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Groundwater is a main type of natural resource, and groundwater evaporation is an important part of the cropland water cycle. Under recent years of poor land management, soil salinization is becoming a serious environmental issue, especially in the arid regions having strong evaporation and shallow groundwater table. Plastic mulching has therefore emerged gradually, becoming a globally applied agricultural practice for its benefits such as salt cumulation control, soil environment regulation, and crop yield improvement. However, knowledge of groundwater evaporation under plastic film-covered cultivation pattern remains vague in terms of action mechanism. This review critically discusses how plastic mulch, salt, and crop cultivation/plant by-products affect groundwater evaporation and further reveals their action mechanisms. For salt-affected cultivated soils, specifically, salt precipitation, crystallization, and capillary force are the non-negligible actions affecting water movement and evaporation. Besides, the physical and chemical effects of formed salt crust at plastic film holes cannot be ignored under plastic mulch underlying condition. Furthermore, the effect of changed canopy cover during growing period should be taken into consideration under crop cultivation underlying condition; meanwhile, the variation of water flow and evaporation induced by crop residues or direct straw return in farmland can be quantified through determining the amount of the hydrophilic oxygen-containing functional groups and the change of soil pore-size distribution. Based on the current research deficiency, future studies should focus on the groundwater contribution to crop, the diurnal variation of groundwater evaporation, the determination of suitable and ecological groundwater table, and the capillary rise models; and future interdisciplinary (e.g., physics and chemistry) research should be put into the interactive of salt and water in order to reveal the mechanisms of fresh and saliferous groundwater flow and evaporation; moreover, the issue on plastic pollution induced by plastic mulch should also be brought to the forefront. A clear understanding of groundwater evaporation under plastic film-covered cultivation on salt-affected soil benefits environmental protection in the saline regions.

Protected cultivation has grown in Brazil. Generally, greenhouses are covered with transparent plastic film and shading screen. The plastic, over time, loses its transparency due to pollution residues, dust and other debris. The loss of transparency reduces lightness, photosynthesis and leads to losses of productivity and product quality. The losses are not always detectable by the farmer. Additionally, internal shading screens are used to reduce heating transmission to the ground. The objective of this study was to evaluate the impact of shading on lettuce crop productivity and to determine the optimum shading to reach the highest productivity. Plots were set up inside and outside the greenhouse, with four shading levels with black screens (0, 35, 50 and 75%). The treatments were converted to real shading from the photosynthetic photon flux measurement. The results of fresh and dry phytomass were treated and analyzed by regression as a function of the real shading. In ambient conditions of photosynthetic photon fluxes around 1000 μmol m-2 s-1, reaching up to 2000 μmol m-2 s-1 at some hours of the day, typical of tropical environment, lettuce may support a shading of up to 50% without risk of productivity reduction; under these conditions, shading between 20 and 35% is beneficial, and can guarantee its maximum productivity in lettuce cultivation. It is recommended that the lettuce producer in protected cultivation monitors the shelf life of the plastic, avoiding that the shading exceeds 50%. In order to compare shading experiments, one should use the incident photon flux (FFI) for the whole crop cycle, indicating the minimum limit value of FFI = 600 mol m-2 cycle-1 for the crispy lettuce at an average temperature close to 21oC. RESUMO O cultivo protegido tem crescido no Brasil. Geralmente, as estufas utilizam plástico transparente e tela de sombreamento na cobertura. A cobertura de plástico, com o passar do tempo, perde a transparência por adquirir resíduos de poluição, poeira e outros detritos. A perda de transparência reduz a luminosidade, a fotossíntese e acarreta a perda de produtividade e de qualidade dos produtos. O objetivo do trabalho foi estudar o impacto do sombreamento sobre a produtividade da cultura da alface e determinar o sombreamento ótimo para alcançar o máximo de produtividade. Foram montadas parcelas dentro e fora da estufa, com quatro sombreamentos com telas pretas (0, 35, 50 e 75%). Os tratamentos foram convertidos em sombreamento real a partir da medição de fluxo de fótons fotossintéticos transmitidos. Os resultados de fitomassa fresca e seca foram tratados e analisados por regressão em função do sombreamento medido. Em condições ambientais de fluxo de fótons fotossintéticos em torno de 1000 µmol m-2 s-1, alcançando até 2000 µmol m-2 s-1 em algumas horas do dia, típico de ambiente tropical, a cultura da alface pode suportar um sombreamento de até 50% sem risco de redução da produtividade. Sombreamentos entre 20 e 35%, nessas condições, são benéficos, podendo garantir o máximo de sua produtividade. Recomenda-se ao produtor de alface em cultivo protegido monitorar a vida útil do plástico, evitando que o sombreamento ultrapasse 50%. Para fins de comparação entre experimentos com sombreamento, propõe-se que seja utilizado o fluxo de fótons incidentes (FFI) para todo o ciclo da cultura, indicando o valor limite mínimo de FFI = 600 mol m-2 ciclo-1 para a alface crespa em temperatura média próxima a 21oC.

Quantitative Fe content determination of powders by Mossbauer spectroscopy is described. In this method, powder samples and internal standard are combined homogeneously in a plastic film ensuring a thin absorber. This method was verified by quantifying the Fe content of a series of samples and independently confirming by inductively coupled plasma optical emission spectroscopic analysis. Additionally, for the first time, Fe contamination in ball-milled Si as a function of milling time was quantified. It was found that Fe contamination increased with time but surprisingly became steady state at 1.12 ± 0.04 at.% Fe after grain size reduction.

The increased competition for water resources has intensified search for the most efficient water-saving techniques and water-use efficient cultivars. A 2-year field experiment was conducted to det...

Farmland surface soil mulching with plastic film is extensively used to enhance agricultural productivity in the Loess Plateau (LP). However, the effect of mulching on the key processes that dominate soil nitrogen dynamics is rarely assessed quantitatively. We quantified the responses of agroecosystem nitrogen cycling to plastic mulching using a comprehensive database drawn from mulching experiments in the LP. Our results indicated that through increasing the soil mineral and dissolved organic nitrogen concentrations, plastic mulching significantly enhanced the soil nitrogen availability by 36.6% at the regional scale, compared with traditional nonmulching. Mulching pattern, nitrogen application, and soil type were found to be the most significant drivers in determining nitrogen availability. Furthermore, nitrogen gaseous releases and hydrological leaching were significantly reduced by 7.0% and 9.4%, respectively, under plastic mulching, which led to an insignificant change in the soil total nitrogen pool. Nitrogen input level and soil organic carbon appeared to be the most important factors influencing soil nitrogen losses. Critically, along with increased root residue inputs to soil and improved water thermal conditions under mulching, soil microbial activity was increased significantly. This was indicated by enhanced microbial biomass nitrogen and soil nitrogen-related extracellular enzyme activity and was driven by nitrogen input, mulching duration, and soil carbon status. We generalize that in the rain-fed agroecosystems of the LP, plastic mulch will have little impact on nitrogen pool size, largely due to reduced gaseous and hydrological nitrogen losses and increased crop-sourced nitrogen inputs, but will strongly stimulate microbial growth, metabolism, and activities, which consequently will speed up biogeochemical cycles of soil nutrients.

The objective of this study was to evaluate the biological parameters and the preference of Artemisia tridentata Nutt (Asteraceae) industrial pollen grains and beer yeast by Ch . externa adults for a more suitable diet for laboratory rearing. To conduct the experiment, 105 adults of newly emerged Ch . externa were used. They were placed in PVC cages (10.0 cm high x 10.0 cm in diameter), closed with PVC plastic film, each cage contained two females and one male (2: 1), and each cage was placed on a diet, being they are: Artemisia pollen ( A. tridentata ), artemisia + honey pollen (mixed), beer yeast, beer yeast + honey (mixed), water, honey, artemisia pollen + honey (separated). The diets 2 (artemisia pollen + mixed honey), 3 (brewer's yeast) and 4 (brewer's yeast + mixed honey) were shown to be statistically good diets at 5% confidence, according to the results analyzed for the parameters fecundity, oviposition, oviposition, mean number of eggs/day and viability of eggs. As the other diets 1 (artemisia pollen), 5 (water), 6 (honey) and 7 (artemisia pollen + separated honey) did not obtain statistically results, because they had means zero or close to zero, so these treatments are not feasible for a rearing of Ch . externa in the laboratory.

The influences of ventilation modes and greenhouse structures on radon concentrations in single- and multi-span plastic film greenhouses were studied to find effective engineering measures for controlling indoor radon by numerical simulation. The plants and mulch on ground, and sealing conditions had been considered to ensure the accuracy of simulation. Ventilation mode obviously influenced the indoor radon concentration and distribution, while the ventilation wind speed and structural form exerted no clear influence. Mechanical ventilation could reduce radon concentration to a greater extent than natural ventilation, and side-face ventilation was superior to end-face ventilation.

It is important to reveal the physiological mechanism of water saving and yield increasing of mulched drip irrigation. Three treatments were applied at aspring maize field in Northeast China: mulch...

Ridge-furrow rainwater harvesting with alternate white plastic film-mulching has been shown to be an easy and efficient method to harvest rainwater and improve crop yield in arid and semi-arid regions in China. To explore how this system affects the pattern of water movement, the water content of the soil, and runoff generation, two systems were designed and tested in Fugu, Yulin, Shaanxi, China from 2010 to 2012. There were three treatment groups as follows: a flat control plot with no mulching (NM), a plot with furrow and ridge widths of 60 cm (P60), and a plot with furrow and W-shaped ridge widths of 40 cm (W80). W80 was found to have a higher mean rate of runoff generation than P60 (83.1% and 70.3%, respectively). Additionally, compared with the other groups, W80 exhibited increased rainwater storage beneath the furrow in both rainy and dry seasons. The water content of the soil beneath the ridges of all treatment groups was higher after rainfall than before rainfall, and the rainwater infiltration rate was higher at 24 h after rainfall than at 48 h after rainfall. Moreover, the water content of the soil under the ridge was higher at the pre-measured stage than at the later measured stage, suggesting that it is not effective for short-term rainfall. Yield, water use efficiency, and soil water storage of rainwater harvesting practices had more advantage than that of NM. These findings suggest that using a ridge-furrow rainwater harvesting system with alternate plastic film-mulching can improve runoff generation, increase rainwater storage, and decrease water loss from the soil. In this system, the water from the soil moved from planted furrows to ridges during rainfall, but the water moved from ridges to planted furrows in the dry season. The W80 system with the W-shaped ridge performed better than the other groups with respect to rainwater storage, evaporation control, runoff generation, and water use efficiency.

HighlightsEffectively separating the “white pollution” from agricultural soil.Three different spades for mechanical recycling residual film were tested.All spades had a similar draft requirement and soil disturbance trend.Spade A provided a higher residual film recovery rate.Abstract. Plastic film mulching cultivation provides important support for increasing the crop yield and ensuring food security, but residual plastic film pollution has become a prominent problem affecting the sustainable development of agriculture especially in northwest China. Recovery of thicker film by residual plastic film recycling machines may represent an effective way to solve this problem. In this study, a combined implement comprising three different spades (spades A, B, and C) were tested in a cotton field to compare their performance. All three types of spades were tested at a travel speed of 4.5 kmh-1 and a working depth of 40 mm. The residual plastic film recovery rate, soil draft force, soil disturbance characteristics (furrow profile), and cotton stubble uprooting were measured. Spade B had a higher draft force than the other spades. This trend was also observed for the soil disturbance area. Spades A and C produced stubble uprooting of approximately 5%, and spade B resulted in an approximately 5.7% larger degree of uprooting. Spade A had the largest recovery rate of residual film, while spade C had the smallest one. Overall, considering both recovery rate of residual film and draft force requirement, spade A showed better performance compared to spades B and C. Keywords: Draft force, Residual plastic film, Recovery rate, Soil disturbance, Spade.

In semi-arid and arid areas, crop growth is mainly limited by low rainfall (mm). Using plastic film-mulched and special soil tillage can be employed to harvest limited rainfall for crop growth so as to assure food production. The objective of this work was to find out how to exploit limited rainfall (mm) to increase yield of proso millet. Effects of different rainfall harvesting systems based on plastic film-mulched in proso millet were managed in semi-arid regions of Loess Plateau in 2010-2012, and soil type that study involved was calciccambisols. The hypothesis was that proso millet could improve growth and yield of proso millet by using rainfall harvesting system. Experiment designed three rainfall harvesting systems based on plastic mulched and no mulching (NM) as a control. A flat plot with no mulching was a control (NM), the width of furrow was 60 cm with 60 cm wide ridge (P60), the width of furrow was 60 cm with 100 cm wide M-shaped ridge (M160), and the width of furrow was 40 cm with 40 cm wide W-shaped ridge (W80). Control plot and systems were laid out in a randomized block design with three replications. Only the ridge was mulched with white plastic film. The results showed as follows: rainfall harvesting systems based on plastic film-mulched could increase water content of topsoil by 19.6%-43%, move up in temperature of topsoil by 0.1oC-2.7oC, improve agronomic traits (P

Plastic, a material obtained from nonrenewable resources such as petroleum products, has so many advantages. Specifically, the main application of plastic is found in food packaging. But every entity has its advantages and disadvantages. Apart from the advantages, plastic has so many disadvantages that should not be neglected. The main problem of plastic is its disposal, as it would result in pollution in terms of landfills, incineration, etc. But, it is also true that we cannot neglect its advantages, which are seen in every field/sectors such as medical, automobile, packaging, etc. So, the scientist has developed biodegradable plastic which completely replaces it with the same advantages and applications. One of the main applications of bioplastic is made from polylactic acid (PLA). This study describes the development of plastic films by utilizing PLA and halloysite nanotubes (HNTs), which ultimately removes the pollution problem with an increase in the plastic films’ mechanical properties. So, the main aim of this study is to determine the characteristics of the novel plastic film that is developed using PLA and HNTs.

Rocket species are rich in nutrients with well-known bioactive activity, but their content depends on several factors, such as plant–UV radiation interaction. In this work, we measured the production of nutritional elements in wild rocket (Diplotaxis tenuifolia L.) leaves as a function of exposure to UV-B radiation by adopting a combined approach. The wild rocket plants were grown under three greenhouse cover films (A, B, and C) having different transmittivity to UV-B and the fresh-cut leaves were exposed to UV-B in postharvest for 45, 150, 330, and 660 s. The content of chlorophyll, carotenoids, phenolic compounds, ascorbic acid, and the antioxidant activity were determined. Chlorophyll, carotenoids, and total phenolic content were significantly increased by the combination of Film C and treatment with UV-B for 45 s. The predominant phenolic compounds were kaempferol, isorhamnetin, and quercetin. Film C also elicited an increase in ascorbic acid (the most abundant antioxidant compound in the range 374–1199 per 100 g of dry matter) and antioxidant activity. These findings highlighted an increase in bioactive compound content in the wild rocket when it was cultivated under Film C (diffused light film with a tailored UV-B transmission dose) and treated with UV-B radiation for 45 s postharvest, corresponding to an energy dose of 0.2 KJ m−2.

This study investigated the offset effect between green manure (GM) application and plastic film mulching (PFM) on soil organic carbon (SOC) stock change during maize cultivation. Within PFM and no-mulching treatments, three different fertilization sub-treatments were applied: (a) chemical fertilizer, (b) barley and (c) hairy vetch. The SOC balance were evaluated by analyzing the net ecosystem carbon budget (NECB). The results showed that the NECB value was negative during maize cultivation regardless of mulching or fertilization condition, indicated SOC loss. The PFM increased maize yield (P

Mulching has been widely used to increase soil temperature and promote seedling emergence in areas with cold springs. However, soil temperature regulation with mulching is not well controlled, whic...

Mulches have been evaluated extensively as a weed management tool in container plant production, but most research has focused on loose-fill wood-derived mulch materials, such as pine bark or wood chips. In this experiment, pine (mixed Pinus sp.) bark (PB), shredded hardwood (HW), and pine sawdust were evaluated for weed control and crop response both alone and in combination with a guar gum tackifier alongside a plastic film mulch, a paper slurry mulch, and the paper slurry mulch + PB and compared with a nonmulched, nontreated control and a single application of preemergence herbicide (oxyfluorfen + pendimethalin). Mulch materials were applied to nursery containers ranging from 7 to 25 gal at two different nurseries and at two research centers in central Florida in 2017 and 2018. Results showed that the plastic mulch provided more than a 90% reduction in hand weeding time and weed weight over a 6-month period, and similar control was achieved with PB, paper slurry + PB, and the HW treatment (64% to 91% reduction in weeding time and weed weight). No growth differences were observed with any mulch treatment in any species evaluated including ligustrum (Ligustrum japonicum), Chinese elm (Ulmus parvifolia), or podocarpus (Podocarpus macrophyllum).

In this study, ‘Rabbab’ pomegranates (Punica granatum L.) were subjected before storage to single-layered wax coating (SLW), double-layered wax coating (DLW), individual-seal film packaging (ISP), tray wrap film packaging (TWP), and combined treatments of SLW + ISP or SLW + TWP. Treated fruits were then stored at ambient temperature (15–20 °C; 45–50% relative humidity – RH) or in cold conditions (5 °C ± 0.5; 85% RH) for 18 weeks. TWP, ISP, DLW, and SLW extended the shelf life of pomegranates for 18, 18, 12, and 11 weeks at cold (5 °C) condition, and also for 6, 5, 3, and 3 weeks at ambient condition, respectively, whereas the shelf life of control fruits were 10 and 2 weeks at cold and ambient conditions, respectively. After 18 weeks of storage, the weight loss in ISP and TWP fruits was 0.6 and 0.4% at cold condition and 12.4 and 5.4% at ambient condition, respectively. In general, film packaging maintained vitamin C, total titratable acidity, and sensory analysis scores for color, freshness, juiciness, and taste of pomegranates more effectively than wax coating and control. However, the combination of SLW and ISP or TWP did not improve the efficiency of pomegranates packaged as either ISP or TWP.

The influence of surface mulching on soil aggregation and associated carbon (C) and nitrogen (N) varies by mulching materials and crop types. The 6 yr effect of straw mulching (SM), plastic film mulching (PM), and no mulching (CK) on soil aggregation and associated C and N concentrations at 0–20 and 20–40 cm soil layers were studied under dryland winter wheat (Triticum aestivum L.) and spring corn (Zea mays L.) in the Loess Plateau of China. Regardless of crop types, aggregate proportion was greater in macroaggregates (2.00–10.00 mm), but lower in microaggregates (

The impacts of climate change on food security have increased interest in research and investments in irrigation technologies and agricultural water management. Agricultural practices such as mulching help to conserve soil moisture by reducing evaporation and mitigate the adverse effects of water stress on crops, especially in semi-arid environments. This study investigated the combined effects of irrigation schedules and different mulching technologies on the growth and yield of two varieties of chilli pepper – Legon 18 (Capsicum frutescens L.) and Kpakpo shito (Capsicum chinense) – in the Guinea Savannah agro-ecological zone of Ghana. Soil temperature and moisture content as well as plant growth parameters were collected over the growth period. The number of days taken for first and 50% flowering and fruiting were also recorded. Total fruit yield and crop water productivity were estimated after harvest. Results show that the combination of irrigation at 100% E T c r o p every three days and rice straw mulch ensured optimal soil temperature and moisture content that improved vegetative growth, shortened the number of days to flowering and fruiting, and significantly improved yield and water use efficiency compared to the other treatment combinations. Fruit yield for this treatment combination was up to 19,042.2 kg/ha and 19,074.6 kg/ha whereas crop water productivity was up to 6.08 kg/m3 and 6.09 kg/m3 for Legon 18 and Kpakpo shito, respectively. Plastic film mulch under each irrigation schedule produced higher growth and yield-related parameters than no mulch treatments. Although findings from this study cannot be directly generalized for the entire Guinea Savannah agro-ecological zone of Ghana due to spatial variability of soil and other climatic variables, the combination of irrigation schedule at 100% E T c r o p every three days and rice straw mulch is recommended for improved yield and water use efficiency in dry season chilli pepper production in semi-arid environments with sandy loam soils.

The surface modification of recycled plastic film-based aggregates was investigated to improve the compatibility between the aggregates and a cement paste. Surface modification was performed using ultraviolet–ozone treatment (UV-O3), a silane coupling agent, O2 atmospheric pressure plasma, and acrylic binder coating methods. The surface properties of the modified aggregates were analyzed using a contact angle measuring instrument. The results revealed that for all surface modification methods, the contact angle decreased with an increase in the treatment time. According to the comparative evaluation results of the changes in the surface characteristics of the aggregates through various surface modification methods, the contact angle reduction rates were 58.9%, 51.4%, 25.5%, and 24.5% for the O2 atmospheric pressure plasma, the acrylic binder coating, the silane coupling agent, and the UV-O3 method, respectively. After 48 h, the contact angle had increased by 110.9%, 29.9%, 16.4%, and 5.9% for the O2 atmospheric pressure plasma, UV-O3, the silane coupling agent, and the acrylic binder coating, respectively. Namely, the surface modification using the acrylic binder coating method was found to be the most effective method in terms of the wettability increase effect and the long-term storage stability.

This study aimed to increase the antibacterial activity of chitosan-polylactic acid (PLA) composite film by adding nisin and ethylenediaminetetraacetic acid (EDTA). We evaluated the mechanical, physicochemical, and antibacterial properties of various PLA composite films, as well as the enhancement effect of PLA composite films with EDTA + nisin on the preservation of grouper fillets. Films of PLA alone, PLA plus chitosan (C5), PLA plus nisin + EDTA (EN2), and PLA plus chitosan plus nisin + EDTA (C5EN1 and C5EN2) were prepared. The addition of EDTA + nisin to the chitosan-PLA matrix significantly improved the antibacterial activity of the PLA composite film, with C5EN1 and C5EN2 films showing the highest antibacterial activity among the five films. Compared with the fish samples covered by C5, the counts of several microbial categories (i.e., mesophilic bacteria, psychrotrophic bacteria, coliforms, Aeromonas, Pseudomonas, and Vibrio) and total volatile basic nitrogen content in fish were significantly reduced in the samples covered by C5EN1. In addition, the counts of samples covered by C5EN1 or C5 were significantly lower compared to the uncovered and PLA film-covered samples.

For the assumed bale volume, its dimensions (diameter, height), minimizing the consumption of the plastic film used for bale wrapping with the combined 3D method, depend on film and wrapping parameters. Incorrect selection of these parameters may result in an optimal bale diameter, which differs significantly from its height, while in agricultural practice bales with diameters equal or almost equal to the height dominate. The aim of the study is to formulate and solve the problem of selecting such dimensions of the bale with a given volume that the film consumption is minimal and, simultaneously, the bale diameter is equal or almost equal to its height. Necessary and sufficient conditions for such equilibria of the optimal bale dimensions are derived in the form of algebraic equations and inequalities. Four problems of the optimal bale dimension design guaranteeing assumed equilibrium of diameter and height are formulated and solved, both free and fixed bale volume are considered. Solutions of these problems are reduced to solving the sets of simple algebraic equations and inequalities with respect to two variables: integer number of film layers and continuous overlap ratio in bottom layers. Algorithms were formulated and examples regarding large bales demonstrate that they can handle the optimal dimensions' equilibria problems.

In this study, seven of the most commonly applied covering materials in smart farms are selected as the representative samples for analysis, namely, glass, soft film (polyethylene, PE), soft film (polyolefin, PO), rigid plastic film (ethylene tetra fluoro ethylene, ETFE), rigid plastic sheet (poly methyl methacrylate, PMMA), rigid plastic sheet (polycarbonate, PC double layer), and woven film. For each covering material, visible light transmittance and reflectivity, solar radiation transmittance and reflectivity, thickness, solar heat gain coefficient, and the coefficient of heat transmission are measured according to the test methods in the Korean Industrial Standards (KS) to derive input data for the respective materials. In addition, using the optical and thermal input data as derived above, simulations are performed on the cooling load and daylight characteristics of smart farms to derive basic reference data for the selection of adequate covering materials for the design. Based on the analysis result of the daylight characteristics for each covering material, for a shading rate of 60%, the average values of indoor illuminance were 19,879 lux, 20,012 lux, 19,393 lux, 19,555 lux, 16,560 lux, 16,228 lux, and 11,173 lux for glass, PE film, PO film, ETFE, woven film, PMMA, and PC double layer, respectively, between 6 a.m. and 8 p.m., which correspond to the hours when daylight enters indoor spaces. Considering the target light intensity for strawberry growth at 10,000–40,000 lux, the above results confirm that all the sample covering materials had an indoor illuminance level above the lower limit range of the target light intensity. For the cooling load evaluation, the PC double layer had the lowest value of 482.8 W/m2, and PO film had the highest value of 633.8 W/m2. The difference between the cooling loads of the PC double layer and the PO film is 151 W/m2, which amounts to 23.8%, thus indicating that the selected covering material significantly impacts the cooling load. The cooling load exhibited a pattern similar to that of the coefficient of heat transmission and solar heat gain coefficient, which are key influencing factors for most of the sample materials. However, for PMMA, the cooling load was low because it had a higher coefficient of heat transmission than other materials, but its solar heat gain coefficient was relatively low. Another possible reason for the difference is that the solar heat gain coefficient impacts the cooling load. When the cooling set temperature was controlled from Case 1-1 to Case 1-2, the cooling load decreased by 10.7% on average. In addition, when the cooling set temperature changed from Case 1-1 to Case 1-3, the cooling load decreased by 26.1% on average. For cooling set temperature control, maintaining the temperature around the lower temperature range of the optimal growth temperature of the plants increases the yield, but it also incurs increased cooling load and cost. In terms of cost only, while maintaining the cooling temperature for 24 h at 30 °C, which is the upper limit of the optimal growth temperature, would be advantageous, it will lead to a deterioration of the quality and reductions in yield. Therefore, as follow-up studies for further investigation of the findings of this research, there is the need for an evaluation of the yield and quality with respect to the range of cooling set temperatures. When the internal shading rate was increased to 40% (Case 2-2) with reference to Case 2-1, which was a greenhouse without the application of internal shading, the cooling load decreased by 27.4% on average. Furthermore, when the internal shading rate increased to 50% (Case 2-3) with reference to Case 2-1, the cooling load decreased by 29.3% on average. When the internal shading rate increased to 60% (Case 2-4), the cooling load decreased by 31.5% on average.

Agricultural plastic film (APF) is widely used in modern agriculture. Under natural environmental conditions, the structure, surface properties and mechanical properties of APFs change because of sunlight, wind and other factors and gradually break into debris, resulting in the generation of microplastics (MPs). Studies have reported that the MPs concentration in soil is positively correlated with the use intensity and duration of APFs. Unfortunately, to the best of our knowledge, no method to measure the emissions of in situ APFs has been developed. In this study, the effects of mechanical abrasion driven by wind on MPs fragmentation by polyethylene (PE) and polyvinyl chloride (PVC) APFs with the increase of exposure time were investigated. Meanwhile, based on the release rate model of PS fragmented MPs under natural sunlight, a modified model to quantify the effect of ultraviolet (UV) radiation exposure duration on the production of APF fragmented MPs was developed. Based on these models, the amount of MPs produced from APFs in farmland in China was estimated. The national annual MPs mass emissions from APFs in agricultural soil were approximately 5 × 104 to 6.8 × 104 tons in 2018 due to wind and 6.5 × 103 tons due to sunlight, and the total emission level due to both wind and sunlight was 5.1 × 104 to 7.0 × 104 tons. Compared with that of wind, the contribution of UV radiation to MPs emission is smaller. Our estimates are comparable to data reported in previous studies, indicating that our models have good practical applications and are of great significance for predicting MPs production from APFs in farmland.

Agricultural plastic films have been proven highly advantageous, but they also cause pollution of plastic debris and associated chemicals. Phthalates (phthalic acid esters, PAEs), an important additive of agricultural films, can be released and contaminate the environment. Here, we analyzed the agricultural plastic usage and assessed plastic debris in China and developed a method to estimate PAE emissions from agricultural films. Additionally, the environmental fate of PAEs was evaluated using a fugacity-based multimedia model. The agricultural plastic film usage in China in 2017 was 2,528,600 tons. After agricultural film recycling and water erosion, the plastic debris amount was estimated as 465,016 tons. The water erosion process carried 4329 tons of plastic debris into the aquatic environment. During its lifetime, the agricultural film released a total of 91.5 tons of two typical types of PAEs. PAEs from the mulching film would mostly be removed through degradation, while those from the greenhouse film accumulate in vegetables. Populated regions exhibited more serious PAE pollution in vegetables but with no immediate health risks. The model was well evaluated using comparable measured concentrations and uncertainty analysis based on the Monte Carlo method. The findings from this study demonstrate the serious agricultural plastic pollution problem and associated PAE contamination in China.