Agroecological Intensification of Smallholder Farming - The Oxford Topic of Food, Politics, and Society - page 110

deal of theoretical and empirical effort has been dedicated to plant breeding, the formal
research sector has invested a relatively paltry effort in optimizing functional diversity.
Concepts, tools, and models of relevance to mixing species in cropping systems were
recently reviewed (Malezieux et al. 2009); some of these points are mentioned below.
“Mimic hypotheses” suggest that benefits derive from system designs that resem-
ble the conditions of natural systems in a given region, or that maintain the levels of
diversity found in natural systems (van Noordwijk and Ong 1999). A recent review
(Malezieux et al. 2009) noted the following principles for cropping systems design based
on natural ecosystems mimicry: the use of complementary traits to ensure production
and resilience; maintenance of soil fertility through soil cover; ensuring complementar-
ity and avoidance of competition; management of pests through multiple trophic levels,
biopesticides, and botanical properties; and the emulation of ecological succession pro-
cesses after disturbance.
Because of the multiple functions of intercrops, some of which are only realized in
the longer term, it can be difficult to assess and compare the merits of different systems
empirically. Carberry et al. (1996) found that simulation using APSIM (the Agricultural
Production Systems Simulator) was useful for exploring the performance of different
farming systems over time and space. APSIM was also used to explore the effect of dif-
ferent cowpea growth habits (morphological traits) and row spacing in intercrops with
maize in low-input production systems (Carberry et al. 2002). That said, the tools of sys-
tems agronomy are poorly developed with regard to multispecies systems (Malezieux
et al. 2009), and this deficit includes the modeling tools.
Lack of dietary diversity is a major issue for too many smallholders. While the Green
Revolution succeeded in increasing the availability of carbohydrate-based calories
to millions of people in Asia and elsewhere, the production of legumes decreased as
cereal production increased. In parts of the world where the Green Revolution had lit-
tle impact, including most of Africa, diets are typically based on starchy staples such as
maize, sorghum, millets, banana, and cassava. Protein-energy malnutrition is an issue
in many places, but micronutrient malnutrition is much more widespread.
A simple case of diversification that has the potential to increase nutrition is the
diversification of maize-based system with legumes (e.g., adding beans or other legumes
in intercrops, relay crops, or rotations). This approach has shown success in improving
nutrition in Malawi when coupled with strategies to ensure that child feeding practices
and gender relations support the use of the legumes for improving child care and feed-
ing (Bezner Kerr et al. 2008). This sort of strategy can be extended by including other
crops or sets of crops that can contribute to ensuring the availability of diverse foods
throughout the year (or crops that can be sold to allow the purchase of diverse foods,
if markets and gender relations support this). Another approach is the use of small
patches to produce diverse foods for household consumption; intensive kitchen gardens
have been successful on a large scale for improving diets in Bangladesh and elsewhere
(Bushamuka et al. 2005). This is feasible because input requirements (labor, imported
nutrients, water) can be managed at the small scale needed to feed an individual family.
Fruit trees are often a component of such home gardens.