Agriculture Reference
In-Depth Information
research programme to expand the scientific
understanding of SOC and its contribution to
multiple environmental services, including
management options towards the optimiza-
tion of these services. These efforts should
lead to coordinated national and international
responses to SOC losses and degradation of
the five essential services and empower SOC
actions at local levels but be beneficial at larger
scales. Thus, in moving towards the realiza-
tion of multiple SOC benefits, we need to
understand better the relationships between
SOC and individual services to achieve long-
term goals through new policy regulation and
the research and development of economic
incentive schemes.
The aim of this chapter is to identify
wide-scale goals for maximizing the benefits
of SOC on the five essential services and to
define the short-term steps towards achiev-
ing these goals. First, we discuss the current
knowledge on SOC and identify the feed-
backs between increasing SOC and the five
essential services. Second, we define the
main long-term (next 25 years) challenges
and uncertainties for managing SOC. We rec-
ognize that 25 years is not long term for soil
carbon processes but is long term for policy
and management actions towards maximiz-
ing the five essential services. Third, we out-
line a set of priorities and actions that will
begin to move us towards optimizing the mix
of benefits from these five essential services.
have caused a decline in productivity and in
the ability to provide ecosystem services (Bai
et al ., 2008). In light of these facts, the goal is
to increase and sustain food production to
meet the demand of a growing population at
both the local and global scale while in-
creasing and sustaining SOC and the ser-
vices it provides.
Soil organic C is imperative for food
production because several SOC-related pro-
cesses govern the availability of nutrients,
water and toxins that control plant growth
(Bationo et al ., 2007). Soil carbon is the source
of energy and substrate for soil microorgan-
isms, which in turn regulate the decompos-
ition and mineralization/immobilization
processes responsible for nutrient availability
(Insam, 1996; Bot and Benites, 2005). Soil
organic C also improves the structure of soils
by increasing the formation of soil aggre-
gates, which enhances water infiltration and
retention, thus reducing nutrient losses
through leaching and runoff (Rawls et al .,
2003; Blanco-Canqui and Lal, 2007).
It is important to acknowledge that the
challenges faced in terms of increasing food
production vary considerably across the
globe. Increasing food production is particu-
larly urgent in areas where current levels of
food production are far below the potential
levels (i.e. mainly in food-deficient regions
such as sub-Sahara Africa). Food-deficient
regions are characterized by low crop and
livestock productivity, due mainly to soil
degradation resulting from intensive land
exploitation without adequate inputs of
nutrients and from overgrazing (Drechsel
et al ., 2001). Low SOC affects vital soil func-
tions such as nutrient cycling and microbial
activity, both required for nutrient availabil-
ity to crops. Current initiatives for fighting
hunger in line with Millennium Develop-
ment Goal 1, such as the African Green
Revolution, need to take increasing SOC as
a core component of interventions to ensure
an efficient use of inputs and a sustainable
increase of food production. Management
practices that increase SOC and food pro-
duction include fertilization, crop rotation,
reduced tillage, organic matter addition, fal-
low, cover crops, agroforestry and improved
livestock management.
Wide-scale Goals and Urgent
Actions
Food production
It is known that conventional agriculture
reduces SOC in surface layers by up to 50%
compared with natural vegetation (Jolivet et al .,
1997; Mishra et al ., 2010). In many parts of
the world, degradation resulting from human
activities has reduced the capacity of land to
produce food. Underlying this degradation
and declining agricultural productivity is
the loss of SOC (Lefroy et al ., 1993; Cheng
et al ., 2013). It is estimated that, on one-quarter
of the global land area, soil carbon losses
 
Search WWH ::




Custom Search