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Arbuscular mycorrhizal fungal community structure and diversity in response to long-term fertilization: A field case from China


Abstract and Figures

The influences of different fertilizer treatments on spore community structure and diversity of arbuscular mycorrhizal (AM) fungi (AMF) were investigated in a long-term fertilization experiment with seven treatments: organic manure (OM), half organic manure N plus half fertilizer N (1/2 OMN), fertilizer NPK, fertilizer NP, fertilizer NK, fertilizer PK, and the control (without fertilization). Fertilization generally increased the nutrient contained in the fertilizer and treatments with NPK and 1/2 OMN produced the highest crop yields. Thirty-five species of AMF within 6 genera, including 8 previously undescribed species, were recovered. Similarly in all seven treatments, the most abundant genus was Glomus, and followed by Acaulospora. All the fertilization treatments changed AM species composition, and NK treatment had the slightest influence. Fertilization with fertilizers NP, PK and NPK markedly increased AM fungal spore density, while 1/2 OMN, OM and NK treatments showed no significant influences. All the fertilizer treatments, especially OM, significantly decreased species richness and species diversity (Shannon-Weiner index). There were no significant correlations between AM fungal parameters (spore density, species richness and species diversity) and soil properties. The findings indicate that long-term fertilization all can change AM fungal community structure and decrease species diversity, while balanced fertilization with NPK or 1/2 OMN is the most suitable fertilization regime if taking both crop yields and AM species diversity into account. KeywordsBiodiversity–Manure–Mineral fertilizer–Maize–Arbuscular mycorrhizae
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Arbuscular mycorrhizal fungal community structure
and diversity in response to long-term fertilization:
a field case from China
Fa Yuan Wang Jun Li Hu Xian Gui Lin
Sheng Wu Qin Jun Hua Wang
Received: 4 February 2010 / Accepted: 23 April 2010 / Published online: 9 May 2010
ÓSpringer Science+Business Media B.V. 2010
Abstract The influences of different fertilizer treatments
on spore community structure and diversity of arbuscular
mycorrhizal (AM) fungi (AMF) were investigated in a
long-term fertilization experiment with seven treatments:
organic manure (OM), half organic manure N plus half
fertilizer N (1/2 OMN), fertilizer NPK, fertilizer NP, fer-
tilizer NK, fertilizer PK, and the control (without fertil-
ization). Fertilization generally increased the nutrient
contained in the fertilizer and treatments with NPK and 1/2
OMN produced the highest crop yields. Thirty-five species
of AMF within 6 genera, including 8 previously unde-
scribed species, were recovered. Similarly in all seven
treatments, the most abundant genus was Glomus, and
followed by Acaulospora. All the fertilization treatments
changed AM species composition, and NK treatment had
the slightest influence. Fertilization with fertilizers NP, PK
and NPK markedly increased AM fungal spore density,
while 1/2 OMN, OM and NK treatments showed no sig-
nificant influences. All the fertilizer treatments, especially
OM, significantly decreased species richness and species
diversity (Shannon-Weiner index). There were no signifi-
cant correlations between AM fungal parameters (spore
density, species richness and species diversity) and soil
properties. The findings indicate that long-term fertilization
all can change AM fungal community structure and
decrease species diversity, while balanced fertilization with
NPK or 1/2 OMN is the most suitable fertilization regime if
taking both crop yields and AM species diversity into
Keywords Biodiversity Manure Mineral fertilizer
Maize Arbuscular mycorrhizae
It is well-known that arbuscular mycorrhizal (AM) fungi
(AMF) are beneficial to plant growth by increasing the
supply of immobile soil mineral nutrients, notably P (Smith
and Read 1997). However, AMF may not always play a
vital role in the nutrition and growth of plants in many
agricultural systems, especially in high-input agriculture
(Ryan and Graham 2002). Numerous reports have shown
the negative or positive influences of fertilizers on AMF
biodiversity, including readily soluble P and N, organic
manure, and slow release mineral fertilizers (Douds and
Millner 1999; Gosling et al. 2006; del Mar Alguacil et al.
2009). In most cases, readily soluble fertilizers have neg-
ative impacts on AM fungal diversity but organic manure
and slow release fertilizers do not suppress AMF and may
even stimulate them (Gosling et al. 2006). However, most
of these studies are based on short-term responses, which
may differ considerably from long-term responses to
different fertilizers.
Generally, long-term fertilization may have more
dramatic impacts on soil characteristics and microbial
community (Elfstrand et al. 2007; Omay et al. 1997). AM
fungal development and diversity are often decreased by
F. Y. Wang J. L. Hu X. G. Lin (&)S. W. Qin J. H. Wang
State Key Laboratory of Soil and Sustainable Agriculture,
Joint Open Laboratory of Soil and the Environment,
Hongkong Baptist University & Institute of Soil Science,
Chinese Academy of Sciences, East Beijing Road 71,
Nanjing 210008, People’s Republic of China
F. Y. Wang
Agricultural College, Henan University of Science
and Technology, Luoyang, Henan Province 471003,
People’s Republic of China
World J Microbiol Biotechnol (2011) 27:67–74
DOI 10.1007/s11274-010-0427-2
long-term fertilization with easily soluble mineral fertiliz-
ers or fertilizer combinations, such as P (Martensson and
Carlgren 1994), N (Bradley et al. 2006), NP (Na Bhadalung
et al. 2005), and NPK (Gryndler et al. 2006; Joner 2000).
However, long-term fertilization with manures often
showed positive effects on AMF (del Mar Alguacil et al.
2009; Gryndler et al. 2006). AM fungal parameters such as
colonization, spore abundance and species diversity, were
significantly higher in the organic than in the conventional
systems (Galvez et al. 2001;Ma
¨der et al. 2000; Oehl et al.
2003,2004). Sometimes, different results have been
reported on long-term fertilization impacts. High levels of
AM fungal colonization/diversity have also been reported
in soils with high available P or N (Gosling et al. 2006).
Only small differences were found in AM fungal com-
munities between the conventional or low-input practices
(Franke-Snyder et al. 2001; Kurle and Pfleger 1996). The
possible reasons may be because besides fertilizers the
factors influencing AMF are diverse in agricultural fields,
such as host plants, climatic conditions, environmental
stresses, and AM fungal characters, which certainly need to
be investigated further.
In China, because of the concern of soil fertility deg-
radation by replacement of organic fertilizers by inorganic
fertilizers, a long-term experiment was set up in the Huang-
Huai-Hai Plain, which is located in the low reaches of the
Yellow, Huai, and Hai rivers within an area of
3.5 910
(Qin et al. 1998). This is one of the most
important agricultural regions in China. Investigating long-
term effects of fertilization on AM fungal communities and
diversity may help to ensure an opportunity for the utili-
zation of AMF in agrosystems and understand the fertil-
ization impacts on soil microorganisms and soil health. In
2007, soil samples were taken from a long-term fertiliza-
tion site with seven different fertilizers or fertilizer com-
binations to analyse AM fungal community structure and
diversity using the classic spore morphology method. Our
aims were (1) to investigate the AM fungal community
structure and diversity in a wheat/maize field fertilized with
seven different fertilization regimes for 18 years, and (2) to
demonstrate the influences of long-term fertilization on
AMF community.
Materials and methods
Field site description
The long-term field fertilizer experiment was carried out in
the Fengqiu Agro-Ecological Experimental Station
(35°000N, 114°240E) of the Chinese Academy of Sciences,
Henan Province, China. The annual precipitation in the
area is 615 mm, 60–90% of which took place from May to
October. Mean temperature was 14.5 °C. The soil, with a
sandy loam texture, was derived from alluvial sediments of
the Yellow River and classified as aquic inceptisol. The
soil contained 5.83 g kg
of organic C, 0.45 g kg
total N, 0.50 g kg
of total P, 1.93 mg kg
available P,
78.8 mg kg
available K and 18.6 g kg
of total K and
had a pH (H
O) of 8.65 at the beginning of the experiment
in September 1989.
Fertilization treatments
Seven treatments (four replicates of each) were established
in completely randomized blocks in 28 plots (9.5 95m
under a rotation of winter wheat (Triticum aestivum L.) and
summer maize (Zea mays L.): organic manure (OM), half
organic manure N plus half mineral N fertilizer (1/2 OMN),
mineral NPK fertilizer (NPK), mineral NP fertilizer (NP),
mineral NK fertilizer (NK), mineral PK fertilizer (PK), and
the control (without fertilization). For NPK treatment, N, P,
and K were applied in the form of urea (300 kg N ha
year), super phosphate (150 kg P
per year), and
potassium sulfate (300 kg K
per year), respec-
tively, while no K, P, or N was applied for the NP, NK, and
PK treatments, respectively. The organic manure was a
composted mixture of wheat straw, oil cake, and cotton
cake in a ratio of 100:40:45. These materials were ground
to achieve lengths of 3–5 mm, mixed completely with
limited water, and composted for 2 months. The oil cakes
and cotton cakes were the machine-dried residues of oil-
harvested rapeseeds and cottonseeds, respectively. Detailed
information on the organic manure has been given before
(Meng et al. 2005). The OM and 1/2 OMN treatments were
designed to give the same application rates of N, P, and K
as those given with the NPK treatment. For the OM
treatment, N was applied as organic manure, while for the
1/2 OMN treatment, half of the N was applied as organic
manure and the other half as urea. Because the amounts of
P and K contained in the organic manure were generally
less than the prescribed doses, supplemental super phos-
phate and potassium sulfate were added to the OM and 1/2
OMN treatments to equal the amounts given in the NPK
treatment. Each plot had received the same fertilizer
management every year since 1989. Detailed information
on the experimental design and field management has been
described by Meng et al. (2005). Wheat and maize were
harvested after maturity and yields were recorded.
Soil samples and analysis
On March 26, 2007, soil samples were collected at a depth
of 0–15 cm in the wheat season. For each plot, soil samples
were collected from 16 points and then mixed and sieved
(\2 mm), with aboveground plant materials, roots, and
68 World J Microbiol Biotechnol (2011) 27:67–74
stones being removed. The soil samples were used for the
analysis of AM fungal spores and soil properties.
Soil pH was determined with a glass electrode using a
soil-to-water ratio of 1:2.5. Soil organic C and total N were
determined by dichromate oxidation (Mebius 1960) and
Kjeldahl digestion (Bremner 1965), respectively. Available
P in soil was extracted by sodium bicarbonate and deter-
mined using the molybdenum blue method (Olsen et al.
1954). Available K in soil was extracted by ammonium
acetate and determined by flame photometry (Carson
Recovery and counting of AM fungal spores
Spores or sporocarps were extracted from 25 g air-dried
soil for each sample by wet-sieving followed by flotation
centrifugation in 50% sucrose. The finest sieve was 30 lm.
The spores were collected on a grid patterned (4 94 mm)
filter paper, washed with distilled water to spread them
evenly over the entire grid and counted using a dissecting
microscope at up to 90-fold magnification. A sporocarp
was counted as one spore.
For observation and identification of spore characters,
spores were mounted on glass slides in polyvinyl-lacto-
glycerol (PVLG) and PVLG ?Melzer’s reagent and then
identified to species using taxonomic manuals (Schenck
and Perez 1990) and internet information from INVAM,
Glomeromycota species (
*schuessler/amphylo/), International Bank for the Glom-
eromycota (BEG) (, Arbus
cular mycorrhizal fungi (Glomeromycota), Endogone and
Complexipes species deposited in the Department of Plant
Pathology, University of Agriculture in Szczecin, Poland,
(*jblaszkowski/), and the
description of the newly reported AM fungal species. If the
species is not yet described, it may be recognized as an
unknown species, and marked as Glomus sp., Acaulospora
sp., etc.
AM fungal diversity
Species richness, spore density, frequency, and relative
abundance of AMF were expressed as follows: species
richness =number of AM fungal species in 25 g air-dried
soil; spore density =number of AM fungal spores in 25 g
air-dried soil; relative abundance =(number of spores of a
species or a genus/total spores) 9100%. Species diversity
was measured by the Shannon-Weiner index (H0=
-PPilnPi) and evenness (E=H0/H
) (Franke-Snyder
et al. 2001). Jaccard index (IS
=c/(a?b?c)) of simi-
larity, based on the morphological determination of spores
was calculated to compare AM fungal species composition
under different fertilization treatments. The IS
is a
measure of the similarity of the spore community between
sites A and B, where ais the number of species occurring
only at site A, bis the number of species occurring only at
site B and cis the number of species occurring at both sites.
Statistical analysis
Analysis of variance (ANOVA), hierarchical cluster anal-
ysis and correlation analysis were all carried out with SPSS
software package (version 13.0). Significance of differ-
ences between treatments with respect to soil properties,
spore abundance, species numbers and AM fungal diversity
(Shannon-Weiner index and evenness) was tested using
Duncan’s multiple range test at P\0.05 after one-way
ANOVA. A hierarchical cluster analysis using complete
linkage (furthest neighbor) method was applied to deter-
mine the similarity with respect to AM fungal species
composition between treatments. Spearman-rank correla-
tion coefficients were calculated to evaluate the strength of
the relationship between soil properties and AM fungal
species richness, diversity, as well as the Jaccard index of
similarity between the control and other fertilization
Soil pH and nutrient contents
Compared with the soil properties at the beginning of the
experiment, after 17 years, soil total N, organic C and
available P decreased in the control treatment, while fer-
tilization generally increased the nutrient contained in the
fertilizer (Table 1). Compared with the control, soil pH did
not change in NK and PK treatments but slightly declined
in other fertilizer treatments, with the lowest value in OM
treatment. Soil organic C did not change in NK and PK
treatments, but significantly increased in other treatments,
especially in OM treatment. Soil total N was significantly
increased by all the fertilizers, especially by the application
of organic manure. Available P was increased by all the
fertilizer treatments except NK. Available K slightly
decreased in NP treatment but greatly increased in other
Crop yields
Dynamics of winter wheat and summer maize yields are
shown in Fig. 1. Because of a flood in July 2000, maize
yields in all the treatments were lost. Generally, both wheat
and maize yields were significantly higher in NPK and 1/2
OMN than those in other treatments, with few exceptions.
World J Microbiol Biotechnol (2011) 27:67–74 69
On average over 17 years, both winter wheat and maize
yields were the highest for the NPK and 1/2 OMN treat-
ment, following an order of NPK C1/2 OMN [NP [
OM [PK [NK =Control.
AMF fungal species composition and similarity
A total of 35 species of AMF within 6 genera of Glom-
eromycota, including 8 previously undescribed species,
were recorded (Table 2). The most abundant genus was
Glomus (24 species), accounting for 79.83–87.38% of
spore counts, and then the genus Acaulospora (7 species),
accounting for 6.56–12.16%. Only 1 species was
found in Ambispora,Archaeospora,Gigaspora and
Scutellospora, respectively. Thirteen species were found in
all the fertilization treatments, among which, the most
abundant species was Glomus claroideum, followed
orderly by G. caledonium,G. mosseae,G. fasciculatum,
G. geosporum,G. intraradices,G. versiforme,Ambispora
lepototicha, A. bireticulata,A. laevis. Three previously
undescribed species (G. sp.1,G. sp.2,A. sp.1) also occurred
frequently in all the fertilization treatments.
Table 3showed that Jaccard index of similarity was
from 0.500 to 0.762. Considering the control treatment, the
highest Jaccard index value was between the control and
NK, which shared 19 AM fungal species, while both 1/2
OMN and OM treatments had the largest differences in
species composition with the control.
Cluster analysis based on the similarity in AM fungal
species composition among different treatments is shown
in Fig. 2. Taking the index of similarity of 0.6 as a base-
line, AM fungal communities may be grouped in three
main clusters. AM fungal species composition had higher
similarities within the groups than between groups.
Spearman correlation coefficients showed that the sim-
ilarities (IS
) of AM fungal species composition between
the control and other fertilization treatments positively
correlated with soil pH (r=0.883, P\0.01), but nega-
tively correlated with soil organic C (r=-0.811,
P\0.05), total N (r=-0.847, P\0.05) and available P
(r=-0.883, P\0.01), and did not significantly correlate
with available K.
AM fungal species richness and species diversity
Compared with the control, spore density markedly
increased in NP, PK and NPK treatments, but did not
change significantly in other treatments (Table 4). Species
richness decreased in all the fertilizer treatments, especially
in OM treatment. However, when considering the total
number of AM fungal species contained in the four repli-
cate plots for each treatment, the species numbers
decreased in the order: Control [NPK [NP [NK [
Table 1 The soil properties after the long-term fertilization
Treatment pH Organic C (g kg
) Total N (g kg
) Available P (mg kg
) Available K (mg kg
Control 8.76 (0.04) c 4.45 (0.25) a 0.37 (0.00) a 0.23 (0.01) a 90.55 (5.84) b
1/2 OMN 8.38 (0.07) b 8.36 (0.83) c 0.74 (0.00) f 17.29 (1.25) c 234.66 (9.63) c
OM 8.12 (0.08) a 10.59 (0.63) d 1.00 (0.03) g 20.96 (3.44) d 229.56 (12.88) c
NP 8.44 (0.08) b 5.76 (0.37) b 0.54 (0.01) d 12.60 (0.79) b 74.61 (3.83) a
NK 8.69 (0.07) c 4.38 (0.61) a 0.41 (0.01) b 0.53 (0.13) a 395.35 (8.84) e
PK 8.65 (0.10) c 4.74 (0.75) a 0.45 (0.02) c 27.89 (2.48) e 348.17 (4.42) d
NPK 8.45 (0.02) b 6.35 (0.36) b 0.57 (0.02) e 12.52 (0.35) b 221.91 (10.12) c
Data are means and SD (n=4). The difference between values in a column followed by different letters is significant at P\0.05
Wheat yield (kg ha-1)
1990 1994 1998 2002 2006
1990 1994 1998 2002 2006
Maize yield (kg ha-1)
Fig. 1 Dynamics of wheat (a) and maize (b) yields in the long-term
experiment from 1990 to 2006
70 World J Microbiol Biotechnol (2011) 27:67–74
PK [1/2 OMN =OM. Diversity expressed by Shannon-
Weiner index decreased in the following order: Control [
NPK C1/2 OMN =PK CNK [OM =NP. Compared
with the control, evenness was lower in NP treatment, but
higher in other treatments.
Correlation between soil properties and AM fungal
Spearman correlation analysis showed that no significant
correlations were found between AM fungal spore density,
Table 2 AMF species composition and relative abundance in long-term fertilization treatments
Acaulospora (7 species)
A. bireticulata 0.99 a 4.67 b 3.62 b 3.53 b 4.47 b 4.41 b 3.76 b
A. delicata 1.13
A. laevis 3.25 b 3.29 b 1.83 a 2.39 ab 3.21 b 2.40 ab 3.10 b
A. scrobiculata 0.47 a 0.91 a
A. sp.1
3.09 b 3.08 b 1.11 a 1.32 a 2.76 b 1.84 ab 2.96 b
A. sp.2
2.50 b 0.54 a 0.45 a 0.54 a 0.81 a 1.50 ab
A. sp.3
Ambispora (1 species)
Am.lepototicha 3.84 a 4.35 a 3.49 a 3.41a 4.29 a 4.13 a 3.24 a
Archaeospora (1 species)
Ar. trappei 0.91 a 4.25 b 1.43 a 1.70 a 2.29 ab 4.27 b
Gigaspora (1 species)
Gi. decipiens 0.40
Glomus (24 species)
G. caledonium 9.22 a 9.83 ab 14.96 b 13.59 ab 14.97 b 13.02 ab 12.68 ab
G. claroideum 24.94 a 26.42 a 32.03 b 35.48 b 23.81 a 22.81 a 20.51 a
G. clarum 2.08 b 0.41 a 1.72 b
G. constrictum 3.09 b 1.99 ab 0.43 a 0.51 a 0.86 a 1.25 a
G. deserticola 2.50 b 0.74 a 2.10 b
G. diaphanum 0.32
G. etunicatum 1.55 b 0.15 a
G. fasciculatum 5.14 a 6.49 ab 6.95 ab 6.65 ab 7.61 b 8.75 b 8.25 b
G. geosporum 4.23 a 5.64 a 5.17 a 4.63 a 5.65 a 5.97 a 6.08 a
G. intraradices 4.82 abc 5.86 bc 5.98 bc 2.18 a 4.55 abc 7.90 c 3.15 ab
G. marcocarpum 0.43
G. melanosporum 2.42 b 0.46 a 0.48 a 1.40 ab
G. mosseae 5.80 a 8.64 b 8.24 ab 7.21 ab 9.80 b 9.47 b 9.05 b
G. pallidum 0.89
G. pulvinatum 1.93 a 1.18 a 1.34 a 0.99 a 1.24 a
G. pustulatum 0.53
G. reticulatum 2.92 c 0.83 a 1.48 ab 0.49 a 2.16 b
G. sp.1
3.87 b 3.50 b 2.22 a 2.87 ab 3.82 b 3.21 ab 3.60 b
G. sp.2
2.66 a 2.56 a 1.94 a 2.79 a 3.30 a 2.43 a 2.49 a
G. sp.3
2.34 b 0.62 a 1.56 ab 1.71 ab 1.51 ab 0.40 a
G. sp.4
0.50 a 1.01 a 0.89 a 0.53 a
G. sp.5
0.41 a 0.47 a 0.32 a
G. versiforme 4.10 a 5.10 ab 4.06 a 4.17 a 4.56ab 4.97 ab 5.50 b
G. vesiculiferum 1.61 b 0.36 a
Scutellospora (1 species)
Scu. gregaria 0.34 a 1.13 b 1.32 b 1.47 b
not found in this treatment. * undescribed species. Data represent the means of four replicates. The difference between values in a row followed
by different letters is significant at P\0.05
World J Microbiol Biotechnol (2011) 27:67–74 71
species richness, species diversity and soil properties,
including pH, organic C, total N, available P and available
AMF occurs widely in agroecosystems (Douds and Millner
1999). A total of 35 AM fungal species were found in the
present trial, considerably higher than the 20–22 species
from other arable lands in China (Gai et al. 2004; Wang
et al. 2008), and also higher than 9–16 species from other
long-term fertilization field trials (Franke-Snyder et al.
2001; Na Bhadalung et al. 2005). Our results are consistent
with a long-term field trial by Oehl et al. (2004) who found
diverse AM fungal species in arable lands.
Glomus is generally the genus with the greatest number
of species found in intensively managed agriculture
(Hamel et al. 1994; Sieverding 1990). Similarly, in our
trial, Glomus dominated in all the fertilization treatments,
which agrees with most studies carried out in arable lands
of China and elsewhere (Gai et al. 2004; Oehl et al. 2003,
2004,2005; Wang et al. 2008). AMF of this genus survive
and propagate more easily because of the high sporulation
rate and the ability to colonize via pieces of mycelium or
mycorrhizal root fragments (Daniell et al. 2001). These
attributes might explain why Glomus species are more
suitable to the changed soil conditions as influenced by
long-term fertilization in this field trial.
In our present study, although AM fungal species
composition changed in the different fertilization treat-
ments, the 13 dominant species were present in all the
treatments. This indicates that the long-term fertilization
treatments maybe did not play such an important role as
expected in the selection of AMF. In this aspect, our results
are in accordance with Franke-Snyder et al. (2001), who
found 15 consecutive years of farming under one conven-
tional and two low-input farming systems did not cause
many differences among AM fungal communities. The
results also showed that NK treatment had the highest
similarity in AM fungal species with the control (Table 3
and Fig. 2), indicating that this fertilization regime is
efficient in maintaining AM fungal structure. This may be
due to the similar soil properties (such as pH, organic C,
available P) between this treatment and the control.
Furthermore, this also partly reflects the significantly
negative effects of soil available P, organic C and total N
on AM fungal species composition. The effects of fertil-
izers, especially combined fertilizers, on AM fungal spor-
ulation are probably variable and need further precise
research in future.
Previous studies (Martensso and Carlgren 1994; Na
Bhadalung et al. 2005) have shown the negative effects of
mineral fertilizer (P, NP) on AM fungal spore number
result from high P concentrations in plant tissue reducing
soluble carbohydrate supply for root exudates, which AMF
require for energy (Sieverding 1990). However, the
response of AMF to available P is variable (Jasper et al.
Table 3 Jaccard index of similarity between the different treatments
Treatments Control 1/2 OMN OM NP NK PK
1/2 OMN 0.552
OM 0.552 0.714
NP 0.633 0.600 0.739
NK 0.679 0.652 0.520 0.500
PK 0.586 0.682 0.762 0.708 0.560
NPK 0.667 0.708 0.640 0.552 0.593 0.680
Fig. 2 Dendrograms of cluster analysis based on the similarity of AMF
species composition
Table 4 AMF spore density, species richness and diversity in the different fertilization treatments
AMF species Control 1/2 OMN OM NP NK PK NPK
Spore density (average of AMF spore number in 25 g
soil of four filed plot replicates)
269 ab 235 ab 216 a 380 d 295 bc 360 cd 399 d
Species richness (average number of AMF species found
in four field plot replicates)
22.8 c 16.3 ab 15.3 a 16.8 ab 16.0 ab 17.0 ab 18.8 b
Total number of AMF species found at the field sites
(sum of four field plot replicates)
27 18 18 22 20 19 23
Shannon-Weiner index (H’) 2.77 d 2.51 bc 2.29 a 2.29 a 2.48 b 2.51 bc 2.62 c
Evenness (E) 0.95 0.99 0.97 0.94 0.99 0.97 0.97
The difference between values in a row followed by different letters is significant at P\0.05
72 World J Microbiol Biotechnol (2011) 27:67–74
1989), and the application of P can influence spore pro-
duction either positively or negatively (Neumann and
George 2004; Subramanian et al. 2006). Our present results
showed that AM fungal spore density was not decreased
but instead increased by NP, PK, NPK containing high P,
and not changed by OM, 1/2 OMN and NK. This may be
due to the complicated interactions among the nutrients,
soil conditions, plant growth status and AMF themselves.
Firstly, other nutrients such as N, K may offset (Guttay
1983; Hayman and Mosse 1972; Hepper 1983) or enhance
(Guttay and Dandurand 1989) the negative effects of high
available P on AM fungi. Secondly, fertilization causes
changes in soil properties (Table 1), which may influence
mycorrhiza formation directly or interact with other factors
(Neumann and George 2004). Thirdly, plant growth dif-
fered in different fertilization treatments (Fig. 1), which
must have influenced the C supply to AMF associated with
them. Additionally, the different sensitivity of AMF to
available P and other nutrients may also affect spore den-
sity under long-term fertilization. Obviously, long-term
fertilization effects on AM fungal spore density may be
diverse and vary with many factors.
In contrast with the conclusions that AM fungal species
richness and diversity are generally negatively influenced
by soluble mineral fertilizers, but positively influenced by
organic manure (Gryndler et al. 2006;Ma
¨der et al. 2000;
Oehl et al. 2003,2004), our results showed that both spe-
cies richness and species diversity were significantly
decreased by all the fertilizer treatments (Table 4), espe-
cially by organic manure. AM fungal sporulation would be
reduced under any adverse soil conditions (Entry et al.
2002), including extremely low as well as high soil fertil-
ity, and nutrient supply imbalance, especially high or low
levels of N and P, extreme pH, etc. On the other hand,
different AM fungal species may show different responses
to fertilization and other soil conditions. Long-term fertil-
ization in this trial greatly increased soil fertility and
changed soil pH, which may play an important role in the
selection of AM fungal species (Johnson 1993). Thus, the
populations of sensitive AMF to soil fertility and pH might
have been decreased or eliminated, accompanying
increased relative abundance of the tolerant species, and
thus leading to decreased species richness, species even-
ness and species diversity.
Besides, overuse of organic manure high in nutrients
may impact negatively on AMF (Gosling et al. 2006). In
this study, organic manure changed some soil properties
more drastically than did mineral fertilizers, so it is easily
understandable that it would have more negative effects on
AM fungal species richness and diversity.
In conclusion, both mineral fertilizers and organic
manure significantly decreased AM species richness and
species diversity. However, fertilization with mineral
fertilizers is necessary for optimum crop yields in China.
We also found fertilization with NPK and 1/2 OMN pro-
duced the highest crop yields (Fig. 1). Considering both the
production of crops and the protection of AM fungal
diversity, balanced fertilization with NPK and 1/2 OMN
may be feasible in this agricultural region. Additionally, as
both wheat and maize are mycorrhizal plants, the role of
AMF in crop production needs more attention and the useful
AM species need to be exploited and manipulated in future.
Acknowledgments We thank Jia Bao Zhang, Lin Yun Zhou, Qi Ao
Jiang and Jian Liu, of the Fengqiu Agro-Ecological Experimental
Station, Institute of Soil Science, Chinese Academy of Sciences, for
their excellent field management and kind support on soil sample
collection. This work is supported by the Knowledge Innovation
Program of the Chinese Academy of Sciences (Grant No. ISSA-
SIP0703, Kzcx2-yw-408, Kscx1-yw-09-05) and National Basic
Research Program of China (Project no. 2005CB121108).
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... For example, in cropping conditions where organic manure is a major nutrient source and where mineralization rates are high and soil pH is low, such as in the tropics, total N may play a more important role in shifting AMF community composition than available P (Jemo et al. 2018;Liu et al. 2012). Moreover, under high soil fertility plant nutrient uptake may occur directly through root hairs without allocation of assimilates to their symbiont, resulting in lower AMF richness and diversity (Qin et al. 2020;Van Geel et al. 2015;Wang et al. 2011). Consequently, low AMF richness and diversity may provide limited symbiotic services to the host plants, mainly attributed to decreased functional complementarity of AMF species (Jansa et al. 2008;Powell and Rillig 2018). ...
... This divergence may be due to the organic amendment type, application intensity and the environmental conditions mediating the accumulation of soil organic carbon , which all contribute to soil nutrient accumulation. For example, a high dose of organic manure increases available P and total N in the soil, more so than the application of synthetic fertilizers equivalent to the same amount of NPK (Wang et al. 2011). Moreover, some studies report no difference in AMF richness and diversity between organically and conventionally managed farms (Van Geel et al. 2017). ...
... This suggests that strong nutrient enrichment through organic amendments may be equally important in limiting AMF richness and diversity. Therefore, a balanced organic manure application in agroecosystems may enhance AMF richness and diversity (Wang et al. 2011). We revealed a diverse AMF community associated with enset roots, composed of 149 OTUs from seven families, among which the Glomeraceae was by far the most dominant, followed by the Claroideoglomeraceae, and the least represented were Pacisporaceae. ...
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Aims In low-input agricultural systems, arbuscular mycorrhizal fungi (AMF) play a role in plant nutrition, protection and water use. Evaluating how agricultural practices affect the composition of AMF communities is therefore an important step towards sustainable intensification. We characterized the AMF communities in enset (Ensete ventricosum) roots in smallholder enset-based farming systems in south Ethiopia and assessed the effects of soil fertility management on those communities. Methods We assessed AMF diversity and community composition in the roots of 181 enset plants from 23 farms by Illumina MiSeq amplicon sequencing. Roots were collected from intensively manured parts of the farms (regular manure application), and from less manured parts of the farms (occasional manure application). Results AMF communities in both intensively and less manured parts of the farms were comprised primarily by species belonging to Glomeraceae, which accounted for 67% of the total operational taxonomic units recorded. However, unlike Glomeraceae, majority of Acaulosporaceae sequences were recovered from less manured parts of the farms. Intensively manured parts of the farms were associated with higher soil pH, available P, organic carbon, total N and C:N ratio, and with significantly lower AMF richness and diversity. Moreover, unexpectedly organic carbon and total N explained a large part of the variation in AMF community composition compared with available P. Conclusions Intensive manure applications enhance soil nutrient availability and soil organic carbon but result in lower AMF richness and diversity, and in a shift in AMF community composition. This may promote less mutualistic AMF community.
... Furthermore and Johnson (1993) showed that increased inorganic fertilizer application would reduce AM sporulation and reduce AM community structure. Given the above evidences Wang et al. (2011) varied the combination of NPK together with other nutrient sources in their investigation to ascertain their efficacy on AM spore density and their species composition. Their investigation concluded that balanced NPK could be desirable for good yield and AM specie composition. ...
... The observed changes in the community structure under NPK amendment could be associated with the specie richness and evenness compared to that of soil that was not amended in this study. Wang et al. (2011) reported that application of inorganic soil amendments in China resulted in a significant decrease in specie richness and diversity of AMF. Liu et al. (2009) further indicated that changes in community structure of AMF in their study were dependent on host phenology, edaphic factors and the habitat of host. ...
... This position conforms to the position of Jansa et al. (2003) where he posited that effect of changes in the community structure of AMF on maize performance could not be explicated. However, Wang et al. (2011) opined that a balanced NPK is good if crop yield and together with species diversity is considered. However this was not confirmed in our own study, since it was only the performance of maize that was observed without NS -not significant, LSD -least significant difference, WAP -weeks after planting, * -significant at 5% probability level, ** -significant at 1% probability level, NPK fertilizer (120 kg N/ha+ 60 kg P 2 O 5 /ha + 60 kg K 2 O/ha) a corresponding improvement in species diversity. ...
... This is because the use of optimum P-based fertilizers in crop cultivation increase P availability for plant uptake reducing the need to establish association with AMF, hence suppressing root colonization and spore production (Sharma et al., 2013). While some AMF species may be suppressed in soils receiving fertilization, others like Ambispora are reported to be stimulated in such soils (Wang et al., 2011), which was what was found in this study where the genus was found only in potato fields receiving mineral fertilizers. Grazed pastures likewise exhibited high spore abundance, richness and diversity which could be attributed to soil disturbance through animal trampling which cause AMF to produce spores in response to stress. ...
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p> Background: Forest conversion to other land use types lead to changes in soil physico-chemical properties and a reduction in soil fertility. Although forest conversion is extensively recognized to alter soil properties, the influence on distribution of soil phosphorus (P) fractions and abundance and diversity of soil biota is not well explored. Objective: To assess the effects of converting undisturbed natural forest to plantation forest (cypress), grazed pastures and potato fields on soil phosphorus (P) fractions and abundance and diversity of arbuscular mycorrhizal fungi (AMF) in Nyandarua County, Kenya. Methodology: Transects laid out in triplicate were established in each land use type. In potato fields and grazed pastures, transects measured 50 m with three sampling points established 15 m apart along each transect, each point measuring 1 m² divided into 25 grids with each grid being 400 cm². Transect length was increased to 150 m in forest sites due to relatively larger size of the area studied and sampling points were placed at 50 m apart, each point measuring 25 m² and divided into 1² m grids. Soil and plant samples were randomly collected from sampling points and were used to determine chemical properties, soil P fractions and AMF spore examination. Data were analyzed by analysis of variance (ANOVA). Results: Soil chemical properties were significantly ( p <0.001) higher in natural forest compared to potato fields, grazed pasture and cypress forest. On the contrary, readily labile and moderately labile P was higher in fields cultivated with potato (125.3 mg and 258.2 mg P kg<sup>-1</sup>, respectively) than in natural forest (51.1 mg and 95.3 mg P kg<sup>-1</sup>) and cypress forest (36.4 mg and 82.7 mg P kg<sup>-1</sup>, respectively). However, non-labile P was higher in natural forest (599.1 mg P kg<sup>-1</sup>) and lower in cypress forest (251.3 mg kg<sup>-1</sup>). Of the ten AMF genera identified, only Glomus and Acaulospora were significantly ( p <0.01) affected by land use change, where they were more abundant in fields cultivated with potato than the other three land use types. Land use type did not significantly influence diversity and richness in AMF. However, AMF composition varied across the land use types. Implication: Land use change may negatively affect soil chemical properties, enhance redistribution of soil P, and change AMF community composition, and this could have long-term implications on soil fertility. Conclusion: Land use change from natural ecosystems to croplands, grazed pastures and tree plantations alter soil chemical properties, AMF composition and spore abundance, and redistribute soil P fractions by increasing labile P and reducing non-labile P fractions showing that the type of land use chosen significantly influence soil physical and chemical properties and soil biodiversity.</p
... The particular increase in Mortierellomycota under the P2 treatment could be attributed to the fact that high P input results in higher plant and root biomass, which maintains nutrition and energy supply through parasitic or symbiotic ways [55,56]. Additionally, rare studies report the rhizosphere fungal community change, while most studies focus on the effect of fertilization on AM fungal communities [57][58][59]. In the present study, we found that the number of identified AM fungal species and the relative abundance of Glomeromycota decreased with the P input rate, indicating that AM fungal diversity was negatively correlated with the P input rate [58]. ...
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Microbes play an important role in rhizosphere phosphorus (P) activation and root P absorption in low P-available soils. However, the responses of the rhizosphere microbial community to P input and its effects on P uptake by tea plants have not been widely reported. In this study, the high-throughput sequencing of the 16S rRNA gene and the ITS2 region was employed to examine the responses of tea rhizosphere microbiomes to different P input rates (low-P, P0: 0 mg·kg−1 P; moderate-P, P1: 87.3 mg·kg−1 P; high-P, P2: 436.5 mg·kg−1 P). The results showed that the P input treatments significantly reduced the soil C: N ratio and C: P ratio compared to the P0 treatment (p < 0.05). Moreover, the P2 treatment significantly increased the soil available P, plant biomass and P content of the tea plant compared to the P0 and P1 treatments (p < 0.05). Both bacterial and fungal communities revealed the highest values of alpha diversity indices in the P1 treatment and the lowest in the P2 treatment. The dominant phyla of the bacterial community were Proteobacteria, Actinobacteria and Acidobacteria, while in the fungal community they were Ascomycota and Mortierellomycota. In addition, P input enriched the relative abundance of Actinobacteria and Proteobacteria but decreased the relative abundance of Acidobacteria. The Mantel correlation analysis showed that the fungal community was influenced by P input, whereas bacterial community was affected by the soil TC and C: N ratio. Furthermore, the P input treatments enhanced the TCA cycle, amino and nucleotide glucose metabolism, starch and sucrose metabolism, and phosphotransferase system expression, which could promote C and N cycling. On the contrary, the P input treatments negatively affected the growth of arbuscular mycorrhizal fungi. The PLS-PM model revealed that the rhizosphere bacterial and fungal communities, respectively, negatively and positively affected the P content by affecting the biomass. Meanwhile, rhizosphere microbial function profiles affected the P content of tea plants directly and positively. In summary, moderate P input favors the rhizosphere microbial diversity and functions in the short-term pot experiment. Therefore, we suggest that moderate P input should be recommended in practical tea production, and a further field test is required.
... In contrast, Gryndler et al. (2008) found that compost added to clay substrate had a strong negative effect on AM fungi and almost eliminated mycorrhizal colonization of plant roots. Furthermore, numerous studies have shown that the soil AMF assemblages are negatively affected by balanced fertilization (i.e., NPK fertilizer) (Mäder et al. 2000;Wang et al. 2011). These results may have occurred because host plants in fertile soils do not need AMF partners to assist them with The Mantel tests were conducted based on 9999 permutations between AM fungal community structure (Bray-Curtis distance) and soil variables (Euclidean distance). ...
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The application of biochar-based fertilizer can improve soil properties in part by stimulating microbial activity and growth. Karst ecosystems, which make up large areas of Southwest China, are prone to degradation. Understanding the response of arbuscular mycorrhizal fungal (AMF) community structure to biochar-based fertilizer application is of great significance to karst soil restoration. A field experiment was conducted in a typical karst soil (calcareous sandy loam) in Southwest China. A high-throughput sequencing approach was used to investigate the effect of biochar-based fertilization on AMF community structure in the karst soil. With the control (CK), compost with NPK fertilizer (MF), biochar (B), a lower amount of biochar with compost and NPK fertilizer (B1MF), biochar with compost and NPK fertilizer (BMF), and a higher amount of biochar with compost and NPK fertilizer (B4MF), the field trials were set up for 24 months. Soil amendments increased soil nutrient content and AMF diversity. The composition and structure of the AMF community varied among the treatments. AMF community composition was significantly impacted by soil chemical properties such as TC (total carbon), TN (total nitrogen), TP (total phosphorus), and AP (available phosphorus). Furthermore, network analysis showed that biochar-based fertilization increased the scale and complexity of the microbial co-occurrence network. Biochar-based fertilization enabled more keystone species (such as order Diversisporales and Glomerales) in the soil AMF network to participate in soil carbon resource management and soil nutrient cycling, indicating that biochar-based fertilizer is beneficial for the restoration of degraded karst soils.
... Earlier observations showed that the presence of essential elements is connected with composition of AMF community structure (Casazza et al., 2017). Simultaneously, pH may be linked with the vertical distribution (Liu et al., 2019) and selection (Johnson, 1993) of AMF species, which may be related in turn to the decline or elimination of some AMF species and the simultaneously increasing abundance of others, leading to disturbances in species evenness, richness, and diversity (Wang et al., 2011). ...
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Despite the presence of arbuscular mycorrhizal fungi (AMF) in temperate forests, knowledge concerning their diversity and interactions with plants is still insufficient. Therefore, we studied the impact of overstorey species identity on AMF abundance and species richness and composition in relation to herbaceous plant cover and soil chemical properties. The effects of 14 tree species grown for 48 years in monospecific plots in the Siemianice Experimental Forest (western Poland) were compared, including the following groupings: deciduous vs coniferous; native to Poland/Europe vs alien; forming vs not forming arbuscular mycorrhizas (AM). Coniferous tree plots were characterised by lower pH values, plots with deciduous trees by higher concentrations of total Ca and exchangeable forms of Ca, K and Mg. AMF abundance in soils and roots increased along with increasing soil alkalinity and macronutrient levels. Concentrations of the PLFA 16:1ω5 AMF hyphal biomass marker were higher in the soils of deciduous and AM-type tree species than those of coniferous and non-AM types. In addition, concentrations of the NLFA 16:1ω5 AMF spore biomass marker were higher in the soils of deciduous tree species. No significant differences were found between groups of native and alien tree species. AMF spore and species numbers were low in comparison to other unforested ecosystems, averaging 77.5 and 1.2 per 50 g of soils, respectively. The presence of 8 AMF species, both widespread (e.g. Funneliformis constrictus) and rare (Acaulospora cavernata) was revealed. Significant divergence in AMF species composition was noted between plots of deciduous and coniferous species. Our study showed that tree species identity, considered as a single factor, has only a slight impact on determining AMF community characteristics. The disparity between AMF community characteristics results from the effects of several factors, as pH and element concentrations in soils, acting within tree species groups.
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CONTEXT: Agricultural intensification contributes to global food security and well-being by supplying the food demand of a growing human population. However, ongoing land-use change and intensification seriously affect the abundance, diversity and distribution of species, besides many other impacts, thereby threatening the functioning of ecosystems worldwide. Despite the accumulating evidence that the current agricultural model is unsustainable, we are far from understanding the consequences of functional diversity loss for functioning and ecosystem service supply and the potential long-term threats to food security and human well-being. OBJECTIVE: In this review, we propose a conceptual framework to understand the relationships between functional diversity and human well-being that also considers agroecosystem health. To this end, we identify the most commonly assumed relationships linking functional diversity to regulating and provisioning agroecosystem services and their importance for human well-being, emphasising the most serious knowledge gaps in the individual pathways of the conceptual framework. METHODS: A consortium formed by an international panel of experts from different disciplines including functional diversity, ecosystem services and human health compiled 275 articles. Members of the consortium proposed literature to exemplify each specific aspect of the conceptual framework in the text, in accordance with his/her field of expertise. The guideline for all experts was to focus mostly in current literature (38% of the references are from the last 5 years and 66% from the last decade), with special interest in reviews and synthesis articles (42% of the references), as well as meta-analyses and global studies (10% of the references). RESULTS AND CONCLUSIONS: The factors that influence agroecosystem health are extremely complex, involving both services and disservices related to land-use management and environmental conditions. The global human population needs sustainable and resilient agroecosystems and a concerted effort is needed to fundamentally redesign agricultural practices to feed the growing human population without further jeopardising the quality of life for future generations. We highlight the potential effects of land-use change and ecological intensification on the functional diversity of plant and animal communities, and the resulting consequences for ecosystem services and ultimately human health. SIGNIFICANCE: The resulting conceptual model is developed for researchers as well as policy makers highlighting the need for a holistic approach to understand diversity impacts on human well-being. Finally, we document a major knowledge gap due to the lack of any studies focusing on the full pathway from diversity to human well-being.
We examined the effects of nitrate nitrogen fertilizer (N), biochar (BC) and arbuscular mycorrhizal fungi (AMF) on Trifolium pratense mycorrhizal colonization, dry mass, nutrient and pollutant accumulation and soil AMF community, aiming to determine a potential approach that is beneficial to clover growth and AMF community under contaminated environment. Result showed that soil pH increased from 6.88 to 7.01 in the presence of N in combination BC treatments. Compared to control, N in combination BC treatments significantly decreased DTPA-Zn, Pb, Cd, As and Cu concentrations, and the average reduction for DTPA-Zn, Pb, Cd, As and Cu concentration by 53.2, 52.5, 48.8, 44.5 and 45.5%, respectively. Root colonization, shoot and root dry masses were increased when receiving both N and BC. On average, the shoot P, Zn, Pb, Cd and As levels were reduced by 39.7, 62.4, 86.7, 84.6 and 87.8% when receiving both N and BC and simultaneously the root Cd and Zn concentrations were reduced by 64.9 and 55.8%, respectively. DTPA-extractable Cd, Zn and Pb were positively correlated to shoot Zn, Pb and Cd concentrations as well as root Zn and Cd concentrations but negatively correlated with pH. Moreover, Glomus species were the soil major AMF present with all treatments. The combination N and BC treatments increased Glomus abundance but did not affect overall AMF diversity. Soil pH, DTPA-Cd, Zn, Pb and Cu had greater effect on AMF community structure as assessed by redundancy analysis (RDA). Glomus abundance was positively related to pH, root colonization, shoot and root dry mass and negatively related to DTPA-Cd, Zn, Pb and Cu. A network analysis indicated that BC and N addition promoted synergistic interactions among Glomus species. Our results demonstrated that the N in combination BC treatments can promote plant growth while decreasing pollutant accumulation in shoot and root, and the N and BC addition can increase Glomus abundance and their synergistic interactions under multi-contaminated soil.
In view of the improper use of chemical fertilizers in sustainable agricultural practices, a pot as well as a field experiment were carried out to evaluate the effect of Glomus mosseae (biofertilizer), sole Nitrogen + Phosphorus + Potassium (NPK) a chemical fertilizer, and the combination of Glomus mosseae + NPK on total growth and yield of groundnut (Arachis hypogaea L.). A significant difference was observed between Glomus mosseae, sole NPK and combination of Glomus mosseae + NPK with respect to the control in the pot as well as field trails. Application of bio-fertilizer in form of Glomus mosseae was more effective in its role of enhancing physiological, biochemical, essential nutrient levels and total crop yield of groundnut as compared to chemical fertilizer used in form of NPK and the combination of Glomus mosseae +NPK. Our study signifies the use of Glomus mosseae as a cost-effective, eco- friendly biofertilizer, which may reduce the amount of excessive use of chemical fertilizer needed for groundnut production and sustainable agricultural practices.
Microorganisms are vital to the overall ecosystem functioning, stability, and sustainability. Soil fertility and health depend on chemical composition and also on the qualitative and quantitative nature of microorganisms inhabiting it. Historically, denaturing gradient gel electrophoresis (DGGE) and temperature gradient gel electrophoresis (TGGE), single-strand conformation polymorphism, DNA amplification fingerprinting, amplified ribosomal DNA restriction analysis, terminal restriction fragment length polymorphism, length heterogeneity PCR, and ribosomal intergenic spacer analysis were used to assess soil microbial community structure (SMCS), abundance, and diversity. However, these methods had significant shortcomings and limitations for application in land reclamation monitoring. SMCS has been primarily determined by phospholipid fatty acid (PLFA) analysis. This method provides a direct measure of viable biomass in addition to a biochemical profile of the microbial community. PLFA has limitations such as overlap in the composition of microorganisms and the specificity of PLFAs signature. In recent years, high-throughput next-generation sequencing has dramatically increased the resolution and detectable spectrum of diverse microbial phylotypes from environmental samples and it plays a significant role in microbial ecology studies. Next-generation sequencings using 454, Illumina, SOLiD, and Ion Torrent platforms are rapid and flexible. The two methods, PLFA and next-generation sequencing, are useful in detecting changes in microbial community diversity and structure in different ecosystems. Single-molecule real-time (SMRT) and nanopore sequencing technologies represent third-generation sequencing (TGS) platforms that have been developed to address the shortcomings of second-generation sequencing (SGS). Enzymatic and soil respiration analyses are performed to further determine soil quality and microbial activities. Other valuable methods that are being recently applied to microbial function and structures include NanoSIM, GeoChip, and DNA stable staple isotope probing (DNA-SIP) technologies. They are powerful metagenomics tool for analyzing microbial communities, including their structure, metabolic potential, diversity, and their impact on ecosystem functions. This review is a critical analysis of current methods used in monitoring soil microbial community dynamic and functions.
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Composted plant residues of corn ( Zea mays L.), eastern hemlock [ Tsuga canadensis (L.) Carr.], and sugar maple ( Acer saccharum Marsh.) were used as the growing media for corn in a pot experiment. Fertilizer components were an added variable. The vesicular-arbuscular mycorrhizae (VAM) of corn were quantitatively low in the corn and hemlock composts and high in the maple compost. Dry-matter production was related to media fertility and independent of VAM quantity. The incidence of VAM in maple compost was negatively affected by added super-phosphate and positively affected by added ammonium nitrate, muriate of potash, and limestone. The incidence of VAM was found to be negatively correlated with extractable phosphorus in the maple compost and positively correlated with extractable potassium.
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A long-term field experiment was established to determine the influence of mineral fertilizer (NPK) or organic manure (composed of wheat straw, oil cake and cottonseed cake) on soil fertility. A tract of calcareous fluvo-aquic soil (aquic inceptisol) in the Fengqiu State Key Experimental Station for Ecological Agriculture (Fengqiu county, Henan province, China) was fertilized beginning in September 1989 and N2O emissions were examined during the maize and wheat growth seasons of 2002–2003. The study involved seven treatments: organic manure (OM), half-organic manure plus half-fertilizer N (1/2 OMN), fertilizer NPK (NPK), fertilizer NP (NP), fertilizer NK (NK), fertilizer PK (PK) and control (CK). Manured soils had higher organic C and N contents, but lower pH and bulk densities than soils receiving the various mineralized fertilizers especially those lacking P, indicating that long-term application of manures could efficiently prevent the leaching of applied N from and increase N content in the plowed layer. The application of manures and fertilizers at a rate of 300kgNha−1year−1 significantly increased N2O emissions from 150gN2O-Nha−1year−1 in the CK treatment soil to 856gN2O-Nha−1year−1 in the OM treatment soil; however, there was no significant difference between the effect of fertilizer and manure on N2O emission. More N2O was released during the 102-day maize growth season than during the 236-day wheat growth season in the N-fertilized soils but not in N-unfertilized soils. N2O emission was significantly affected by soil moisture during the maize growth season and by soil temperature during the wheat growth season. In sum, this study showed that manure added to a soil tested did not result in greater N2O emission than treatment with a N-containing fertilizer, but did confer greater benefits for soil fertility and the environment.
The roots of most plants are colonized by symbiotic fungi to form mycorrhiza, which play a critical role in the capture of nutrients from the soil and therefore in plant nutrition. Mycorrhizal Symbiosis is recognized as the definitive work in this area. Since the last edition was published there have been major advances in the field, particularly in the area of molecular biology, and the new edition has been fully revised and updated to incorporate these exciting new developments. . Over 50% new material . Includes expanded color plate section . Covers all aspects of mycorrhiza . Presents new taxonomy . Discusses the impact of proteomics and genomics on research in this area.
The roots of most plants are colonized by symbiotic fungi to form mycorrhiza, which play a critical role in the capture of nutrients from the soil and therefore in plant nutrition. Mycorrhizal Symbiosis is recognized as the definitive work in this area. Since the last edition was published there have been major advances in the field, particularly in the area of molecular biology, and the new edition has been fully revised and updated to incorporate these exciting new developments. . Over 50% new material . Includes expanded color plate section . Covers all aspects of mycorrhiza . Presents new taxonomy . Discusses the impact of proteomics and genomics on research in this area.
Crop and edaphic factors influence arbuscular mycorrhizal (AM) fungal species composition and populations. This study was conducted to determine the effect of management history, crop, and input system on species composition of AM fungal spore populations. Corn (Zea mays L.)-soybean [Glycine max (L.) Merr.] sequences receiving no inputs (NI), organic inputs (OI), minimum inputs (MI), and conventional inputs (CI) were established in two adjacent areas with differing management histories: one area, the Koch Farm, had received no fertilizer or herbicide inputs for the past 25 yr; the other area, the experiment station, received recommended herbicide and fertilizer inputs. Fifteen AM fungal species were found in a survey of mycorrhizal fungal spore populations. Glomus aggregatum populations were positively correlated with Setaria spp. populations (r = 0.56), pH (r = 0.47), and K (r = 0.25) and negatively correlated with soil P (r = -0.57). Populations of Gl. geosporum, Gl. leptotichum, Gl. macrocarpum, and Gl. occultum were also positively correlated with soil pH and negatively correlated with soil p. Gigaspora margarita spore populations were positively correlated with soil P level (r = 0.272). Although species richness was greater (13 species vs. 10), species diversity (H"W) was lower at the Koch Farm than the experiment station (0.57 vs. 0.64) because of large Gl. aggregatum spore populations. The correlation of AM fungal spore populations with Setaria spp, and P, K, and pH indicates that management practices influence AM fungal species composition through both biotic and abiotic factors.
We conducted two glasshouse experiments to determine the effect of soil disturbance on the infectivity of external hyphae of vesicular–arbuscular (VA) mycorrhizal fungi. A nylon mesh was used to exclude plant roots while allowing fungal hyphae to grow into soil contained by the mesh. Hyphae of VA mycorrhizal fungi that had been separated from the original host plant root were still able to colonize bioassay plants rapidly and extensively. However, disturbance of the soil inside the mesh, by mixing for 1 min, almost eliminated subsequent VA mycorrhiza formation in that soil. Damage to the soil hyphal network by soil disturbance may contribute to the losses in mycorrhizal infectivity that have been observed after mining and cultivation.
The application of increasing amounts of nitrate resulted in higher levels of vesicular-arbuscular mycorrhizal infection in lettuce roots inoculated with Glomus mosseae. This effect was found at three phosphate levels. The application of nutrient solutions containing different concentrations of nitrate and phosphate resulted in different nitrogen and phosphorus levels in the roots. At high concentrations of phosphorus in the roots, infection was inhibited, but at low concentrations the infection level appeared to be related to the nitrogen content of the host tissue. Mycorrhizal infections in low-nitrogen treatments were poorly developed with very few arbuscules and intercellular hyphae. Two methods of estimating infection (gridline intersect and yield of glucosamine) were compared.
Onion plants were grown in a range of soils labeled with 32P. It was found that although the mycorrhizal plants had taken up more phosphorus and grown larger, the proportion of 32P to total P (specific activity) taken up by mycorrhizal and non-mycorrhizal plants after 10 weeks was not significantly different. It is concluded that the mycorrhizal roots used the same source of labile phosphate but explored a greater volume of soil beyond the zone of phosphate depletion near the root surface. There was no indication that mycorrhizal roots had access to sources of phosphate different from those accessible to non-mycorrhizal roots. The specific activity of NaHCO3-extractable phosphorus differed considerably between the eight soils but the specific activity of absorbed phosphorus in the plants always corresponded closely to that of the soil in which they had grown.
The presence of vesicular-arbuscular mycorrhizæ diaspores in two long-term Swedish field experiments at Ultuna and Offer was studied. The number of diaspores decreased rapidly over time with increasing annual additions of an easily soluble phosphorus fertilizer, 45 kg P ha−1 year−1. Five years after the start of the experiment, at this level of fertilization, the spore frequencies were reduced by 50% and 7% at Ultuna and Offer, respectively. The spore frequencies later stabilized and fluctuated between 0.08 and 0.56 diaspores g−1 of soil. Moderate additions of easily soluble phosphorus fertilizers, 5 and 15 kg P ha−1 year−1, did not affect spore frequencies, which fluctuated between 0.48 and 1.96 diaspores g−1 of soil. When excluding phosphorus fertilization, spore frequencies doubled within 5–14 years. Twenty-eight years after the start of the experiment, the spore frequencies of the zero-phosphorus fertilized soils had doubled and trebled, respectively at the two locations. The phosphorus additions increased the amounts of easily soluble phosphorus in the soils, which adversely affected the diaspores. No relationships existed between the number of VAM diaspores and other soil parameters such as the amount of difficulty soluble phosphorus, pH, organic matter, or total nitrogen content. A plant-production parameter, estimated as dry matter production, was independent of the presence of VAM diaspores but another plant production related parameter, uptake of phosphorus by the plants, was dependent on the presence of VAM diaspores.