terminate. In this case, labor available for planting
becomes the most important evaluation criterion. For
most small farmers, cash is a very limiting resource. For
these farmers, the needs of the family and the home
compete directly with the needs of the crops and livestock
for the limited cash resources available. Non-cash inputs
are more important on these farms and only a limited use
is made of inputs which require a source of cash. In this
case a relevant choice criterion is the comparison of
return to cash costs.

Labor Input as an Evaluation Criterion

 In all of the above cases, it is necessary for the
researcher to have information on the use of the resource
in question in order to be able to employ the appropriate
evaluation criterion. For example, if labor at weeding
time is critical, any changes in technology which
influence weeding will create a need for the researcher to
monitor weeding labor. Weeding of the individual crop in
question is important, but the effect of utilizing more
labor on any one particular crop can also have an
influence on labor availability for other crops,
livestock, or household activities. This should also be
taken into consideration. Other important considerations
are which members of the household are involved and
whether or not labor is hired.
 In order to evaluate changes in labor requirements
from on-farm or on-station research, it is usually
necessary to have larger plots than are required for
strictly agronomic evaluation. Plots need not be full
field size, however. In on-farm research, records must be
kept of the labor utilized by farmers on their own fields
for the particular operations in question. Labor use
should take into consideration the time lost in going to
and from the field, and for resting, drinking water,
eating, sharpening implements, or anything else that
reduces the amount of time that land can be worked in a
day. Records should also be kept of the labor required
for the same tasks in the trial plots. Usually, a test
plot will be completed without any rest, implement
sharpening, or other delays which are normal in field
work.