agricultural sectors of the developed countries. The developing countries have followed the developed countries along the same path but at a slower pace. Although agriculture uses only a small share of the world's total energy consumption, it is generally recognized that its needs are crucial, because the existing technologies for increasing production rely so heavily on energy-intensive inputs. Farm use of energy accounts for only 4 percent of total commercial energy use in developing countries and 3 percent in the developed countries. Commercial energy includes oil, natural gas, and coal. Noncommercial sources of energy include fuel-wood, plant and animal residues, and human and animal energy. Noncommercial energy uses are very important in the developing countries, especially in rural areas.

There is a two-way relationship between agriculture and energy because agriculture is both a consumer and a producer of energy. Directly or indirectly, the whole agricultural process involves the input of energy. The ability of plants to capture and store the sun's energy through photosynthesis can be increased through the input of energy in the form of fertilizer, pesticides, and fuel to drive machinery used in production. The production of nitrogen fertilizers is very energy intensive input because it requires hydrogen-dissociation from water or fossil fuels (natural gas) to fix nitrogen in synthetic fertilizers. Production of pesticides similar to nitrogen fertilizers requires large amounts of energy. The gasoline and diesel fuel used for agricultural machinery also consumes a lot of energy, but has dropped significantly since the early 1970s because of better technology.

The role of energy in agricultural production has become crucial as population and income growth put pressure on the demand for food. By discovering new technologies (hybrid seeds, drought and disease-resistant crops, as well as genetically modified crops), dramatic increases in crop yields per hectare have been achieved in the developed countries. The pace of growth, however, has been uneven among developing countries. Asia has shown significant increases in agricultural productivity, while many countries in Africa and Latin America have had modest productivity growth. Although many developing countries have reserves of unused but potentially productive land, most have to meet rising food demands by substantially raising yields on both used and new land. The growth in yields does not come automatically. An increase in agricultural research investment is essential both to increase the yield and to expand the area under cultivation. Clearing less accessible new land for cultivation, which is the goal of many environmentalist groups, will require greater investment in inputs of commercial energy and often the provision of drainage, irrigation, and soil conservation systems. Once the land is under production, additional energy will be needed for maintenance.

CLASSIFICATION OF AGRICULTURAL PRODUCTION

World production of food and fiber could be classified into three distinct groups: traditional, transition from traditional to modern, and modern farming methods.

Traditional Agriculture

Traditional farms rely on labor, draught animals, and hand tools. The only commercial energy input in traditional farming is that required to produce hand tools and animal implements. No commercial energy inputs are used for irrigation; the land either gets rain or it's irrigated by traditional methods.

Traditional methods continue to be the mode of operation in many parts of the world. Currently agriculture production in many of the lowest income countries in Africa, Latin America, and Asia are based on traditional methods. Agriculture is largely operated by small family farms using human and animal power and organic fertilizer with little access to or knowledge of modern inputs such as chemicals, fertilizers, hybrid seeds, or mechanical drive. Low soil fertility and inadequate or irregular rainfall sharply limit the productivity of low-input farms in developing countries.

The Transition to Modern Farming

In the transition to modern farming methods, the use of commercial energy, especially machinery and fertilizer, increases sharply. Primary tillage is usually one of the first operations to be mechanized, requiring an increase in commercial energy use not only for the production of farm machinery, but also for its operation. Improved crop varieties are often introduced during the transitional phase, requiring commercial energy for their production and distribution. To help realize their yield potential entails the use of chemical fertilizers and pesticides. Both of these inputs require commercial energy for their manufacture. In addition to the traditional irrigation methods, supplementary irrigation with mechanically powered pumps is often introduced during the transitional phase. This process substantially increases commercial energy requirements but also increases yields. The growing needs for investment during transition influence farm size. To achieve economies of scale, the number of family farms is reduced and they are replaced with larger commercial farms.

This general trend toward larger farms, greater mechanization, and greater use of commercial inputs in most countries results in greater productivity but at the cost of greater direct and indirect energy use. The combination of increased irrigation, use of high yield variety crops, and new inputs has contributed to steady increases in both absolute and percapita agricultural production.

Modern Commercial Agriculture

To feed the growing population, agricultural productivity must increase. Modern inputs are needed to increase agricultural production. Commercial fuel inputs to agriculture include mechanized land preparation, mechanized irrigation, and synthetic fertilizer. Modern commercial agriculture is greatly dependent on high yielding varieties, and modern pesticides.

The degree of utilization of the above inputs varies widely, but generally increases with economic development. These modern technologies reduce the time and labor needed for land preparation, plowing, planting, and harvesting crops. In favorable areas, it also aids double cropping management.

In the developed countries, stages in the historical development of agricultural production have been characterized by differing combinations of inputs: differences in relative proportion of land, labor and capital, and in the composition of the capital inputs. Such changes reflect primarily the changing structure of the economy and the successive advances that have been made in agricultural technology.

The well-documented case of the United States serves as an illustration. During the period 1870 to 1900 the farm population was increased through a rapid expansion of the agricultural area. The agricultural labor force increased by 60 percent, but there was a replacement of labor by nonland capital in the form of horses and mules. New and more efficient types of horse-drawn machinery including plows, cultivars, seed drills, grain harvesters, and mowers became available.

The following period, from 1900 to 1930, was a period of transition: the first half was the beginning of the end for traditional farming, based predominantly on large inputs of relatively unskilled labor, and the second half the beginning of commercial agriculture, technologically oriented and capital intensive. The crop-land use continued to increase until about 1920 but remained relatively stable thereafter, and the agricultural labor force continued to increase until about 1918. Equally significant, however, were the shifts that became evident in the composition of non-real-estate capital input: the replacement of horses and mules by tractors, automobiles and trucks; of manpower by motor-driven machinery and equipment; and the purchase of production inputs such as fertilizer, lime, seed, and feed required for the application of improved production techniques.

Between 1935 and 1960 outputs per man-hour of labor increased about 4.5 times, and crop production per hectare of crop-land almost doubled. Inputs of labor were decreased by 50 percent, inputs of land remained relatively stable, but inputs of non-real-estate capital inputs were nearly tripled. Among these capital inputs, those of seed, feed, and livestock purchased increased by about four times, and those of mechanical power and machinery by more than 2.5 times.

It has been estimated that of the total U.S. increase in farm output between 1940 and 1955, 43 percent is attributable to increased crop yields per hectare, 27 percent to increases in value added by livestock production, 23 percent to reduction in farm-produced power, and 7 percent to changes in the amount of capital used. While it is not possible to isolate the effect of a single input, it is estimated that increased use of fertilizer accounted for more than half of the increase in crop production per hectare. Other important causes of increased crop yields include the use of hybrid maize and other improved plant varieties, irrigation, better soil tillage practices, more timely planning, cultivation and harvesting operations, and better weed, insect, and disease control.

ENERGY USE IN TRADITIONAL AND MODERN AGRICULTURE

Commercial energy plays a major role in modern methods of production. Energy use even with modern methods varies by crop. Crops requiring irrigation use much more energy than rain-fed crops. About 42 percent of total energy is used for irrigation, 20 percent for the manufacture and operation of farm machinery, 18 percent for fertilizers, and 7 percent for drying. For modern rice production in the United States, the commercial energy input is more than 500 times that in traditional production and more than 10 times in transitional production in the Philippines. For modern corn production in the United States, total commercial energy use is only about half that in modern rice production, mainly because little or no irrigation is required. Regardless of the crop produced, energy use is much higher with modern production method. For example, commercial energy input in the United States is more than 174 times that in traditional production in the Mexico.

With modern production methods 1500 kilograms of petroleum per hectare are needed for rice and 700 kilograms for maize. However, with this commercial energy use, yields of 5.8 metric tons per hectare have been obtained for rice and 5 metric tons per hectare for maize—about five times those obtained with traditional methods, Thus, 20 to 25 people can be fed on an all-grain diet from a single hectare compared with 4 to 6 people by traditional methods.

Total energy used to produce a kilogram of rice on Philippine traditional farms requires three grams of petroleum and in transitional farms 55 grams. In the U.S. modern rice farming system the requirement increases to 258 grams of petroleum. Similarly, the ratio for corn production in Mexico for traditional farming is equal to four grams of petroleum, and for modern corn farming in the United States is equal to 137 grams of petroleum.

Despite higher dependence on energy in modern methods of production, agriculture is responsible for only a small part of total energy use. Total energy use as well as energy used in agricultural production in selected developing and developed countries and for the largest food producers in the world; the United States and China are compared in Table 1. In 1996, agricultural shares of energy use for all developed countries were 2 percent, whereas in the developing countries the proportion was slightly higher. Agricultural shares of total commercial energy use in the developing countries ranged from 0.67 percent in Egypt to 5.08 percent in Brazil. For the developed countries agricultural share of energy ranged from 1.09 percent in the United States to 3.39 percent for the European Community.

COMMERCIAL ENERGY USE IN AGRICULTURE

Agriculture uses a variety of commercial energy forms, directly for operating machinery and equipment on the farm and indirectly through the use of fertilizer and pesticides produced off the farm. In addition, commercial energy is used in manufacturing of farm machinery and farm equipment. During 1972 to 1973 farm machinery manufacture and operation, the largest user of commercial energy in agriculture, accounted for 51 percent of the world total and ranged from 8 percent in the Far East to 73 percent in Oceania. Chemical fertilizer was second with 45 percent of the world total and ranged from 26 percent in Oceania to 84 percent in the Far East. However, in the developing countries chemical fertilizer was first.

About 1.5 billion hectares of crop land are planted for annual crops and permanent crops. About one third of the arable and permenant crop-land is located in the United States, India, and China. Out of 1.5 billion hectares, 263 million hectares are irrigated. Irrigated lands in China and India account for the largest share—about 110 million hectares.

Reports by the International Energy Agency indicate that total renewable energy use in developing countries and in agriculture is high, but no data is available. The available data on selected countries shows that the use of renewable energy in developing countries varies from 5 percent in Egypt to 86 percent in Nigeria. Energy share of the renewable energy in the developed countries ranged from 1 percent in Japan to 6 percent in Australia.

To measure the efficiency of energy use in

agriculture, energy use in agriculture is compared with agriculture's share of gross domestic products (GDP). For many developing countries, the share of agricultural GDP is much larger than the share of energy used in agriculture, which suggests that much of the agricultural sector is still engaged in subsistence, low input, labor-intensive farming. For some middle income countries such as Brazil, Egypt, and Indonesia the two ratios are in better balance. Developed countries have a very close balance between agriculture's share of GDP and share of energy use in agriculture. Energy use share is lower than agricultural GDP share except for Japan and the European Union which both rely heavily on intensive production methods.

Energy use per hectare of arable and permanent crop-land can be used as an indicator of the efficiency of energy use in agriculture, although definite conclusions from this indicator are hard to draw unless countries with the same scale of operations are compared. Low energy use per hectare can reflect low-input, low-yield agriculture, which is the case for some developing countries such as Bangladesh, India, Indonesia, Nigeria, and Pakistan. On the other hand, low energy use (dry-land farming with less fertilizer and pesticide use) per hectare can also indicate the extensive farming practices of countries such as Australia and Canada where low yield relative to high-input use countries have not prevented these countries from being competitive agricultural exporters. Japan and the European Union stand out as being very high energy users relative to their land base. The United States has a relatively low energy use per hectare, especially when compared to the European countries.

INPUT USE

Land Use and Irrigated Area

Using data from the United Nations Food and Agriculture Organization (FAO) for arable and permanent crop-land for 1966 to 1996, developing countries have experienced the most significant growth in land area. The highest growth was realized in Brazil, China, and India. In contrast, most developed countries have experienced a decline in arable and permanent crop-land, with Australia and Canada being the exceptions. For some developing countries, such as Egypt and India, increases in area as well as yields have been important in increasing output. For developed countries, increases in output have been a function of higher yields rather than increases in area. The U.S. agricultural area increased more than 12 million hectares during the 1970s and 1980s and declined in the 1990s, with an overall decline of one-half million hectares.

Irrigated areas increased in the last three decades in all countries except Japan. Growth has been rapid in Bangladesh and Brazil. Growth in irrigated areas in the United States has been among the slowest of the selected developed countries. The share of agricultural area under irrigation varies considerably, reflecting resource endowments and crop composition. In 1996, Egypt had 100 percent of its area under irrigation, followed by Pakistan with 81 percent and Japan with 63 percent. More than a third of land is irrigated in China, India, and Bangladesh. Canada, Australia, and the United States, with large-scale, extensive farming practices, have lower shares of irrigated areas.

Fertilizer Use

Fertilizer use (measured in tons of active ingredients) has increased most rapidly in developing countries, where yields generally lagged behind those in developed. Among developed countries, fertilizer use per hectare is very high in Japan and the European countries. Fertilizer use is also high in some of the developing countries, including Egypt, China, Bangladesh, and Pakistan. Fertilizer use in the United States is low compared to the European countries, as is true for other large crop producers such as Canada, Australia, and Brazil.

Pesticide Use

Data on pesticide use, including insecticides, herbicides, fungicides, and other chemicals is scarce. Similar to fertilizer use, pesticide use is the highest in the United States followed by the European countries, and Australia. Pesticide use per hectare is much higher than in other developed countries because farmers are trying to maximize the yield per hectare. Among developing countries pesticide use is also high in Egypt, Brazil, and Pakistan. The trend in developing countries is for more use of chemicals in agriculture to increase yield per hectare.

Machinery Use

Machinery use has followed a similar pattern to fertilizer use, with the largest increases occurring in developing countries and smaller increases or declines in developed countries. The data do not reflect changes in quality or complexity of agricultural machinery. The relative intensity of use is highest in Japan followed by the European countries. Machinery use in the United States is much lower than in Europe and has remained steady because the average farm is much larger in the United States, which translates into better utilization of farm equipment. Machinery use increased in all developing countries. Growth has been rapid in Pakistan, Indonesia, and India, followed by Japan. In the developing countries, machinery use per hectare is lowest in Bangladesh and highest in Egypt.

Roger Conway Hosein Shapouri

See also:Biological Energy Use, Ecosystem Functioning of; Chemical Energy, Historical Evolution of the Use of; Nitrogen Cycle.

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