ArticlePDF Available

Abstract and Figures

In recent time Bangladesh faces a serious problem of soil pollution due to plastic contamination. However, the degree of the extent to which the effects of plastics on plant growth occur is not properly identified. An experiment was conducted to measure the effects of mixed plastic (polyethylene and dis-posable plastic glass) on the growth of Amaranthus viridis. Different doses of mixed plastics (T0, T1, T2, and T3) were applied with a fixed amount of soil for each of the treatments e.g., T0 (control), T1 (10 gm mixed plastics/3kg soil), T2 (15 gm mixed plastics/3kg soil) and T3 (20 gm mixed plastic/3kg soil), and the growth response of Amaranthus viridis against plastic was ob-served for six consecutive weeks. The growth was measured in terms of plant height and girth diameter. The results showed that the presence of mixed plastic had a significant effect on the growth of Amaranthus viridis and par-ticularly in treatment T3 (3 kg soil/20gm mixed plastic), the plants showed a slower growth response compared to control and the rest of the treatments applied in case of both plant height as well as girth diameter. The statistical analysis (one-way Analysis of Variance) also proved the significance of the treatments (p-values < 0.05) for six consecutive weeks. The experiment was successfully able to set an index on which plastics had their effects on the growth of green amaranth. In addition, the obtained data will be helpful in future research of the study in determining the possible effects of plastic on plant growth viz. green amaranth.
Content may be subject to copyright.
American Journal of Plant Sciences, 2021, 12, 926-933
ISSN Online: 2158-2750
ISSN Print: 2158-2742
10.4236/ajps.2021.126062 Jun. 23, 2021 926 American Journal of Plant Sciences
Macroplastics on Soil-Plant System: Inhibiting
Effects of Macroplastics on the Growth of
Green Amaranth (Amaranthus viridis)
Marzan Ferdous, Arifur Rahman Bhuiyan*, Khadiza Akter Tania
Department of Environmental Science, Faculty of Science and Technology, Bangladesh University of Professionals,
Mirpur Cantonment, Dhaka, Bangladesh
In recent time Bangladesh faces a serious problem of soil pollution due to
plastic contamination. However, the degree of the extent to which
the effects
of plastics on plant growth occur is not properly identified. An experiment
was conducted to measure the effects of mixed plastic (polyethylene and dis-
posable plastic glass) on the growth of
. Different doses of
mixed plastics (T0, T1, T2, and T3) were applied with a fixed amount of soil
for each of the treatments e.g., T0 (control), T1 (10 gm mixed plastics/3kg
soil), T2 (15 gm mixed plastics/3kg soil) and T3 (20 gm mixed plastic/3kg
soil), and the growth response of
against plastic was ob-
served for six consecutive weeks. The growth was measured in terms of plant
height and girth diameter. The results showed that the presence of mixed
plastic had a significant effect on the growth of
and par-
ticularly in treatment T3 (3 kg soil/20gm mixed plastic), the plants showed a
slower growth response compared to control and the rest of the treatments
applied in case of both plant height as well as girth diameter. The statistical
analysis (one-way Analysis of Variance) also proved the
significance of the
treatments (p-
values < 0.05) for six consecutive weeks. The experiment was
successfully able to set an index on which plastics had their effects on the
growth of green amaranth. In addition, the obtaine
d data will be helpful in
future research of the study in determining the possible effects of plastic on
plant growth viz. green amaranth.
Green Amaranth, Soil Pollution, Polyethylene Contamination, Disposable
Plastic, Abiotic Stress, Slow Growth of Plants
How to cite this paper:
Ferdous, M.,
an, A.R. and Tania, K.A. (2021) Ma-
astics on Soil-Plant System: Inhibit-
g Effects of Macroplastics on
the Growth
f Green Amaranth (
American Journal of Plant Sciences
May 10, 2021
June 20, 2021
June 23, 2021
Copyright © 20
21 by author(s) and
Research Publishing Inc.
This work is licensed under the Creative
Commons Attribution International
License (CC BY
Open Access
M. Ferdous et al.
10.4236/ajps.2021.126062 927 American Journal of Plant Sciences
1. Introduction
Plastic is a synthetic polymer and without it, modern life would be impossible.
Due to a wide spectrum of positive characteristics such as light, flexibility, non-
rusting, and highly persistent, plastic products hold a very important role in our
daily activities [1]. A tiny part of plastic used all over the world is being recycled
or incinerated in waste-to-energy facilities. Bangladesh is reportedly 10th in
plastic waste disposal in the world [2]. Every year 800,000 tons of waste are gen-
erated in Bangladesh, out of which 200,000 tons are from plastics [3]. However,
the chemical bond of the monomers responsible for the durability of plastic
makes it resistant to the different natural processes of degradation. The plastic
waste does not decompose, rather they accumulate on landfill and marine envi-
ronment [4]. Once in the soil, plastics can be further degraded into small par-
ticles via physical, chemical, and biological processes [5].
Additionally, the presence of plastic affects soil fertility in several ways. Plas-
tics might alter the physico-chemical properties of soil by changing its texture
and structure due to the distinctive characteristics of plastics compared with
natural soil components [6]. When soil is contaminated with plastics, its pore
structure, bulk density, and water holding capacity can be altered [7]; as a result,
soil water evaporation and shrinkage cracking may also be affected. The compo-
sition and diversity of microbial communities in soils play an important role in
maintaining soil quality [8] [9]. Microbes are sensitive to soil contaminants, and
their composition and activity are the primary biological indicators of changes in
the soil environment, as they play a key role in carbon, nitrogen, phosphorus,
and potassium cycling in the soil [10] [11].
Soil enzymes with a high capacity for catalysis are closely associated with mul-
tiple soil biochemical processes; these enzymes act as an indicator for evaluating
soil fertility and play an essential role in the regulation of soil nutrient cycling
for nutrients such as C, N, and P [12] [13]. The soil system is the chief source for
agriculture [14]. So maintained good soil conditions is mandatory to meet our
present and future food demand. Some research already proves that Plastic waste
remaining in a wide area of the soil are accumulating over a long period, causing
the soil to harden and affects the crops absorption of nutrients and water con-
sequently. It leads to a reduction in crop outputs [15]. One Research also esti-
mated the negative impacts of plastic bags on agriculture, e.g., reduction in soil
fertility, decrease in nitrogen fixation, huge loss of nutrients in the soil, decrease
in crop harvest, the disparity in flora, and fauna on soil, etc [16].
The present study examined the effects of mixed plastic on the growth of
Green amaranth plants. The result of the study might help the researchers in a
future study to identify the effects of plastic on plant growth and determine the
threshold limit of plastics in soil against which plants can be able to grow.
2. Materials and Methods
2.1. Experimental Procedure
The experiment was carried out from August to December 2020. A Completely
M. Ferdous et al.
10.4236/ajps.2021.126062 928 American Journal of Plant Sciences
Randomized Design (CRD) was followed. The experimental procedure involved
three steps:
2.1.1) Plant Preparation;
2.2.2) Soil Preparation;
2.2.3) Set up of the Experimental Pots.
2.1.1. Plant Preparation
Green amaranth was selected for this study which is a cosmopolitan species in
the botanical family
[17]. The reason for choosing green ama-
ranth was, it is fast growing and the responses could be observed within the
shortest period. It is an annual herb with an upright, light green stem that grows
to about 60 - 80 cm in height. It has several nutritional values such as it can con-
tain up to 38% protein by dry weight. The leaves and seeds contain lysine, an
essential amino acid [18]. Seeds of green amaranth were collected from the seed
market at Tongi, Gazipur, Dhaka, Bangladesh in July 2020. Seed viability test
was carried out before planting by floatation method. The seeds were sown at
first in the seedbed and allowed to grow until they were about 3.40 - 3.45 cm tall
before transferring them into the treatment pots.
2.1.2. Soil Preparation
The experimental soil was silty loam, which was collected from a local nursery at
Tongi, Dhaka, Bangladesh. After the soil was air dried, it was grounded with
mortar and pestle and passed through a sieve and the pH was measured by using
a pH meter.
Two types of plastic were used in this experiment: 1) polyethylene bag and 2)
disposable plastic glass. For the experiment, both types of plastics were cut into
pieces using scissors to reduce the plastic size. 10 grams, 15 grams, 20 grams of
mixed plastics granule was prepared for three treatments and the ratio of one-
time plastic glass and polyethylene was 1:2.3.
2.1.3. Setup of Experimental Pots
The experiment consisted of four (4) treatments each with three replications as
T0 = control (untreated 3 kg soil);
T1 = 0.33% treatment level (10 gm shredded mixed plastic/3kg soil);
T2 = 0.5% treatment level (15 gm of shredded mixed plastic/3kg soil);
T3 = 0.66% treatment level (20 gm of shredded mixed plastic/3kg soil).
Healthy and stable seedlings with a height of approximately 3.40 - 3.45 cm
were uprooted from the seedbed and four seedlings were transplanted in each
treatment pot. All the pots were exposed to natural sunlight conditions and care
was taken to keep the plants free from weed or insect infestation. The plant
height was observed for six consecutive weeks and was measured from the soil
surface to the apical tip just after plantation. Plant steam diameters were meas-
ured in the 2nd week, 4th week, and 6th week of the plantation.
M. Ferdous et al.
10.4236/ajps.2021.126062 929 American Journal of Plant Sciences
2.2. Data Analysis
All data were statistically analyzed by using Microsoft Excel (version 2010).
One-way ANOVA (Analysis of Variance) was conducted to establish significant
differences among the treatments at a 5% level of significance using Microsoft
Excel (version 2010).
3. Results
3.1. Observation on Plant Height
Measured average heights of
against different treatments were
plotted against the number of observations (in weeks) and shown (Figure 1).
At 0-week height of all treatment plants were approximately the same size
(3.42 - 3.45 cm). At 1st week after planting, the plant’s growth response of all the
treatments was observed where all the treatments showed similar height except
T3 (5.36 cm). This difference in treatment T3 has been distinctly observed after
the 2nd week, followed by the 3rd week, and continued up to the 6th week. On six
weeks of observation, plants showed the slowest growth response in treatment
T3. On the other hand, treatment T0 continued to show a significant response
with the increase of plant height. Treatment T1, T2, and T3 showed a gradual
decrease in the growth of plants (Figure 1).
After 3rd week, a noticeable reduction of growth was observed in treatment T2
and T3 (Figure 1). In 4th week, the value of treatment T0 was 20.98 cm. Howev-
er, the growth of plants in case of other treatments were 17.15 cm (T1), 15.15 cm
(T2), 12.4 cm (T3) (Figure 1).
After the 5th and 6th week, the highest growth response was observed in T0 and
the lowest was found in treatment T3. However, moderate growth was observed
in treatment T1 and T2 (Figure 1). At 5th Week the height of treatment T0, T1,
and T2 was respectively 34.48 cm, 28.5 cm, 20.51 cm, 17.74 cm and for 6th week
40.05 cm (T0), 35.52 cm (T1), 24.84 cm (T2), 19.6 cm (T3). So, it was clearly
observed that T3 had the slowest growth response compared to the control T0,
whereas treatment T1 and T2 had moderate growth response.
Figure 1. Average height (cm) of
in six consecutive weeks.
M. Ferdous et al.
10.4236/ajps.2021.126062 930 American Journal of Plant Sciences
The similar result was found from some other researchers experiment [19]
[20]. They [19] conducted a study with five treatments in eight weeks. Among
them, one treatment served as a control and the other contained several doses of
polyethylene. They also identified significant height reduction of maize plants in
the presence of polyethylene granules and observed the lowest growth rate in the
highest doses of treatment. Another researcher also revealed that the presence of
both macro-and micro-plastic residues of polyethylene mulch films has negative
effects on both above-ground and below-ground parts of wheat [20].
3.2. Observation on Steam Girth Diameter
Figure 2 clearly indicates that, plants of treatment T0 had the widest diameter
value (0.9 cm) while treatment T3 had the least stem girth diameter value (0.56
cm) detected at the 6th week of observation after the plantation. They [19] also
found a similar result in their experiment 8 weeks after planting. They detected
the reduction of girth diameter of
while several doses of polyethylene
were applied.
4. Discussion
The results obtained from Sections 3.1 and 3.2, show that the growth (consider-
ing both height and girth diameter) of
was highest in the
absence of mixed plastic in soil (T0). Whereas the presence of mixed plastics in
treatment T1, T2, and T3 showed a reduction of growth rate in
(Figure 1 and Figure 2). Additionally, it had been observed that the higher
the doses of plastics in treatment, the slower the growth rate e.g., the amount of
mixed plastic was highest in treatment T3, and it showed the lowest growth rates
. Hence the significant effect of mixed plastic on growth
was clearly visualized with a gradual increase with time. For example, after 3rd
week the growth reduction was more easily detected (Figure 1 and Figure 2).
On the 4th, 5th, and 6th week, treatment T2 and T3 showed significantly slower
growth response compared to other weeks (Figure 1). Girth diameter also
reduced with time in the case of various treatments particularly in T3 (Figure 2).
Figure 2. Average girth diameter of
observed at 2nd, 4th, and 6th week.
M. Ferdous et al.
10.4236/ajps.2021.126062 931 American Journal of Plant Sciences
The reasons behind this might be, with the increasing time plants need to up-
take more nutrients for their growth. But the shredded plastic obstructs the free
movement of root hair. Additionally, soil pore spaces also block by shredded
plastics that contain adequate air and water. As a result,
could not uptake sufficient water and nutrient for their growth. However, plant
respiration was also hampered due to a lack of well-aerated conditions in the
soil. As the presence of shredded mixed plastic disturbed soil natural condition,
growth was also affected.
Statistical Analysis
One-way ANOVA was done to determine the significance of the treatments
applied at a 5% level of confidence using Excel. ANOVA test also showed that,
height at the first week of observation, the p-value was
0.001185 which was less than 0.05 and it indicates that, there had been signifi-
cant differences in the treatments. Additionally, the p-value of week 2, week 3,
week 4, week 5, and week 6 were respectively 1.8 × 10−6, 7.61 × 1011, 1.95 × 1014,
4.07 × 1024, 6.08 × 1026 and all the values were less than 0.05 for between and
within the groups. It was also observed that after the 2nd week the p-value was
drastically reduced.
Similar results were also found in the case of steam girth diameter. The
p-value of ANOVA test found for week 2, week 4, and week 6 was respectively
1.47 × 10−9, 1.35 × 10−5, 2.69 × 1010 and all the values were less than 0.05 for be-
tween and within groups which clearly indicate that there had been significant
differences in the treatments applied to observe the plants growth. So, the statis-
tics proved the significant differences between and within the groups (within
5. Conclusion
The study suggests that the presence of macroplastics in soil had significant ef-
fects on plant growth. The results also proved that there is a certain withstand
point beyond which the plants will collapse to show any growth progress further.
Thus, these indexing or threshold values could be helpful in future research and
will provide valuable data regarding plant’s tolerance limit against plastic con-
tamination in soil.
Conflicts of Interest
The authors declare no conflicts of interest regarding the publication of this
[1] Stubenrauch, S. and Ekardt, F. (2020) Plastic Pollution in Soils: Governance Ap-
proaches to Foster Soil Health and Closed Nutrient Cycles.
, 7, Article
No. 38.
[2] Chowdhury, G.W., Koldewey, H.J., Duncan, E., Napper, I.E., Niloy, H.N., Nelms,
M. Ferdous et al.
10.4236/ajps.2021.126062 932 American Journal of Plant Sciences
S.E., Sarker, S., Bhola, S. and Nishat, B. (2020) Plastic Pollution in Aquatic Systems
in Bangladesh: A Review of Current Knowledge.
761, Article ID: 143285.
[3] Begum, F.A. (2018) Sustainability of Plastic Sector. The Financial Express, Bangla-
[4] Browne, M.A., Crump, P., Niven, S.J., Teuten, E., Tonkin, A., Galloway, T. and
Thompson, R. (2011) Accumulation of Microplastic on Shorelines Worldwide: Sources
and Sinks.
Environmental Science & Technology
, 21, 9175-9179.
[5] Peng, J., Wang, J. and Cai, L. (2017) Current Understanding of Microplastics in the
Environment: Occurrence, Fate, Risks, and What We Should Do.
Integrated Envi-
ronmental Assessment and Management
, 13, 476-482.
[6] Wan, Y., Wu, C., Xue, Q. and Hui, X. (2019) Effects of Plastic Contamination on
Water Evaporation and Desiccation Cracking in Soil.
, 654, 576-582.
[7] de Souza Machado, A.A., Lau, C.W., Till, J., Kloas, W., Lehmann, A. and Becker, R.
(2018) Impacts of Microplastics on the Soil Biophysical Environment.
mental Science & Technology
, 52, 9656-9665.
[8] Kennedy, A. C. and Smith, K. L. (1995) Soil Microbial Diversity and the Sustaina-
bility of Agricultural Soils.
, 170, 75-86.
[9] Rong, Y., Wang, Y., Guan, Y., Ma, J., Cai, Z. and Yang, G. (2017) Pyrosequencing
Reveals Soil Enzyme Activities and Bacterial Communities Impacted by Graphene
and Its Oxides.
Journal of Agricultural and Food Chemistry
, 65, 9191-9199.
[10] Avidano, L., Gamalero, E., Cossa, G.P. and Carraro, E. (2005) Characterization of
Soil Health in an Italian Polluted Site by Using Microorganisms as Bioindicators.
, 30, 21-33.
[11] Bergkemper, F., Scholer, A., Engel, M., Lang, F., Kruger, Schloter, M. and Schulz, S.
(2016) Phosphorus Depletion in Forest Soils Shapes Bacterial Communities To-
wards Phosphorus Recycling Systems.
, 18, 1988-2000.
[12] Allison, S.D. and Jastrow, J.D. (2006) Activities of Extracellular Enzymes in Physi-
cally Isolated Fractions of Restored Grassland Soils.
Soil Biology and Biochemistry
38, 3245-3256.
[13] Trasar-Cepeda, C., Leiros, M.C. and Gil-Sotres, F. (2008) Hydrolytic Enzyme Activ-
ities in Agricultural and Forest Soils. Some Implications for Their Use as Indicators
of Soil Quality.
Soil Biology and Biochemistry
, 40, 2146-2155.
[14] Marie, M.J.A.M and Tiwari, D. (2020) Depleting the Usage of Plastics to Enhance
the Agricultural Land. An Attitudinal Study for Sustainable Generation.
, 12, 1-6.
[15] Chae, Y. and An, Y.J. (2018) Current Research Trends on Plastic Pollution and
Ecological Impacts on the Soil Ecosystem: A Review.
, 240,
[16] Jalil, A., Mian, N. and Rahman, M.K. (2013) Using Plastic Bags and Its Damaging
M. Ferdous et al.
10.4236/ajps.2021.126062 933 American Journal of Plant Sciences
Impact on Environment and Agriculture: An Alternative Proposal.
, 3, 1-14.
[17] Tanaka, Y. and Van, K.N. (2007) Edible Wild Plants of Vietnam: The Bountiful
Garden. Orchid Press, Thailand.
[18] Grubb, A., Rowland, A.R. (2012) The Weed Foragers Handbook. Hyland House
Publishing Pty Ltd., Australia.
[19] Atuanya, E.I., Aborisade, W.T. and Nwogu, N.A. (2012) Impact of Plastic Enriched
Composting on Soil Structure, Fertility, and Growth of Maize Plants.
, 4, 105-109.
[20] Qi, Y.L., Yang, X., Pelaez, A.M., Huerta, E., Beriot, N., Gertsen, H., Garbeva, P. and
Geissen, V. (2018) Macro- and Micro-Plastics in Soil-Plant System: Effects of Plastic
Mulch Film Residues on Wheat (
) Growth.
, 645, 1048-1056.
Technical Report
Full-text available
Plastic enters the environment from various emission sources. In particular, light plastics may be transported long distances from their original emission sources. Plastics may also carry alien species, pathogens, and hazardous substances. Plastics are released into the environment from all stages of their life cycle, but one of the most significant sources is plastic waste generated at the end of the life cycle. In the environment plastics are extremely persistent. Large plastics items can be further broken down into smaller pieces which, due to their small size, are more easily transported into organisms. Once released into the environment, plastics may have a wide range of various impacts. In an aquatic environment, the most common disadvantages of large plastics are the tangling of organisms in them, and the problems caused by organisms eating plastic pieces. There is a lack of information on the impacts of plastics on terrestrial ecosystems. However, according to the information available the impacts on the terrestrial environment seem to be quite parallel to the aquatic environment. Microplastics have been found to have adverse impacts on several organisms at different trophic levels. In an aquatic environment various species have been found to be exposed to microplastic particles. Microplastics introduced into organisms can cause many types of unwanted side effects. In a terrestrial environment, soil animals can also act as a pathway for microplastics into the terrestrial food web. Humans are exposed to microplastics on a daily basis through food, indoor and outdoor air, and the skin, but the extent of the exposure and its potential effects on health are not well known. Laboratory studies in animals and cell models have shown evidence of adverse effects, but the high doses and uniform plastic types used in these studies do not correspond to normal human exposure. Even though the evidence for health effects is limited, international scientific community has estimated that microplastic exposure is currently so low that it does not pose a significant risk to human health. However, the situation may change as the amount of microplastic pollution in the environment keep increasing. More information is required, especially on the behavior of nanosized plastic particles in the human body, the exposure of young children to plastics, the possible intestinal effects and the consequences of long-term accumulation. Waste prevention and optimizing the circular economy are important ways to minimize the environmental impact of plastics. The Plastic Roadmap launched in 2018 has set several proposals for measures to reduce and replace plastic use and to increase the efficiency of recycling. Ecologically sustainable product design that also takes into account safety perspectives plays a key role in reducing climate and environmental emissions from plastics. Although the legislation and regulative measures of plastics and their impacts has increased in recent years, shortcomings still remain. The prevention of plastic emissions to the environment can be seen as a primary control measure. One key problem, however, is that there are no direct control methods to prevent secondary plastics emissions. As plastic keeps playing a key role in many activities in society, multi-level management measures are still required to reduce the environmental and health impacts of plastics.
Full-text available
Purpose The present study provides quantitative data on the degree of macroplastic contamination of two conventionally treated arable areas in North Rhine-Westphalia (Germany), which differ only in the use of organic fertilizers (e.g., compost). Methods The plastic contamination of both areas was determined by means of field sampling. The study areas were divided into edge and central areas to minimize and identify direct influences from the boundaries. After cleaning and drying, the collected macroplastic particles were analyzed by phototechnical and optical methods for number and size of particles. Results The arable area with compost fertilization showed a substantially higher macroplastic pollution with 9247 particles per hectare compared to the 220 particles per hectare found on the arable land without compost application. Furthermore, the differences in plastic forms and types on both areas, the presence of plastic directly related to household and garden products, and the homogeneous distribution of plastic particles on the arable area with compost application allow to conclude that compost can be regarded as reason for substantially higher pollution. Areas close to a road showed a higher degree of contamination and differences in the found plastic products compared to the center areas, which indicates littering as a further considerable entry path. Conclusions The causes of plastic contamination of the investigated arable areas (e.g., contaminated compost by improper waste management and littering) are predominantly external to agricultural practices. The knowledge gained contributes to the knowledge about quantities, impacts, and fate of plastic in the environment.
Full-text available
Plastic pollution in soils pose a major threat to soil health and soil fertility that are directly linked to food security and human health. In contrast to marine plastic pollution, this ubiquitous problem is thus far scientifically poorly and policy approaches that tackle plastic pollution in soils comprehensively do not exist. In this article, we apply a qualitative governance analysis to assess the effectiveness of existing policy instruments to avoid harmful plastic pollution in (agricultural) soils against the background of international environmental agreements. In particular, environmental and fertiliser legislation relevant to soil protection in the European Union and in Germany are assessed. Regulatory weaknesses and gaps of the respective legislation are identified, and proposals for enhanced command-and-control provisions developed. However, the legal analysis furthermore shows that plastic pollution ecologically is also a problem of quantity, which is difficult to solve exclusively through command-and-control legislation. Instead, comprehensive quantity-control instruments to phase out fossil fuels (worldwide and in all sectors) as required by climate protection law can be effective approaches to tackle plastic pollution in environmental media like agricultural soils as well.
Full-text available
Plastic residues have become a serious environmental problem in the regions with intensive use of plastic mulching. Even though plastic mulch is widely used, the effects of macro- and micro- plastic residues on the soil-plant system and the agroecosystem are largely unknown. In this study, low density polyethylene and one type of starch-based biodegradable plastic mulch film were selected and used as examples of macro- and micro- sized plastic residues. A pot experiment was performed in a climate chamber to determine what effect mixing 1% concentration of residues of these plastics with sandy soil would have on wheat growth in the presence and absence of earthworms. The results showed that macro- and micro- plastic residues affected both above-ground and below-ground parts of the wheat plant during both vegetative and reproductive growth. The type of plastic mulch films used had a strong effect on wheat growth with the biodegradable plastic mulch showing stronger negative effects as compared to polyethylene. The presence of earthworms had an overall positive effect on the wheat growth and chiefly alleviated the impairments made by plastic residues.
Full-text available
Graphene (GN) and graphene oxides (GOs) are novel carbon nanomaterial, they have been attracted much attention because of their excellent properties and are widely applied in many areas including energy, electronics, biomedicine and environmental science etc. With industrial production and consumption of GN/GO, they will inevitably enter the soil and water environment. GN/GO may directly cause certain harm to microorganisms and lead to ecological and environmental risks. Graphene oxides are graphene derivative with abundant oxygen-containing functional groups in its graphitic backbone. The structure and chemistry of graphene show obvious differences compared with graphene oxide, which lead to the different environmental behaviors. In this study, four different types of soil (S1, S2, S3 and S4) were employed to investigate the effect of GN and GO on soil enzymatic activity, microbial population and bacterial community through pyrosequencing of 16S rRNA gene amplicons. The results showed that soil enzyme activity (invertase, protease, catalase and urease) and microbial population (bacteria, actinomycete and fungi) changed after GN/GO release into soils. Soil microbial community species are more richness and the diversity also increase after GO/GN application. The phylum of Proteobacteria increased at 90 days after treatment (DAT) after GN/GO application. The phylum of Chloroflexi occurred after GN applying at 90 DAT in S1 and reached 4.6%. Proteobacteria were the most phylum in S2, S3 and S4 soils, it ranged from 43.6% to 71.4% in S2, 45.6% to 73.7% in S3, 38.1% to 56.7% in S4, respectively. The most abundant genus were Bacillus (37.5% - 47.0%), Lactococcus (28.0% - 39.0%) in S1, Lysobacter and Flavobacterium in S2, Pedobacter in S3 and Massilia in S4 soil. The effect of GN and GO on soil microbial community is time dependent, and there are no significant differences between the samples at 10 and 90 DAT.
Agriculture is the main source of support for past, present and future generations who depends on it for sustainable development. Now a day’s modern agronomy skills developed plentiful to cater the need of the growing population which is highly encouraged but at the same time it leads to numerous issues like land pollution, negative environmental impacts, toxic problems, proliferation of carcinogenic diseases and so on. One of the main factors which affects our land is the usage of plastics in our regular life. This plastic usage and it improper waste management also plays an consequential role in polluting the soil system. Soil system is chief source for agriculture, if soil system is maintained with good conditions like acidic and basic nature than good yield of crops was expected. This paper mainly focuses on the types of plastics and how it affects the life. Many studies have been done in this area and as an educationalist it is essential to develop positive attitude towards agronomy skills without damaging the soil system. The study also intends to develop positive attitude towards agronomy skills for students and how to prepare soil for better agricultural crops and the main intention of this paper is to reduce the use of plastics to sustain the sustainable generation.
Environmental contamination of plastics is becoming an issue of concern globally. Detection of plastics, particularly microplastics, has been increasingly reported in both marine environments and inland waters. Recent work has indicated that soil in terrestrial environments has also been contaminated by plastics. Research has also shown that plastics can have adverse effects on soil biota. However, the impact of plastics on soil physical properties is still unclear. In this work, effects of plastic film of different sizes at environmental relevant concentrations on water evaporation and desiccation cracking in two clay soils were studied. The results showed that the presence of plastics in soil significantly increased the rate of soil water evaporation by creating channels for water movement. The effect was more pronounced in soils treated with 2 mm plastics than in soils treated with 5 and 10 mm plastics, and increased with increasing plastic content. Desiccation cracking was observed on the surface of soil treated with 5 and 10 mm plastics likely due to the destruction of soil structural integrity. While 2 mm plastics increased the rate of desiccation shrinkage, the shrinkage ratio was reduced at the residual stage. Results from this work suggest that plastic contamination can alter the water cycle in soils, which may exacerbate soil water shortages and affect the vertical transport of pollutants. Further work is required to study the effects of plastics of other shapes, and laboratory observations should be tested at field scale.
Soils are essential components of terrestrial ecosystems that experience strong pollution pressure. Microplastic contamination of soils is being increasingly documented, with potential consequences for soil biodiversity and function. Notwithstanding, data on effects of such contaminants on fundamental properties potentially impacting soil biota are lacking. The present study explores the potential of microplastics to disturb vital relationships between soil and water, as well as its consequences for soil structure and microbial function. During a 5-weeks garden experiment we exposed a loamy sand soil to environmentally relevant nominal concentrations (up to 2 %) of four common microplastic types (polyacrylic fibers, polyamide beads, polyester fibers, and polyethylene fragments). Then, we measured bulk density, water holding capacity, hydraulic conductivity, soil aggregation, and microbial activity. Microplastics affected the bulk density, water holding capacity, and the functional relationship between the microbial activity and water stable aggregates. The effects are underestimated if idiosyncrasies of particle type and concentrations are neglected, suggesting that purely qualitative environmental microplastic data might be of limited value for the assessment of effects in soil. If extended to other soils and plastic types, the processes unravelled here suggest that microplastics are relevant long-term anthropogenic stressors and drivers of global change in terrestrial ecosystems.
Microplastics pollution has been documented in the global environment, including at sea, in freshwater and in atmospheric fallout. Ingestion of microplastics by multiple kinds of organisms has been reported and has received increasing attention, because microplastics not only act as a source of toxic chemicals but also a sink for toxic chemicals. To better understand the great concerns about microplastics and associated toxic chemicals potential exposed to the organisms ingesting the debris, we should know more about the occurrence, fate, and risks of microplastics in the environment. What we should do depends on this better understanding. Integr Environ Assess Manag 2017;13:476–482.
Phosphorus (P) is an important macronutrient for all biota on earth but similarly a finite resource. Microorganisms play on both sides of the fence as they effectively mineralize organic and solubilize precipitated forms of soil phosphorus, but conversely also take up and immobilize P. Therefore, we analyzed the role of microbes in two beech forest soils with high and low P content by direct sequencing of metagenomic DNA. For inorganic P solubilization, a significantly higher microbial potential was detected in the P-rich soil. This trait especially referred to Candidatus Solibacter usiatus, likewise one of the dominating species in the datasets. A higher microbial potential for efficient phosphate uptake systems (pstSCAB) was detected in the P-depleted soil. Genes involved in P starvation response regulation (phoB, phoR) were prevalent in both soils. This underlines the importance of effective phosphate (Pho) regulon control for microorganisms to use alternative P sources during phosphate limitation. Predicted genes were primarily harbored by Rhizobiales, Actinomycetales and Acidobacteriales.
Many world ecosystems are in various states of decline evidenced by erosion, low productivity, and poor water quality caused by forest clearing, intensive agricultural production, and continued use of land resources for purposes that are not sustainable. The biological diversity of these systems is being altered. Little research has been conducted to quantify the beneficial relationships between microbial diversity, soil and plant quality, and ecosystem sustainability. Ecosystem functioning is governed largely by soil microbial dynamics. Differences in microbial properties and activities of soils have been reported but are restricted to general ecological enumeration methods or activity levels, which are limited in their ability to describe a particular ecosystem. Microbial populations and their responses to stresses have been traditionally studied at the process level, in terms of total numbers of microorganisms, biomass, respiration rates, and enzyme activities, with little attention being paid to responses at the community or the organismal levels. These process level measurements, although critical to understanding the ecosystem, may be insensitive to community level changes due to the redundancy of these functions. As microbial communities comprise complex interactions between diverse organisms, they should be studied as such, and not as a black box into which inputs are entered and outputs are received at measured rates. Microbial communities and their processes need to be examined in relation to not only the individuals that comprise the community, but the effect of perturbations or environmental stresses on those communities.