Another alternative is to test technologies, either on research plots or on
farms. Technology trials compare the performance of specific agroforestry
technology designs with alternative agroforestry or non-agroforestry technologies.
An example would be to compare crop production in plots with
Leueaena planted at 4 x 0.5 m spacing and cut back twice a year with that
in plots of Gliricidia planted at 4 x 1 m spacing and cut back four times a
year, or with farmers' standard practice of manuring every other year.
Technology trials may also be undertaken comparing the relative performance
of design variations (e.g. different species, spacings or management
techniques). However, firm conclusions about performance response to
specific factors can generally not be drawn from this type of trial due to
inadequate consideration for factorial levels (Roger 1989). Results from
technology trials can be used to identify the most promising agroforestry
systems for extension, and to quantify likely benefits to farmers from
adoption.