Biodegradable mulch film-enriched with biochar, chicken feather, and oyster shell powder for improved soil quality and crop productivity.

Agriculture is causing unprecedented pressure on water resources to meet a growing food demand. This determines the necessity of implementing innovative, sustainable, and measurable systems to improve water use efficiency while increasing crop yield. This study tested the use of biodegradable mulching (BM) film for irrigated lettuce and the FAO AquaCrop model was used to simulate a precision irrigation scheme. The trials were conducted in the middle Arno River Valley, Tuscany, in Farm 1 (F1) and Farm 2 (F2) during the cropping seasons 2021 and 2022. In 2021 the BM film was tested in late spring at F1 and mid-summer at F2. In 2022, BM was tested twice at F2, in July and September, and once at F1, in June. The AquaCrop model was used only for the F2 mid-summer lettuce trial. Water Productivity (WPi) and ISO 14046 Water Footprint (WF) were measured, and a correlation analysis was performed. The study's outcome reported larger lettuce plants in the F2 BM July trial (0.806 kg plant-1) and smaller ones in F1 trial (0.100 kg plant-1), where the plant density was higher. The amount of irrigation water required was reduced in all the BM trials, ranging between 8%-50%, with the best performance in the F2 BM September trial where the amount was halved. In general, WF was always reduced in the BM trials and the best performance was with the F2 BM July trial (0.13 m3kg-1). Moreover, F2 indirect WF for the BM film production has a major share of impact on water resources ranging from 0.07 m3kg-1 to 0.17 m3kg-1. The best WP was also reached by F2 BM September trial (40.8 kg m-3). The Pearson coefficient (r) reported a strong negative correlation between WF and WP (-.73, p = .01), while, the determination coefficient ( R2) was 0.545. Hence, is confirmed how the reduction of WF is followed by the rise of WP. However, the low R2 shows how the two indicators are not specular but arrays of different useful information. Finally, AquaCrop simulation measured a fall in irrigation requirement (-86%, - 95%) in both treatments, reflecting an overestimation of the farmer irrigation scheme. The results confirmed the positive effect of BM and how using the WF can help farmers track their hotspots on water resources. The production of the BM films presented has a significant impact on water resources due to limited reuse over multiple crop cycles. Longer lasting films should be tested to investigate the reduction of indirect WF.This study was carried out within the FEASAR-PSR 2014/2020 GO PEI PSGO 40/2017 ORTI BLU fund and the Agritech National Research Center and received funding from the European Union Next-Generation EU (PIANO NAZIONALE DI RIPRESA E RESILIENZA (PNRR) – MISSIONE 4 COMPONENTE 2, INVESTIMENTO 1.4 – D.D.1032 17/06/2022, CN00000022). This manuscript reflects only the authors’ views and opinions, neither the European Union nor the European Commission can be considered responsible for them.

Soil pollution caused by the residual polyethylene film is a potential threat to agricultural sustainability. Biodegradable films are generally effective alternatives to reduce this pollution. However, soil quality changes responding to continuous biodegradable film mulch are still unclear. To reveal the accumulative effects of biodegradable film mulch on soil quality, we conducted a positioning experiment from 2016 to 2019 in North China Plain (NCP). Four treatments, including transparent polyethylene film mulching (PM), transparent biodegradable film mulching (TM), black biodegradable film mulching (BM), and non-mulching (CK) were employed. The results showed that compared with CK, both BM and TM treatments significantly reduced soil bulk density and increased soil microbial activity and soil enzyme activity; however, BM and TM did not affect soil nutrient content. Compared with CK, BM treatment significantly increased soil quality index (SQI) by 7.2% (in 2019) due to higher soil fertility content and bioactivity; however, TM and PM treatments decreased SQI by 3.2% and 3.8%, respectively. Besides, compared with CK, BM significantly enhanced summer maize grain yield by 30.35%. Therefore, black biodegradable film is a potential alternative to polyethylene film to improve soil quality and maize production in NCP.

Biodegradable mulch film enhances the environmental sustainability compared with traditional polyethylene film from multidimensional perspectives

The effects of biodegradable and plastic film mulching on nitrogen uptake, distribution, and leaching in a drip-irrigated sandy field

An enormous amount of plastic waste resulting from the agricultural activities is produced every year. Part of this plastic remains in the fields, while the other part is sent to recycling or landfill. The use of biodegradable (BD) mulch films can play a key role towards a sustainable development in agricultural sector because they can be plugged in the soil, after its use, together with the crop residues. The aim of this study was to evaluate the performance of white-on-black biodegradable mulch films in contrast to the conventional polyethylene (PE) mulch film in autumn-winter cycle strawberry production, monitoring the variation on soil warming, lifetime of the films in the field as well as the effects on fruit yield. Soil temperatures showed differences among treatments during summer period under open field conditions and autumn-winter season under tunnel. Although the degradation rate of BD mulch films varied along the crop cycle, they provided adequate bed cover and weed suppression until crop end. Plants had similar monthly crop yield distribution, and percentage of commercial and uncommercial fruits between mulch treatments. From the overall results obtained, biodegradable mulch films may be a promising alternative to PE mulching but there should be economic incentives for growers to implement this sustainable practical as its price at present are not yet competitive.

Biochar (BC) and biodegradable mulch film (BMF) are both commonly used means of production in agriculture. In recent years, most studies have focused on the effects of BC or BMF on soil heavy metal pollution, while they have neglected the combined effects. In this study, a pot experiment was conducted to examine the impacts of BMF, BC, and combined BMF and BC (CMB) on the mobility of chromium (Cr) and the agronomic characteristics of flue-cured tobacco. Compared with the control, BMF, BC, and CMB significantly reduced the concentrations of diethylenetriamine pentaacetic acid (DTPA) extractable Cr in soils by 29.07–29.75%, 45.35–48.54%, and 34.21–37.92%, respectively. In comparison to the application of BMF and BC alone, co-application reduced the availability of Cr in soil via increasing the adsorption of soil Cr and soil enzyme activity, which resulted in the decrease of Cr content and bioconcentration factor and in plants. Moreover, the combined application increased the plant height, stem diameter, leaf area, total root area, root tip number, and root activity of tobacco, which leaded to increase in leaf and root biomass by 11.40–67.01% and 23.91–50.74%, respectively. Therefore, the application of CMB can reduce the heavy metal residues in tobacco leaves and improve tobacco yield and quality.

Mulch films are widely used in modern agriculture due to their many benefits, including extension of the growing season, control on weeds, and saving irrigation water. Biodegradable mulch films (BDMs) — films containing one or more polymer(s) that can be fully metabolically utilized by soil microorganisms to form CO2 and microbial biomass — are considered a viable substitute to conventionally used, environmentally persistent polyethylene films that accumulate in soils over time if not completely removed after harvest. The European Norm for BDMs (EN 17033:2018) stipulates laboratory incubations at 20-28°C to test biodegradation of BDMs for certification. However, to comprehend and predict the fate of BDMs in situ in field soils, it is crucial to understand how temperatures (and variations thereof in the field) affect biodegradation dynamics. Research on this subject is currently limited. In the work presented here, we systematically assess the effect of temperature on the biodegradation dynamics of three commercially available BDMs which are mainly composed of the biodegradable polyesters poly(butylene adipate-co-terephthalate) (PBAT) and polylactic acid (PLA). Laboratory soil incubations were conducted at four environmentally relevant temperatures (i.e., 5, 15, 25, and 35°C) across three different agricultural soils over a two-year period. The biodegradation extents were monitored by quantifying residual PBAT and PLA in the soils at five specific timepoints by Soxhlet extraction of the polymers from the soils combined with polymer quantification using proton nuclear magnetic resonance spectroscopy analysis (1H-NMR). The results show that the biodegradation of both PBAT and PLA is substantially affected by temperature, with a general trend of higher temperatures leading to increased biodegradation rates and extents. In the case of PLA, increasing temperature consistently increased biodegradation across all tested soils and BDMs. PBAT exhibited similar trends, except for one soil, in which the highest temperature (35°C) did not result in the highest PBAT biodegradation extents. The differences between PLA and PBAT likely reflect their distinct primary hydrolysis pathways — enzymatic hydrolysis for PBAT and abiotic hydrolysis for PLA — as well as differences in the presence and activity of polymer-specific microbial degraders between the soils. The results of modeling efforts will be presented that aim to further clarify the temperature effects on biodegradation rates and assess the extent to which these dynamics can be captured by temperature-reactivity relationships, such as the Arrhenius rate law. The results of this work will provide a basis towards predicting the effects of temperature on in situ field biodegradation rates, using laboratory incubations at temperatures of 20-28°C (as specified by the European Norm for BDMs (EN 17033:2018)) as a basis.

Plastic mulch films are increasingly used in agriculture to enhance productivity by assisting in weed control, saving water, and extending the growing season. Many commercial, certified soil-biodegradable mulch films (including the film Bionov B tested herein) contain varying amounts of the two polyesters poly(butylene adipate-co-terephthalate) (PBAT) and polylactic acid (PLA). These polyesters are biodegraded by soil microorganisms as demonstrated under favorable soil incubation conditions. These biodegradable mulch films are seen as viable alternatives to the non-biodegradable conventional mulch films typically composed of low-density polyethylene (LDPE). While the tested biodegradable mulch is certified biodegradable according to the EN:17033:2018 norm, this biodegradability was tested under controlled laboratory incubation conditions with constant temperature and soil moisture. An in-depth understanding of the impact of soil moisture content and the interplay between moisture and temperature on the biodegradation dynamics of these biodegradable mulch films is still missing. In this work, we assessed the effect of soil moisture content on the biodegradation dynamics of PBAT and PLA from the tested mulch film and compared it to that of LDPE-based mulch film (negative control) and poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH) powder as positive control. Laboratory incubations in three soils (a German standard clay soil (LUFA 6S), a Dutch silty loam soil (LOESS), and a Swiss silt clay loam soil (AGR2)) were performed over two years at 23°C at four soil moisture contents (20, 35, 50, and 65% of the soil water holding capacities (WHC)) and, in addition, at 15°C in LUFA6S at all four water contents. Biodegradation was assessed by quantifying residual PHBH, PBAT, and PLA in the soils after 6 and 12 months of incubation by Soxhlet extraction coupled to proton nuclear magnetic resonance spectroscopy analysis (1H-NMR) and, for PE, gravimetrically. PE did not biodegrade under any conditions. After six months, PHBH had extensively biodegraded in all soils at all water contents, except for LUFA6S and AGR2 at the lowest water content with much smaller extents of biodegradation. Residual amounts of both PBAT and PLA after six months were generally higher than for PHBH, demonstrating slower biodegradation of mulch film polyesters than of the positive control. PBAT and PLA exhibited very similar trends. LOESS showed a continuous decrease in biodegradation of PBAT and PLA with increasing water content; ARG2 showed the highest biodegradation at the highest water content; LUFA6S showed optimal biodegradation at intermediate water content. These findings as well as results after 12 months, clearly show that the effect of soil water content on biodegradation of PBAT and PLA is large and highly soil dependent. By comparison, lowering the temperature from 23°C to 15°C had a smaller effect on biodegradation. Ongoing efforts are directed towards linking the effects of soil moisture to soil texture. Our results provide the basis on which to assess the effect of soil water content on the biodegradation dynamics of biodegradable mulch films in field soils under in situ conditions.

Growers are interested in biodegradable alternatives to petroleum-based polyethylene mulch film (PEM). However, many growers cite limited knowledge about biodegradable mulch films (BDMs) as a significant barrier to adoption. Agronomic field tests of BDMs are often limited temporally or spatially, and the variability of performance results relative to PEM may be contributing to this perceived knowledge gap. Our objective was to use data available in the scientific literature to provide the first quantitative performance benchmark of BDMs against PEM. We extracted data from 66 articles for meta-analysis. Response ratios were calculated for comparison of BDMs relative to black PEM, and differences among categorical groups were determined using 95% bootstrap confidence intervals. Overall, BDMs reduced soil temperature by 4.5% ± 0.8% (±one standard error) compared to PEM, and temperatures were coolest beneath paper-based BDM. Starch-polyester BDM was less effective than PEM for weed control, but paper-based BDM reduced weed density and biomass by 85.7% ± 9.2%. Paper-based BDMs were particularly useful for controlling Cyperus spp. weeds. Despite differences in soil temperature and weed suppression, crop yields were not different between BDMs and PEM. Future research should focus on reducing costs, adding functional value, and increasing the biodegradability of BDMs.

Biochar, compost and biochar-compost: effects on crop performance, soil quality and greenhouse gas emissions in tropical agricultural soils

Data-driven analysis of soil quality indicators using limited data

Biodegradable mulch films (BMFs) are becoming increasingly popular in agricultural practices. However, research on the ecological impact of biodegradable mulch films on pepper–soil systems is still scarce. To compare the differential effects of BMFs and polyethylene (PE) mulch on soil chemical properties, soil bacterial community composition, and pepper cultivation, a study was conducted encompassing eight distinct treatments. These treatments included three varieties of polybutylene adipate terephthalate (PBAT) combined with polylactic acid (PLA) mulches: PP-JL, PP-SD, and PP-SH; a black polypropylene carbonate mulch (PPC-BK); a brown PPC mulch (PPC-BR); a polyethylene (PE) mulch; straw mulching (NCK); and an uncovered control (PCK). After applying mulches for 129 days, most PPC and PBAT + PLA films had reached the rupture phase, whereas the PE film was still in the induction phase. Pepper yield was obviously higher in all mulched treatments (4830 kg hm−1) than in the un-mulched control (3290 kg hm−1), especially the BMF PP-JL treatment, which showed the most notable improvements in yield. Although BMF treatments maintained a lower soil temperature than the PE film mulch, they were still higher than the un-mulched control. Furthermore, the soil bacterial community composition and ecological network were not markedly affected by different mulching conditions. However, the PP-SH treatment significantly increased the abundance of Pseudomonas, Nitrosomonas, and Streptomyces genera. Moreover, Lactobacillus and Gp16 were substantially more abundant in the PPC-black (BK) and PPC-brown (BR) treatments compared to the PE mulching treatment. This study could provide valuable insights into the ecological benefits of BMFs in pepper cultivation. However, as our experiments were conducted for only one season, it is imperative to undertake long-term experiments across consecutive seasons and years for a thorough understanding and comprehensive study.

Is biodegradable film an alternative to polyethylene plastic film for improving maize productivity in rainfed agricultural areas? — Evidence from field experiments

Polyethylene mulch film (PEM) is widely utilized in garlic cultivation, significantly enhancing garlic yield. However, the prolonged use of this material leads to serious environmental issues that adversely affect soil health and plant growth. To promote the adoption of biodegradable mulch film (BDM) in garlic cultivation, we investigate the effects of BDMs with thicknesses of 0.006 mm, 0.008 mm, and 0.010 mm on garlic growth and soil properties, comparing them with the commonly used PEM 0.008 mm. The results indicated that the agronomic traits of garlic were significantly improved under both PEM and BDMs compared to no mulching, with yield increases ranging from 75.42% to 90.39%. The highest garlic yield was observed with the BDM 0.008 mm. Most above-ground agronomic traits of garlic did not exhibit significant differences between PEM and BDMs, although a few traits showed slight increases under the BDMs 0.008 mm and 0.010 mm. The quality characteristics of garlic bulbs, including the contents of soluble sugar, vitamin C, and allicin, did not differ significantly between PEM and BDMs. Soil temperature was significantly higher under both PEM and BDMs compared to no mulching. In comparison to PEM 0.008 mm, the application of BDMs 0.006 mm and 0.008 mm significantly enhanced potassium availability in the soil. Furthermore, the activities of catalase, phosphatase, and invertase were notably increased under the BDM 0.008 mm, suggesting that this type of mulch could improve the physicochemical properties of the soil. Additionally, the BDM 0.008 mm remained intact throughout the low-temperature overwintering period, began to partially degrade as temperatures rose in March and April, and exhibited considerable fragmentation during the maturity and harvest periods of garlic. Its degradation rate was well aligned with the growth requirements of garlic. Taken together, these findings suggested that the BDM 0.008 mm is particularly effective, resulting in significant yield increase and an appropriate degradation rate. These results provided a valuable reference for the selection and application of BDM in garlic cultivation.

To effectively address land degradation, a clearer understanding of changes in soil quality indicators within agroecosystems is necessary, along with insights into how these indicators with land characteristics. This study aims to identify the minimum dataset (MDS) required to assess the soil quality index (SQI) across different land uses in the Guinean High Savana agroecological zone of Cameroon specifically in the Faro and Deo subdivision. A total of 100 topsoil samples (0–30 cm) were analyzed for their physicochemical properties, with 70 in GL, 22 in CL, and eight in NF. One‐way ANOVA results clearly show significant differences across land use for N (p < 0.0001), OC (p < 0.0001), C:N ratio (p < 0.0001), K (p < 0.0001), Al (p < 0.05), and silt fraction (p < 0.05). Principal component analysis (PCA) was applied to determine key soil indicators. These indicators were used to evaluate and compare the SQI across various land uses. The identified MDS includes organic carbon (OC), cation exchange capacity (CEC), pH (water), silt fraction, sum of exchangeable bases (SEBs), total nitrogen (N), and magnesium (Mg). The different land use systems significantly influenced the variation of these soil parameters. The SQI was highest (0.55–0.60) in native forests (0.59), moderate (0.45–0.54) in grazing (0.50) land, and lowest (0.38–0.44) in cultivated lands (0.43), with the sequence of soil quality across land uses following the order: native forest > grazing land > cultivated lands. This study highlights the critical role of land use practices in influencing soil properties, soil quality, and the intensity of degradation. Therefore, the sustainable land management practices (agroforestry) are essential for maintaining and improving soil health, particularly in cultivated and grazing lands. Additionally, spatial and temporal variation of the selected MDS and SQI can offer further agricultural land use planning insights.