Agriculture Reference
In-Depth Information
tion in root zone soil of about 1.1 % is essential for maintaining optimum soil health
and agronomic conditions. Soil C sequestration can reduce CO
2
concentration in
the atmosphere by locking the C as humus in the soil system for quite a long time.
Depletion of SOC depends on climate, soil type and cultural management practices.
Adoption of proper management practices can improve the SOC pool as well as
increase productivity and enhance soil resilience to adapt to changing climatic sce-
narios (Lal
2004
). Lal et al. (
2006
) estimated that an increase in SOC by 1 t/ha could
increase grain yield by 6.4 million t in Africa and 11.7 million t in Asia. Lal (
2011
)
estimated that increase of 1 t C/ha/yr in the rhizospheric soil can increase foodgrain
production by 24-32 million t in the developing countries of the world. The study
also quantified the potential of soil C sequestration of the agro-ecosystems of the
world to be approximately 1.2-1.3 billion t C per year. The study also showed that if
the SOC pool is increased by 10 % over the twenty-first century, it can cause reduc-
tion of 110 ppm of atmospheric CO
2
concentration (one billion t of soil C = 0.47 ppm
of atmospheric CO
2
). Hansen et al. (
2008
) showed that bio-sequestration can reduce
CO
2
concentration by 50 ppm by the year 2150.
7.2 Conservation Agriculture
The concept of Conservation agriculture (CA) was put forward by FAO for address-
ing the growing concern over sustainable agriculture. Conservation agriculture is
a package of management practices that mainly includes reduced tillage, No till-
age, direct seeding, soil cover (i.e., cover crops, relay crops, intercrops) to manage
soil erosion, improvement of soil health, crop rotation for controlling weeds, etc.,
(Derpsch
2001
). These practices lead to increase in soil organic carbon. No tillage
system is better than reduced tillage system as far as accumulation of soil C is con-
cerned (West and Post
2002
). Under 'No Tillage' system, SOC gets accumulated
in the top soil that creates a vertical stratification of soil C which regulates the soil
microbial activity (Dennis et al.
1994
; Stockfisch et al.
1999
; Moreno et al.
2006
).
Conservation agriculture helps to improve soil's physical properties like porosity,
soil structure, and water holding capacity (Medvedev et al.
2004
; Josa et al.
2005
).
Chivenge et al. (
2007
) studied the effect of tillage and management practices on
SOC dynamics in red clay soil and sandy soil and reported that tillage disturbance
is the major factor influencing the C dynamics in agricultural soil. The study also
indicated that practice of Conservation agriculture can improve soil C status and
maintain long-term sustainability. Ghimire et al. (
2011
) conducted an experiment in
Chitwan Valley of Nepal and reported that 'No Tillage' system is far better than that
of conventional tillage system for C sequestration in rice-wheat cropping system.
Datta et al. (
2011
) showed that crop diversification can reduce cumulative methane
emission and also reported that rice potato sesame was most suitable cropping sys-
tem for mitigation of greenhouse gas emissions. The study suggested that methane
fluxes from different cropping systems and reported that GWP of rice-rice system
is very high whereas rice-potato-sesame system is most profitable in terms of total
revenue ($ 1248.21 per ha) as well as C-credit ($38.60 per ha).
