An Economic Assessment of Banana Genetic Improvement and ...

94 CHAPTER 7
ity in the two technology demand equations
is also correlated. Estimating them jointly
was not considered to be worthwhile, because
the set of explanatory variables is
identical in both equations (Greene 2000,
616), implying no gains in statistical efficiency.
Thus, each technology was treated
separately.
Dependent Variables
We considered eight practices recommended
to farmers for soil fertility management in
banana groves: (1) mulch with grass; (2)
mulch with crop residues; (3) mulch with
kitchen residues; (4) addition of cattle manure,
(5) goat manure, (6) pig manure, or (7)
poultry manure; and (8) composting of
homestead refuse to make manure (compost
manure). The eight practices were subjected
to a factor analysis procedure using principal
components to analyze correlation between
them and determine whether they
could be represented by a smaller number of
components. 3 Based on the criterion of an
eigenvalue greater than unity, the eight soil
management practices were grouped into
four independent packages according to four
unobserved factors. 4 The latent factors were
interpreted as mulching, animal manure,
composting, and traditional technologies.
Based on the results from the factor
analysis, the eight types of organic fertilizers
were collapsed into two dependent variables:
mulching practices and manure application.
Use of mulching technology is
defined as the practice of applying crop residues
(nonbanana crop residues) or grass to
mulch banana plantations. Use of this type
of mulch materials in banana production
involves costs for gathering, transportation,
and application, which may not be affordable
by some households. Use of manure
technology is defined as the practice of applying
animal waste (from cattle and pigs)
or compost manure in the banana plantations.
These organic fertilizers also involve
a cost of access, transportation, and application
that may limit their use.
The omitted category (1 – δ) is the traditional
method of recycling banana residues
and applying household refuse, used by virtually
every farmer on at least some mats.
Organic household refuse (kitchen residues,
goat and poultry waste) is collected in mixtures
from the homestead as part of the
cleaning activity and spread between mats
to control weeds, though some farmers reported
that use was not deliberate. Farmers
are advised to compost the household refuse
and other organic materials before applying
it in banana plantations to facilitate quick
decomposition (Tushemereirwe et al. 2003).
Therefore, this method may not be adequate
for soil fertility management in banana
plantations. In addition, little additional information
would be gained by investigating
3
A principal components analysis with Varimax rotation was applied (STATA 8.0). Principal components
analysis partitions the sum of the variances for a set of variables by taking uncorrelated, linear combinations of
those that account for the latest eigenvalues of the covariance matrix. The components are not easily interpreted,
however. The Varimax rotation procedure, one of several types of rotation, enables a more straightforward
interpretation of components in terms of factors “loading” high on some variables and low on others (Stevens
2002).
4
The four factors explain 73 percent of total variance in the adoption components. Only variables with factor
loading equal to or greater than 0.5 were considered significantly correlated with the underlying latent variable
and hence grouped together. Factor 1 explains about 28 percent of the variance in the eight management
practices. Organic household refuse (kitchen residues, goat manure, and poultry manure) were highly correlated
with the first latent factor. Mulching techniques using the organic materials that are gathered from sources
other than the banana crop (crop residues and grass) loaded on factor 2 and explain 18 percent of the total variance
in the use of soil fertility management practices. Organic manure from animals that are rarely kept in the
homestead (cattle and pigs) also clustered together, while the technique of composting household refuse before
applying it to banana plants instead of applying it directly seems to be used independently of other soil fertility
management practices.