stock of soil organic carbon and soil organic matter quality in

XI CONGRESO NACIONAL DE LA CIENCIA DEL SUELO
XI CONGRESO NACIONAL DE LA CIENCIA DEL SUELO
STOCK OF SOIL ORGANIC CARBON AND SOIL ORGANIC MATTER
QUALITY IN ARID SOILS OF THE COQUIMBO REGION
Resultados obtenidos en la viña V, indicaron la efectividad del manejo en terrazas, presentando
una menor erosión (0 – 4,73 mm del horizonte Ap) que las vides en sentido de la pendiente
(0,14 – 5,11 mm del horizonte Ap). Así mismo, al comparar los resultados obtenidos en
la viña V, plantadas en sentido de la pendiente, con los de la viña N, se encontró que las
pérdidas de suelo en la viña N (con un menor grado de pendiente) fueron entre un 33 a 61%
menores, que las encontradas en la viña V.
Gerardo SOTO1,2. Santa Rosa 11.315 – 8820808 – La Pintana, Santiago, Chile / Casilla 1004 /
gesoto@uchile.cl / Gerardo.Soto@cnrs-orleans.fr
Ary BRUAND2. 1A, rue de la Ferollerie 45071 Orlèans cedex 2 – Francia /
Ary.Bruand@univ-orleans.fr
Jean-Robert DISNAR2. Jean-Robert.Disnar@univ-orleans.fr
Pablo ALVAREZ3. Avenida La Paz 1.108 – 1842646 – Ovalle / pabloa@userena.cl
Audrey GALLAUD2. Audrey.Gallaud@univ-orleans.fr
Dado que una de las ventajas de la aplicación de esta técnica es presentar un menor impacto
sobre el suelo, es necesario precisar las condiciones de muestreo para cada sitio de estudio,
en particular el efecto de cobertura y el grado de disturbación del suelo entre períodos de
muestreo.
Universidad de Chile, Facultad de Ciencias Agronómicas.
ISTO Université d’Orléans / CNRS / Université François Rabelais-Tours (UMR 6113). 3
Universidad de La Serena, Facultad de Ciencias, Depto.de Agronomía.
1
2
Referencias
Walling, D.E., Quine, T.A. 1995. The use of fallout radionuclide measurements in soil erosion
investigations. En: IAEA (Ed.), Proceedings of the International FAO/IAEA Symposium on
Nuclear Techniques in Soil-Plant studies for Sustainable Agriculture and Environmental
Preservation, Vienna 17-21 October, 1995. IAEA Proc. Series STI/PUB/947. IAEA,
Vienna, Austria, pp 597-619.
Walling D.E., He Q., Appleby P.G. 2002. Conversion Models for use in soil-erosion, soilredistribution and sedimentation investigations. En: Zapata F. (Ed.) Handbook for the
Assessment of Soil erosion and Sedimentation Using Environmental Radionuclides. Joint
FAO/IAEA Division, International Atomic Energy Agency, Vienna, Austria, Capítulo 7, pp
111-164.
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RESUMEN
This work reports the effects of goat grazing on the soil organic carbon stock and soil organic
carbon (SOC) quality at the experimental station of Las Cardas, Coquimbo region. The soils
are classified as Typic Haplodurids (US Soil taxonomy). Three treatments were selected for
study: native vegetation (NV), moderate grazing (MG) and intensive grazing (IG). Three pits
were studied under NV, four under MG and three under IG. The particle size-distribution, the
stone content and the cation exchange capacity (CEC) were measured. The organic carbon
content (OCC) was determined in the 0-5 and 5-10 cm layers and then every 10 cm down
to 100 cm depth and we modelled the prediction between stocks of soil organic carbon in
the layer 0-30 cm and 0-100 cm. Indications on SOC quality were obtained by Rock-Eval
pyrolysis, namely the Hydrogen and Oxygen Indexes (IH and IO in mg Hydrocarbon and mg
CO2 per gram of OC, respectively), which are related to the hydrogen and oxygen content of
the organic matter. Results showed that the soils were sandy loam textured with a relatively
CEC with respect to the clay content. The OCC in the 0-5 cm topsoil ranged from 6.1 to
11.8 g·kg-1 under NV, from 2.8 to 13.4 g·kg-1 under MG and from 4.7 to 8.0 g·kg-1 under IG.
The total organic carbon stocks (TOCS) decrease with soil use intensity, i.e. from 31.1 to
42.6 Mg·ha-1 under NV, from 24.3 to 29.3 Mg·ha-1 under MG and from 10.2 to 15.5 Mg·ha-1
under IG. The qualitative analysis showed that SOC is very altered even at the soil surface,
with increasing alteration with depth. Statistical analysis of the averaged total stocks showed
significant difference (P=0.95) between the three treatments, grazing affecting mainly the
organic stock within the 0-30 cm topsoil because of its consequences on the production of
litter and roots. Finally, our results showed the possibility to predict the TOCS by using the
stock of soil organic carbon within the 0-30 cm topsoil alone with a satisfactory prediction
quality, the bias was less than 1.29 Mg·ha-1 and the precision is equal to 4.1 Mg·ha-1.
37