Effect of Different Doses of Glyphosate on Soil Physical Parameters in the Prefecture of N'Zérékoré, Guinea

Abstract

This study examines the effect of different glyphosate doses on the soil texture in four rural communes of the N'Zérékoré prefecture in Guinea. A complete randomized block design was used to assess the impact of glyphosate doses on several soil parameters, including granulometry, aggregate stability, bulk density, and porosity. The analysis of variance (ANOVA) revealed that glyphosate doses significantly influence Granulometry A (p = 0.02881) and show a trend toward affecting soil aggregate stability (SI) and overall stability (Sg), although these effects are not significant at the 0.05 threshold. Conversely, glyphosate doses had no significant effect on Granulometry Lf, Granulometry Lg, bulk density, and soil porosity, as these parameters were more influenced by soil type and year. These results suggest that higher doses of glyphosate can alter soil structure, but the effect varies depending on specific environmental conditions, particularly soil type and annual variations. Careful management of glyphosate doses is therefore recommended to preserve soil quality and support sustainable agricultural practices.

Full text

International Journal of Research and Review
Volume 11; Issue: 11; November 2024
Website: www.ijrrjournal.com
Research Paper E-ISSN: 2349-9788; P-ISSN: 2454-2237
International Journal of Research and Review (ijrrjournal.com) 496
Volume 11; Issue: 11; November 2024
Effect of Different Doses of Glyphosate on Soil
Physical Parameters in the Prefecture of
N'Zérékoré, Guinea
Paul Lamah1,2, Hamidou Bah1,4, Adoté Hervé Gildas Akueson4,
Gbadieu Prosper Soumaoro2, Diawadou Diallo4
1Ecole doctorale en Agriculture Durable et Gestion des Ressources en Eau, Institut Supérieur Agronomique
Valery Giscard d’Estaing de Faranah, BP: 131 Faranah, République de Guinée
2Départment de Gestion des Ressources Naturelles, Institut de Recherche Environnementale de Bossou, BP: 20
Lola, République de Guinée.
3Départment de Primatologie, Institut de Recherche Environnementale de Bossou, BP: 20 Lola, République de
Guinée.
4Département Agriculture, Institut Supérieur Agronomique Valery Giscard d’Estaing de Faranah, BP: 131
Faranah, République de Guinée
Corresponding Author: Hamidou Bah
DOI: https://doi.org/10.52403/ijrr.20241150
ABSTRACT
This study examines the effect of different
glyphosate doses on the soil texture in four
rural communes of the N'Zérékoré
prefecture in Guinea. A complete
randomized block design was used to assess
the impact of glyphosate doses on several
soil parameters, including granulometry,
aggregate stability, bulk density, and
porosity. The analysis of variance
(ANOVA) revealed that glyphosate doses
significantly influence Granulometry A (p =
0.02881) and show a trend toward affecting
soil aggregate stability (SI) and overall
stability (Sg), although these effects are not
significant at the 0.05 threshold.
Conversely, glyphosate doses had no
significant effect on Granulometry Lf,
Granulometry Lg, bulk density, and soil
porosity, as these parameters were more
influenced by soil type and year. These
results suggest that higher doses of
glyphosate can alter soil structure, but the
effect varies depending on specific
environmental conditions, particularly soil
type and annual variations. Careful
management of glyphosate doses is
therefore recommended to preserve soil
quality and support sustainable agricultural
practices.
Keywords: Glyphosate, granulometry,
aggregate stability, bulk density, porosity,
Guinea.
INTRODUCTION
Glyphosate is the most widely used
herbicide globally due to its effectiveness in
eliminating a wide variety of weeds, making
it an essential tool for modern farmers
(Benbrook, 2016). However, its long-term
and large-scale use raises questions about its
impact on soil, particularly on soil texture
and its ability to support sustainable
agricultural practices (Giesy et al., 2000).
Soil texture, which refers to the relative
proportions of sand, silt, and clay, strongly
influences essential characteristics such as
water retention, permeability, porosity, and
cation exchange capacity (CEC), which are
crucial for agricultural productivity (Gee &
Bauder, 1986).
Recent research has shown that repeated
glyphosate application can lead to changes
in the physical composition of soils. These

Paul Lamah et.al. Effect of different doses of glyphosate on soil physical parameters in the prefecture of
N'Zérékoré, Guinea
International Journal of Research and Review (ijrrjournal.com) 497
Volume 11; Issue: 11; November 2024
changes may affect soil structure,
particularly by disrupting soil aggregates
and reducing soil stability (Zobiole et al.,
2011). Consequently, soils may lose their
ability to retain nutrients, making crops
more vulnerable to water and nutrient stress
(Silva et al., 2018). Additionally, studies
have also highlighted that glyphosate can
interact with the organic and inorganic
components of soil, influencing particle size
distribution and fine particle dynamics,
which could have implications for erosion
and long-term fertility (Casabe et al., 2007).
While the impact of glyphosate on soil
chemistry and microbial biodiversity has
been widely studied, its specific effect on
soil texture remains relatively under-
researched, especially in tropical regions
such as the N'Zérékoré Prefecture in Guinea
(Simonsen et al., 2008). This region is
characterized by ferralitic soils, subject to
intensive agricultural practices, where
glyphosate use has become common in
agroforestry systems and food crops. It is,
therefore, essential to examine how different
doses of glyphosate influence soil texture in
this specific environmental context.
This article aims to address this gap by
evaluating the effect of multiple doses of
glyphosate on soil texture in four rural
municipalities in the N'Zérékoré Prefecture.
Specifically, this study analyzes changes in
soil particle size distribution, porosity, and
water retention capacity after the application
of various doses of glyphosate. The results
of this research will provide practical
recommendations for sustainable soil
management while offering a better
understanding of the underlying
mechanisms of glyphosate's impact on soil
texture in tropical areas (Duke & Powles,
2008). Furthermore, this study contributes
to the broader discussion on the
environmental effects of intensive
agriculture and on balancing herbicide
efficiency with soil sustainability (Mertens
et al., 2018).
MATERIALS & METHODS
Study Area
The study was conducted in four rural
municipalities (RM) of the N'Zérékoré
Prefecture (Konipara in the RM of Kobéla,
Kwèliyépoulou in the RM of Samoé,
Kéréma in the RM of Bounouma, and
Pilimou, a peri-urban area of the city of
N'Zérékoré), as shown in Figure 1.
Figure 1. Sampling Area in the N'Zérékoré Prefecture.

Paul Lamah et.al. Effect of different doses of glyphosate on soil physical parameters in the prefecture of
N'Zérékoré, Guinea
International Journal of Research and Review (ijrrjournal.com) 498
Volume 11; Issue: 11; November 2024
The climate of the study area is sub-
equatorial, with abundant and nearly
continuous rainfall throughout the year
(approximately 8 to 9 months). The average
annual rainfall varies between 1800 and
2300 mm. The temperature remains
moderate year-round, averaging around
25°C.
The dense, humid forest promotes the
formation and preservation of shallow and
relatively thick ferralitic soils. This region is
home to both food and industrial crops
(Coffea arabica, Theobroma cacao, Cola
acuminata, Elaeis guineensis Jacq., Hevea
brasiliensis, etc.). Its ecosystem supports
three types of agricultural systems: (1) the
hillside slash-and-burn food crop system
based on rainfed rice cultivation, a staple for
the local population, combined with
secondary food crops (Abelmoschus
esculentus, Capsicum frutescens, Rumex
acetosa, Colocasia esculenta) rotated with
Arachis hypogaea and Manihot esculenta;
(2) complex agroforestry systems, later
referred to as “agroforests,” consist of
perennial crops, including a primary crop
(Coffea arabica, Cola acuminata, Elaeis
guineensis Jacq., or Theobroma cacao),
along with secondary perennial crops (fruit
trees) grown under a forest canopy with
varied composition; and (3) lowland
farming systems, primarily used for flooded
rice cultivation. An analysis of these soils at
the 0-30 cm horizon provides the following
characteristics (Table 1).
Table 1. Physical Characteristics of the Soils
Studied
Parameters
Upland soil
Lowland soil
Clay (%)
6,5
9,8
Silt (%)
4,2
7,5
Sand (%)
45,7
25,30
Plant Material
For the trial, we first inventoried the weeds
in the palm groves at the experimental sites
of Konipara in the RM of Kobéla,
Kwèliyépoulou in the RM of Samoei,
Kéréma in the RM of Bounouma, and
Pilimou in the urban municipality of
N'Zérékoré. We then proceeded to
georeference the soil sampling areas.
Technical Material
This includes: a GPS, a computer, a map of
the study area, sprayers (continuous
pressure sprayer with a mirror nozzle and a
capacity of 450 L/ha, pneumatic sprayer
with an adjustable flow rate between 400
and 500 L/ha), buckets, plastic bags,
individual protective masks, a rain gauge, a
digital camera, a stopwatch, a thermometer,
measuring tape, rebar, wire, paint,
paintbrushes, arm guards, hoes, and
pickaxes.
Laboratory Material
The equipment we used in the laboratory to
analyze indicators of soil fertility included:
burette, autoanalyzer, colorimetric
autoanalyzer, conductometer, and pH meter.
Data Collection, Methodology
Data were collected from field experiments,
where measurements of soil chemical
parameters were taken at different time
intervals after glyphosate treatments were
applied. The data were recorded in a
database and cleaned to remove outliers and
duplicates. Once cleaned, the data were
grouped by treatment to facilitate analysis.
The experiment was conducted using a
randomized complete block design, with
four treatment levels corresponding to
different glyphosate doses: T (full dose), N,
2/3N, and 3/2N. Four trials were carried out
in four rural communes of the N'Zérékoré
prefecture over a two-year period (2022 and
2023) to account for annual variations in
soil characteristics. The blocks were set up
over a length of 19.25 m with a width of 5
m, spaced 1 m apart. The plastic pots for the
individual plots, measuring 25 cm in
diameter and 35 cm in height, were filled
with 3 kg of composite soil samples. Two
soil types (Upland and Lowland) were
considered in the analysis, allowing for a
comparative evaluation of soil responses to
different glyphosate doses. Two weeks after
treatment, samples were collected from the

Paul Lamah et.al. Effect of different doses of glyphosate on soil physical parameters in the prefecture of
N'Zérékoré, Guinea
International Journal of Research and Review (ijrrjournal.com) 499
Volume 11; Issue: 11; November 2024
treated soils, labeled according to sample
details, and transported to the National Soil
Service Laboratory of Guinea (SENASOL,
Guinea).
STATISTICAL ANALYSIS
The collected data were analyzed using a
statistical approach to evaluate the impact of
glyphosate doses on various soil parameters,
including granulometry, aggregate stability,
bulk density, and porosity. The analysis
proceeded as follows: Analysis of variance
(ANOVA) was used to test the main effects
and interactions between the following
factors: Glyphosate dose (T, N, 2/3N, 3/2N),
Soil type (Upland and Lowland), and Year
(2022 and 2023).
ANOVA tested the null hypothesis that
there were no significant differences
between the groups. A significance level of
0.05 was set for all analyses. p-values were
used to determine whether the observed
effects among the groups were statistically
significant.
Following ANOVA, Student-Newman-
Keuls (SNK) post-hoc tests were conducted
to compare the means of the different
groups and identify pairs with significant
differences. This allowed for a more
detailed analysis of the observed differences
between glyphosate doses, soil types, and
years for the studied parameters. These tests
helped identify specific treatments with
significant effects on granulometry,
aggregate stability, and other parameters.
In addition to ANOVA and post-hoc tests, a
multinomial regression was conducted to
evaluate the effect of glyphosate doses on
soil texture, considering the different soil
types and measurement years. The objective
of this regression was to model the
likelihood of a specific texture type
appearing as a function of applied
glyphosate doses, while controlling for
factors such as soil type and year.
A multinomial regression was used to
examine the association between glyphosate
doses and soil texture. The dependent
variable in this regression was soil texture,
categorized into different classes: Las
(reference texture), LS (loamy sand), and
Lfs (sandy loam). Glyphosate doses served
as the main explanatory variables, with dose
levels 3/2N, N, and T (full dose). Soil type
(Upland or Lowland) and year (2022, 2023)
were included as covariates in the model.
RESULT
• Granulométry (A)
The analysis of variance for granulometry
(A) shows that the glyphosate dose factor
has a significant effect (p = 0.02881),
indicating that different glyphosate doses
influence soil granulometry. Additionally,
the year factor has a highly significant effect
(p = 0.00308), suggesting that granulometry
varies depending on the year. In contrast,
neither the soil type factor (p = 1.000) nor
the interaction between glyphosate dose and
soil type (p = 1.000) have significant
effects. These results show that
granulometry is affected by glyphosate
doses and year-specific conditions but not
by soil type.
The SNK structuring test reveals differences
in granulometry based on doses and years.
In 2022, the T dose (full dose) shows the
highest value (22.80%), followed closely by
the 2/3N (20.80%) and 3/2N (20.08%)
doses. The N dose shows the lowest
granulometry (16.80%). In 2023, the values
are generally lower, with the T dose
(18.80%) remaining slightly higher than the
others, while the 2/3N, N, and 3/2N doses
have similar, lower granulometric values.
This shows that high glyphosate doses
increase granulometry A, but these effects
can vary depending on the year (Table 2,
Figure 2).
• Granulométry (Lf)
The analysis of variance (ANOVA) for
Granulometry Lf indicates that the
glyphosate dose factor has no significant
effect on granulometric proportions (p =
0.715). This suggests that different
glyphosate doses do not significantly
influence soil granulometry. Similarly, soil
type (p = 1.000) and year (p = 0.138) have
no significant effect on this variable. The

Paul Lamah et.al. Effect of different doses of glyphosate on soil physical parameters in the prefecture of
N'Zérékoré, Guinea
International Journal of Research and Review (ijrrjournal.com) 500
Volume 11; Issue: 11; November 2024
interaction between glyphosate dose and
soil type (p = 1.000) is also non-significant.
These results reveal that variations in
Granulometry Lf are not related to
glyphosate doses, soil type, or years.
In summary, Granulometry Lf appears
relatively stable regardless of the glyphosate
doses applied, soil types, and years
considered. These results indicate that
Granulometry Lf may be less sensitive to
glyphosate treatments or that other
unmeasured factors could influence this
characteristic. It could also suggest
homogeneity in soil texture for this specific
granulometry, independent of treatment
variations (Table 2, Figure 2).
• Granulométry (Lg)
The analysis of variance (ANOVA) for
Granulometry Lg shows that the glyphosate
dose factor has no significant effect on
granulometric proportions (p = 0.1605).
This indicates that different glyphosate
doses do not significantly influence soil
granulometry. Similarly, soil type has no
significant effect (p = 1.000), nor does the
interaction between glyphosate dose and
soil type (p = 1.000). However, the year
factor has a significant effect (p = 0.0331),
indicating that variations in Granulometry
Lg may be influenced by year-specific
conditions. The SNK structuring test reveals
that Granulometry Lg in 2023 is higher than
in 2022, with respective values of 5 and 4.
This difference suggests that factors related
to the year, such as climatic conditions or
management practices, may affect
Granulometry Lg.
In summary, while glyphosate doses have
no significant impact, the observed
variations in Granulometry Lg are mainly
due to yearly conditions, highlighting the
importance of considering environmental
factors when evaluating this soil
characteristic (Table 2, Figure 2).
• Soil Aggregate Stability (SI)
The analysis of variance (ANOVA) for SI
(Soil Aggregate Stability) indicates that the
glyphosate dose factor shows a significant
trend (p = 0.0927), although it is not quite at
the traditional significance level of 0.05.
This suggests a potential influence of
glyphosate doses on soil aggregate stability,
but this influence should be interpreted
cautiously. The other factors, namely soil
type (p = 1.000) and year (p = 0.6986), have
no significant effect on SI. Furthermore, the
interaction between glyphosate dose and
soil type (p = 1.000) is not significant,
indicating that the effects of glyphosate
doses on aggregate stability are not
modified by soil type.
These results indicate that, while glyphosate
doses do not show a significant effect, a
trend may suggest some influence on
aggregate stability. It would be worthwhile
to further explore this relationship through
additional analyses or larger sample sizes to
better understand the potential impact of
glyphosate doses on soil structure and
stability (Table 2, Figure 2).
• Overall Soil Stability (Sg)
The analysis of variance (ANOVA) for Sg
(overall soil stability) shows a significant
trend for the glyphosate dose factor (p =
0.0927), indicating a potential effect of
glyphosate doses on overall soil stability.
However, this result does not meet the
traditional significance threshold of 0.05,
meaning these conclusions should be drawn
with caution. Other factors, such as soil type
(p = 1.000) and year (p = 0.6986), have no
significant effects on overall soil stability.
The interaction between glyphosate dose
and soil type is also not significant (p =
1.000), indicating that the effect of
glyphosate doses is not modified by soil
type.
These results suggest that, although the
effect of glyphosate doses on overall soil
stability is not yet fully established, a trend
may reveal some influence. This may
warrant further research to explore this
relationship more deeply and determine if
significant effects might emerge under
different conditions or with additional
samples (Table 2, Figure 2).

Paul Lamah et.al. Effect of different doses of glyphosate on soil physical parameters in the prefecture of N'Zérékoré, Guinea
International Journal of Research and Review (ijrrjournal.com) 501
Volume 11; Issue: 11; November 2024
Table 2: Summary of Physical Parameters According to Glyphosate Dose
Figure 2. Boxplot of soil physical parameters according to glyphosate dose treatments.
Year
Glyphosate
Dose
Granulométry A?
Mean ± Standard
Deviation
Granulométry_Lf Mean
± Standard Deviation
Granulométry Lg
Mean ± Standard
Deviation
SI Mean ±
Standard
Deviation
Sg Mean ±
Standard
Deviation
Da Mean ±
Standard Deviation
Porosity Mean ±
Standard Deviation
2022
2/3N
20.8 (± 0) ab
2.00 (± 0.1) a
4.00 (± 0) b
29.3 (± 0) a
43.9 (± 0) a
1.07 (± 0.0707) a
45.8 (± 2.12) a
2022
3/2N
20.1 (± 0) abc
4.00 (± 1.96) a
4.00 (± 0) b
28.5 (± 0) a
42.7 (± 0) a
1.09 (± 0.0424) a
44.8 (± 0.707) a
2022
N
16.8 (± 0) bc
4.00 (± 1.92) a
4.00 (± 0) b
30.1 (± 0) a
45.1 (± 0) a
1.12 (± 0.0707) a
45.5 (± 1.41) a
2022
T
22.8 (± 0) a
2.00 (± 0).2 a
4.00 (± 0) b
28.5 (± 0) a
42.7 (± 0) a
1.12 (± 0.0283) a
46.3 (± 3.54) a
2023
2/3N
16.8 (± 0) bc
6.00 (± 3.6) a
6.00 (± 2.96) a
28.5 (± 0) a
42.7 (± 0) a
1.10 (± 0.0283) a
44.1 (± 2.12) a
2023
3/2N
14.8 (± 0) c
2.00 (± 0.92) a
6.00 (± 3.1 a
30.9 (± 0) a
46.3 (± 0) a
1.16 (± 0.141) a
45.5 (± 1.41) a
2023
N
16.8 (± 0) bc
4.00 (± 0) a
4.00 (± 2.6) b
30.1 (± 0) a
45.1 (± 0) a
1.20 (± 0.106) a
47.1 (± 2.83) a
2023
T
18.8 (± 0) abc
8.00 (± 0) a
4.00 (± 1.6) b
27.7 (± 0) a
41.5 (± 0) a
1.13 (± 0.0707) a
45.3 (± 2.83) a

Paul Lamah et.al. Effect of different doses of glyphosate on soil physical parameters in the prefecture of
N'Zérékoré, Guinea
International Journal of Research and Review (ijrrjournal.com) 502
Volume 11; Issue: 11; November 2024
• Overall Soil Stability (Sg)
The analysis of variance (ANOVA) for Sg
(overall soil stability) shows a significant
trend for the glyphosate dose factor (p =
0.0927), indicating a potential effect of
glyphosate doses on overall soil stability.
However, this result does not meet the
traditional significance threshold of 0.05,
meaning these conclusions should be drawn
with caution. Other factors, such as soil type
(p = 1.000) and year (p = 0.6986), have no
significant effects on overall soil stability.
The interaction between glyphosate dose
and soil type is also not significant (p =
1.000), indicating that the effect of
glyphosate doses is not modified by soil
type.
These results suggest that, although the
effect of glyphosate doses on overall soil
stability is not yet fully established, a trend
may reveal some influence. This may
warrant further research to explore this
relationship more deeply and determine if
significant effects might emerge under
different conditions or with additional
samples (Table 2, Figure 2).
• Bulk Density (Da)
The analysis of variance (ANOVA) for Da
(bulk density) reveals that the glyphosate
dose factor has no significant effect (p =
0.15384), indicating that different
glyphosate doses do not appear to influence
soil bulk density. However, soil type shows
a significant effect (p = 0.00132), indicating
that soil type has a marked impact on bulk
density. Additionally, the year also has a
significant effect (p = 0.04663), suggesting
that variations in environmental or
management conditions from year to year
may influence this soil characteristic. The
interaction between glyphosate dose and
soil type is not significant (p = 0.55497),
meaning that the effects of glyphosate doses
on bulk density are not modified by soil
type.
The SNK test shows that bulk density is
highest for upland soil in 2023, with an
average of 1.2075, followed by the same
soil type in 2022 (1.1375). The densities for
lowland soil are lower, with values of
1.0850 for 2023 and 1.0625 for 2022, with
no significant differences between them.
This highlights the importance of soil type
in evaluating bulk density and suggests that
environmental factors, such as moisture or
soil texture, may play a role in the observed
variations. Overall, although glyphosate
doses have no significant impact on bulk
density, soil type and year have notable
effects that should be considered in soil
management (Table 2, Figure 2).
• Porosity
The analysis of variance (ANOVA) for
porosity reveals that the glyphosate dose
factor has no significant effect (p =
0.334655), indicating that different
glyphosate doses do not appear to influence
soil porosity. However, soil type has a
significant effect (p = 0.000901),
highlighting the importance of soil nature in
determining porosity. Lowland soils show
higher porosity (47.04) compared to upland
soils (44.04). The effect of year is not
significant (p = 0.818274), suggesting that
porosity variations are not dependent on the
measurement year. Furthermore, the
interaction between glyphosate dose and
soil type is not significant (p = 0.358258),
indicating that glyphosate dose effects on
porosity are not influenced by soil type.
The SNK test confirms that porosity is
significantly higher in lowland soil
compared to upland soil. These results
demonstrate that soil porosity, which is
essential for air and water movement, varies
significantly by soil type, potentially
impacting land management practices. It is
therefore important for farmers and soil
managers to consider these differences
when applying treatments and implementing
soil management practices to optimize soil
and crop health. In conclusion, although
glyphosate doses do not seem to influence
porosity, soil type plays a crucial role,
justifying the need for a management
approach tailored to soil type (Table 2,
Figure 2).
• Texture
Since texture is categorical with multiple
levels, the odds ratio (OR) analysis through

Paul Lamah et.al. Effect of different doses of glyphosate on soil physical parameters in the prefecture of
N'Zérékoré, Guinea
International Journal of Research and Review (ijrrjournal.com) 503
Volume 11; Issue: 11; November 2024
multinomial regression reveals significant
impacts of different glyphosate doses on
membership in soil texture classes,
particularly “Ls” and “LS” compared to the
reference “LAS.” For the “LS” class, the
odds ratio for the “N” dose is very high
(7.42e+16), indicating that this dose
substantially increases the odds of
belonging to this class compared to the
reference. In contrast, the “3/2N” dose has a
very low odds ratio (3.74e-6), suggesting an
almost negligible probability of belonging
to the “Ls” class. Upland soil and year show
weak effects on this class, with odds ratios
close to zero or one, indicating that these
factors do not significantly influence
membership in the “Ls” class.
For the “LS” class, the odds ratio for the
“intercept” is 3.27e-1, indicating a reduced
probability of belonging to this class
compared to the reference. The “N” and “T”
doses show odds ratios (4.19e-1), which
also suggest decreased odds of belonging to
the “LS” class. However, upland soil has a
positive effect with an odds ratio of 2.38,
indicating that this soil type increases the
chances of belonging to the “LS” class.
Overall, these results highlight the
importance of glyphosate doses and soil
type in determining soil texture, revealing
complex interactions that merit careful
attention when interpreting data (Table 3).
DISCUSSION
The results of this study show that
glyphosate doses have varied effects on soil
granulometric and physico-chemical
characteristics. For Granulometry A,
glyphosate doses significantly influence soil
texture, with higher doses tending to
increase the proportion of coarse particles.
This corroborates the observations of Silva
et al. (2018), who demonstrated that
repeated applications of glyphosate can
disrupt the physical structure of soil, thereby
reducing aggregate stability. Zobiole et al.
(2011) also reported similar effects on soil
structure in intensive agricultural systems.
Granulometry Lf, however, appears to be
relatively stable, regardless of the
glyphosate doses applied. This result
suggests that certain granulometric types
may be more resistant to herbicide-induced
changes. Duke and Powles (2008) suggested
that soil resistance to certain chemical
alterations could be linked to intrinsic
properties such as base texture and mineral
composition. Furthermore, the relative
stability of Granulometry Lf in this study
may indicate that other environmental
factors, such as agricultural management
practices or climatic conditions, play a more
determining role in preserving this specific
soil characteristic.
For Granulometry Lg, the results show that
variations are mainly influenced by annual
conditions rather than by glyphosate doses
or soil type. This is in line with the studies
of Mertens et al. (2018), who demonstrated
that annual climatic conditions, such as
temperature and humidity, can significantly
affect soil structure, independently of
agricultural inputs. The changes observed
between 2022 and 2023 may therefore be
attributed to climatic factors, such as
precipitation, which directly influence the
distribution of fine particles and soil
compaction.
Aggregate Stability (SI) and overall stability
(Sg) show a trend toward an impact of
glyphosate doses, although the results are
not quite significant at the 0.05 threshold.
These trends suggest that with higher doses
or prolonged applications, glyphosate could
influence overall soil structure. Simonsen et
al. (2008) demonstrated that the
accumulation of glyphosate in soil could
alter soil microstructure by affecting
interactions between clay particles and
organic matter. Additionally, Casabe et al.
(2007) noted that indirect effects of
glyphosate on soil microbial communities
could reduce the production of binding
substances, thereby compromising
aggregate stability.
Bulk density (DA) and porosity were more
influenced by soil type and annual
conditions than by glyphosate doses. This
demonstrates that intrinsic soil
characteristics, such as texture and

Paul Lamah et.al. Effect of different doses of glyphosate on soil physical parameters in the prefecture of
N'Zérékoré, Guinea
International Journal of Research and Review (ijrrjournal.com) 504
Volume 11; Issue: 11; November 2024
composition, play a more significant role in
these parameters than chemical inputs. Gee
& Bauder (1986) emphasized that bulk
density is heavily influenced by
granulometry and organic matter content,
two factors not directly modified by
glyphosate. Furthermore, Giesy et al. (2000)
demonstrated that herbicide use can have
differentiated impacts depending on soil
type, with clay soils more likely to retain
herbicide residues than sandy soils.
In summary, although glyphosate doses
have a perceptible effect on some aspects of
soil texture, such as Granulometry A and
aggregate stability, other characteristics, like
Granulometry Lf and bulk density, are more
influenced by soil type and environmental
conditions. These results highlight the
complexity of interactions between
agricultural practices and soil quality and
underscore the importance of adopting
integrated soil management to mitigate the
negative impacts of herbicides on soil
structure.
The impact of glyphosate on soil physical
characteristics also raises concerns,
particularly regarding soil structure, texture,
and porosity. Many authors have examined
the effects of glyphosate on the physical
properties of soil due to its frequent use in
agricultural practices. For example, Cerdeira
and Duke (2006) showed that glyphosate
can influence the physical composition of
soil by altering its structure. Continuous
exposure to this herbicide can affect soil
aggregate stability, leading to compaction
and reduced porosity (Simonsen et al.,
2008). This can decrease the soil's ability to
retain water and promote air circulation,
which is essential for plant root health and
soil organism activity. Consequently, more
compact soils may also reduce root
penetration, limiting the ability of plants to
access water and nutrients (Zobiole et al.,
2011).
Moreover, the effect of glyphosate on soil
texture may vary depending on specific soil
properties and management practices (Duke
& Powles, 2008). For example, glyphosate
application may alter soil particle
distribution, which can influence water
retention and infiltration capacity (Giesy et
al., 2000). In some cases, this may also
impact erosion dynamics, as less-structured
soil is more vulnerable to runoff losses
(Silva et al., 2018). Thus, while glyphosate
may offer agronomic benefits as an
herbicide, it is essential to carefully assess
its impact on soil physical characteristics.
Proper management of glyphosate
applications is crucial to minimizing
adverse effects on soil structure, ensuring
agricultural sustainability, and preserving
ecosystem health (Casabe et al., 2007).
CONCLUSION
This study revealed that glyphosate doses
differently influence soil granulometric and
physico-chemical characteristics.
Granulometry A showed significant
responses to glyphosate doses, indicating
that high doses can alter soil particle
distribution. In contrast, Granulometry Lf
and bulk density appear to be more
influenced by soil type and environmental
conditions rather than herbicide doses.
These results highlight the need for careful
management of glyphosate doses,
particularly in tropical regions like
N'Zérékoré, where soils are fragile and
subjected to intensive agricultural use.
Sustainable management practices,
including regulating herbicide doses and
paying close attention to soil types, could
contribute to the long-term preservation of
soil structure and fertility. Future research
could explore the long-term effects of
glyphosate accumulation in tropical soils
and examine other environmental factors,
such as organic matter management and the
impact of climate change on soil resilience
to chemical inputs. These studies would
support the development of sustainable
agricultural strategies that balance
productivity and soil health.
Declaration by Authors
Acknowledgement: None
Source of Funding: None

Paul Lamah et.al. Effect of different doses of glyphosate on soil physical parameters in the prefecture of
N'Zérékoré, Guinea
International Journal of Research and Review (ijrrjournal.com) 505
Volume 11; Issue: 11; November 2024
Conflict of Interest: The authors declare no
conflict of interest.
REFERENCES
1. Benbrook C. M. Trends in glyphosate
herbicide use in the United States and
globally. Environmental Sciences Europe
2016; 28(1), 1-15.
2. Casabé N, Piola L, Fuchs J, Oneto ML,
Pamparato L, Basack S, et al.
Ecotoxicological assessment of the effects
of glyphosate and chlorpyrifos in an
Argentine soya field. Journal of Soils and
Sediments, 2007; 232-239.
3. Cerdeira AL. Duke SO. The current status
and environmental impacts of glyphosate-
resistant crops: A review. Journal of
Environmental Quality, 2006; 35(5), 1633-
1658.
4. Duke SO, Powles SB. Glyphosate: A once-
in-a-century herbicide. Pest Management
Science, 2008; 64(4), 319-325.
5. Gee GW, Bauder JW. Particle-size analysis.
In Methods of soil analysis. Agronomy
Monographs, 1986; (pp. 383-411).
6. Giesy JP, Dobson S, Solomon KR.
Ecotoxicological risk assessment for
Roundup® herbicide. Reviews of
Environmental Contamination and
Toxicology, 2000; 167, 35-120.
7. Mertens M, Höss S, Neumann G, Afzal J,
Reichenbecher W. Glyphosate, a chelating
agent—relevant for ecological risk
assessment? Environmental Science and
Pollution Research, 2018; 25(6), 5298-5317.
8. Silva V, Montanarella L, Jones A,
Fernández-Ugalde O, Mol HGJ, Ritsema
CJ, Geissen V. Distribution of glyphosate
and aminomethylphosphonic acid (AMPA)
in agricultural topsoils of the European
Union. Science of the Total Environment,
2018; 621, 1352-1359.
9. Simonsen L, Fomsgaard IS, Svensmark B,
Spliid N.H. Fate and availability of
glyphosate and AMPA in agricultural soil.
Journal of Environmental Science and
Health Part B, 2008; 43(5), 365-375.
10. Zobiole LHS, Kremer RJ, Oliveira Jr, RS,
Constantin J. Glyphosate affects
chlorophyll, nodulation, and nutrient
accumulation of "second generation"
glyphosate-resistant soybean. Pesticide
Biochemistry and Physiology, 2011; 99(1),
53-60.
How to cite this article: Paul Lamah, Hamidou
Bah, Adoté Hervé Gildas Akueson, Gbadieu
Prosper Soumaoro, Diawadou Diallo. Effect of
different doses of glyphosate on soil physical
parameters in the prefecture of N'Zérékoré,
Guinea. International Journal of Research and
Review. 2024; 11(11): 496-505. DOI:
https://doi.org/10.52403/ijrr.20241150
******