Agroecological Intensification of Smallholder Farming - The Oxford Topic of Food, Politics, and Society - page 107

agriculture” (Keating et al., 2010) and “ecological intensification” (Doré et al. 2011) to
refer to the same or a similar concept. The concept of AEI can be loosely and flexibly
defined as producing more of what is wanted based on the efficient use of biological
interactions. AEI entails the integration of diverse components to produce heteroge-
neous, multifunctional systems that are locally adapted. The principles of AEI include
improving productivity under resource limitations; improving water and nutrient cap-
ture and cycling efficiency within the system; improvement of components to support
systems functions; development of local, context-specific options; and adapting social
institutions to support the use of biological interactions. The research frontiers of AEI
include systems diversification; soil and water management; pest, weed, and disease
management; and social innovation (including value chains) to support diversification.
In some systems, such as much of Asia's irrigated ricelands, the major grain-producing
areas of North America, and most intensive vegetable-production systems worldwide,
productivity increases have been achieved through input intensification, with accompa-
nying environmental costs and with declining returns on investment. In these systems,
AEI would mean reducing the reliance on external inputs and increasing ecological effi-
ciencies. Many other farming systems are on degenerative trajectories, with depletion
and erosion of soil, water, and genetic resources. For these systems, AEI may require both
ecological engineering and the selective use of purchased inputs. Ethiopia and Malawi,
for example, have large rural poor populations that depend on agriculture. Agricultural
productivity is constrained by degraded and unproductive soils. Government policy in
both of these countries focuses on increasing fertilizer use, through subsidies and input
supply. Detractors point out that the strategy is unsustainable, noting that alternative
methods of maintaining soil fertility must be employed, such as the increased integra-
tion of leguminous crops. While the debate often seems polarized between voices advo-
cating for one approach or the other, a hybrid approach could be regarded as the most
pragmatic. The use of fertilizers can be critical for reversing a degenerative pathway.
When soil fertility is too low, plant growth may not be sufficient to develop biomass
for improving soil organic matter; such systems may require mineral fertilizers to allow
legumes to thrive. That is, legumes can enrich the carbon and nitrogen content of soils
and contribute to diets, but only if adequate P is supplied. At some point, the system may
be on a sufficiently regenerative pathway so that lower input levels are effective.
There is mounting evidence to support the view that a combination of agroecologi-
cal methods and judicious use of inputs is the most appropriate strategy for support-
ing the improved performance of smallholder agriculture. For instance, Snapp et al.
(2010) found that the use of semi-perennial legumes together with modest quantities
of mineral fertilizer was more effective and accessible for Malawian smallholders than
the use of mineral fertilizers or legumes alone. Similarly, Vanek et al. (2010) found that
phosphorous (P) fertilizer was required to support legume productivity in the Andes.
Marenya and Barrett (2009) found that nitrogen fertilization was only cost-effective for
Kenyan smallholders when soil carbon levels were adequate. When soil organic matter
was too low, the increased maize yields associated with applied nitrogen fertilizer did
not compensate for the cost of the fertilizer.