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 Strategic
and component research to date has been conducted largely
at the plot or field scale, where interactions among various
agricultural enterprises are seldom considered. Although TSBF-CIAT's
strength remains at the plot level, the diversity of forces
impinging on the plot naturally draws attention towards a
hierarchical or nested systems-based approach. The next generation
of work will be at higher scales, particularly the farm and
landscape scales.
The rationale for working at the farm scale is the need to
improve nutrient-use efficiency through better allocation
of limited organic and inorganic resources among different
enterprises, taking into consideration inherent soil variability
within the farming system. Inadequacies in supplies of both
organic and inorganic nutrients have created strong fertility
gradients even within the smallest farms. Smallholder farmers
typically remove harvest products and crop residues from their
food producing "outfields" and devote their scarce
soil inputs to their smaller market "infields,"
resulting in large differences in soil productivity over time
between these two field types. Understanding how to manage
the limited nutrient supplies across such fertility gradients
is a key component in raising productivity in fields of staple
crops.
Environmental services, particularly hydrological response
and soil erosion control, can be managed effectively only
at larger landscape scales. Research at the watershed scale
is critical in the tropical regions. Given projections that
indicate Central America and eastern and southern Africa will
be critically short of water in the coming decades, extending
TSBF-CIAT's research agenda into this area is warranted. The
projects funded by the Water and Food Challenge Program for
the Volta basin in West Africa and on the Quesungual systems
in Central America offer the opportunity to address constraints
related to water and its interaction with soil fertility and
other environmental challenges.
The assessment of services provided by agroecosystems at different
spatial and temporal scales is an extremely important and
challenging research area. Soils play a central role for the
provision of ecosystem services such as regulation of water
quality and quantity, carbon storage and control of net fluxes
of greenhouse gases to the atmosphere. Appropriate soil management
could result in enhanced provision of services. However, reliable
quantification of such services and the development of mechanisms
to compensate farmer communities who manage the soils, continue
to be major challenges. TSBF-CIAT intends to contribute to
filling this knowledge gap through partnerships with other
CIAT projects, regional networks/consortia (e.g., AfNet,
Amazon Initiative, CONDESAN, MIS)
and global projects (e.g., BGBD). TSBF-CIAT recognizes the
exciting intellectual content and potential impact of this
research area for sustainable land management and restoration
of degraded lands in the tropics.
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