Agroecological Intensification of Smallholder Farming - The Oxford Topic of Food, Politics, and Society - page 115

Sweetpotato and other vegetatively propagated crops are plagued by virus diseases that
might also be effectively managed through transgenic resistance, allowing farmers to
maintain high-quality planting material for longer periods (e.g., Kreuze et al. 2008).
Thus, while transgenic crops are associated with limiting farmers' seed-saving because
of the notorious “terminator” technology, the technology can be utilized to support the
opposite ends.
Many crops of importance in the developing world are not served by well-resourced
breeding programs. Legumes have particular potential to improve soil fertility
and human nutrition, but are they are particularly vulnerable to pests. Combining
well-designed field-based breeding with participatory methods could go a long way to
improving these programs. In addition, a strategic combination of molecular genetics
and ecological genetics would enable more breeding programs to confront the specific
pest challenges at hand (Salvaudon et al. 2008). Plants may be selected to attract pests'
natural enemies. Populations can be designed to incorporate functional diversity for
pest resistance while maintaining the degree of agronomic uniformity desired for pro-
duction, harvest, and processing.
Managing Soil and Water
Integrated soil fertility management is an area that is well researched and documented.
Successful cases have shown evidence of increased productivity, better resource use
efficiency, and reduced risk, among other effects. There is a range of aspects that can
be combined through a stepwise approach, including integration of improved crop
germplasm.
The success and limitations of conservation agriculture provide an encouraging and
illustrative example of a significant transformation in production technology that has
been widely adopted (and sometimes oversold). Crop cultivation is traditionally con-
sidered to be synonymous with tilling of the soil (Hobbs et al. 2008). Since the 1930s,
various practices have been developed to reduce or eliminate tillage, to cover the soil
with a permanent or semipermanent layer of mulch, and to practice rotation. This set of
practices has matured into a set of systems, collectively termed “conservation agricul-
ture” (CA), that employ broad principles (cover, reduce tillage, rotation) that contribute
to maintenance of soil fertility in different ways in different contexts (Ekboir 2001). The
application of the principles is endlessly variable, depending on the context.
CA has been transformative on vast areas, reducing costs and reducing soil erosion.
As of 2009, over 100 million hectares were estimated to be grown under CA practices
(Kassam et al. 2009). There has been little ideological divide on this—where it works,
it is widely accepted. Its relevance is not universal, however, and the principles can fail
in specific contexts (Giller et al. 2009). For example, when there is not enough avail-
able biomass to provide soil cover, or where there are better uses for available organic
matter, it cannot be applied. Kassie et al. (2009) compared plot-level data on the use of
reduced tillage and chemical fertilizer in two areas of Ethiopia. They found that reduced