"The image is counterintuitive but true: survival of the peasants in the rice fields of Hunan or Guangdong - with their timeless clod-breaking hoes, docile buffaloes, and rice-cutting sickles - is now much more dependent on fossil fuels and modern chemical synthesis than the physical well-being of the American city dwellers sustained by Iowa and Nebraska farmers cultivating sprawling grainfields with giant tractors. These farmers inject ammonia into soil to maximise operating profits and to grow enough feed for extraordinarily meaty diets; but half of all peasants in Southern China are alive because of the urea cast or ladled onto tiny fields - and very few of their children could be born and survive without spreading more of it in the years and decades ahead." In the last half century the technological development of agriculture has dramatically changed the performance of farming. The changes have been both positive and negative: on the positive side changes have resulted in a more stable and abundant food supply; on the negative side it has created more environmental degradation, more dependence on fossil energy, and a lower energy efficiency. Understanding the reason for these changes requires an examination of the relationship between technological development, population, natural resources and environmental sustainability for development. For the time being, North America and much of the industrial world have achieved very high agricultural production and low food costs on the basis of extremely intensive industrialised farming systems which use modern technology and chemicals. Whereas, in less developed countries, agricultural production is more traditional (subsistence and extensive farming systems) and more a means of preventing starvation than increasing the standard of living of farmers and others.

For example, modern techniques for cereal farming in North America ar based on a massive injection of fossil energy. This results in lowering the energy efficiency (output-input ratios), and a rapid depletion of non-renewable oil stocks. The two forces driving this development are: (i) the increasing productivity per hour of labour of farmers ( = increasing the income and standard of living of farmers, and making available more labour for other economic sectors), and (ii) the increasing productivity per unit of land area ( = increasing the total food supply). These types of high-technology / high -yield cereal farming, depend on non-renewable energy, impacting negatively on the environment by lowering the sustainability of the agro-ecosystem. These impacts include soil erosion, reduced biodiversity, and chemical contamination of the environment by fertilisers, herbicides and pesticides, and mining of groundwater. However, to get approximately the same yield as North America, Asian farmers must work more than 1, 000 hours / year per hectare in cereal production compared to only 10 hours / hectare for North American agriculture.

The U. S. economy manages in this way to sustain its farmers at an income level that is almost comparable to that of workers in other U. S. economic sectors, but that is almost a hundred times higher than the income of Chinese farmers.

The large increases in fertilisers and pesticides used in North America are again due to the abandonment of traditional agricultural technologies. For example, for some major crops like corn, crop rotation has been abandoned; nearly 50 percent of U. S. corn is grown continuously as a monoculture. This has caused an increase in the number of corn pests and the need for more pesticides to protect the crop. Since 1945 the use of synthetic pesticides in the U.

S. has grown 33-fold, yet crop losses to pests continue to increase. In Asia, it is more population pressure and poverty that forces the abandonment of sound techniques in agricultural production, such as fallows and crop rotations. Population growth means shrinking environmental resources per capita (land, soil, water and biological resources), a need for increasing yields per hectare and sooner or later a dependence on fossil fuels. When the development of a country is prevented by its demographic trap, negative ecological side effects are generated by the increased use of energy in agriculture.

Environmental degradation tends to drive down the income of farmers and the available food supply per capita. Currently worldwide there is serious degradation of land, water, and biological resources generated by the increasing use of fossil energy by the world's population. More fossil energy is used than is available in the form of a sustainable supply of biomass, more nitrogen fertiliser is used per year than could be obtained by natural supply, water is pumped out of underground reservoirs at a higher rate than it is recharged, and more minerals are taken out of mines than are formed. Fossil energy and technology enabled humans to (temporarily) sustain excesses. On the whole, increased food demand in Asia and North America will have to be met primarily through higher yields on remaining land and by more intensive cropping.

Primary strategy for the future will be to raise yields on less productive land by expanding use of organic fertilisers and sustainable crop through an ecological agriculture program. A sustainable use of renewable resources is only possible if; (i) known environmentally sound agricultural technologies are implemented, (ii) various known renewable energy technologies are put in place, (iii) major increases in energy efficiency are achieved to reduce the exponential energy consumption per capita, and (iv) population size and the consequent level of withdrawal of natural resources are compatible with maintaining the stability of environmental processes. Clearly, there is a flaw in human logic. If we are to safeguard the earth for future generations humans must learn how to manage natural resources in a sustainable manner and determine what is an acceptable standard of living for the human race as a whole.