Agriculture Reference
In-Depth Information
• Requires more herbicides and pesticides
than standard conventional practices to
control weeds and other pests.
• Due to the large size of the original soil
carbon pools, the contribution of conser-
vation tillage can appear to be small, and
a signifi cant amount of time is required
to detect changes.
• Sizable amounts of non-CO 2 greenhouse
gases (N 2 O and CH 4 ) can be emitted
under conservation tillage compared to
the amount of carbon stored, so that the
benefi ts of conservation tillage in storing
carbon can be outweighed by disadvan-
tages from other GHG emissions.
According to Brown ( 2008 ), zero-till is widely
used in fi ve countries in particular: 15 million
hectares in the USA, 24 million hectares in
Brazil, 18 million hectares in Argentina, and
13 million hectares in Canada. Australia has 9
million hectares under zero-till, making a total of
79 million hectares for these fi ve countries with
the most hectarage. Worldwide, the use of zero-
till is increasing. In 1999, it was used on 45 million
hectares, and by 2005 it had more than doubled
to reach 95 million hectares. Using the latter
fi gures, all the other countries than those in the
top fi ve accounted for only 17 % of the total.
In general, conservation tillage has been most
successful in Brazil and Argentina (Abrol et al.
2005 ) in the developing world. In these countries,
45-60 % of all agricultural land is said to be man-
aged by conservation agriculture systems. In the
2001-2002 seasons, conservation agriculture
practices are estimated to have been used on
more than 9 million hectares in Argentina and
13 million hectares in Brazil. In Africa, the Africa
Conservation Tillage Network (ACT) was estab-
lished in 1998 to promote conservation agricul-
ture as a sustainable means to alleviate poverty,
make more effective use of natural and human
resources, and reduce environmental degradation
(Abrol et al. 2005 ).
Less labor, time, and cost are required under a
reduced tillage system due to fewer tillage trips
and cultivation operations for seedbed prepara-
tion. The savings range from $2.47/ha to $19.13/
ha (Kimble et al. 2007 ).
• A large number of studies have estimated the
potential fuel cost savings as a result of reduc-
ing tillage. They range between $3.58/ha and
$28.29/ha (Kimble et al. 2007 ).
• Generally, reduced tillage systems have lower
machinery repair and maintenance costs due
to less use of tillage implements (Kimble et al.
2007 ).
• Zero-tillage technology reduces costs of fi eld
preparation up to US$70 (Rs. 3,200) per hect-
are (Verma and Singh 2009 ), and it also saves
time and labor (up to 10-20 %). A saving of
fuel consumption by 26.5-43.7 l per hectare
(Verma and Singh 2009 ) results in reduced
fuel cost and reduced carbon emitted to the
atmosphere.
• Zero-tillage can save farmers around 1 million
liters of water per hectare (100 mm) compared
with conventional practices due to the mulch
on the soil surface which reduces evapotrans-
piration (Rehman 2007 ).
• Zero-tillage increases soil carbon from 0.1 to
0.7 metric tons ha −1 year −1 (Paustion et al.
1995 ) under subtropical conditions.
13.1.3.2 Biochar
Biochar is a charcoal-like substance produced
from agriculture and forest wastes. It has high
active carbon surface area that is produced
through anaerobic heating of biomass.
Composition-wise, it contains 70 % carbon and
the remaining elements are hydrogen, oxygen,
and nitrogen. Biochar is used as soil enhancer to
increase fertility, to prevent soil degradation, and
to sequester carbon in the soil. It improves soil
fertility by retaining water and nutrients in soil,
encouraging benefi cial soil organisms and
thereby reducing the need for additional use of
fertilizers. Biochar can store carbon in the soil for
as many as hundreds to thousands of years.
Biochar technology is different from the conven-
tional charcoal production because it is highly
effi cient in the conversion of carbon and harmful
pollutants are not released upon combustion.
Hence, it is a cleaner and more effi cient technol-
ogy. If this technology is used sustainably, the
by-products in the form of oil and gas can substi-
tute for a cleaner and renewable fuel option.
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