Agricultural Plastic Research Articles

Prediction analysis of cotton yield based on BP neural network and multiple linear regression

With the rapid development of the economy and agricultural production, cotton is an indispensable crop in people's production and life, and the average annual cotton yield is particularly significant in production. The unit yield of cotton is affected by many factors, so it is extremely important to analyze the factors affecting future cotton yield forecast. This article varies seven relevant indicators, including fertilizer cost,consumption of agricultural plastic, pesticide cost, seed cost, irrigation cost, chlorpyrifos control area, and labor input, and establishes a prediction model based on Back Propagation (BP) neural network. The model uses the function approximation ability of BP neural network and gradient descent algorithm to predict the nonlinear functional relationship between the unit output and the seven factors. Meanwhile, a multiple linear regression model is used to forecast the unit yield and the prediction accuracy of the two methods for unit output is compared. The experimental results show that compared with multiple linear regression, BP neural network has higher accuracy in predicting cotton unit yield, which can be used as an idea for future prediction.

How to enhance agricultural plastic waste management in China? Insights from public participation

Agricultural plastics play a pivotal role in agricultural production. However, due to expensive costs, agricultural plastic waste management (APWM) encounters a vast funding gap. As one of the crucial stakeholders, the public deserves to make appropriate efforts for APWM. Accordingly, identifying whether the public is willing to pay for APWM and clarifying the decisions’ driving pathways to explore initiatives for promoting their payment intentions are essential to address the dilemma confronting APWM. To this end, by applying the extended theory of planned behavior (TPB), the study conducted an empirical analysis based on 1,288 residents from four provinces (autonomous regions) of northern China. Results illustrate that: 1) respondents hold generally positive and relatively strong payment willingness towards APWM; 2) respondents’ attitude (AT), subjective norm (SN), and perceived behavioral control (PBC) are positively correlated with their payment intentions (INT); 3) environmental cognition (EC) and environmental emotion (EE) positively moderate the relationships between AT and INT, and between SN and INT, posing significant indirect impacts on INT. The study’s implications extend to informing government policies, suggesting that multi-entity cooperation, specifically public payment for APWM, can enhance agricultural non-point waste management.

A Preliminary Study on the Utilization of Hyperspectral Imaging for the On-Soil Recognition of Plastic Waste Resulting from Agricultural Activities

Plastic in agriculture is frequently used to protect crops and its use boosts output, enhances food quality, contributes to minimize water consumption, and reduces the environmental impacts of agricultural activities. On the other hand, end-of-life plastic management and disposal are the main issues related to their presence in this kind of environment, especially in respect of plastic degradation, if not properly handled (i.e., storage places directly in contact with the ground, exposure of stocks to meteoric agents for long periods, incorrect or incomplete removal). In this study, the possibility of using an in situ near infrared (NIR: 1000–1700 nm) hyperspectral imaging detection architecture for the recognition of various plastic wastes in agricultural soils in order to identify their presence and also assess their degradation from a recovery/recycling perspective was explored. In more detail, a Partial Least Squares—Discriminant Analysis (PLS-DA) classifier capable of identifying plastic waste from soil was developed, implemented, and set up. Results showed that hyperspectral imaging, in combination with chemometric approaches, allows the utilization of a rapid, non-destructive, and non-invasive analytical approach for characterizing the plastic waste produced in agriculture, as well as the potential assessment of their lifespan.

Plastic Mulch Films in Agriculture: Their Use, Environmental Problems, Recycling and Alternatives

Agricultural plastic mulching is an important horticultural process for increasing crop yields because it preserves soil moisture, soil temperature, and nutrients, and avoids the need for weed herbicides. However, there are risks to using plastic mulch, since residual macroplastic (MaP), microplastic (MP), and nanoplastic (NP) in fields have a significant negative impact on the environment, causing damage to soil properties, harming microorganisms in the soil, and entering the human body via the food chain. Plastic mulch is often disposed of in landfills or used in techniques like the thermal process to gain energy or recycling to generate plastic granules for the plastic industry. Pretreatments are occasionally required before recycling, such as cleaning the mulch from the soil to fit the recycling process. This review provides an overview of the quantities and negative impacts of plastic, especially plastic mulch films after use, as well as their decomposition products, on the environment, soil, and human health, and presents alternatives. The possibilities and problems of collecting and recycling films are discussed in addition to the alternatives, for example, the use of biodegradable films. Overall, agricultural advancements to reduce plastic waste in the environment by using thicker films, collection after use, and recycling in developed countries are on a good path. However, NP poses a risk, as it is still completely unclear how it affects human health. Alternatives to plastic mulch have found little acceptance so far due to the significantly higher material costs.

Estimation and Spatial Analysis of Agriculture Plastic Waste Case Study: Karangdowo Subdistrict, Klaten Regency, Central Java Indonesia

Plastic waste is well known as generated from domestic activities; however, agricultural activities, including fertilizing, spraying pesticides, and soil covering, have the potential to generate plastic waste. Many studies indicated that agricultural plastic waste (APW) can cause pollution of agricultural land, impacting soil health, biodiversity, and productivity. Therefore, this study aims to estimate the loading rate of APW and its potential for recycling. The data was collected from farmers in Karangdowo district, Klaten City, Central Java province, Indonesia, based on clustering and random samples. Data on land area, crop type, planting frequency, pesticide and fertilizer application was determined to estimate APW loading rate. Mapping of the estimation of the loading rate of APW and plastic-type in each village was processed using QGIS software. The results show four types of plastic with a total estimation per year: plastic sacks (949.6 kg/year), plastic bottles (182.9 kg/year), plastic bags (697.0 kg/year), and mulch (12913.6 kg/year). There were three types of plastics: High Density polyethylene (HDPE), Low Density Polyethylene (LDPE), and polypropylene (PP). Although the horticulture area was less than 10% of total agricultural area in each village, it generated the highest LDPE from the use of mulch. Ringinputih village has the highest estimation of recycle potential HDPE, LDPE, and PP compared with the other villages due to having the most significant horticultural area and variation of crops.

Mulch-derived microplastic aging promotes phthalate esters and alters organic carbon fraction content in grassland and farmland soils

Agricultural plastic mulch is a major microplastics (MPs) source in terrestrial ecosystems. However, knowledge about the aging characteristics of mulch-derived MPs entering natural and agricultural soils and their effects on phthalate esters (PAEs) and organic carbon fractions is still limited. Black (contains black masterbatches) and white polyethylene (PE) and biodegradable (Bio, Poly propylene carbonate and Polybutylene adipate terephthalate synthetic material (PPC+PBAT)) mulch-derived MPs, at 0.3% (w/w) dose, were added to grassland and farmland soils for eight-week incubation. Microplastic (MP) aging degree was explored by quantifying the carbonyl index (CI). The soil PAEs and organic carbon fractions were also analyzed. After incubation, black and white PE-MP aged greater in farmland than in grassland. PAEs accumulated highest in PE-MP treatment (5.27–6.41 mg kg−1) followed by Bio-MP (1.88–2.38 mg kg−1). Soil organic carbon (SOC), particulate organic carbon (POC), and microbial biomass carbon (MBC) were reduced by 5.3%–8.2%, 31.8%–41.6%, and 39.7%–63.0%, dissolved organic carbon (DOC) was increased by 10.1%–27.6% in grassland containing MP compared to control. MPs’ aging degree promoted PAEs content or altered nutrients, then regulated soil microbial biomass and extracellular enzyme activity directly or indirectly, ultimately affecting SOC. Environmental implicationMicroplastics are persistent environmental pollutants that gradually undergo surface aging in response to extracellular enzymes secreted by microorganisms. As microplastics age, their surface roughness and functional groups change; thus, organochemical contaminants gradually leach out. Therefore, this study analyzed the aging of mulch film-derived microplastics under the action of diverse microorganisms in farmland and grassland soils and the effect on plasticizer and organic carbon fractions. The results proved that polyethylene microplastic aging degree was highest in farmland soil. Besides, biodegradable microplastic caused lower contamination of phthalate esters than polyethylene, but they affected soil carbon balance in grassland and farmland soils. Statement of environmental implicationThis study highlights that MPs affect organic carbon fractions by influencing the PAEs, available nutrients, and extracellular enzyme activity.

Impact of attitudes, factual and causal feedback on farmers’ behavioral intention to manage and recycle agricultural plastic waste and debris

There is a growing concern about the pollution of agricultural systems caused by plastic residue and debris. This pollution poses a threat to the quality of food products. To gain a deeper understanding of how to maintain cleaner farmlands and reduce plastic residue and debris pollution, this cross-sectional study investigated the intention and behavior of plastic residue management (BPRM) in farmlands. Using random sampling method, the study surveyed 338 farmers in northwestern Iran. The resulting evidence found that 37.6% of farmers perform the BPRM with a mean score above average. The path analysis cleared that among the conceptualized ecological, economic, and social connotations, only the ecological attitude had a significant and positive impact on the BPRM (βEcoAtti→BHV = 0.28, p < 0.001). It was found that both fact feedback (βFFBs→Int = 0.76, p < 0.001) and causal feedback (βCFBs→Int = 0.22, p < 0.001) contribute to reducing plastic residue pollution and forecasting the intention to perform the BPRM. The intention, in turn, directly predicts BPRM (βInt→BHV= 0.30, p < 0.001). Using a 2 × 2 cross-tabulation of causal feedback and the scenario of landfilling, derived from perceived action-based life cycle analysis of plastic wastes, the association between the two variables was found to be statistically significant (x2 (df) = 3.24(1), p < 0.05). The resulting evidence would provide essential information for farm management strategists and governmental authorities to reduce plastic residue pollution in farmlands. This can be achieved by implementing policy initiatives that aim to change farmers’ intentions and behaviors.

Occurrence and characteristics of microplastics in soils from greenhouse and open-field cultivation using plastic mulch film

There is a major knowledge gap concerning the extent of microplastic pollution in agronomic regions of China, which represent a plastic use hotspot. In order to clarify the amendment of agronomic region and plastic film mulching mode to microplastics distribution, the characteristics of microplastics distributed in agricultural soils from three typical regions (Beijing (BJ), Shandong (SD), and Xinjiang (XJ)) with two plastic film mulching modes (greenhouse (G) and conventional field-based film mulching (M)) in China were investigated. Microplastics weight and their response to planting regions were also evaluated in this study. The result showed that the average abundance of microplastics in soils from BJ, SD, and XJ was 1.83 × 104 items kg−1, 4.02 × 104 items kg−1, and 3.39 × 104 items kg−1, and the estimated weight of microplastics per kg of dry soils was 3.12 mg kg−1, 5.63 mg kg−1, and 7.99 mg kg−1, respectively. Microplastics in farmland were mainly of small particle size (50 to 250 μm), with their abundance decreasing with increasing particle size. Among the microplastics detected, polyethylene and polypropylene were the two dominant types present, accounting for 50.0% and 19.7%, respectively. The standard total effect of planting regions on microplastic number and weight was 31.8% and 32.3%, and plastic film mulching modes (G vs. M) could explain 34.4% of the total variation of microplastic compositions with a contribution rate of 65.6% in this study. This research provides key data for an assessment of the environmental risk of microplastics and supports the development of guidelines for the sustainable use of agricultural plastic film. Further, it is necessary to quantify and assess the contribution of other different plastic sources to microplastics in soil. Big data technologies or isotope tracer techniques may be promising approaches.

An Assessment of the Factors Inhibiting the use of Plastic Materials among Selected Agro-Enterprises and Farmers in Calabar Agricultural Zone of Cross River State, Nigeria

This study assessed the factors inhibiting the use of plastic materials among selected agro- enterprises and farmers in Calabar Agricultural Zone of Cross River State, Nigeria. The objectives of the study were to indicate the number of registered agro-enterprises that uses plastic materials in the study area, ascertain the ways in which the Government can discourage the use of plastic among farmers and their agro-enterprises in the study area, ascertain the level of participation of respondents in sustainable plastic use in the study area and identify inhibiting factors or constraints to utilization of plastic products by agro-firms in the study area. Both primary and secondary data were used for the study. Primary data was through a structured questionnaire while secondary data was gotten from the Cross River State Ministry of Agricultural. A total of 153 respondents were surveyed. The population of the study included farmers who operates selected agro-enterprises in the study area. Findings revealed that there are about 1230 registered agro-firms in the Calabar Agricultural Zone of Cross River State which make use of plastic input. Ways in which the government can discourage the use of plastic materials were; Government policies that restrict the import/export of plastic materials ( ? =1.7), Government taxes on plastic production ( ? =1.9), among others which were all significant. The highest level of participation in sustainable plastic use in the study area occurred among agro-packaging enterprises ( ? =2.6). Farmers indicated that the constraints of plastic use as identified in this study are insignificant except that it causes death due to ingestion and entanglement. This study therefore recommend the support of the government at all level to support the use of plastic in agriculture due to it many benefits, while seeking better ways to manage plastic menace.

Microplastic characteristics and microplastic-heavy metal synergistic contamination in agricultural soil under different cultivation modes in Chengdu, China

Microplastics have significant implications for global ecosystems. The microplastic distribution, types, sources, and quantified microplastic-heavy metal synergistic pollution in agricultural soil in Chengdu, China were analyzed. The microplastics were detected in all soil samples collected from 103 sites, with concentrations ranging from 1333 to 15067 particle kg−1. The abundance of microplastics in grassland (12,667 ± 3394 particle kg−1) was more than twice higher than that in open field, vegetable field, orchard, and woodland. The main morphological types of microplastics included fibers, films, and granules (all “3-Dimensional” microplastics), with the colors red, blue, and transparent. Granular and fiber microplastics were predominantly in particles < 500 mm, while film microplastics were uniformly distributed at all sizes. The plastic compositions were mainly polypropylene and polyethylene plastics, accounting for 20.73% and 27.90% of the soil microplastic, respectively. Agricultural plastic applications and irrigation water were the sources of soil microplastics. The concentration of Cd, Cr, and Cu in the microplastics was strongly correlated with the corresponding concentration in the soils (p < 0.01), and the microplastic-heavy metal synergistic pollution might deteriorate the soil environment. The results of soil TOC measurements were influenced by microplastics in the soil. The results provide important data for the characteristics of microplastics in the agroecosystem.

The Plastic Age: River Pollution in China from Crop Production and Urbanization.

Many rivers are polluted with macro (>5 mm)- and microplastics (<5 mm). We assess plastic pollution in rivers from crop production and urbanization in 395 Chinese sub-basins. We develop and evaluate an integrated model (MARINA-Plastics model, China-1.0) that considers plastics in crop production (plastic films from mulching and greenhouses, diffuse sources), sewage systems (point sources), and mismanaged solid waste (diffuse source). Model results indicated that 716 kton of plastics entered Chinese rivers in 2015. Macroplastics in rivers account for 85% of the total amount of plastics (in mass). Around 71% of this total plastic is from about one-fifth of the basin area. These sub-basins are located in central and eastern China, and they are densely populated with intensive agricultural activities. Agricultural plastic films contribute 20% to plastics in Chinese rivers. Moreover, 65% of plastics are from mismanaged waste in urban and rural areas. Sewage is responsible for the majority of microplastics in rivers. Our study could support the design of plastic pollution control policies and thus contribute to green development in China and elsewhere.

Advances in the Sustainable Use of Plastics in Horticulture—Perspectives, Innovations, Opportunities, and Limitations

The use of plastics in horticulture is reviewed with respect to its sustainability based on the traditional criteria of triple Rs (reduce, reuse, and recycling) plus a re-place strategy, taking into account possible alternatives. Hail (and insect) nets made of HD-PE, with their long-term use mostly on apple and polytunnels of LD-PE for cherry and strawberry as well as solarisation mulches (reuse), were found to be relatively sustainable solutions for their needs and are currently without alternatives. In contrast, standard black mulch, with its largest share among horticultural plastics, had the widest range of sustainable alternatives, ranging from biodegradable to spray mulch; few sustainable alternatives are available for fleeces and reflective mulches. For the third sustainable option, pilot recycling schemes were examined, such as PolieCoTM (Italy), MAPLATM (Spain), and ERDETM (Germany); they collect 30–50% of the agricultural plastics used in their respective areas, with a successful retrieval growth rate of ca. 20% per year in the case of ERDETM. For the fourth new R option (replace), future sustainability perspectives for the predominant black mulch are research into and development of better, biodegradable, non-fossilbased plastics, sprayable mulch; microbes for the digestion of deployed polyolefins and, for a certain limited range (on shade tolerant crops or in high-light intensity environment), hail nets and polytunnels that are equipped/substituted by/with solar panels (“agri pv”) for the concomitant sustainable production of green renewable energy.

Farmers’ participation into the recovery of waste agricultural plastic film: An application of the Theory of Planned Behavior

This study aims to address the lack of relevant researches in the field of waste recycling using the Theory of Planned Behavior (TPB). A village-scale social survey was conducted to investigate the degree of farmers’ participation in a waste plastic film program, i.e. Old for New in northwest China. The program required farmers to recycle plastic film residues in exchange for new films. Survey results showed that 67.5% of farmers accepted the program, yet only 14.5% of them actually participated. Logistic regression analysis was used to analyze questionnaire data and identify the factors that significantly affected farmers' recycling behavior. Principal component and weight analysis further showed that farmers' participation was mainly influenced by their attitudes (p < 0.01), with a relative weight (RW) of 46.3%. Yet, subjective norms (p < 0.1) and perceived behavior control (p < 0.1) had less effect on the degree of participation, and their RWs were 4.2% and 4.1% only, respectively. Moreover, the RW of plastic film usage characteristics and household characteristics reached up to 13.2% and 6.4%, respectively. Interestingly, environmental awareness (β = 0.083) and compulsory environmental education (β = 0.130) as surface factors strongly affected the farmers' adoption and response, with the RW of 25.7%. As such, the extended TPB model was established to analyze the participation behavior of farmers for stronger explanatory power. This study highlighted a promising strategy based on TPB for waste plastic film recycling and similar environmental management practices.

Analysis and Prediction of the Impact of Socio-Economic and Meteorological Factors on Rapeseed Yield Based on Machine Learning

Rapeseed is one of China’s major oil crops, and accurate yield forecasting is crucial to the growth of the rapeseed industry and the country’s food security. In this study, the data on natural and socio-economic factors from 2001 to 2020 and the yield of rapeseed in China were used as the data basis. The Pearson correlation coefficient was used to analyze the relationship between the influencing factors and the yield of rapeseed, and the prediction effect of four machine learning models (linear regression (LR), decision tree (DTR), random forest (RF), and support vector machine (SVM)) on the yield of rapeseed was compared in China’s main rapeseed-producing area. The results demonstrate that the yield of rapeseed in China showed an increasing trend, but fluctuated greatly. Rural electricity consumption, gross agricultural production, the net amount of agricultural fertilizer application, effective irrigation area, total power of agricultural machinery, and consumption of agricultural plastic film had a positive effect on the increase in rapeseed yield. However, due to the impact of climate change and disasters, the yield of rapeseed has had significant fluctuations. A Pearson correlation analysis showed that socio-economic factors (rural electricity consumption, gross agricultural production, effective irrigation area, total power of agricultural machinery, consumption of agricultural plastic film, etc.) played a dominant role in rapeseed yield changes. The RF model had a good prediction effect on rapeseed yield, and natural factors and socio-economic factors had different effects on spring rapeseed and winter rapeseed. Winter rapeseed yield was mainly affected by socio-economic factors, accounting for as high as 89% of the importance. Among them, the sown area of rapeseed and the effective irrigation area had the greatest impact. The effects of natural factors and socio-economic factors on spring rapeseed yield were similar, accounting for 47% and 53%, respectively, and the mean annual precipitation, sunshine duration, and sown area of rapeseed were the most influential variables.

Mechanical and friction properties of agricultural plastic film during autumn harvest period of cotton in Xinjiang, China.

Agricultural plastic films have caused serious plastic pollution. There are many studies that consider mechanical recycling an appropriate system for the recovery of post-consumption agricultural mulch film. The recovery effect of plastic film depends on the mechanical properties, the level of dirtiness of the post-consumption film, and the recycling process itself. In this study, the mechanical properties of four types of polyethylene plastic films with a thickness of 8, 10, 12, and 10μm, weather-resistant, commonly used in Xinjiang cotton fields, were tested. As well as the friction coefficient between the film and soil, the cotton stalk, boll shell, and leaf with different moisture contents were measured. Then, the self-propelled straw chopping and residual film recycling combined machine collected the four types of mulch films. The results showed that the longitudinal mechanical properties of the plastic film were greater than the transversal ones, with the exception of the nominal tensile strain at break, and the tensile characteristics of the mulching film covered with soil were greater than those without soil. The dynamic or static friction coefficient between the film and the contact material had a linear relationship with the moisture content of the material. During the recycling operation, the better the mechanical properties of the plastic film, the higher the pick-up rate of the mulch film. The maximum longitudinal tensile force of 12-μm plastic film was 3.42 N, and the nominal tensile strain at break was 303.09%. The pick-up rate reached more than 93% when the 12-μm plastic film was recovered in autumn, which effectively reduced the residue of plastic film coverage in the current year. Moreover, the more soil that was present on the much film, the greater the soil content of the recycled film roll, and the stalk content also increased, but the change was small. The research provides a reference for the mechanical and the friction features of agricultural plastic film in Xinjiang, and provides a theoretical basis for the formulation of standards for film thickness and mechanical properties, as well as the design and optimization of a residual film collecting machine in the cotton field.

Release of Additives from Agricultural Plastic Films in Water: Experiment and Modeling.

Globally, more than 6 million metric tons of agricultural plastic films are used to increase crop yields and reduce the use of water and herbicides, resulting in the contamination of soil and water by plastic debris and additives. However, knowledge of the occurrence and release of additives from agricultural films is limited. In this study, suspect screening with high-resolution mass spectrometry, one-dimensional Fickian diffusion models, and linear free energy relationships (LFERs) were used to determine the occurrence and mass transfer of various additives from agricultural plastic films. A total of 89 additives were tentatively identified in 40 films, and 62 of them were further validated and quantified. The aqueous concentrations of 26 released additives reached mg L-1 after a 28 day incubation at 25 °C. Diffusion models and LFERs demonstrated that the film-water partition coefficient and the diffusivity in the polymer, the two critical parameters controlling the mass transfer, could be predicted using Abraham descriptors. The findings of this study highlighted the need for future research on the environmental fate and risk assessment of previously neglected additives in agricultural plastic films and other similar products.

Increasing concentration of pure micro- and macro-LDPE and PP plastic negatively affect crop biomass, nutrient cycling, and microbial biomass

Over the last 50 years, the intense use of agricultural plastic in the form of mulch films has led to an accumulation of plastic in soil, creating a legacy of plastic in agricultural fields. Plastic often contains additives, however it is still largely unknown how these compounds affect soil properties, potentially influencing or masking effects of the plastic itself. Therefore, the aim of this study was to investigate the effects of pure plastics of varying sizes and concentrations, to improve our understanding of plastic-only interactions within soil-plant mesocosms. Maize (Zea mays L.) was grown over eight weeks following the addition of micro and macro low-density polyethylene and polypropylene at increasing concentrations (equivalent to 1, 10, 25, and 50 years mulch film use) and the effects of plastic on key soil and plant properties were measured. We found the effect of both macro and microplastic on soil and plant health is negligible in the short-term (1 to <10 years). However, ≥ 10 years of plastic application for both plastic types and sizes resulted in a clear negative effect on plant growth and microbial biomass. This study provides vital insight into the effect of both macro and microplastics on soil and plant properties.

Effect of agricultural microplastic and mesoplastic in the vermicomposting process: Response of Eisenia fetida and quality of the vermicomposts obtained

This work evaluates the effect of agricultural plastic waste (APW) in two particle sizes, microplastic and film debris, and subjected to a pre-treatment by exposure to UV-C, in the development of the vermicomposting process. Eisenia fetida health status and metabolic response and the vermicompost quality and enzymatic activity were determined. The environmental significant of this study is mainly related to how can affect plastic presence (depending on plastic type, size and/or if it is partially degraded) not only to this biological process of organic waste degradation, but also to the vermicompost characteristics, since these organic materials will be reintroduced in the environment as organic amendments and/or fertilizers in agriculture. The plastic presence induced a significant negative effect in survival and body weight of E. fetida with an average decrease of 10% and 15%, respectively, and differences on the characteristics of the vermicomposts obtained, mainly related with NPK content. Although the plastic proportion tested (1.25% f. w.) did not induce acute toxicity in worms, effects of oxidative stress were found. Thus, the exposure of E. fetida to AWP with smaller size or pre-treated with UV seemed to induce a biochemical response, but the mechanism of oxidative stress response did not seem to be dependent on the size or shape of plastic fragments or pre-treated plastic.

Insights into the mechanism of plastics’ fragmentation under abrasive mechanical forces: An implication for agricultural soil health

AbstractThe application of agricultural plastic products such as mulch, greenhouse covers, and silage films is increasing due to their economic benefits in providing an early and better‐quality harvest. However, mechanical abrasion of these plastic materials by soil particles could result in generation of microplastic (MP) pollutants that could harm soil organisms and impact food safety. This study aims to better understand the physicochemical mechanisms resulting in the fragmentation of low‐density polyethylene (LDPE). Herein, we used pellets and films to study the impacts of abrasive wear forces on their surface morphology variations and fragmentation behavior. An innovative laboratory approach was developed to abrade the plastic surface under controlled normal loadings and abrasion durations. The investigation of the plastics’ surface morphology variations due to the abrasion process revealed microcutting as the dominant process at low normal force (4 N). However, a combination of microploughing and microcutting occurred for new LDPE films by increasing the normal force to 8 N. Despite the significant surface morphology variations of the new LDPE film due to the abrasion process; the water contact angle did not alter. Furthermore, the fragmentation behavior of photodegraded LDPE pellets and films was compared to the new plastics. The extent of MPs (3 µm &lt; dp &lt; 162 µm) generation due to fragmentation was studied using fluorescence microscopy imaging. The localized stress and strains at the contact sites of plastic and sand particles resulted in abrasion of the plastic surface. According to the results, the normal loadings and duration of abrasion played a significant role in the degree of fragmentation of plastics. Increasing the normal loading applied during the abrasion process from 2 to 8 N linearly increased the number of generated plastic fragments by more than five times for pellets and more than three times for film. Photodegradation significantly enhanced the extent of MPs fragmentation. Moreover, the limitations of this study and the implications for agricultural soil health were discussed.

Physiological analysis and transcriptome profiling reveals the impact of microplastic on melon (Cucumis melo L.) seed germination and seedling growth

The wide application of agricultural plastics leads to microplastic (MP) accumulation in the soil and inevitably result in MP pollution. Melon is an economically important horticultural crop that is widely cultivated with plastic film mulching. However, the impact of MP pollution on plant growth remains largely unclear. Here we reported the morphological, physiological, biochemical responses and transcriptome re-programing of melon responses to MP on seed germination and seedling growth. Polyvinyl chloride particles were added to potting mix to simulate MP exposure environment (MEE). The results showed that low and medium concentrations (1–4 g kg−1) of MEE had a significant adverse effect on seed germination and seedling growth. In both cases, the germination potential was decreased, young root forks increased, and tips decreased; and the dry weight of seedlings, the total length, surface area, forks and tips of root were also decreased. However, the root activity was increased. The concentration of MEE to give the best parameters was at 2 g kg−1. Catalase enzymatic activity and reactive oxygen species (ROS) in roots were decreased continuously with increased MEE concentrations. The peak values of peroxidase activity, O2.- content and generation rate, ROS enrichment and malondialdehyde content all reached the highest at 2 g kg−1. MEE also increased the proline content and decreased the contents of ascorbic acid, soluble sugar and soluble protein in these seedlings. Medium and high concentrations of MEE (4–8 g kg−1) also increased the chlorophyll b content. Low concentrations MEE (1–2 g kg−1) inhibited actual photochemical efficiency of photosystem II and photochemical quenching, two key chlorophyll fluorescence parameters. Transcriptome analysis showed that the differentially expressed genes caused by the MEE were mainly belonged to defense response, signal transduction, hormone metabolism, plant-pathogen interaction, and phenylpropanoid biosynthesis. The results of this study will help to understand the ecotoxicological effects of MEE on melons and provide data for ecological risk assessment of Cucurbitaceae vegetable cultivation.