An Economic Assessment of Banana Genetic Improvement and ...

14 CHAPTER 2
ples of adoption discontinuities caused by
either technical or institutional factors.
Once a crop cultivar has been released,
farmers’ choices are influenced by market
conditions for seed, related inputs, and the
crop, as well as their surrounding agroecosystem
(soils, pests and plant disease pressures,
moisture, elevation, and environmental
heterogeneity). Explanatory factors that
vary among farmers are documented in a
broad literature on adoption of agricultural
innovations in developing countries (reviews
include Feder, Just, and Zilberman
1985; Feder and Umali 1993). Informal
organizations, village associations, and social
networks may substitute or complement
extension services as sources of the
information that is critical for farmers to
perceive and earn benefits from cultivars or
practices.
The agricultural household model is
used as the conceptual framework in the
four chapters of this report analyzing the
use and impact of banana technologies at
the farm level (Chapters 6–9). Input markets,
in particular, are often incomplete for
banana growers in Uganda and Tanzania. In
this framework, the agricultural household
maximizes utility (u) from consumption of
banana goods (x B ), other purchased goods
(x G ), and leisure or home time (h), conditioned
on a set of household characteristics
(Ω HH ) over a vector of choice variables,
defined as ψ:
B G
max ux 7 , x, hX HH A.
ψ
The household maximizes utility subject
to a number of constraints. The production
technology is defined by a set of variable
inputs, denoted by a vector N, used for
the production of banana output (q) on a
predetermined amount of land (A) in the
banana grove or plantation. Variable inputs
comprise primarily planting material, labor,
and organic fertilizers. The production technology
is conditioned on the physical characteristics
of the farm (Ω F ):
gq 7 , N, A X F A = 0.
Household budget limitations are depicted
by the full income constraint for all
traded banana products (T), where p B is a
vector of banana product prices, p G is the
price of other goods consumed by the household,
p N is a vector of input prices (for example,
the wage rate, w, being one element
of this vector) and I is exogenous income:
!
j ! T
( qj
x B B G G
j ) p p x p
N
- - - N + I = 0.
j
Semisubsistence households may face
sufficiently large transactions costs of market
participation that they opt for autarky
with respect to some goods or services (de
Janvry, Fafchamps, and Sadoulet 1991). For
nontraded goods (NT), households equate
quantities produced and consumed:
qj - x B j = 0, j ! NT.
With imperfect input markets, constraints
on factors of production are also
imposed, depending on the context of the
model, including time, planting material, or
land constraints. This general analytical approach
is then adapted by authors to test
specific research hypotheses. The structure
of household preferences, choice variables,
and explanatory variables in the reducedform
equations depends on the application.
Chapter 6 formulates a trait-based model of
cultivar demand. Farmers’ planting decisions
are hypothesized to be a function of
the consumption attributes and production
traits of bananas, controlling for other
household, farm, and market characteristics.
To explain the use of recommended
soil fertility practices in banana production,
Chapter 7 introduces social capital in addition
to these factors. Chapter 8 estimates the
productivity and efficiency of banana production,
focusing on soil characteristics and
labor use. The adoption equation estimated
in Chapter 9 builds on the same general