Plastic Film Mulching Treatment Research Articles

Incorporating canopy radiation enhances the explanation of maize yield change and increases model accuracy under film mulching

Plastic film mulching (PM) has been extensively used to increase crop yields in dryland regions in China. However, the impact of differently colored PM on crop radiation utilization due to the optical properties of the underlying PM surfaces remains unclear. We conducted a two-year field experiment in northwest China to evaluate the dynamics of photosynthetically active radiation interception and absorption (fIPAR and fAPAR), as well as the radiation use efficiency for intercepted and absorbed radiation (RUEi and RUEa) during spring maize (Zea mays L.) growth periods. Two fertilization levels (high and low) and 3 PM treatments (transparent film, black film, and no film) were considered in this study. We also developed empirical regression functions to calculate canopy fAPAR, accounting for both canopy and underlying surface characteristics. Furthermore, we used canopy absorption radiation to drive the Soil-Plant-Atmosphere Continuum System (SPACSYS) model to simulate maize biomass and yield. We found that transparent film mulching (TM) exhibited higher fIPAR and fAPAR than black film mulching and no mulching (CK). TM had an increase of RUEi and RUEa by 10.6% and 9.7%, respectively, relative to CK, resulting in a 9.3–19.2% increase in maize yield and a 25.8–30.2% increase in the partial factor productivity of nitrogen. These increases were mainly attributed to the increased relative chlorophyll content, net photosynthesis rate, and extended grain-filling period under TM. We found that the modified radiation input increased the accuracy of the SPACSYS model in simulating maize biomass and yield. We underscore the importance of using TM in dryland areas to increase crop yields and advocate for incorporating canopy radiation data into crop models, especially in agricultural regions where plastic film mulching is used, to enhance the accuracy of yield simulations.

Alfalfa Cultivation Patterns in the Yellow River Irrigation Area on Soil Water and Nitrogen Use Efficiency

Establishing lucerne field is an efficient way to protect natural steppes, alleviate conflicts between meadows and livestock, and promote the development of animal husbandry. However, problems such as extensive field management, valuing yield over quality, and low resource utilization are endemic in production. Exploring reasonable cultivation patterns can contribute to improving the current situation of artificial grassland production and promoting the high-quality development of husbandry and prataculture. Lucerne the field experiment was carried out in Jingtai, Gansu Province, China in 2021–2022; this study compared and analyzed the effects of three cultivation patterns—ridge tillage with plastic film mulching (PM), ridge tillage with biodegradable film mulching (BM), and traditional flat planting (FP)—on soil water, heat, and fertilizer, as well as lucerne growth, yield, quality, and water and nitrogen use efficiency. The results show that: (1) during the growth period of lucerne, PM and BM treatments augment the average moisture content of the soil layer of 0–120 cm by 31.19% and 24.03% compared to the FP treatment, respectively. In the soil layer of 0–40 cm, PM and BM treatments abate the soil moisture content of the ridges by an average of 19.29% and 7.89% compared to that in the ditches, respectively. In the soil layer of 40–120 cm, PM and BM treatments elevate the soil moisture content of the ridges by 4.40% and 4.65% on average compared to that in the ditches, respectively. The average soil temperature in a soil layer of 5–25 cm shows PM > BM > FP. In contrast with the FP treatment, PM and BM treatments increase the soil temperature of the ridges by an average of 1.87 °C and 0.96 °C and decrease that of the ditches by an average of 0.47 °C and 0.46 °C, respectively. After two years of planting, the three cultivation patterns all promote the soil nutrient content. Compared to the FP treatment, PM and BM treatments increase the organic matter content by 9.94% and 19.94%, respectively. (2) Ridge tillage with film mulching can evidently stimulate the growth of lucerne and enhance yield and quality. Compared to the FP treatment, PM and BM treatments enhance plant height by an average of 15.37% and 4.04%, stem diameter by an average of 34.14% and 14.58%, yield by an average of 21.20% and 14.77%, crude protein content by an average of 13.47% and 7.68%, and relative feed value by an average of 8.71% and 4.41%, respectively. (3) During the two-year growing period, the irrigation amount of lucerne was 508.60–615.30 mm, and the evapotranspiration was 563.70–761.80 mm. Compared to the FP treatment, PM and BM treatments hoist water use efficiency by an average of 43.50% and 17.56%, nitrogen partial factor productivity by an average of 21.20% and 15.22%, and net income by an average of 14.78% and 11.05%, respectively. In summary, in ridge tillage, both ordinary film mulching and biodegradable film mulching can create a favorable soil environment for lucerne growth and heighten production effect. The former has a better effect on advancing the lucerne production effect, and the latter exhibits superior performance in improving soil fertility.

Response of plastic film mulched maize to soil and atmospheric water stresses in an arid irrigation area

Water stress can severely decrease crop productivity by restricting photosynthesis, while the use of plastic film mulching can mitigate these water stress effects. However, the intricacies of photosynthetic and stomatal responses to soil water stress under plastic film mulching, particularly when combined with atmospheric water stress, have not been well studied, especially in arid irrigation areas. Limited research has investigated photosynthetic chlorophyll fluorescence parameters, stomatal responses, grain filling process and crop productivity to soil and atmospheric water stress under plastic film mulching. Our study addresses this knowledge gap through a comprehensive field experiment in an arid irrigation area involving maize (Zea mays L.). Well-watered and water deficit conditions with and without plastic film mulching treatments, alone or combined with atmospheric water stress (different vapor pressure deficits) were conducted. Our findings revealed that soil water stress significantly increased stomatal limitations (by 6.4–12.4 %) and may cause non-stomatal limitations. Plastic film mulching significantly improved plant photosynthetic performance (increased net photosynthesis rate by 12.2–39.8 %), chlorophyll fluorescence parameters, and stomatal regulation. Under mulched conditions, soil water stress primarily affected photosynthetic performance through stomatal limitations. Moreover, plastic film mulching significantly improved grain filling process (increased grain-filling rate by 6.3–78.5 %) and productivity (increased grain yield by 12.1–45.8 %) in spring maize subjected to soil water stress. Atmospheric water stress, alone or combined with soil water stress, influenced plant photosynthetic performance, decreasing the net photosynthesis rate and stomatal conductance. Mulching enhanced photosynthetic performance under atmospheric water stress. Overall, the positive effect of mulching on spring maize photosynthetic performance and productivity under soil and atmospheric water stresses holds promise for alleviating water resource shortages and addressing global climate warming issues in arid irrigation areas.

Long-term plastic film mulching altered soil physicochemical properties and microbial community composition in Shiyang River Basin, Northwest China

Plastic film mulching (PM) is used widely to improve crop water productivity in the arid regions of Northwest China. However, there are increasing concerns about the potential harm to soil health due to the presence of residue plastic film (RPF) mixed into the soil after long-term field mulching. In our study, we investigated the density of RPF in farmland topsoil (0 to 40 cm) (Exp. I) by analyzing 75 soil samples collected from 15 fields with varying durations of PM (ranging from 3 to 27 years). In addition, we examined the impact of long-term PM and PM + BM (BM, biodegradable film mulching) on soil health (Exp. II) based on an 8-year field experiment. The results illustrated that the weight of RPF ranged from 42.7 to 165.9 kg ha−1 after 3 to 27 years of mulching, with 10 out of 15 fields exceeded the national standard of China (75 kg ha−1). Compared with no film mulching treatment (NM), the long-term PM treatment significantly increased aggregate stability, while significantly decreased soil pH and the enzymatic activities of sucrase by 1.5 % and 33.4 %, respectively. Further, the Chao1, Shannon and Pielou's indices of bacteria significantly decreased after 8 years of PM. Compared with PM and NM, PM + BM treatment significantly improved the Chao1, Shannon and Pielou's indices of bacteria and altered the relative abundance of dominant bacterial and fungal phyla. The principal coordinates analysis (PCoA) revealed significant changes in the soil bacterial and fungal community structure under PM + BM, with the soil fungal community displaying higher sensitivity to PM + BM compared to PM. No significant differences were observed in soil organic matter (SOM), soil microbial biomass C (MBC), soil microbial biomass N (MBN) contents and the enzymatic activities of soils between PM + BM and PM treatments. Overall, BM could be a promising alternative to polyethylene plastic film for improving soil health and is recommended for farming practice in the arid regions of Northwest China.

Is adding biochar be better than crop straw for improving soil aggregates stability and organic carbon contents in film mulched fields in semiarid regions? –Evidence of 5-year field experiment

Plastic film mulching is used widely to increase crop yields in semiarid areas, but improving the soil fertility in film mulched fields is also important for achieving sustainable high yields in northwest of China. In this study, a completely randomized two–factor field design experiment was conducted in Pengyang, Ningxia, China during 2017–2021. In order to investigate the effects of plastic film mulching with straw/biochar addition on the soil aggregate characteristics, organic carbon content, and maize yield. Six treatments were established as follows: control (C), straw (S), biochar (B), plastic film mulching (F), plastic film mulching with added straw (FS) or biochar (FB). After 5 years of continuous production, each straw and biochar addition treatments significantly improved the soil aggregate distribution and stability, and the average aggregate content >0.25 mm increased significantly by 47.32%. Compared with the treatments without plastic film mulching, the mean weight diameter and geometric mean diameter of the soil particles increased by 9.19% and 4.15%, respectively, under the plastic film mulching treatments. The organic carbon content of the 0–60 cm soil layer increased significantly under each straw and biochar addition treatment compared with the without straw. The aggregate organic carbon contents under each treatment increased as the aggregate particle size increased, where the straw and biochar addition treatments significantly increased the organic carbon content of the aggregates, whereas the contents decreased under the plastic film mulching treatments. The contributions of the soil aggregates >0.25 mm to the organic carbon contents of the 0–60 cm soil layer were significantly higher under FS (37.63%) and FB (56.45%) than F. Structural equation modeling showed that straw/biochar added, plastic film mulching, and a greater soil organic carbon content could significantly promote yield increases, where the straw and biochar addition treatments significantly increased the average maize by 14.6% on average. In conclusion, carbon input as straw, especially biochar, had a positive effect on improving the soil organic carbon content and maize yield under plastic film mulching farmland in a semiarid region.

Use of metagenomics and metabolomics to quantify changes in rhizosphere soil microbial function in response to mulching regimes

AbstractThe effects of distinct mulching regimes on the microbial functional properties and metabolic profiles of rhizosphere soil remain largely unknown. Here, we conducted metagenomic and metabolomic analyses to explore the microbial functional specificity and metabolic pathways under three mulching regimes, namely, traditional flat planting with non‐mulch (TP), ridge‐furrow plastic film mulching (RF), and plastic film mulching (PFM). Compared to TP treatment, RF and PFM treatments significantly improved the soil temperature and moisture content, stimulated the increase of five extracellular enzyme activities, thereby reducing soil nutrient content (soil pH, total N, soil organic carbon, NH4+‐N, and NO3−‐N) to meet crop demand for nutrients. In addition, RF treatment significantly decreased the relative abundance of nxrA, while increasing the relative abundance of nasA, thereby further decreasing NO3−‐N content. However, RF and PFM treatments had no significant effect on the relative abundance of nirB, nirD, nrfA, and nrfH. Meanwhile, PFM and RF treatment stimulated the increase of extracellular enzyme activities accelerated microbial metabolism, thereby promoting the synthesis of metabolites involved in carbohydrate metabolism, lipid metabolism, nucleotide metabolism, and amino acid metabolism. Metabolomics and network analyses revealed that RF and PFM treatments not only enriched organoheterocyclic compounds, organic acids and derivatives, lipids and lipid‐like molecules, and organic oxygen compounds but also increased their relative abundance in the major modules. Overall, this study provides deep insights into how mulching regimes alter soil microbial functional potential and metabolic profiles, which may have predictable impacts on the rhizosphere soil nutrient cycling of agroecosystems under mulching systems in semiarid regions.

Plastic film mulching regime altered fungal, but not bacterial community structure at the regional scale

Plastic film mulching (PFM) can influence soil nutrients, thereby improving plant growth and yield in vast dryland areas. However, it is unclear how PFM treatment affects soil microbial communities, especially with respect to community diversity, assembly processes, and co-occurrence patterns in multiple sites. In the present study, we explored the effects of traditional flat planting (TP) and PFM on the crop yield as well as the soil quality, bacterial and fungal diversity, community composition, assembly processes, and co-occurrence networks in broomcorn millet (Panicum miliaceum L.) fields in northern China. The results showed that compared with TP, PFM significantly enhanced soil hydrothermal conditions and soil nutrients, thereby improving the agronomic characteristics and yield of broomcorn millet in the nine study sites. Furthermore, PFM significantly reduced the fungal alpha diversities and changed the fungal community composition and relative abundances of some bacterial and fungal taxa. Random forest (RF) analysis indicated that fungal alpha diversity, soil temperature, and pH were the most important factors affecting broomcorn millet yield. PFM decreased the stochastic processes of the fungal community, also reduced the complexity and stability of the bacterial and fungal networks, which was reflected in the lower number of nodes, edges, ACC, and degree. Moreover, PFM also altered the bacterial and fungal keystone taxa. In summary, we were able to accurately estimate the influence of PFM on soil quality and microbial ecology, and our results provide valuable information for the sustainable development of dryland agriculture in northern China.

Effects of tillage with mulching on potato yield and the characteristics of soil water and temperature in arid area of southern Ningxia

To clarify the effects of tillage with mulching on potato yield and soil water and heat characteristics, we conducted a field experiment for two consecutive years in arid region of southern Ningxia. The results showed that tillage depths and mulching materials had significant impacts on soil water storage at 0-100 cm layer during the potato sowing period. The interactive effects of tillage depths and mulching materials were not significant. In 2019, the highest soil water storage was obtained in the subsoiling 30 cm with plastic film mulching, while soil water storage under the subsoiling 40 cm with straw mulch was the highest in 2020. Subsoiling 30 cm with plastic film mul-ching and subsoiling 40 cm with straw mulch significantly increased soil water storage by 16.9% and 33.4% compared with the plowing 15 cm with no mulch (CK), respectively. Tillage depths and mulching materials significantly affected soil water storage in the key growth period of potato. Among the tillage systems, the straw mulching plots and plastic film mulching plots had the strongest effect of soil water conservation. Irrespective of the mulching materials, soil water storage was significantly improved in the subsoiling 30-40 cm plots. Mulching materials and the interaction between tillage depths and mulching materials significantly affected soil effective accumulated temperature at 0-25 cm soil layer after sowing to budding. Among the tillage systems, the plastic film mulching plots significantly increased the average soil effective accumulated temperature by 9.3%, whereas the straw mulching plots significantly reduced the temperature by 18.7%, in comparison with no mulching plots. The highest soil effective accumulated temperature during the whole growth period was obtained in the subsoiling 30 cm with plastic film mulching and subsoiling 40 cm with plastic film mulching treatments in 2019 and 2020. The highest potato tuber yield and economic benefit in 2019 were found in the subsoiling 30 cm with straw mulching treatment, respectively, being 84.6% and 107.9% higher than CK. In 2020, the improvement effect of subsoiling 40 cm with straw mulch on potato tuber yield and economic benefit was the strongest, respectively, which were significantly increased by 81.7% and 105.7%, compared with CK. Tillage depths and mulching materials had significant interactive effects on the water and heat use efficiency of crop. The higher water use efficiency was obtained in the subsoiling 30-40 cm with straw mulch treatments, whereas the accumulated temperature use efficiency was increased significantly under different tillage depths with straw mulching treatments compared with CK. Soil water and effective accumulated temperature during the tuber formation stage were the main factors affecting potato total yield, with stronger effect of soil water than that of soil effective accumulated temperature. Therefore, the treatments of subsoiling 30-40 cm with straw mulch could improve soil moisture and heat condition, and realize potato yield and income increase and efficient use of water and heat resources, which have application and popularization value in dryland potato cultivation of southern Ningxia.

Black Plastic Film Mulching Increases Soil Nitrous Oxide Emissions in Arid Potato Fields

Black plastic film mulching is a common practice for potato production in the arid area of Northwest China. Many studies have reported the significant positive effect of black plastic film mulch on potato harvest, while the effect of black plastic film mulch treatment on soil nitrous oxide (N2O) emissions is still unclear. As a consequence, this study aimed to examine the effect of black plastic film mulch treatment on N2O emission from arid upland potato fields. With the static chamber-gas chromatography method, soil N2O emissions were measured. The results showed that black plastic film mulching treatment significantly increased cumulative soil N2O emissions by 21-26% compared with non-mulched treatment. Cumulative N2O emission positively correlated with soil temperature, soil moisture, soil CO2 concentration, and amoA-AOB abundance. This study indicated that black plastic film mulching, mainly through increasing soil temperature and soil moisture, increasing soil carbon dioxide (CO2) concentration, and promoting the abundance of nitrification-related functional gene of amoA-AOB, regulated N2O emissions. This study also highlighted that the specific soil environment under black plastic film mulch is conducive to N2O emissions and lay the foundation for settling the contradiction between food production and greenhouse gas mitigation in upland soils. The negative effects of black plastic film mulching on the environment should be considered in future applications in food production.

Decreased greenhouse gas intensity of winter wheat production under plastic film mulching in semi-arid areas

Greenhouse gas intensity (GHGI), the evaluation of GHG emissions per unit yield rather than per unit land area, has recently received much attention. Plastic film mulching (PFM) is one of the major agricultural practices in semi-arid areas, but few studies have synthetically studied the effects of PFM on GHGI, grain yield, soil characteristics, and their potential relationships at different winter wheat (Triticum aestivum L.) growing stages. Here in the semi-arid Chinese Loess Plateau, we simultaneously investigated two cropping systems from 2018 to 2020: PFM with 100 % cover and no film mulching (control). Averaged across two growing seasons, the PFM treatment significantly increased soil temperature, water-filled pore spaces and soil water storage, while sustaining high aboveground biomass (31.9 %) and grain yield (45.5 %). The PFM treatment significantly increased cumulative N2O emissions by 56.2 %, CO2 emissions by 39.7 %, and CH4 uptake by 151.4 % compared to the control treatment. GHGI are on average 14.2 % lower in the PFM treatment than in the control treatment. Moreover, the PFM treatment significantly improved soil enzyme activities (alkaline phosphatase, catalase, invertase, and urease) and microbial biomass carbon and nitrogen from grain filling to maturity stage. Altogether, the reductions in GHGI suggest that PFM-induced increases in grain yield could outweigh the adverse impacts on GHG emissions, underscoring the potential to apply PFM for sustainable intensification of crop production in semi-arid areas.

Effects of Plastic Film Mulching on Soil Enzyme Activities and Stoichiometry in Dryland Agroecosystems.

Soil extracellular enzymes are pivotal for microbial nutrient cycling in the ecosystem. In order to study the effects of different nitrogen application rates under plastic film mulching on soil extracellular enzyme activities and stoichiometry, five nitrogen application levels (i.e., 0, 90, 150, 225 and 300 kg·hm−2) were set based on two treatments: plastic film mulching (PM) and no film mulching (LD). We measured the soil extracellular enzyme activities (EEAs) and stoichiometry (EES) of four enzymes (i.e., β-1,4-glucosidase (βG), leucine aminopeptidase (LAP), β-1,4-N-acetylaminoglucosidase (NAG) and alkaline phosphatase (AP)) involved in the C, N and P cycles of soil microorganisms in surface soil at five maize growth stages (seedling stage, jointing stage, trumpet stage, grout stage and harvest stage). The results showed that there were significant differences in soil EEA at different maize growth stages. The soil nutrient content and soil EEA were significantly improved under PM, and the stoichiometric ratio of extracellular enzymes (EC:N:P) was closer to 1:1:1, which indicated that PM was beneficial to the balance of soil nutrients and the activity of microorganisms. At each stage, with the increase in nitrogen application levels, the soil EEA showed a trend of increasing first and then decreasing (or remained unchanged), and both LD and PM treatments reached their highest activity at the 225 kg·hm−2 nitrogen application rate. When the nitrogen application level was less than 225 kg·hm−2, the soil enzyme activity was mainly limited by the N nutrient, and when the nitrogen application level reached 300 kg·hm−2, it was mainly limited by the P nutrient. RDA and correlation analysis showed that the soil C:P, C:N, N:P and pH had significant effects on soil βG, NAG + LAP and AP activities as well as EC:N, EC:P and EN:P.

Plastic Film Mulching Improved Maize Yield, Water Use Efficiency, and N Use Efficiency under Dryland Farming System in Northeast China.

This 2-year field study analyzed plastic film mulching (PFM) effects on nitrogen use efficiency (NUE), and soil N pools under rainfed dryland conditions. Compared to no-mulching (NM, control), maize yields under PFM were increased by 36.3% (2515.7 kg ha−1) and 23.9% (1656.1 kg ha−1) in the 2020 and 2021 growing seasons, respectively. The PFM improved (p < 0.01) the water use efficiency (WUE) of maize by 39.6% and 33.8% in the 2020 and 2021 growing seasons, respectively. The 2-year average NUE of maize under the PFM was 40.1, which was 30.1% greater than the NM. The average soil total N, particulate organic N, and microbial biomass N contents under the PFM soil profile were increased by 22.3%, 51.9%, and 35%, respectively, over the two growing seasons. The residual 15N content (%TN) in soil total N pool was significantly higher (p < 0.05) under the PFM treatment. Our results suggest that PFM could increase maize productivity and sustainability of rainfed dryland faming systems by improving WUE, NUE, and soil N pools.

Interaction between soil water and fertilizer utilization on maize under plastic mulching in an arid irrigation region of China

Plastic film mulching (PM) has become a widely used cropping method in arid and semiarid areas. However, it is unknown how different PMs affect crop water and N utilization and their interaction under different N supplies. A two-year field experiment was conducted in the Hetao Irrigation District (HID), in northwest China. Following local irrigation practices, 500 mm border irrigation was used to grow spring maize over two growing seasons (2019 and 2020) with two N levels: high-N (225 kg N ha–1) and low-N (150 kg N ha–1). Combined with three mulching methods, the experiment had five treatments: (i) no mulching with high-N (control, CK), (ii) black plastic film with high-N (HB), (iii) transparent plastic film with high-N (HT), (iv) black plastic film with low-N (LB), and (v) transparent plastic film with low-N (LT). The 4 PM treatments had higher average soil water storage (0–120 cm) than CK. The PM treatments had the highest water consumption coefficients (Kwcn) at 6–leaf to 12–leaf stage (Kwc2) and milking to maturity (Kwc5) stage. The HP treatments (HB and HT) had higher soil nitrogen storage than CK during the growth period. Averaged across two seasons, HB and HT had 23.9%, 29.2% respectively, higher grain yields than CK. Averaged across two seasons, the transparent PM treatments had 7.49%, 5.31%, and 1.72% higher water use efficiency (WUE), partial factor productivity of nitrogen (PFPN), and harvest index, respectively, than the black PM treatments. The PM treatments showed the relationship between water use efficiency of biomass (WUEb) and nitrogen use efficiency of biomass (NUEb), with WUEb increased, NUEb also increased. Given these results, we recommend the high-N level and transparent PM for maize cropping to increase yield and resource utilization efficiency in the HID.

Increased soil organic matter after 28 years of nitrogen fertilization only with plastic film mulching is controlled by maize root biomass

Nitrogen (N) fertilization and plastic film mulching (PFM) are two widely applied management practices for crop production. Both of them impact soil organic matter individually, but their interactive effects as well as the underlying mechanisms are unknown. Soils from a 28-year field experiment with maize monoculture under three levels of N fertilization (0, 135, and 270 kg N ha−1 yr−1) and with or without PFM were analyzed for soil organic C (SOC) content, total soil nitrogen (N), root biomass, enzyme activities, and SOC mineralization rates. After 28 years, N fertilization increased root biomass and consequently, SOC by 26% (averaged across the two fertilizer application rates) and total soil N by 25%. These increases, however, were only in soil with PFM, as PFM reduced N leaching and loss, as a result of a diurnal internal water cycle under the mulch. The SOC mineralization was slower with N fertilization, regardless of the PFM treatment. This trend was attributed to the 43% decrease of β-glucosidase activity (C cycle enzyme) and 51% drop of leucine aminopeptidase (N cycle) with N fertilization, as a result of a strong decrease in soil pH. In conclusion, root biomass acting as the main source of soil C, resulted in an increase of soil organic matter after 28 year of N fertilization only with PFM.

Effects of mulching on soil temperature and yield of winter wheat in the semiarid rainfed area

• Mulching significantly increased winter wheat productivity. • The cooling effect may be beneficial to vegetative growth and yield formation. • Mulching reduced the daily variable amplitude of soil temperature. • Mulching showed the warm effect in the season with lower air temperature. Mulching is a major production mode with highly effective use of water in the hydrothermal deficient area of northwest China. However, given the differences in environments and crop species among regions, it is important to further understand whether the mulching-induced changes in soil temperature are beneficial to crop production. Here, we used winter wheat to study the effect of mulching on soil temperature, soil water content, dry matter and yield. Two 3-year field experiments were conducted at two sites over 6 consecutive years (2012–2015 at site 1, and 2015–2018 at site 2) in the semiarid rainfed thermal deficient areas of northwest China. In each experiment, three mulching treatments, including straw strip mulching (SSM), plastic film mulching (PFM) and non-mulching (CK), were tested in a replicated randomized block design. Compared with CK, SSM and PFM significantly increased grain yield by 18.6–69.1 % and 35.5–61.3 % in 2012–2017 growing seasons, except that there was no significant difference in the wet year (2017–2018). In the SSM treatment, soil temperature generally decreased at different growth stages, resulting in a slight decline of 0.9–1.9 ℃ in the 0–25 cm soil layer, whereas in the PFM treatment, soil temperature increased before the jointing stage and decreased subsequently. SSM reduced the daily variable amplitude of soil temperature by decreasing the maximum soil temperature, whereas PFM produced the same effect by decreasing the maximum soil temperature and increasing the minimum soil temperature, which could promote the winter wheat vegetative growth and yield formation in the six experimental years. SSM and PFM decreased accumulated soil temperature from the overwintering stage to maturity stage by 60.1–234.6 ℃ and 30.5–148.5 ℃, respectively. The beneficial effect of the change in soil temperature in SSM and PFM plots expanded the storage capacity of winter wheat. Overall, the moderately cooling effect of mulching was conductive to promoting vegetative growth and expanding storage capacity, ultimately improving crop yield. Our results suggest that SSM can be adopted for sustainable winter wheat production in semiarid rainfed areas under thermal deficient conditions.

Carbon footprint of a winter wheat-summer maize cropping system under straw and plastic film mulching in the Loess Plateau of China

The objective of this study was to calculate the carbon footprint (CF) of straw and plastic film mulching practices in order to identify the optimum field management for low-carbon agriculture. A four-year field experiment was conducted to determine the effects of different mulching measurements on greenhouse gas (GHG) emissions, grain yield, and CF of a winter wheat-summer maize cropping system in the Loess Plateau of China. Mulching treatments were no mulching (NM), straw mulching (SM), half plastic film mulching (HPM); full plastic film mulching (FPM), and ridge-furrow planting with film mulching over ridges (RPM). Plastic film mulching decreased N2O emissions compared with NM. However, SM significantly increased direct N2O emissions by 59.2% and indirect N2O emissions by 16.2%. Average annual total GHG emissions calculated by life cycle assessment were 5199–7631 kg CO2-eq ha−1 yr−1. Nitrogen (N) fertilizer was the largest contributor to total GHG emissions, accounting for >41%. For plastic film mulching treatments, the second greatest contributor was plastic film, accounting for 21.1–35.7% of total GHG emissions. In contrast, the second greatest contributor was direct and indirect N2O and CH4 emissions under NM (17.2%) and SM (21.6%). Emissions from diesel consumption was the third largest component of total GHG emissions. All mulching treatments showed significantly greater annual grain yield than the NM treatment. The CF of summer maize yield was higher than that of winter wheat. SM showed the lowest CF (0.38 kg CO2-eq kg−1), and plastic film mulching increased CFs compared with NM. These results suggest that SM should be the priority mulching practice used to increase yield and to reduce the CF of winter wheat-summer maize production in the Loess Plateau, China. Optimizing N fertilizer application rates should be one of the key production strategies employed to mitigate agricultural GHG emissions.

Impact of plastic film mulching on global warming in entire chemical and organic cropping systems: Life cycle assessment

Plastic film mulching (PM) has been exploited as a beneficial cropping tool to control weeds and to improve soil conditions in temperate-monsoon climate regions. However, the impact of PM on global warming is not clearly understood because it can increase both net primary production (NPP) and soil organic matter decomposition. In particular, the additional greenhouse gas (GHG) emissions from the film manufacturing industry and from waste disposal processes have not been properly considered. To investigate the influence of PM on GHG fluxes in the entire cropping system, PM and no-mulching treatments were installed under organic and chemical fertilization treatments for maize cultivation. The net global warming potential (GWP) was determined by using two GHG (CH4 and N2O) fluxes and soil carbon (C) stock changes with CO2 equivalents within the entire cropping system. PM significantly increased the net GWP by 95 and 35% compared to no-mulching under the organic and chemical fertilization treatments, respectively, whereas most of the net GWP (88–91%) was affected by the GHG flux of the inner cropping boundary. In the cropping process, an average 83 and 91% of the net GWP was influenced by the decrease in the soil C stock in the organic and chemical fertilization treatments, respectively. In contrast, organic fertilization was effective in decreasing the net GWP under the same mulching system due to the reduced soil C stock. PM increased maize grain yield by an average of 52 and 70% compared to no-mulching in the organic and chemical fertilization treatments, respectively, and PM decreased the GHG intensity (GHGI), which implies a net GWP per grain yield of 20 and 30%, respectively, compared to no-mulching. In conclusion, PM can be an effective tool to reduce the GHGI compared to no-mulching; however, PM was more effective in the chemical fertilization treatment than in the organic amendment treatment.

Effect of plastic film mulching on maize productivity and nitrogen use efficiency under organic farming in South Korea

Winter cover crop cultivation and its biomass recycling as green manure (GM) were accepted as an ideal nutrient management practice in temperate organic farming fields. Since its biomass growth was boosted with air temperature rising from late Spring to early Summer, this stage overlapped with cash crops' seeding or transplanting. Thus, organic farmers were suffering from low crop productivity, due to delayed mineralization of incorporated biomass. To accelerate the mineralization of biomass nutrients and control weeds, plastic film mulching (PM) was broadly utilized in organic farming fields of temperate-monsoon climate region. However, the effect of PM on increasing nutrient use efficiency was not properly quantified in GM amended soil. To determine the effect of PM on crop productivity and nutrient use efficiency in GM amended soils, PM and no-mulching treatments were installed under different levels of GM biomass amended soils (0, 25, 50 and 100% of harvested aboveground biomass). The biomass productivity of barley and hairy vetch mixture as cover crop and biomass nitrogen productivity were dramatically increased from the mid May to the early June. PM significantly improved soil temperature and moisture regimes during maize cropping seasons, and then increased inorganic N (NH4+ and NO3−) contents in soils. These improved soil properties under PM highly increased maize productivity and nitrogen use efficiency (NUE). Comparing with no-mulching, as GM application level was increased, the effect of PM on increasing maize productivity became greater, but its effect on increasing NUE became smaller. In conclusion, PM could be very useful tool to improve productivity and NUE of cash crop maize in organic cropping fields, in which the harvesting time of GM biomass might be sustained to increase GM biomass productivity.

Ammonium oxidizing bacteria and archaea vary with season under plastic film mulching and long-term fertilization

ABSTRACT Agronomic practices such as long-term use of plastic film mulching (PFM) and application of organic and inorganic fertilizers have profound effect on soil microbial community. However, there is limited information on the abundance and community structure of ammonia-oxidizers where these practices have been employed. In this study, we investigated soil ammonia oxidizers in a long-term application of fertilizer plots with or without PFM in two seasons of a maize-growing period. The fertilization treatments included: non-fertilizer control (CK), nitrogen fertilizer (N), organic manure (M), nitrogen fertilizer plus organic manure combined (MN). Real-time quantitative polymerase chain reaction (qPCR) of ammonia monooxygenase (amoA) genes revealed that the abundances of ammonia-oxidizing archaea (AOA) (1.0 x 107 to 2.0 × 1011 per copies g−1 dry soil weight) significantly (p < 0.05) out-numbered ammonia-oxidizing bacteria (AOB) (5.0 x 105 to 4.0 × 109 copies g−1 dry soil weight) abundances for June, July and October respectively. The phylogenetic analyses of denaturing gradient gel electrophoresis (DGGE) 16S rRNA gene revealed that AOB-uncultured Nitrosospira sp dominated bacterial ammonia oxidizers in fertilized and non-fertilized soils, regardless of PFM treatments for July and October. The non-fertilization treatment significantly increased bacterial richness (15.67 ± 0.33) under PFM treatment relative to fertilized treatments.

Evaluating the effects of plastic film mulching patterns on cultivation of winter wheat in a dryland cropping system on the Loess Plateau, China

Plastic film mulching (PFM) can increase or stabilize crop yields worldwide when applied to agricultural planting systems, especially in arid and semi-arid areas. Although the adverse effects that are caused by residual plastic film, such as plastic pollution, are becoming a global concern, the application of PFM will not be replaced by other materials in the short-term in agriculture. It is important to understand the various PFM patterns (different mulching periods and coverage rates) that impact on soil physicochemical properties and characteristics of crop growth. Therefore, based on a field experiment that we established in 2002, we conducted consecutive field observations from 2013 to 2016 to determine the optimum PFM mulching period and coverage rate. Three mulching periods were included: (I) summer fallow period (FM), (II) growth period (GM), and (III) whole growth year (WM). Two coverage rates were included: (i) 50%, half mulching (HM), and (ii) 100%, total mulching (TM). That is, there were six different PFM treatments. No mulching (NM) over the growth years was considered the CK treatment. PFM increased canopy height and leaf area index of winter wheat (Triticum aestivum L.) in the growing season by 29.5% and 19.4%, respectively. Average winter wheat grain yields of various PFM patterns were 5318.5 kg ha−1 and 4557.7 kg ha−1 in 2013–2014 and 2015–2016, respectively; these yields were 13.8% and 23.7% higher than NM in 2013–2014 and 2015–2016, respectively. However, the difference in the growth characteristics and grain yield of winter wheat under various PFM patterns resulted from the change in the mulching period and coverage rate. Winter wheat grain yield and biomass increased with GM and WM compared with FM and NM in normal rainfall years. PFM coverage rates improved yield significantly (P < 0.05) and influenced soil nutrient concentrations. HM maintained or increased soil organic matter (SOM) and total nitrogen concentrations, but TM decreased SOM concentration by 8.3%. Water use efficiency (WUE) and rainfall use efficiency (RUE) were improved by various PFM patterns. Furthermore, WM had the most significant impact on SOM concentrations, GM was second, and FM was minor. Considering the costs and benefits of PFM patterns, the half coverage rate of PFM during the whole year (FWH) had the best index (BI) value, and the total coverage rate of PFM during the growth period (FGT) and the half coverage rate of PFM during the growth period (FGH) had higher BI values than other PFM patterns; the values for BI for FWH, FGT, and FGH were 10.3, 8.9, and 8.5, respectively. In conclusion, ignoring the amount of PFM pollution in the environment (or use biodegradable film instead of polyethylene film), FWH was the best PFM pattern with the highest WUE and RUE in dryland rainfed agriculture. But, to decrease the amount of PFM application and pollution, FGH was more beneficial for soil health with a low coverage rate and short mulching period. FGH was the optimal pattern for PFM when applied to winter wheat on the Loess Plateau, China based on our field experiment.