The abundance of plant pests in the tropics, including weeds and disease, makes agriculture successful mainly in the plantation system, where needed control measures can be financed. The alternative is to move from deteriorated land to newer fields; this practice of shifting agriculture has also been common, because tropical soils lose their productive capacity so rapidly.
Even when oilseeds (esterified, partially refined or crude) are used as diesel fuel extenders, the economic difficulty still persists and will continue until such time as diesel oil supplies begin to dwindle or until a more appropriate substitute fuel (renewable or nonrenewable) should emerge. Should diesel fuel supplies run out and an appropriate substitute fuel fail to emerge, tractors and other engine-driven equipment could convert to spark-ignition engines. These are more versatile in terms of fuel use (e.g. renewable alcohol, as well as nonrenewable hydrocarbons) even if less suited to the heavy workloads in agriculture.

The history of agricultural growth and mechanization in some of today's industrial countries illustrates this generalization. In 1880, factor endowments differed widely among these countries, with Japan having only 0.65 hectares of land per male worker and the United States about forty times as much (see Binswanger and Ruttan 1978, tables 3-1 and 3-2). High capital costs (relative to labor) retard mechanization and lead to selective emphasis on power-intensive operations. Machinery design adjusts to high capital costs by lack of convenience features, simplicity, and reduced durability. Energy is only one of the costs of using machines. Capital and maintenance costs are often larger.

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