Total farmland more than doubled between 1870 and 1920. Since average farm size stayed roughly constant, total farm employment must have nearly doubled as well. The agricultural work force, far from being displaced, was redeployed within agriculture, along with large numbers of immigrants. Mechanization did not produce higher yields, however; they came later and were linked to fertilizers and biological innovations.
First, they reduce the profitability of all forms of agricultural investment, including land improvements, irrigation, animals, and buildings. Second, they may cause farmers to allocate whatever investment funds are available away from mechanical inputs. This trend will be stronger the more expensive and long-lived the mechanical inputs are and the easier it is to produce other forms of capital (such as land improvements) by hand.
Local autonomous power supply systems are generally limited to stationary applications which, although of vital importance to farm mechanization, still represent a considerably smaller fraction of total energy than that used in mobile mechanization systems powered by tractors and other engine-driven vehicular equipment.Apart from tractors, the agricultural equipment that has most caught the public imagination has been crop harvesters probably because of their (frequently massive) size, multiplicity of functions and bewildering variety of designs reflecting the huge variety in crop products and growth patterns whether the product to be harvested resides in the soil, above the soil surface, or on bushes or trees. Harvesting equipment is described in detail in Harvesters (EOLSS on-line, 2002).Such machinery has facilitated the full or partial replacement of human- and animal-powered equipment in developed countries and increasingly in developing countries as well. The net result has been higher productivity and the welcome elimination of much of the drudgery of manual farm labor. For example, one person involved in agricultural production can now provide enough food and fiber for 128 others whereas only a century ago one person could provide food and fiber for only eight others (see also, Technology and Power in Agriculture).
Provision of a guaranteed profitable income to primary producers is a powerful but expensive food policy instrument. The poorest countries that typically have the highest population growth and the greatest need to produce more food are least well placed to afford such a policy. As such, the international community and its agencies could make a huge contribution to food security by investing heavily in a program of guaranteed profitable income for farmers based on food production. Such a policy presupposes individual ownership of the land or a tenancy beneficially linked to productivity increase.