General Introduction - Integrated Assessment of Health and Sustainability of Agroecosystems - page 14

Ruminants (mainly cattle, but also sheep and goats) are the most important and
are kept on the farm all year-round (Delgado, 1989). Hand hoeing, use of manure,
intercropping, and sometimes mulching are common practices, but crop rotation,
especially with perennial vegetation, is rare, and fallowing is not practiced. Only a
few farmers retain small plots of grass for grazing purposes (Mati, 1989). Crop resi-
dues are used as fodder (Powell and Williams, 1995), especially for stall-fed cattle.
Traditionally, there was low population pressure, and labor was the major con-
straint—with its cost higher compared to land (Powell and Williams, 1995). Soil
fertility was maintained through fallowing, which was preferred to manure because
it required less labor (Stangel, 1995). The low inelastic demand for agricultural pro-
duce also ensured low demand for agricultural inputs. Productivity was increased—
if required—by placing more land under cultivation. As the population increased,
consumption patterns changed, and the land reserves became exhausted, the scope
for these practices diminished greatly (Mohamed-Saleem and Fitzhugh, 1995).
Despite this, technology substitutes have not been widely adopted. The result has
been a decline in productivity in the long run due to loss of soil fertility (Ransom
et al., 1995) and its basic chemical and physical coherence (Stangel, 1995). Some
smallholder farmers now maintain constant or slightly increasing returns by increas-
ing labor input (Mohamed-Saleem and Fitzhugh, 1995), but the continued use of
traditional technologies to intensify land use results in declining returns.
The mixing of crop and livestock production in smallholder farms is important
for several reasons. For one, mixed farming is the most viable agricultural enterprise
on resource-poor and highly fragmented farm units (Delgado, 1989; McIntire et al.,
1992; Winrock International, 1992) as it facilitates both recycling of nutrients and
intensification of land use. The complement between crops and livestock produces
a synergy between the two, thus increasing overall productivity (Davendra, 1993).
The diversification spreads out the risk and increases the stability and resilience of
the system while allowing higher labor input per unit of land (Delgado, 1989).
Agricultural intensification of smallholder agriculture, involving improved tech-
nology and inputs (McIntire et al., 1992), is inevitable (Mohamed-Saleem and Fit-
zhugh, 1995). In other developing regions, intensification has occurred gradually
over many years, but in Africa it will need to happen over a very short time due to
rapid population growth (Mohamed-Saleem and Fitzhugh, 1995). Some countries
have relied on yield-increasing technologies based on fossil energy, but the costs of
these are prohibitive to the majority of smallholder farmers in Kenya (Mohamed-
Saleem and Fitzhugh, 1995). High-input technologies have also been associated with
environmental pollution, while fossil energy is no longer considered a renewable
resource. The challenge in Kenya is to increase per hectare and per animal yields by
introducing yield-increasing and environmentally sound production innovations that
are technically feasible and economically viable now and adaptable and sustainable
into the future.

1.5.2 i n it e r n A l e n v i r o n m e n t

Kiambu district comprises 2,500 km 2 of the central highlands. It is one of the most
densely populated districts in the highlands, having an estimated density of 480