Agriculture Reference
In-Depth Information
tillage was superior in the low-rainfall area of Tigray, where it was associated with lower
production costs, higher production, and environmental benefits. In the higher rain-
fall area in the Amhara region, however, chemical fertilizer was much more profitable.
This variability has implications for the adoption of CA practices by farmers, which has
been patchy. Synthesis studies have failed to find common factors that explain adoption,
except the need for practices to be profitable (Knowler and Bradshaw 2007; de Graaff
et al. 2008). Thus, efforts to adapt and promote uptake of CA practices must be location
specific.
Many projects promote the composting of crop residues to maintain soil fertility. This
may well be preferable to some alternatives, but in Africa, a continent of negative nutri-
ent balances (Cobo et al. 2010), it cannot be the complete answer. Some reported effects
are very small, and many are extremely variable (Sileshi et al. 2010; Bastiaans 2008).
This variability can be interpreted as unreliability, or as a risk for farmers and others.
Legumes and other crops are known as “green manures” when they are grown and incor-
porated into the soil as nutrient sources for subsequent crops. A meta-analysis of green
manures for maize, analyzing the results of fifty-two studies, showed a significant posi-
tive contribution to maize yields from woody and herbaceous green manures (Sileshi
et al. 2010), though with huge variation in the results. This huge variation has important
consequences for strategies to use the findings. While green manures improve soil fer-
tility, farmers prefer multifunctional legumes to straight green manures (Amede 2003;
Kikafunda 2003).
Water is a limiting resource for agriculture in many environments. Water scarcity cre-
ates one set of problems, and the damage caused by rainfall creates another; in particu-
lar, soil erosion is an important threat to sustainability in many systems. An increase in
the frequency of destructive rain events is predicted for some areas as a feature of cli-
mate change. AEI approaches must confront these challenges. At the plot level, options
include the use of drought-tolerant species and varieties, building soil carbon levels to
enhance water retention, and the construction of strips and terraces to increase water
infiltration and reduce runoff. Many of the options for water management must occur at
higher levels, such as the watershed level.
AEI and Markets
Most government and donor initiatives emphasize market-driven development, with
little emphasis on system health, sustainability, or better meeting the nutritional needs
of rural households. To meet their various objectives, smallholder farmers can generally
benefit from improved market access and better performance of input and output mar-
kets. But insofar as initiatives neglect issues such as risks induced by pests and climate,
they may subject households to potential ecological, nutritional, and financial hazards.
Approaches that consider markets to the exclusion of self-provisioning, agroecology to
the exclusion of inputs and markets, or markets without concern for stability and sus-
tainability will subject people to unnecessary risk. In keeping with the needs of farm
Search WWH ::
Custom Search