trials is higher than with experiment station trials,
because much depends on the cooperation of the farmers.
There are many examples of "lost" on-farm trials due to
decisions made by the farmers without consultation with
the researchers. An increase in the market price of the
product might cause a decision for an early harvest of
part or all of the trial. A new variety or crop that is
considered especially attractive might promote harvest by
farmers or their neighbors before the final data are
recorded. Under some circumstances, preliminary results
satisfy the curiosity of the farmers and they lose
interest before the trial is completed. When trials
involve more than one cycle of production, or when it is
necessary to evaluate a rotation of crops, the risk of not
completing an on-farm experiment increases.
 Farmers who do not fully comprehend the nature of the
trial may enter into competition with researchers. For
example, a check treatment that is meant to simulate the
farmers' practices and is to be conducted by the farmers
may receive special care because the farmers know how to
do it better and want to prove this to the researchers.
On a small plot, they can afford to do it even if they
cannot do it on their own fields. Or, the farmers may not
understand fully that they are supposed to manage the plot
exactly the way they do their own fields, so they wait for
the visits of the researchers before they carry out
practices that they normally do earlier on their own land.
In either case, errors are created in measuring the
farmers' level of production.
 Finally, periodic review of all aspects of the trial,
along with frequent conversations between the researchers
and the farmers concerning the progress being observed, is
critical to fruitful on-farm research.

On-Farm Experimental Procedures

Location on the farm

 Homogeneous or uniform experimental areas are the
rule rather than the exception on experiment stations.
The opposite is true on farms. Nevertheless, researchers
can reduce experimental error by following a few common-
sense rules. For example, it is never wise to locate a
research area adjacent to a habitation unless that is the