SOIL PROPERTIES, CONDITION AND SOIL LOSSES FOR SOUTH AND EAST BRAZILIAN FOREST AREAS
systems and management on soil detachment within a field; iii) evaluation of
range management and treatment alternatives on soil erosion and sediment
delivery from rangeland areas; iv) effect of road design and construction in
forests on sediment delivery from forest lands; v) effect of ridge height on
sediment delivery from a field; vi) evaluation of grassed waterways; vii)
appraisal of Natural Resource Inventory (NRI) sites for estimates of sediment
delivery from fields and farms; viii) use of NRI sites and real-time weather to
make same-day estimates of soil loss; ix) effect of autumn stubble management
on the capture of snow and its consequent effect on soil erosion. These effects
would include those due to increased soil moisture, altered hydraulics due to
crop residue, and increased runoff during thawing periods. On the other hand,
the major disadvantages of the WEPP model are: i) it needs extensive data sets
as input and many calibration parameters; ii) it requires either complex
laboratory analyses or difficult and expensive field data collection, which may
be unfeasible in many developing countries; and iii) in spite of having some
calibration parameters, the model does not have an optimization method
embedded in the software.
4.2 The GeoWEPP Interface
The need of a spatially distributed erosion prediction model capable of
using larger and more detailed data sets, usually managed with geographic
information system (GIS) or precision farming software packages, has led to the
development of the Geospatial interface for WEPP (GeoWEPP) (Renschler,
2003).
The GeoWEPP model is a continuous simulation, process-based model
that allows simulation of small watersheds and hillslope profiles for evaluating
land use management. The GeoWEPP prepares WEPP model inputs
automatically through a GIS-based wizard, runs the WEPP hillslope and
7
watershed model, and analyzes the model output. The GeoWEPP utilizes digital
geo-referenced information such as Digital Elevation Model (DEM) and
topographical maps to derive and prepare valid model input parameters and
defaults to start site-specific soil and water conservation planning for a small
watershed with a single soil and land use for each sub-watershed (Renschler &
Flanagan, 2008). In addition, the automatic delineation procedure of the
drainage networks and slope shapes is favored in comparison to a manual
delineation of hillslopes and channels in watersheds (Nearing et al., 2005).
Despite of the WEPP channel routing algorithms for the watershed simulation
(Ascough II et al., 1997; Lui et al., 1997) was originally designed to simulate
channel processes in watersheds smaller than 260 ha (Flanagan & Nearing,
1995), the GeoWEPP allows delineation of larger watersheds beyond the
recommended watershed size for WEPP watershed simulations (Renschler,
2004).
The goal of the GeoWEPP project is to provide a series of interfaces for
users with different levels of GIS knowledge that are capable to utilize these
different data sources in a standard format provided by GIS users, by precision
farmers with Global Positioning Systems (GPS) databases and/or through
accessing commonly readily available U.S.-nationwide data sets that are free of
charge (GeoWEPP, 2009).
8
5 REFERENCES
ASCOUGH II, J. C.; BAFFAUT, C.; NEARING, M. A.; LIU, B. Y. The WEPP:
watershed model, I. hydrology and erosion. Transactions of the American
Society of Agricultural and Biological Engineers, Saint Joseph, v. 40, n. 4, p.
921-933, July/Aug. 1997.
BATCHELOR, P. Models as metaphors: the role of modeling in pollution
prevention. Waste Management, Oxford, v. 14, n. 3/4, p. 243-251, May/June
1994.
BEVEN, K. Changing ideas in hydrology-the case of physically based models.
Journal of Hydrology, Amsterdam, v. 105, n. 1/2, p. 157-172, Jan. 1989.
BHATTARAI, R.; DUTTA, D. Estimation of soil erosion and sediment yield
using GIS at catchment scale. Water Resources Management, Amsterdam, v.
21, n. 10, p. 1635-1647, Oct. 2007.
DE ROO, A. P. J.; WESSELING, C. G.; RITSEMA, C. J. LISEM: a single event
physically-based hydrologic and soil erosion model for drainage basins: I,
theory, input and output. Hydrological Processes, Chinchester, v. 10, n. 8, p.
1107-1117, Aug. 1996.
FLANAGAN, D. C.; NEARING, M. A. USDA-water erosion prediction
project hillslope profile and watershed model documentation. West
Lafayette: USDA-ARS National Soil Erosion Research Laboratory, 1995.
(SERL Rep., 10).
GASSMAN, P. W.; REYES, M. R.; GREEN, C. H.; ARNOLD, J. G. The Soil
and Water Assessment Tool: historical development, applications, and future
research directions. Transactions of the American Society of Agricultural
and Biological Engineers, Saint Joseph, v. 50, n. 4, p. 1211-1250, July/Aug.
2007.
GEOWEPP. The Geo-spatial interface for the water erosion prediction
project: GeoWEPP. Buffalo: The State University of New York, 2009.
Available at: <http://www.geog.buffalo.edu/~rensch/geowepp/>. Accessed in:
15 Apr. 2009.
9
GRAYSON, R. B.; MOORE, I. D.; MCMAHON, T. A. Physically-based
hydrologic modeling: II, is the concept realistic? Water Resources Research,
Washington, v. 26, n. 10, p. 2659-2666, Oct. 1992.
LANE, L. J.; RENARD, K. G.; FOSTER, G. R.; LAFLEN, J. M. Development
and application of modern soil erosion predict technology: the USDA
experience. Australian Journal of Soil Research, Melbourne, v. 30, n. 6, p.
893-912, Dec. 1992.
LIU, B. Y.; NEARING, M. A.; BAFFAUT, C.; ASCOUGH II, J. C. The WEPP
watershed model: III, comparisons to measured data from small watersheds.
Transactions of the American Society of Agricultural Engineers, Saint
Joseph, v. 40, n. 4, p. 945-952, July/Aug. 1997.
MORGAN, R. P. C.; QUINTON, J. N.; SMITH, R. E.; GOVERS, G.; POESEN,
J. W. A.; AUERSWALD, K.; CHISCI, G.; TORRI, D.; STYCZEN, M. E. The
European Soil Erosion Model (EUROSEM): a dynamic approach for predicting
sediment transport from fields and small catchments. Earth Surface Processes
and Landforms, Sussex, v. 23, n. 6, p. 527-544, June 1998.
NEARING, M. A.; JETTEN, V.; BAFFAUT, C.; CERDAN, O.; COUTURIER,
A.; HERNANDEZ, M.; LE BISSONNAIS, Y.; NICHOLS, M. H.; NUNES, J.
P.; RENSCHLER, C. S.; SOUCHÈRE, V.; VAN OOST, K. Modeling response
of soil erosion and runoff to changes in precipitation and cover. Catena, v. 61,
n. 2/3, p. 131-154, June 2005.
RENARD, K. G.; FOSTER, G. R.; WEESIES, G. A.; MCCOOL, D. K.;
YODER, D. C. Predicting soil erosion by water: a guide to conservation
planning with the Revised Universal Soil Loss Equation (RUSLE). Washington:
U.S. Department of Agriculture, 1997. 404 p. (Agriculture Handbook, 703).
RENSCHLER, C. S. Designing geo-spatial interfaces to scale process models:
the GeoWEPP approach. Hydrological Processes, Chinchester, v. 17, n. 6, p.
1005-1017, Apr. 2003.
RENSCHLER, C. S. GeoWEPP tutorial appendix. In: WEPP/GeoWEPP
Workshop at the Bureau of Land Management National Training Center,
Phoenix: National Training Center of the BLM, 2004. Available at:
<http://www.geog.buffalo.edu/~rensch/geowepp/>. Accessed in April 2009.
10
RENSCHLER, C. S.; FLANAGAN, D. C. Site-specific decision-making based
on RTK GPS survey and six alternative elevation data sources: soil erosion
predictions. Transactions of the American Society of Agricultural and
Biological Engineers, Sait Joseph, v. 51, n. 2, p. 413-424, Mar./Apr. 2008.
TUCCI, C. E. M. Modelos hidrológicos. Porto Alegre: ABRH/UFRGS, 1998.
669 p.
WILLIAMS, J. R. Sediment-yield prediction with Universal Equation using
runoff energy factor. In: Present and prospective technology for predicting
sediment yield and sources. Washington: USDA, 1975. p. 244-252. (ARS-S-
40).
WISCHMEIER, W. H. Upland erosion analysis. In: SHEN, W. H. (Ed.)
Environmental impacts on rivers. Fort Collins: CSU, 1972, p. 15-1-15-26.
WISCHMEIER, W. H.; SMITH, D. D. Predicting rainfall erosion losses from
cropland east of the Rocky Mountains. Washington: USDA, 1965. 47 p.
(Agriculture Hand-book, 282).
WISCHMEIER, W. H.; SMITH, D. D. Predicting rainfall erosion losses: a
guide to conservation planning. Washington: USDA, 1978. 58 p. (Agriculture
Hand-book, 537).
11
CHAPTER 2
SOIL PROPERTIES AND HEMC FROM SOILS CULTIVATED
WITH EUCALYPTUS, BRAZIL
1 ABSTRACT
Eucalyptus cultivation has increased in all Brazilian regions. In order
to recommend good management practices it is necessary to understand
differences in soil properties where eucalyptus is planted. In addition,
aggregate stability analyses have proved to be a useful tool to measure soil
effects caused by changes in management practices. Thus, the objectives of
this study were to determine the main soil properties for different soil
classes, and assess the relationship between aggregate stability and changes
in soils properties under eucalyptus plantation. We studied representative
soils within three eucalyptus cultivated regions. Physical, chemical, and
mineralogical analyses were performed for the A horizon to characterize the
predominant soil profiles. Aggregate stability was measured using the highenergy
moisture characteristic (HEMC) technique. The X-ray diffraction
patterns showed kaolinite as predominant crystalline mineral for all soils,
whereas, a small amount of hydroxy-interlayered vermiculite was found in
some profiles. Aggregate stability ratio was greater than 50% for all soils.
This fact shows, for highly weathered soils with large amount of 1:1 clay
minerals, that the aggregate stability index was high. In these soils, the
stability ratio did not show a good relationship with clay content, soil
organic matter, or Feo/Fed ratio. Aggregate stability differences under
eucalyptus plantings are not directly related to soil properties but are due to
other possible feature.
12
2 RESUMO
O cultivo de eucalipto tem aumento em todas as regiões brasileiras.
O conhecimento dos diferentes atributos do solo nestes sistemas é necessário
para uma boa recomendação das práticas de manejo. Além disso, a análise
de estabilidade de agregados tem mostrado ser uma boa ferramenta para
medir os efeitos no solo causados pelas mudanças nas práticas de manejo.
Deste modo, objetivou-se com este estudo determinar os principais atributos
do solo para diferentes classes de solo e avaliar a relação entre a estabilidade
de agregados e estes atributos nos solos sob o cultivo do eucalipto. Foram
estudados solos representativos de três regiões com cultivo de eucalipto.
Análises físicas, químicas e mineralógicas foram realizadas nos horizontes A
para caracterização dos solos. A estabilidade de agregados foi analisada por
meio do método high-energy moisture characteristic (HEMC). As análises
dos difratogramas de raio-X mostraram que a caulinita foi o mineral
predominante em todos os solos, enquanto uma pequena quantidade de
vemiculita com hidroxi-intercamada foi encontrada em alguns perfis. A
estabilidade de agregados foi maior que 50% para todos os solos estudados.
Este fato mostrou que para solos com grande quantidade de minerais de
argila 1:1, o índice de estabilidade de agregados foi alto. Para estes solos, a
estabilidade de agregados não mostrou boa correlação com o conteúdo de
argila, com a matéria orgânica ou com a razão molecular Feo/Fed. As
diferenças na estabilidade de agregados para plantios de eucalipto não estão
relacionadas diretamente com os atributos do solo, mas possivelmente
devido a outras variáveis.
13
3 INTRODUCTION
Eucalypt plantations play an important role at economy of several
countries. In Brazil, Eucalyptus plantations area reached 4.3 million hectares
in 2008, with an increase of 7.3% compared to 2007 (Associação Brasileira
de Produtores de Floresta Plantada - ABRAF, 2009). Despite of great
amount of cultivated area, little is known about how this kind of cultivation
management system affects soil properties. In addition, soil chemical and
physical properties can be greatly modified by different soil land use and
management practices.
Aggregate stability influences several aspects of a soil physical
behavior (Le Bissonnais, 1996). However, many physical and chemical
properties and agriculture management practices can affect aggregate
stability (Levy & Mamedov, 2002; Levy et al., 2003; Norton et al., 2006;
Ruiz-Vera & Wu, 2006). The breakdown of aggregates can be governed by:
(i) slaking, i.e., breakdown caused by compression of entrapped air during
fast wetting; (ii) breakdown by differential swelling during fast wetting; (iii)
breakdown by raindrops impact; and (iv) physical-chemical dispersion due
the osmotic stress upon wetting with low electrolyte water. These
mechanisms differ in many ways including the type of forces involved,
interactions with soils properties, size of aggregates involved in the
breakdown process, and intensity of disaggregation (Le Bissonnais, 1996).
14
The three soil properties that are most often mentioned affecting
aggregate stability are (i) exchangeable-sodium-percentage, (ii) iron and
aluminum oxides (a general term that includes oxides, oxydroxides and
hydroxides in this paper) that cement aggregates, particularly for tropical
soils, and (iii) organic matter which is a bonding agent between mineral soil
particles, which may protect the surface against raindrop impact, improve
water infiltration and impart hydrophobic characteristics that reduces wetting
rate and slaking (Le Bissonnais, 1996). In addition, soil texture and other
factors play an important role in aggregation. For example, interaction
between aggregation and clay content and its mineralogy have been reported
by many researchers such as Reichert & Norton, 1994; Levy & Mamedov,
2002; Lado et al., 2004; Denef & Six, 2005; Ruiz-Vera & Wu, 2006; Norton
et al., 2006; and Mamedov et al., 2007. Thus, an increase in clay content in
the soil could increase slaking forces during soil wetting. Under faster
wetting, an increase in clay content in the aggregate also increases the extent
of differential swelling and the volume of entrapped air that, in turn, can
increase aggregate slaking. Therefore, an increase in clay content in the soil
might have two opposite effects on seal formation: (i) an increase in
aggregate stability and a reduction in seal formation, and/or (ii) increase in
aggregate slaking, upon wetting, and an increase in soil susceptibility to
sealing (Lado et al., 2004). Thus, an increase in clay content does not always
result in increased stability, since clay type is an important factor in
aggregation (Reichert & Norton, 1994).
15
Aggregation by iron oxides is evident in the Oxisols on Tertiary age
sediments. This indicates that remobilization of iron during soil formation is
essential for iron playing a role in aggregation. These findings suggest that
the mode of formation and iron mineralogy affect aggregation (Muggler et
al., 1999). In Brazilian Oxisols, the presence of Al-oxides (gibbsite)
conferred a good correlation with aggregate stability, conversely, kaolinite
showed a strong negative relationship (Ferreira et al., 1999).
Soil organic matter (OM) is expected to be the primary binding
agent in 2:1 clay-dominated soils because polyvalent-organic matter
complexes form bridges between the negatively charged clay platelets. In
contrast, soil OM is not the only binding agent in oxides and 1:1 clay
dominated soils (Six et al., 2000b). The electrostatic interaction between
kaolinite, oxides, and vermiculite seem to result in a soil stability not as
dependent on soil OM content as soils dominated by 2:1 clays. Due to the
binding of particles by electrostatic interactions, soil OM does not have to
function as critical binding agent (Six et al., 2000a). This is supported by the
observation of aggregate size in kaolinitic soil (Six et al., 2000b). For the
more weathered kaolinitc soils (1:1 type clay minerals), soil OM and
biological processes played only a partial role in the binding of aggregates
(Denef
& Six, 2005).
The aforementioned facts showed aggregate stability can be affected
by many factors such as texture (Levy & Mamedov, 2002; Lado et al., 2004;
Norton et al., 2006; Mamedov et al., 2007), clay mineral type (Reichert &
16