option to evaluate plastic pollution in soil (Ziajahromi et al. 2017), advanced
techniques provide more accurate results. But they are comparatively costly and
demand collection of soil from different conditions and carrying them safely to the
laboratory for accurate evaluation of the results is also important.
7.4.3 Impact of Plastics on Soil Environment
In recent times, as mentioned earlier effects of microplastics on terrestrial
ecosystems are moving into focus from the aquatic ecosystem. Once it reaches the
soil, it will impact physical properties of the soil such as structure and texture and
also its associated microbial components. Once it is altered, definitely it will impact
on the plant growth, whether in good or bad way. Hence Rillig et al. (2019) are of the
opinion that there is a necessity to develop mechanistic pathways through which
impact of microplastics on plant growth whether positively or negatively can be
evaluated. They are of the opinion that the effect will definitely depend on the plant
species and the type of plastics.
The research on microplastic pollution in agriculture fields begun mostly from the
last few years and it was related to its impact on soil biota (Huerta Lwanga et al.
2016, 2017; Maass et al. 2017; Rillig et al. 2017). Availability of the standard
methods in the beginning to quantify the microplastics might have hindered the
thorough research (Machado et al. 2018a), but at present few reliable methods are
available and hence the research related to this is gaining momentum.
The current research on microplastics highlights this as a physical contaminant of
the soil (Machado et al. 2018a) and initial reports revealed that the microfibrils lead
to lowered bulk density (Machado et al. 2018b). Earlier this was reported to favor the
increased plant root penetration and better soil aeration leading to increased plant
growth (Zimmermann and Kardos 1961). But recent findings by Wan et al. (2019)
reveal that microplastics will create a channel through which water movement is
favored leading to increased loss of water through evaporation, which in turn lead to
soil drying. It is a negative consequence; hence, these two reports highlight the need
for thorough research on possible impact of plastics on soil environment directly and
plant growth indirectly. Rillig et al. (2019) highlighted another impact, if it alters the
soil structure, then naturally the microbial flora has to alter, it will also impact
microbial interaction with plant roots, its positive influence on plant growth and
this shift may alter mycorrhizal association and even nitrogen fixers.
In this connection Machado et al. (2018b) is of the opinion that changes in overall
structure of the soil will have significant effect on soil aggregation. If the microfibers
facilitate more soil aggregation which in turn favors significant soil aeration and
hydration, then it will have a positive influence on root growth. If by chance the soil
aggregate fails to accommodate air and water in an altered cycle, then it will
definitely impact negatively for the growth of the plant.
It is a proven fact that the soil microflora is important component of the plant
performance in the field (Wagg et al. 2014; Powell and Rillig 2018). If soil structure
is altered due to microplastics accumulation it will definitely impact microbial
238
M. P. Raghavendra
techniques provide more accurate results. But they are comparatively costly and
demand collection of soil from different conditions and carrying them safely to the
laboratory for accurate evaluation of the results is also important.
7.4.3 Impact of Plastics on Soil Environment
In recent times, as mentioned earlier effects of microplastics on terrestrial
ecosystems are moving into focus from the aquatic ecosystem. Once it reaches the
soil, it will impact physical properties of the soil such as structure and texture and
also its associated microbial components. Once it is altered, definitely it will impact
on the plant growth, whether in good or bad way. Hence Rillig et al. (2019) are of the
opinion that there is a necessity to develop mechanistic pathways through which
impact of microplastics on plant growth whether positively or negatively can be
evaluated. They are of the opinion that the effect will definitely depend on the plant
species and the type of plastics.
The research on microplastic pollution in agriculture fields begun mostly from the
last few years and it was related to its impact on soil biota (Huerta Lwanga et al.
2016, 2017; Maass et al. 2017; Rillig et al. 2017). Availability of the standard
methods in the beginning to quantify the microplastics might have hindered the
thorough research (Machado et al. 2018a), but at present few reliable methods are
available and hence the research related to this is gaining momentum.
The current research on microplastics highlights this as a physical contaminant of
the soil (Machado et al. 2018a) and initial reports revealed that the microfibrils lead
to lowered bulk density (Machado et al. 2018b). Earlier this was reported to favor the
increased plant root penetration and better soil aeration leading to increased plant
growth (Zimmermann and Kardos 1961). But recent findings by Wan et al. (2019)
reveal that microplastics will create a channel through which water movement is
favored leading to increased loss of water through evaporation, which in turn lead to
soil drying. It is a negative consequence; hence, these two reports highlight the need
for thorough research on possible impact of plastics on soil environment directly and
plant growth indirectly. Rillig et al. (2019) highlighted another impact, if it alters the
soil structure, then naturally the microbial flora has to alter, it will also impact
microbial interaction with plant roots, its positive influence on plant growth and
this shift may alter mycorrhizal association and even nitrogen fixers.
In this connection Machado et al. (2018b) is of the opinion that changes in overall
structure of the soil will have significant effect on soil aggregation. If the microfibers
facilitate more soil aggregation which in turn favors significant soil aeration and
hydration, then it will have a positive influence on root growth. If by chance the soil
aggregate fails to accommodate air and water in an altered cycle, then it will
definitely impact negatively for the growth of the plant.
It is a proven fact that the soil microflora is important component of the plant
performance in the field (Wagg et al. 2014; Powell and Rillig 2018). If soil structure
is altered due to microplastics accumulation it will definitely impact microbial
238
M. P. Raghavendra