designed to assure the advantages and acceptability of new
technology by the collaborating farmers. Materials and
methods that move through this evaluation phase come from
experiment stations and other sources. Depending upon the
nature of the technology being evaluated, it is usually
possible to initiate on-farm activities with site-specific
or regional trials.
 On-farm research is not a substitute for experiment
station research--it is a means of providing much wider
exposure to station results, both with respect to
environment and to potential users. It is also a means of
conveying to station researchers any problems that require
experiment station facilities for solution. That is,
on-farm research provides an opportunity for station
researchers to expose their results to a much wider range
of environmental conditions. On-farm research also
provides an opportunity for more and smoother interaction
between extension personnel and the research procedure.
 In moving through the sequence from experiment
station results to extension and farm production, the
complexity of the trials (number of treatments and
replications) at each location diminishes as plot size and
number of locations increase. In this sequence, the
extent of farmer management of the trials increases, and
the need for researcher management decreases (making
possible the larger number of locations). Concomitantly,
the capability and need to control sources of variation
decreases, while the need and possibility of measuring the
sources of variation increases. As the above changes
occur, biological precision and discrimination among
variables decreases, while the ability to test
socioeconomic interactions under farmers' conditions
increases. All of the above changes increase the number
of farmers involved in formalized research and increase
the direct investment farmers make in that research.
Finally, as the number of farmers increases, the potential
interaction of extension with research is enhanced.