Low-density Polyethylene Mulch Research Articles

Effects of biodegradable (PBAT/PLA) and conventional (LDPE) mulch film residues on bacterial communities and metabolic functions in different agricultural soils

Soil health is a crucial aspect of sustainable agriculture and food production, necessitating attention to the ecological risks associated with substantial amounts of mulch film residues. Biodegradable mulch films (BDMs) carry the same risk of mulch film residues formation as low-density polyethylene (LDPE) mulch films during actual use. More information is needed to elucidate the specific impacts of mulch film residues on the soil environment. Integrated 16S rRNA gene sequencing and non-targeted metabolomics, this study revealed the response patterns of bacterial communities, metabolites, and metabolic functions in the soil from three different agricultural regions to the presence of mulch film residues. LDPE mulch film residues negatively impacted the bacterial communities in the soils of Heilongjiang (HLJ) and Yunnan (YN) and had a lesser impact on the metabolic spectrum in the soils of HLJ, YN, and Xinjiang (XJ). BDM residues had a greater negative impact on all three soils in terms of both the bacterial communities and metabolites. The impact of BDM treatment on the soils of HLJ, YN, and XJ increased sequentially in that order. It is recommended that, when promoting the use of biodegradable mulch films, a fuller assessment should be made, accounting for local soil properties.

Assessment of Yield and Quality of Eggplant (Solanum melongena L.) Fruits Improved by Biodegradable Mulching Film in Two Different Regions of Southern Italy

Low-density polyethylene (LDPE) mulching films have an important function in crop cultivation; at the end of their life, however, their removal and disposal become both an economic and environmental problem. One possible alternative to low-density polyethylene (LDPE) mulch is provided by certified soil-biodegradable mulch films, such as those produced by Novamont and commercially available under the trade name MaterBi®. MaterBi is a biodegradable thermoplastic material made with starch and a biodegradable copolyester based on proprietary technology. In this study, we compared two biodegradable MaterBi®-based films (commercial and experimental films) with bare soil and a low-density polyethylene to evaluate their effect on yield and on a number of qualitative characteristics (organoleptic and nutraceutical composition) of eggplant fruits (cv Mirabelle F1) grown in two different regions in Southern Italy (Sicily and Campania). In our study, the use of biodegradable MaterBi® films improved not only yield and production parameters, such as the number and average weight of fruits, but also lipophilic and hydrophilic antioxidant activity and phenolic and ascorbic acid content. For many parameters, responses differed according to the cultivation environment and, in particular, the site’s pedoclimatic conditions. Our results suggest that biodegradable MaterBi®-based mulching films are a potentially valid alternative to traditional LDPEs, providing the production and quality benefits reported above and promoting environmental sustainability, thanks to their positive biodegradable properties.

Yield and Quality Traits of Tomato ‘San Marzano’ Type as Affected by Photo-Selective Low-Density Polyethylene Mulching

The aim of the present study is to investigate the effect of differently colored low-density polyethylene mulching films (black, silver/brown, and yellow/brown) in comparison with bare soil (BS) on soil temperatures, yield and yield components (number of fruit and average fruit weight), and fruit quality traits (color, firmness, total soluble solids content, polyphenols, flavonoids, ascorbic acid, carotenoids, and antioxidant activity) of a ‘San Marzano’ tomato crop grown in Southern Italy over two years (2014 and 2015). The warmer season (2015) shortened the cropping cycle (124 vs. 178 days, 2015 vs. 2014), thereby accelerating fruit ripening and improving firmness and redness (on average, the color parameter a/b was greater than in 2014). It determined the best yield response (53 vs. 44 Mg ha−1) by increasing the number of commercial fruits per unit land area despite the lower average fresh weight (AFW) than the first year. Regardless of the different plastic films, in both years, soil heat storage produced by mulching improved yield as compared to BS and showed a positive and significant effect on the contents of total soluble solids, polyphenols, flavonoids, and carotenoids without affecting the antioxidant activity. The highest values of quality traits were reached in the second year with silver and yellow mulches. Therefore, since the colored mulching films (yellow and silver) had a contradictory effect on yield and quality in the two years, further investigation is desirable.

Multifunctional soybean protein isolate-graft-carboxymethyl cellulose composite as all-biodegradable and mechanically robust mulch film for “green” agriculture

Multifunctional mulch films with robust mechanical behaviors of biopolymer-based biodegradable mulch materials were highly demanded in promoting the development of “green” agriculture. Herein, a sort of mechanically robust and all-biodegradable soybean protein isolate-graft‑sodium carboxymethyl cellulose composite mulch film was innovatively proposed through the amidation reactions between -COOH on protonated sodium carboxymethyl cellulose and -NH2 on soybean protein isolate. Arising from the reinforced intermolecular interactions upon chemical covalent bonds and physical hydrogen bonds, the maximum tensile strength and the elongation at break were increased from 10.61 MPa and 20.67 % for sodium carboxymethyl cellulose film to 42.15 MPa and 24.8 % for the optimized soybean protein isolate-graft‑sodium carboxymethyl cellulose composite mulch film, respectively. In addition, experimental results showed that the optimized soybean protein isolate-graft‑sodium carboxymethyl cellulose composite mulch film possesses soil moisture retention and controlled urea release properties. When employed as mulch film in practice, the cabbage seed presents higher germination when soil was covered with this versatile mulch film compared to commercial low-density polyethylene mulch film. Our discoveries build a prototype for the manufacture of eco-friendly mulch films with high mechanical strength, soil moisture retention, controlled urea release features.

Scale-up fabrication of a biodegradable PBAT/PLA composite film compatibilized with a chain extender for industrial agricultural mulch film application

Low-density polyethylene (LDPE) mulch films have become a prevalent practice in agriculture to increase crop yield. However, because of their high environmental impact after use, biodegradable plastic films are considered desirable alternatives in agroecosystems. Herein, a polybutylene adipate-co-terephthalate (PBAT) and polylactic acid (PLA) composite film compatibilized with a chain extender (CE) was prepared via a two-step extrusion process. First, PBAT and PLA were blended at different ratios in a laboratory-scale twin-screw extruder, and the PBAT/PLA blends (80/20 wt.%) compatibilized with 1 phr of CE exhibited the most comparable physicochemical properties. The CE integration into the PBAT/PLA binary blend significantly increased mechanical rigidity and strength (p ≤ 0.05). The enhanced compatibility between the immiscible polymers was verified through thermal and phase morphological analyses. The optimum composite was then produced using a pilot-scale extrusion system. The pilot-scale extruded optimal biodegradable mulch composite exhibited excellent water barrier properties, as evidenced by a water vapor permeability of 0.83 g mm/m2·day·kPa and a water contact angle of 93.77° These values surpassed those of commercially available biodegradable mulch films. Furthermore, it demonstrated a weight reduction of 2.9% during a 3-month period of soil burial, exhibiting durability compared to commercial biodegradable mulch films. These results suggest that the developed film has great potential for practical food and agricultural applications.

A review of soil pollution from LDPE mulching films and the consequences of the substitute biodegradable plastic on soil health

The plastic film mulching system has a significant role in increasing crop grain yields by changing the microenvironment of the plant. On the other hand, plastic mulching materials pollute the land and water because they are not degraded or disposed of properly. Biodegradable plastic mulches (BPM) may be used as a substitute for conventional low-density polyethylene (LDPE) to protect soil health. In this review, the effect of micro(nano)plastics on soil health and function has been discussed in light of their distribution in soil, changes in soil biochemistry, interactions between microplastics with soil microbes and plants, and their growth patterns. The nano-plastics are now incorporated into the food chain from the soil through plants and finally harm the whole ecosystem, including humans. The use of BPM has been practiced recently, but only 1% of the world’s total plastic production is from biodegradable materials. In the second part of the review, the confusing terms "bio-based" and "biodegradable" were clarified based on their polymeric constituents. The physical parameters of different constituent materials for mulching purposes and their capability for sustainable solarization have been discussed. The effect of biodegradable mulches on soil health and other ecotoxic effects on plants, soil microorganisms, and other soil dwellers like Daphnia magna, Vibrio fischeri bacteria, green algae, slime mould, protozoa, invertebrates like earthworms, and common water fleas have been focused on in this review. In conclusion, the use of BPM for mulching purposes was reported to improve crop quality and yield and reduce weed growth in comparison to naked soil. The recent short-term studies ensured that mulches stayed unbroken throughout the growing season. But simultaneously, the biodegradable mulches affect soil health and have a substantial impact on physical parameters such as soil pH, electrical conductivity, aggregate stability, infiltration, nitrate-N, exchangeable potassium, etc. Therefore, a lot of long-term research is required for the use of BPM as a substitute for conventional LDPE as a mulching film in the agricultural field.

Large mulch film residues are more unfavourable to the reduction of soil antibiotic resistance genes induced by organic fertilisation than small mulch film residues

Plastic film mulching and organic fertilisation result in the coexistence of mulch film residues of multiple sizes and antibiotic resistance genes (ARGs) in farmlands. However, the differential effects of large and small low-density polyethylene mulch film (LDPEM) and biodegradable mulch film (BDM) residues on ARGs have not yet been studied. In this study, we investigated the dynamic variations in soil ARGs induced by organic fertiliser application under treatments with different LDPEM and BDM residue sizes. The results indicated that the target ARGs could be divided into six clusters according to their variation characteristics with sampling time. The reduction rates of most target ARGs, including ermC, aadA-01, qacEdelta1-01, sul1, sul2, tetM-01, tetM-02 and tetPA in treatments with large mulch film residues were lower than those with small mulch film residues for both LDPEM and BDM, which resulted from the higher average degree and positive correlation ratio in the networks between the soil bacterial community and ARGs. The results of structural equation modelling indicated that soil bacterial communities directly affected soil ARGs, with a path coefficient of −0.6428. Soil physicochemical properties and soil enzyme activities affected soil ARGs through the soil bacterial community with path coefficients of 0.24 and 0.28, respectively. The results of the present study emphasise that the environmental impact of large mulch film residues should not be ignored.

Intensive vegetable production under plastic mulch: A field study on soil plastic and pesticide residues and their effects on the soil microbiome

Intensive agriculture relies on external inputs to reach high productivity and profitability. Plastic mulch, mainly in the form of Low-Density Polyethylene (LDPE), is widely used in agriculture to decrease evaporation, increase soil temperature and prevent weeds. The incomplete removal of LDPE mulch after use causes plastic contamination in agricultural soils. In conventional agriculture, the use of pesticides also leaves residues accumulating in soils. Thus, the objective of this study was to measure plastic and pesticide residues in agricultural soils and their effects on the soil microbiome. For this, we sampled soil (0–10 cm and 10–30 cm) from 18 parcels from 6 vegetable farms in SE Spain. The farms were under either organic or conventional management, where plastic mulch had been used for >25 years. We measured the macro- and micro-light density plastic debris contents, the pesticide residue levels, and a range of physiochemical properties. We also carried out DNA sequencing on the soil fungal and bacterial communities. Plastic debris (>100 μm) was found in all samples with an average number of 2 × 103 particles kg−1 and area of 60 cm2 kg−1. We found 4–10 different pesticide residues in all conventional soils, for an average of 140 μg kg−1. Overall, pesticide content was ∼100 times lower in organic farms. The soil microbiomes were farm-specific and related to different soil physicochemical parameters and contaminants. Regarding contaminants, bacterial communities responded to the total pesticide residues, the fungicide Azoxystrobin and the insecticide Chlorantraniliprole as well as the plastic area. The fungicide Boscalid was the only contaminant to influence the fungal community. The wide spread of plastic and pesticide residues in agricultural soil and their effects on soil microbial communities may impact crop production and other environmental services. More studies are required to evaluate the total costs of intensive agriculture.

Mechanical Properties of Metallocene Linear Low-Density Polyethylene Mulch Films Correlate with Ultraviolet Irradiation and Film Thickness

Mulching technology has created a major problem of agricultural plastic pollution. This is because the mulch is severely degraded by UV (ultraviolet) irradiation and the mechanical properties deteriorate, which makes mechanical recycling or manual recycling difficult. This study was conducted on m-LLDPE (metallocene linear low-density polyethylene) mulch films. The difference in mechanical properties of specimens in the TD (transverse direction) and PD (parallel direction) was investigated, and the changes in the mechanical properties after UV irradiation were compared. Finally, an initial mulch mechanical property evaluation model was developed to adapt to different recovery machines and crop agronomic requirements. The results suggest that the mechanical properties of m-LLDPE mulch films were strongly influenced by the film thickness, and also showed directional differences in tensile and tear properties. After UV irradiation, the mechanical properties of the specimens were enhanced after a short period of time, but the overall trend was a non-linear decay which gradually slowed down with time.

Integrated effects of residual plastic films on soil-rhizosphere microbe-plant ecosystem.

Intensive application of low-density polyethylene mulch films has resulted in substantial accumulation of residual plastics in agricultural soil. Although considerable concerns have been raised on the residual plastic pollution, their impacts on the soil-rhizosphere microbe-plant ecosystem have not been fully elucidated. In this study, we used a pot experiment to determine the effects of residual plastic films with different sizes (La, Ma, Mi and Mx) on properties, enzyme systems and nutrients of soil, composition of rhizosphere microbial community, and physiology, growth and stress response of rice plants. Residual plastic films significantly decreased soil bulk density and increased soil porosity, leading to the alteration of extracellular enzyme activities, and accumulation of dissolved nitrogen (NO3-N+NH4-N). The structures of both bacterial and fungal communities were significantly changed by residual plastic films with rhizosphere microbes more sensitive to small-sized plastics. Plant growth was inhibited to different extents by residual plastic films with different sizes. The weighted gene co-expression network analysis (WGCNA) showed that photosynthesis and carbon fixation of rice plants were repressed by residual plastic films, due to the reduced chlorophyll content and rubisco activity. In addition, the endogenous jasmonic acid and antioxidant enzyme system were induced to activate tolerant responses in rice plants to the stress imposed by residual plastic films. The partial least squares path models (PLS-PMs) revealed that residual plastic films had direct and/or indirect effects on the soil-rhizosphere microbe-plant system.

Soil bacterial community and metabolism showed a more sensitive response to PBAT biodegradable mulch residues than that of LDPE mulch residues

Biodegradable mulch film (BDM) is considered as an environmentally sustainable alternative to low density polyethylene (LDPE) mulch film. However, the low degradation rate of BDM resulted in residues in soil after service period which were similar to LDPE mulch film. Distinguishing the differential responses of crop growth, soil bacteria and metabolism to residues of BDM and LDPE mulch films is favourable for comparing the environmental toxicities of the two materials. The results indicated that emergence rate and yield of Chinese cabbage (Brassica campestris L. ssp. chinensis Makino) were significantly inhibited by two types mulch residues. BDM residues significantly decreased bacterial diversity by 1.2–2.3% through the enrichment of dominant phyla and inhibition of inferior phyla, while LDPE mulch residues not. The effects of BDM residues on soil metabolite spectrum were stronger than LDPE mulch residues with significant increase (3.9% 5.8%) in the abundance of total metabolites. Besides the pathways of metabolism, organismal systems, environmental information processing influenced by LDPE mulch resides, differential pathways including human diseases and cellular processes were also determined in soil with BDM residues. According to all the results of the present study, prior to the promotion of BDM, its influences on soil safety must be carefully investigated through critical and systematic research.

Activated carbon prepared by co-pyrolysis of waste tobacco straw and waste LDPE mulch film: characterization and application for methylene blue removal.

Efficient and inexpensive sorbents play a key role in removing organic pollutants from water bodies. In this study, a series of high surface area activated carbons (ACs) with excellent adsorption performance was prepared by co-pyrolysis of the waste tobacco straw and the waste low-density polyethylene (LDPE) mulch film. Using the maximum adsorption capacity of methylene blue (MB) as an indicator, the variables such as LDPE content, K2CO3 to raw material ratio, activation time, and activation temperature were optimized. The optimal synthesis conditions were as follows: LDPE content of 40%, K2CO3/raw material ratio of 1 : 2, activation temperature of 900 °C, and activation time of 100 min. The maximum adsorption capacity of MB was up to 849.91 mg g-1. The results of scanning electron microscopy (SEM), X-ray powder diffraction (XRD), Raman, X-ray photoelectron spectroscopy (XPS), and BET showed that the moderate addition of LDPE was beneficial to the pyrolysis of the waste tobacco straw, bringing about the enrichment of surface groups (-OH, -COOH) and increasing its specific surface area and pore volume (up to 1566.7 m2 g-1 and 0.996 cm3 g-1, respectively). The equilibrium data of MB adsorption by the composite activated carbon (PAC) was consistent with the Langmuir isotherm, while the adsorption kinetics were better described by a pseudo-second-order kinetic model. This work reveals the feasibility of LDPE mulch film and waste tobacco straw as potential and inexpensive precursors for preparing high surface area AC adsorbents.

Fabrication and evaluation of biodegradable multi-cross-linked mulch film based on waste gelatin

Microplastics from wasted traditional nondegradable plastic mulching films pose a great threat to both the ecological environment as well as human health. Currently, eco-friendly and cost-effective biodegradable films are considered the most promising substitutes for nondegradable plastic mulching films. In this study, we demonstrate a simple and eco-friendly strategy to utilize the gelatin extracted from scrap skin in leather processing and prepare novel biodegradable mulch films. The gelatin chains were covalently cross-linked with tetrakis(hydroxymethyl)phosphonium chloride to reduce the hygroscopicity of gelatin. Then, polyvinyl alcohol (PVOH) was introduced into the gelatin network. The hydrogen bonds between the gelatin and PVOH and several PVOH crystalline domains acted as sacrificial bonds for energy dissipation. Thus, the multi-cross-linked gelatin matrix (GP) films showed high fracture stress (12.03–31.99 MPa) and fracture strain (211.99%–379.73%). Such high mechanical performance is comparable to that of traditional low-density polyethylene mulch films and conforms to the GB/T 35,795 regulatory standards. In addition to their excellent mechanical properties, the mulch films exhibited good water resistance, excellent light transmittance, and good biodegradability in soil. All properties of the GP films are tunable, and their eco-friendliness, low cost, and excellent properties endow them with great application potential as eco-friendly mulch films for agriculture.

Combined effects of mulch film-derived microplastics and atrazine on oxidative stress and gene expression in earthworm (Eisenia fetida)

With the wide use of mulch film and pesticides, mulch film-derived microplastics are very likely to produce combined effects with pesticides in agricultural soil. However, little is known about their combined toxicity on terrestrial organisms. This study aimed to investigate the combined toxicity of unused or farmland residual transparent low-density polyethylene mulch film-derived microplastics (MPs and MPs-aged, respectively) (550–1000 μm) and atrazine (ATZ; 0.02 and 2.0 mg/kg) on the earthworm (Eisenia fetida). After single and combined exposure to ATZ and microplastics for 28 d, the results showed an accumulation of reactive oxygen species, a decrease in superoxide dismutase, catalase, and glutathione-S-transferase activities, an increase in the malondialdehyde and 8-hydroxydeoxyguanosine levels, and abnormal expression of annetocin, heat shock protein 70, translationally controlled tumor protein and calreticulin genes. Integrated biological response (IBR) values calculated at the biochemical level indicated that the combined exposure to ATZ and microplastics, particularly to high concentrations of ATZ, induced greater oxidative stress in E. fetida compared with that of exposure to ATZ or microplastics alone. In addition, the IBR values calculated at the gene level did not show regular changes after combined exposure to ATZ and microplastics compared with those of a single exposure. The oxidative stress and abnormal expression of genes in E. fetida induced by MPs-aged were higher than those induced by MPs; a similar trend was observed for oxidative stress induced by MPs/MPs-aged + ATZ2.0, whereas an opposite trend was observed for the abnormal expression of genes in E. fetida induced by MPs/MPs-aged + ATZ0.02/ATZ2.0. Our results suggest that mulch film-derived microplastics have the potential to enhance the toxicity of ATZ within the soil environment.

The effect of novel biodegradable films on agronomic performance of zucchini squash grown under open-field and greenhouse conditions

The soil mulching is an important agricultural practice for increasing crop productivity and earliness. Mulching can be made with natural or synthetic materials. The common films being used these days are usually made of low density polyethylene (LDPE), but its disposal can represent a serious environmental and economic problem. The biodegradable mulching can overcome these problems. Two experiments were carried out comparing the effects of biodegradable and LDPE mulching films on yield and quality of zucchini (Cucurbita pepo L.) grown in two environments (open-field vs. greenhouse). In both the environments a randomized complete block design was adopted. The treatments composed of no-mulched crop (control), soil covered by 15 microns black biodegradable film (MB15) and soil covered by 50 microns black LDPE film. The results showed that MB15 was able to maintain discrete technical proprieties until the end of cycle, especially in greenhouse, assuring a sufficient heating of soil, similar to LDPE. The soil heating promoted crop development. Furthermore, earliness was increased (84 in greenhouse vs. 99 days in open air) in greenhouse. The early production of zucchini grown on MB15 was similar to the one in LDPE production in greenhouse. The total marketable yield of plants grown on both films was not different but it was lower in open air. The biodegradable film significantly improved fruits quality, with higher values of firmness and total soluble solid than fruits grown on LDPE.

Adsorption, desorption and persistence of fomesafen in soil.

Fomesafen provides control of glyphosate-resistant Palmer amaranth in cotton but frequent seedling injury has been reported. This study evaluated soil adsorption, desorption, and field persistence of fomesafen. The Freundlich distribution coefficient (Kf ) for fomesafen on seven US soils varied from 1.30 to 9.28 µg1-1/n g-1 mL1/n . The pesticide distribution coefficient (Kd ) and soil organic carbon normalized adsorption coefficient (KOC ) varied from 1.11 to 12.76 mL g-1 and 58 to 1467 mL g-1 , respectively. The soils evaluated had desorption rates of 11.06% to 81.31% after a single desorption cycle. Soil pH, organic matter, sand, silt and clay content had a significant impact on fomesafen adsorption and desorption. Fomesafen field half-lives (DT50 ) in Cecil sandy loam were 47 and 34 days, compared with 6 and 4 days in Tifton loamy sand when fomesafen was applied at 1× and 2× the label rate, respectively. The fomesafen dissipation rate decreased significantly under low-density polyethylene (LDPE) mulch compared with bare ground. Fomesafen soil adsorption to soils was not strong and was affected by multiple soil properties. Fomesafen field persistence varied significantly between soil types and under ground cover. The data suggest that soils with a lower pH and higher clay content are less likely to produce crop injury due to greater fomesafen adsorption. © 2018 Society of Chemical Industry.

Teores de clorofila nas plantas e produtividade de frutos de morangueiros cultivados sobre mulching

This study aimed to evaluate productive characteristics and levels of photosynthetic pigments in two strawberry cultivars on different types of mulching, in an open cultivation system. The experiment was a 2 x 4 factorial completely randomized block design, with 2 varieties (Camarosa and Camino Real) and 4 ground covers (black low-density polyethylene, silver low-density polyethylene, non-woven and no mulching), with three replications. The cultivars were analyzed for chlorophyll a and b content, total chlorophyll, and chlorophyll a/b ratio, number of fruits per plant, yield (ton ha-1), weight fruit mass, soluble solids (oBrix), total acidity, pH and soluble solids/total acidity ratio. The Camarosa showed higher yield than cv. Camino Real. The silver low-density polyethylene and non-woven mulching treatment exhibited negative results, and are not recommended for the cultivation of Camarosa and Camino Real strawberries. The black low-density polyethylene mulching was the most recommended for growing such cultivars. Among the types of mulchings evaluated, the black low-density polyethylene achieved the best results and it is recommended for the Camarosa and Camino Real strawberry cultivars.

Halosulfuron-Methyl Degradation from the Surface of Low-Density Polyethylene Mulch Using Analytical and Bioassay Techniques

Vegetable injury and yield loss has occurred when applying halosulfuron to low-density polyethylene mulch (LDPE) prior to transplanting. Research determined vegetable crop response to halosulfuron applied over LDPE mulch from 1 to 28 d prior to transplanting using (1) temperature effects in aqueous solution in laboratory experiments, (2) analytical evaluation of degradation from LDPE under field conditions, and (3) a field bioassay. Halosulfuron stability was evaluated on a thermal gradient table for temperatures at 10 to 42 C for 15 d. Half-life was inversely related to temperatures ranging from 38.5 d at 20 C to 3.2 d at 42 C, with little to no degradation at temperatures of 11 and 15 C. Analytical data indicated that the field half-life of halosulfuron at 26 or 52 g ha−1applied to LDPE mulch under dry conditions was 2.6 and 2.8 d, respectively. Given the changes in the microclimate effects at the mulch surface by absorption of solar radiation, daily thermal energy quantified halosulfuron degradation (at the same rates) to be 51 and 55 MJ m−2, respectively. At 21 d after treatment (DAT), 90% of halosulfuron had dissipated from the mulch, with none detectable 35 DAT under dry conditions. When watermelon or yellow crookneck squash was transplanted into mulch previously treated with halosulfuron at 79 g ha−1, plant growth and development were equal to nontreated controls as long as there was a 14 d prior to transplant (DPT) interval accompanied by 13.5 cm of rain, or a 17 DPT interval accompanied by 6.2 cm of rain. However, at 79 g ha−1applied at 9 or 1 DPT in 2013, and 1 DPT in 2014, halosulfuron injured yellow squash and reduced yield and fruit number. Halosulfuron at 79 g ha−1applied 1 DPT significantly reduced watermelon yield in 2013, which was confirmed by vine length and plant biomass reductions in 2014. Halosulfuron POST controlsCyperusspp. in mulch vegetable production, but time and rainfall are required for dissipation to occur in order to prevent injury and yield loss.

Post-harvest tomato plants and urban food wastes for manufacturing plastic films

Poly(vinyl alcohol-co-ethylene) was compounded with 2–10% post-harvest tomato (PHT) plant powder and processed by single-screw extrusion to yield composite films. Upon increasing the filler content, the values of the mechanical properties indicators were found to decrease as follows: Young's modulus from 1797 to 750 MPa, stress at yield from 36 to 15 MPa, maximal stress from 39 to 15 MPa, stress at break from 35 to 14 MPa, and strain at break from 6.6 to 4.3%. The results are discussed in comparison with other composite films containing poly(vinyl alcohol-co-ethylene) and water soluble biopolymers obtained by alkaline hydrolysis of fermented municipal biowastes, and with other commercial materials, such as starch based and low density polyethylene mulch films. Depending on the intended application, the post-harvest tomato blend films may be competitive for cost, performance and sustainability.

Effect of Plastic Mulch Type on Fomesafen Dissipation in Florida Vegetable Production Systems

Mulches used in plasticulture systems could decrease dissipation of fomesafen, a protoporphyrinogen oxidase inhibitor, and dissuade producers from using the herbicide for fear of crop injury in subsequent growing seasons. Field experiments were conducted in Balm, FL, in 2015 and 2016 to investigate the effect of different plastic mulches on fomesafen dissipation, squash tolerance, and efficacy on purple nutsedge. Squash was injured less than 5% from fomesafen applications. The use of plastic mulches reduced purple nutsedge density at transplant by 60% compared with the no-mulch treatment. At transplant, treatments with low-density polyethylene mulch (LDPE), virtually impermeable film (VIF), and totally impermeable film (TIF) mulch had greater than 2-fold the fomesafen concentrations than treatments with clear or no mulch. At harvest in 2015, LDPE, VIF, and TIF treatments had greater fomesafen concentrations than clear and no-mulch treatments; however, concentrations in 2016 were similar for all treatments. Fomesafen can persist at high concentrations throughout the growing season in Florida plasticulture possibly limiting producer options for crop rotation and the use of cover crops.