1. Production of Nitrogen Fertilizers. It is estimated that almost one third of the fossil fuel used in industrialized agriculture is consumed by the production of nitrogen-based fertilizers. The production of nitrogen fertilizers requires large amounts of natural gas for the synthesis of ammonia. Nitrogen is commonly the most limiting nutrient to plant productivity, and most intensive farming systems use large amounts of this nutrient to increase yields per hectare. Some estimates suggest that traditional farming systems in Africa could triple their productivity with fertilization. Savings in energy can be accomplished by:
- Applying fertilizers more carefully to crops to reduce over fertilization. Europeans use twice the fertilizer as compared to the average North American farm without any difference in crop yields. This data suggests that Europeans are applying too much fertilizer to their fields. More efficient analysis of soil nutrient status and crop needs could reduce the problem of over fertilization.
- Changing the method of application to the crop. In general, surface applications of fertilizer only get 30-40 % of the nitrogen applied to the crop. Using more efficient methods, like sub-surface banding, could significantly reduce losses to the environment.
- Using crop rotations. The planting of legumes (peas, beans, vetch, alfalfa, and leucaena trees) on alternative years can be used to re-charge the soil with nitrogen naturally.
- Increasing the use of organic fertilizers. In China, the efficient use of organic nutrients from animal wastes, compost and green manure greatly supplements the use of inorganic fertilizers.
2. Irrigation. In the United States, 13 % of agricultural energy consumption is used to pump water, primarily from groundwater sources, for irrigation. Energy consumption could be decreased in this process by employing more efficient irrigation systems that reduce loss of water.
3. Mechanical Tillage of the Soil Surface. Tillage and seedbed preparation consumes large amounts of energy for the operation of machinery. The diesel fuel consumption for plow-based conventional tillage systems ranges from 60-80 litres per hectare. New techniques, like conservation tillage, have been developed where the application of herbicides and the use of specially developed seeding machines can replace the tilling process. This switch to this technology could reduce energy consumption significantly. This technique also benefits the soil by improving its structure and moisture holding capabilities.
4. Livestock Raising. Raising livestock requires enormous quantities of fossil fuels. Energy is required for growing, harvesting, processing and transporting animal feed, handling manure, and maintaining climate controlled surroundings. Fuel savings could be produced by developing more efficient means of livestock keeping and by reducing the consumption of meat and other livestock products.
5. Food Processing. A lot of energy is required to store, process, package, transport, refrigerate and cook both plant and animal farm products. Studies in industrialized countries have revealed that for every calorie of food consumed, on average, 10 calories of energy are used to produce, process and package the product. For comparison sake, one unit of human labor energy expended by the traditional farming techniques results in approximately one unit of food energy for consumption.
Modern energy intensive agriculture can continue to expand for perhaps several more decades. However, with depleting oil reserves, energy prices are likely to escalate to a point where their use in industrial agricutural systems will be too expensive. Several things can be done now to minimize the use of fossil fuels. Farmers can begin to use local perpetual and renewable energy sources including wind, water, sun, animal and crop wastes. Agricultural systems can also be made more energy efficient. Some studies suggest that the application of organic farming techniques can reduce energy use by more than 40 percent.
