Biodiversity can support a greener revolution in Africa

Abstract

The Asian green revolution trebled grain yields through agrochemical intensification of monocultures. Associated environmental costs have subsequently emerged. A rapidly changing world necessitates sustainability principles be developed to reinvent these technologies and test them at scale. The need is particularly urgent in Africa, where ecosystems are degrading and crop yields have stagnated. An unprecedented opportunity to reverse this trend is unfolding in Malawi, where a 90% subsidy has ensured access to fertilization and improved maize seed, with substantive gains in productivity for millions of farmers. To test if economic and ecological sustainability could be improved, we preformed manipulative experimentation with crop diversity in a countrywide trial (n = 991) and at adaptive, local scales through a decade of participatory research (n = 146). Spatial and temporal treatments compared monoculture maize with legume-diversified maize that included annual and semiperennial (SP) growth habits in temporal and spatial combinations, including rotation, SP rotation, intercrop, and SP intercrop systems. Modest fertilizer intensification doubled grain yield compared with monoculture maize. Biodiversity improved ecosystem function further: SP rotation systems at half-fertilizer rates produced equivalent quantities of grain, on a more stable basis (yield variability reduced from 22% to 13%) compared with monoculture. Across sites, profitability and farmer preference matched: SP rotations provided twofold superior returns, whereas diversification of maize with annual legumes provided more modest returns. In this study, we provide evidence that in Africa, crop diversification can be effective at a countrywide scale, and that shrubby, grain legumes can enhance environmental and food security.ecosystem services | nitrogen | rural development | sustainable agriculture

Toward the Integrated Framework Analysis of Linkages among Agrobiodiversity, Livelihood Diversification, Ecological Systems, and Sustainability amid Global Change

“…This type of conceptual categorization is well suited to elevated policy interest in the intensification and sustainability of food-growing [3,4,52,62,65]. For example, it predicts how RALDS with less significant livelihood diversification may turn out to be associated with either low or high agrobiodiversity levels (Table 5).…”

“…The selective integration of these four fields is needed to address the multi-faceted issues that arise in the livelihood-environmental interactions of smallholders. Such issues range from poverty alleviation, resilience, and food security [60,61] to sustainability and the intensification of land use [4,52,[62][63][64][65][66].…”

“…Our discussion of livelihood interactions with agrobiodiversity and ecological systems using this spatial framework reflects the need for sustainability research with a meso-level focus. Focus on meso-level geographic and thematically specified social-ecological systems has gained importance in light of the growing number of high-profile and influential yet general summary-style calls in science and policy for sustainable intensification, ecological intensification, and smallholder sustainability ( [3,4,11,62,64,65,77]; see example of related meso-level research in [52,66]). …”

Field-scale experiments reveal persistent yield gaps in low-input and organic cropping systems

“…Our findings suggest that this difference will be still greater at the farm scale, emphasizing the special need in developing countries to create technologies that are less time-sensitive and make efficient use of labor. This will be especially important where reduced-input farming is pursued out of necessity rather than choice, for example, in sub-Saharan Africa (32).…”

Do Organic Inputs in African Subsistence Agriculture Raise Productivity? Evidence from Plot Data of Malawi Household Surveys

“…Diversification in crop cultivation through intercropping, mixed cropping, relay cropping or crop rotation is also claimed to have beneficial impacts in terms of environmental sustainability, soil improvement and crop productivity, mainly through suppressing outbreaks of pests and diseases, dampening pathogen transmission and, thereby, increasing resilience (see e.g. Lin, 2011;Snapp et al 2010). .…”