Power-intensive operations are shifted most rapidly to new power sources. Control-intensive operations are shifted to the more mechanized techniques when wages are high or rapidly rising. Power-intensive processing and pumping.
The mechanization of power-intensive processing and pumping operations always precedes the mechanization of harvesting and crop husbandry operations and can be profitable at low wages. Land preparation. Unlike the power-intensive operations, land preparation requires mobile sources of power, such as animals, tractors, or power tillers (hand tractors).
For these reasons (environmental enhancement, sustainability) intensive research and development in renewable fuels (including oilseed oils and alcohols) continues and has lead to a small number of commercial applications in niche markets. The future market for renewable fuel use is difficult to predict but will remain an active issue in the continuing debate on alternative fuels for vehicles including agricultural vehicles. Finally, the use of on-farm generated electricity, as opposed to that purchased from a utility, is discussed below (see also, Agriculture and Autonomous Power Supply).The overall sequence of operations (Figure 8) is orientated towards protecting post-harvest product quality and minimizing loss due to deterioration occasioned by respiration, microbial activity, insects or rodents. Control of respiration (i.e. conversion of carbohydrates to carbon dioxide and water) in crop products is achieved by temperature reduction, most usually by refrigeration but also by periodic ventilation typically of the cold night air.The performance of such wet biomass (animal waste) systems is outlined in Agriculture and Autonomous Power Supply, EOLSS on-line, 2002, and summarized in Table 3. Autonomous power supply must also include human and animal power (as discussed in Human and Animal Powered Machinery, EOLSS on-line, 2002) which, although of great relevance to small farms in the poorest regions, is otherwise declining in relative importance.
Japan, in particular, has developed many machines for small farms and plots. For certain operations, mechanization spreads to small farms when machinery can be rented rather than bought. For a rental market to be established, the optimal farm size for owning a machine must be bigger than that of numerous small farms. In addition, it is easier to establish rental markets for operations that do not need to be done on all farms at the same time: threshing and milling are examples.