those farms which normally do not produce more than 1.5
tons/ha of local maize without fertilizer (the traditional
technology), the local material is superior whether or not
the farmer fertilized at the rate used in the trial.
However, if local, unfertilized maize usually yields more
than 1.5 tons/ha on a particular field or for a particular
farmer (the better maize environments with e > 2), the new
material is superior whether or not it is fertilized at
the rate used in the trial. These conclusions apply to a
field or a farm.
 Although results from two or more years could be used
in the analysis, use of the environmental index negates
many of the problems associated with only one year's data.
It measures response to good or poor environments
regardless of the reasons that those environments are good
or bad. If another year is better or worse for maize, the
data points for an individual farm will shift to the right


C
.0
e


.u
G)
E
- 2


-J I
>-


YL=O.77 +0.98e Y=-0.23+1.46e
 R2=.85 R2=.89



 0


SI 2 3 4
 ENVIRONMENTAL INDEX (e), metric tons


FIG.VII-2.


Response of local maize (L) and CCA composite
(C) to environment, with fertilizer, Phalombe
Project, Malawi.