Agriculture Reference
In-Depth Information
of the gains of the whole 0-17.5 cm soil pro-
file occurred below the 17.5 cm depth, rein-
forcing the importance of subsoil as a C
source or sink. The average C sequestration
rate of legume-based cropping systems
(with N) were 0.83 Mg C ha
-
1
year
-
1
in the top
0-17.5 cm layer and 1.42 Mg C ha
-
1
year
-
1
in
the profile, indicating the remarkable poten-
tial of legume cover crops and N fertiliza-
tion under no-tillage to improve soil carbon
stocks and thus soil and environmental
quality in humid subtropical regions.
The adoption of NT and soil cover also
brings about favourable soil physical condi-
tions that improve water infiltration and
storage (Fernández
et al
., 2008) and prevent
water and wind erosion (Hevia
et al
., 2007),
which is very important in semi-arid re-
gions. For temperate environments in east-
ern Argentina, NT combined with pasture
rotations was shown to be a sustainable
agricultural practice that combined high
yields with carbon storage in soils (Studdert
et al
., 1997; Studdert and Echeverría, 2000).
Similar results were also obtained in Uru-
guay when NT was incorporated into crop-
pasture rotations (Garciaprechac, 2004).
Other benefits of NT include higher bio-
logical activity of the soil ecosystem (Quiro-
ga
et al
., 2009; Fernández
et al
., 2010a),
which also promotes the diversity of soil
organisms, as confirmed by studies on Chil-
ean and Argentinean NT soils (Abril
et al
.,
1995; Borie
et al
., 2006). Crops cultivated
under NT are usually more efficient in water
use and produce higher yields (Noellemeyer
et al
., 2013). All of the mentioned benefits
were enhanced, without negative impacts on
crop yields, when cover crops were used to
improve soil cover and residue biomass
input to the soil (Fernández
et al
., 2010b;
Mohammadi, 2010; dos Santos
et al
., 2011;
Restovich
et al
., 2012). Cover crops or
double cropping can also help to retain
more water in the soils of a region compared
to single crops under conventional tillage
(Nosetto
et al
., 2012), by reducing losses
through deep drainage and surface runoff.
Cover crops and NT technology has been
widely adopted both in Brazil and Argen-
tina, and is also applied in important areas
of Chile, Paraguay, Bolivia and Uruguay,
resulting in manifold benefits. Generally,
crop yields are higher under NT, resulting
in improved provision of goods, but also
many ecosystem services such as water fil-
tration and storage, erosion prevention, soil
formation and biodiversity conservation are
enhanced.
In conclusion, crop residue manage-
ment is a key point of NT systems, and
includes selecting crops that produce suffi-
cient quantities of residues (e.g. maize, sor-
ghum, etc.) and the introduction of cover
crops in rotation schemes that provide an
effective ground cover. Rather than turning
under plant materials or crop residues fol-
lowing harvest, the residues are left on the
soil surface to protect the soil against the
erosive forces of rainfall and wind. Crop
residue management is also a key point for
enhancing SOC under energy crops such as
sugarcane. Here, there is room to improve
management simply by changing the tillage
system during the reform of the sugarcane
fields.
References
Abril, A., Caucas, V. and Nuñez Vazquez, F. (1995) Sistemas de labranza y dinámica microbiana del suelo
en la región central de la Provincia de Córdoba (Argentina).
Ciencia del Suelo
13,
104-106.
Abril, A., Salas, P., Lovera, E., Kopp, S. and Casado-Murillo, N. (2005) Efecto acumulativo de la siembra
directa sobre algunas características del suelo en la región semiárida central de la Argentina.
Ciencia
del Suelo
23,
179-188.
Alvarez, R. and Steinbach, H.S. (2009) A review of the effects of tillage systems on some soil physical prop-
erties, water content, nitrate availability and crops yield in the Argentine Pampas.
Soil and Tillage
Research
104,
1-15.
Amado, T.J.C., Fernandez, S.B. and Mielniczuk, J. (1998) Nitrogen availability as affected by ten years of
cover crop and tillage systems in Southern Brazil.
Journal of Soil and Water Conservation
53,
268-271.
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