Principles of Soil Management - Principles of Sustainable Soil Management in Agroecosystems - page 7

Yield gap controls

Natural resources Te chnology adaption Institutional support Human dimensions

Climate
Rainfall
Growing season

Soil management Extension/

outreach

Land tenure

Water
Nutrient
Organic matter
Crop management
Species
Variety
Rotation/coverage
Pest control
Energy management
Farm operations
Use eciency
Adaption and
mitigation of climate
change

Government
policies

Equity

Te rrain
Slope
Drainage

Culture

Access to
market

Soil Depth
Parent material
We athering

Education

Credit
facilities

Traditional
knowledge

Input supply

Water

Surface
Ground water

Farm size

Incentivization

Pests and
pathogens

e human capital
management

Linkages between scientists, policy makers and land managers

FIGURE 1.2 Determinants of a crop yield gap.

extension, government policies, access to market and credit, and so forth; and (4) the
human dimensions such as land tenure, equity (gender and social), education, farm
size, and so forth. The strategy is to identify and fine-tune soil-based technology
for site/crop-specific situation. The goal is to optimize soil conditions that support
favorable crop growth even under harsh climatic conditions. Adoption of this strategy
implies enhancing soil/ecosystem resilience through improvement in soil quality. It
is because of the lack of focus on soils, by taking soil resources for granted, that the
Green Revolution of the 1970s bypassed Sub-Saharan Africa.

1.3.1 S oil Q uality M anageMent
Soil degradation is a serious threat especially in the tropics and subtropics of a Sub-
Saharan Africa, South/Central Asia, and the Caribbean (Bai et al. 2008; Oldeman
1994). It is caused by the interactive effects of natural and anthropogenic factors
( Figure 1.3 ). The effects of natural factors (e.g., soil quality, climate—especially
rainfall, temperature, and erosivity) and land (slope gradient) are strongly moderated
by the management (i.e., land use, cropping/farming system). Socioeconomic factors
are important determinants of soil degradation, especially of accelerated soil erosion.
It is in this context that Halim et al. (2007) developed a methodology that integrated
both biophysical and socioeconomic aspects into a framework for soil erosion hazard
assessment using principal component analysis at the land unit level. Therefore, any
program designed to alleviate the problem of soil erosion must be consistent with
farmers' knowledge and their perception of the erosion and its short- and long-term