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Producing more food with a lower environmental cost is one of the most crucial challenges worldwide. Plastic mulching has developed as one of the most dominant practices to improve crop yields, however its impacts on greenhouse gas (GHG) emissions during the production life cycle of a crop are still unclear. The objective of this work is to quantify the impacts of plastic film on GHG emissions and to reduce GHG emissions with innovative agronomic practices. Carbon footprint per unit of area (CFa), per unit of maize grain yield (CFy), and per unit of economic output (CFe) were evaluated for three maize cultivation systems: a no mulch system, a conventional plastic mulching system (PM) and a biennial plastic mulching pattern, namely a ‘one film for 2 years' system (PM2), during 2015–2018 in a maize field located on the Loess Plateau of China. The results suggested that PM induced a 24% improvement in maize yields during the four experimental years compared to a no-mulch treatment (NM). However, PM dramatically increased the CFa by 69%, 59% of which was created by the input of the plastic film material, and 10% was created by increases in the soil N2O emissions. The yield improvements from PM could not offset the increases in CFa, and CFy and CFe were both increased by 36%. Shifting from PM to PM2 did not reduce crop yields, but it led to a 21% reduction in CFa and 23% reductions in CFy and CFe due to the reduced input amount of plastic film, decreased soil N2O emissions, and less diesel oil used for tillage. Compared to NM, CFy and CFe were only 5% higher in PM2. This study highlights the necessity of reducing the amount of plastic film input in the development of low-carbon agriculture and shifting from conventional PM cultivation to PM2 could be an efficient option for mitigating GHG emissions while sustaining high crop yields in plastic mulched fields.

Plastic mulching (PM) has become an important agricultural practice to improve crop yields worldwide, while there is still a lack of methods to quantify the complex spatial variations of soil water content (SWC) in the PM field. In this study, a methodology for using Electrical Resistivity Tomography (ERT) to get SWC information in the PM field was presented. Its performance in monitoring SWC was validated, and the spatial variation of SWC was analyzed using the ERT results. A simplified Waxman and Smits model was selected to calibrate the pedo-physical relationship, and it showed good performance (coefficient of determination > 0.92). With the calibrated model, the SWC obtained using ERT showed good agreement with soil moisture sensors in different soil layers (RMSE

China is a large agricultural country, and food security is significantly limited by the shortage of water resources. Plastic mulching technology can effectively modify the crop growth environment and crop production due to differences in climatic conditions, spatial distribution characteristics, and cropping systems and methods. In this study, a meta-analysis was conducted to quantitatively analyze the effects of plastic film mulching and residual plastic on yield and water use efficiency (WUE) of maize, wheat, potato, and cotton in China based on 266 peer-reviewed publications. The results showed that plastic mulching significantly increased crop yield (24.32%) and WUE (27.63%). Plastic mulching had the greatest effect of potato on yield (30.62%) and WUE (30.34%) in China. At a regional scale, plastic mulching performed best in Northwest China, and crop yield and WUE were influenced by film color, mulching method, and crop type. Black film and ridge row mulching were more favorable to crop growth and increased crop yield and WUE in arid areas of China. There was no significant effect on crop yield of residual plastic between 0 and 240 kg/ha, but the yield decreased significantly with increased time and residual plastic film >240 kg/ha. In conclusion, although plastic mulching can significantly increase crop yield and WUE, especially in dryland agriculture, we should also improve the technology for recovering residual plastic film to protect the environment.

The extensive application of plastic-film mulching (PFM) has brought a series of environmental pollution due to the lack of awareness of plastic-film rational use and absence of plastic residues recycling in China. In addition, the use of degradable film instead of common polyethylene plastic film (PE film) can effectively alleviate this situation. The substitution of PE film with biodegradable film in the agricultural production of processed tomato in Xinjiang region was investigated in this study. Using bare soil as the control, we compared the effects of PE film and biodegradable film mulching on crop growth, yield, and economic benefits in processed tomato. The results indicated that: (1) Biodegradable film with a thickness of about 8 μm can meet the mechanical operation requirements, and the effect of biodegradable film mulching was completely consistent with that of PE film, (2) Four kinds of biodegradable film can meet the requirements of processed tomato growth and development, although slightly different from PE film in increasing temperature and water retention, (3) Plastic-film planting can ensure a net profit of 1.14–1.64 ten thousand CNY per hectare under the current production conditions and mode of Xinjiang region, and biodegradable film planting was observed to be essentially equal to those of PE film, (4) Nearly 50%–70% of the biodegradable film was ruptured and degraded during processed tomato harvesting, which avoided the occurrence of the winch of the plastic-film winding harvester and improves the efficiency and commodity rate of the processed tomato harvest operation. As the biodegradable film mulching causes no residual pollution, it is accepted to be an alternative to plastic-film mulching for agricultural applications and supports the sustainable development of agroecosystems in Xinjiang region.

The use of plastic much films has been fundamental to promoting food production in many regions of the world. However, concern is growing about the progressive accumulation of plastic residues in soil after crop harvest and its subsequent impact on soil health and potential to enter the food chain. Although biodegradable films have been developed to prevent these problems, it is still unclear whether they are environmentally benign. Here we evaluated the physical and chemical breakdown of four commercial poly(butylene adipate-co-terephthalate) based biodegradable mulch films (BMF1, BMF2, BMF3 and BMF4) in an agricultural soil over a 26-month period. Based on visual examination, degradation followed the series BMF4 > BMF1, BMF2 > BMF3. Importantly, microplastic residues (fragments

Upon environmental weathering, plastic materials form smaller sized microplastics, of which the contamination in agricultural fields is of significant importance and increasing social concern. Plastic mulch films are considered a major source of agricultural soil microplastic pollution. However, the mechanism and kinetics of microplastic formation from plastic mulch films were rarely understood. In this study, the rate of microplastic generation from typical mulch films, such as oxodegradable, biodegradable, and conventional non-degradable (polyethylene, PE) mulch films, were quantified in soil under simulated UV irradiation. Results showed that microplastic formation was more rapid from biodegradable mulch film, followed sequentially by oxodegradable mulch film, white PE mulch film, and black PE mulch film. The kinetics of microplastic generation strictly followed the Schwarzchild's law, with exponential growth at indexes between 1.6309 and 2.0502 in the microplastic generation model. At a cumulative UV irradiation of 2.1 MJ/m

The actctivated carbon + solar radiation membrane is an eco-friendly soil disinfestations method for managing soil-borne plant pathogens. However, little was known the impact of Activated carbon + solar radiation membrane on bacterial community structure in strawberry production systems under field conditions. A comprehensive evaluation of the impacts of different soil disinfection methods on the bacterial community structure is fundamental to understand the role of disinfection in maintaining soil health. The changes in the soil bacterial diversity and community composition were detected using realtime fluorescence quantitative PCR (RTFQ PCR) and next-generation sequencing techniques to better understand the effect of soil disinfection. The bacterial community composition was monitored after disinfection using dazomet (DZ), chloropicrin (CP), 100 kg/ha activated carbon + solar radiation membrane (AC1), 200 kg/ha activated carbon + solar radiation membrane (AC2), and 300 kg/ha activated carbon + solar radiation membrane (AC3) and compared with the control (CT). The results indicated that the different dosages of activated carbon (AC1, AC2, and AC3) did not affect the bacterial community structure. On the other hand, DZ and CP considerably reduced the soil biomass and abundance of bacterial species. Chemical fumigants influenced the bacterial community structure, with DZ treatment leading to the dominance of the phylum Firmicutes, accounting for approximately 54%. After fumigation with CP, Proteobacteria and Acidobacteria were the dominant phyla. Beta diversity analysis and principal coordinate analysis revealed that the bacterial communities in the soil treated with DZ and CP formed clusters. Redundancy analysis indicated that soil pH, available potassium, and available phosphorus were the key factors influencing microbial metabolic functional diversity. Thus, it was verified that the damage caused by activated carbon + solar radiation membrane&mdash, a potential alternative for chemical fumigant&mdash, to the soil bacterial community was less than that caused by chemicals DZ and CP.

Predicting the change in carbon storage in regions of high carbon uptake and those under highly intensive human disturbance is crucial for regional ecosystem management to promote sustainable development of the economy and ecology in the future. We use a process‐based model to estimate the terrestrial carbon storage in Yangtze River Economic Belt (YREB) and to predict the change of carbon storage over the next 100 years. The results show that the vegetation carbon (VC) and soil organic carbon (SOC) storage were 8.97 and 28.85 Pg C in the YREB from 1981 to 2005, respectively. The highest VC density is distributed in the southern region of the YREB, and the highest SOC density distributes in subalpine and alpine area of the western region of the YREB. Carbon storage in the YREB continued to increase from 1981 to 2005 and in future projections, under both the representative concentration pathway 4.5 (RCP4.5) and the RCP8.5 scenarios. The increased rate of carbon storage in the YREB under the RCP8.5 scenario is higher than that under the RCP4.5 scenario. Under the RCP4.5 scenario, the increasing trend of VC storage tends to be reduced after the 2060s; conversely, the increase of both VC and SOC is accelerated after the 2050s under the RCP8.5 scenario. The SOC density in Western Sichuan will decrease in the future, especially under the RCP8.5 scenario. Western Sichuan has the highest SOC density in the YREB; therefore, it is important to manage the ecosystems there in order to cope with significant warming. The positive impact of warming and the CO2 fertilization effect on vegetation growth and carbon uptake will be predominantly attributed to the increase of terrestrial carbon storage in the YREB. However, warming will stimulate the decomposition of soil organic carbon, contributing directly to reducing SOC storage in high‐altitude regions (e.g., alpine and subalpine regions of Western Sichuan)., The vegetation and soil carbon storage is 8.97 Pg C and 28.85 Pg C, respectively, which accounts 42.13% and 26.04% of Chinese terrestrial ecosystems. Rising temperature and elevated atmospheric CO2 concentration stimulate the increase of carbon storage in Yangtze River Economic Belt, and the increase is higher under RCP8.5 than that under RCP4.5. Soil carbon storage in western Sichuan province, where has the highest soil carbon storage, decrease in the future under both scenarios.

Management strategies are needed to solve the problem of low soil temperatures under no‐tillage combined with residue retention, which can reduce crop yields in cold semiarid regions. Plastic mulching has been proposed as a solution. A 4‐year field study was conducted to investigate the effects of no‐tillage combined with residue retention and plastic mulching (NTRP), compared with no‐tillage with residue retention (NTR) and conventional tillage (CT) on soil moisture content, soil temperature, water use efficiency (WUE) and maize yield at a cold semiarid site in northern China. Compared with CT, NTR significantly increased soil moisture content by 11.5% in the 0–1.8‐m soil profile (p

Numerical solution of the Richards equation with Hydrus-2D model is a low cost and fast way to get information on spatio-temporal soil water dynamics. Previous researches with Hydrus-2D have developed two different approaches to represent the rainfall infiltration in irrigated field with plastic mulching: ‘BP’ – an approach comprised by bare strip boundary and plastic strip boundary without consideration of film side infiltration;‘BP + ’- an approach comprised by bare strip and plastic strip with integrating the process of film side infiltration by increasing the rainfall infiltration amount in bare strip. Nevertheless, the performance of these approaches has not yet been evaluated in rain-fed fields. Considering much more dominant role of rainfall infiltration in rain-fed agriculture, we tested an additional approach which comprised a bare strip, plastic strip and planting hole (BPH) to take into account the effect of the rainfall canopy redistribution and film side infiltration, and we compared its performance to the two existing approaches. Results suggested BP completely failed to reproduce the soil water content (SWC) in all soil layers of plastic strip and in the deep soil layers of bare strip. BP+ overestimated the SWC in 0–20 cm of the bare strip, while the performance of BPH was acceptable in different positions. After that, we compared the soil water distribution between no-mulched field (NM) and plastic mulched field (PM) with approach BPH. Our simulation showed that the highest SWC in PM occurred near the planting hole, SWC in the center zone of plastic strip was lower, while SWC in the bare strip was lowest. PM improves the soil water availability not only in the plastic strip but also in the bare strip as compared to NM.

Soil carbon dioxide (CO2) emission from agricultural areas is a complex phenomenon with high temporal and spatial variability. Tillage practices can affect drivers of CO2 production and therefore influence emissions by soils. However, the impact of tillage management on CO2 emissions from soil is uncertain due to specific climate and soil characteristics. A field experiment was initiated in 1992 in Shanxi, China including the no-tillage plots with straw mulching (NT) and conventional-tillage (CT) treatment. In 2012, another treatment (NT0) was conducted during which the straw was not returned to the plots when the winter wheat harvested. The CO2 emissions, soil temperatures and soil moisture content were measured during the fallow and wheat-growing periods from 2013 to 2015. Results showed that the rate of CO2 emissions was significantly higher immediately after tillage operation in the CT treatment. The annual CO2 emission rate in the NT treatment was significantly greater than that in the CT and NT0 treatments (P

Biodegradable plastics have been developed to eliminate the progressive accumulation and ever-growing threat posed by conventional fossil fuel-derived plastics. The impact of these bioplastics, particularly in an agricultural context (e.g. biopolymer mulch films), however, remains poorly understood. In this study, we compared the biotoxicity of biodegradable (polylactic acid, PLA; polypropylene carbonate, PPC) and non-degradable (polyethylene, PE) microplastics using a series of standardized bioassays using the earthworm Eisenia fetida. The responses studied included: avoidance behavior, mortality, biomass, and reproduction responses. We incubated earthworms in artificial soils amended with different concentrations of microplastic (0, 0.125, 1.25, 12.5, 125, 250, and 500 g kg−1) under laboratory conditions. This wide range allowed linear regression modeling and estimation of microplastic effect thresholds. Our results showed that microplastic concentration rather than plastic type was more important in regulating earthworm responses to soil contamination. The critical threshold for microplastic contamination was 40 g kg−1, after which earthworms exhibit microplastic avoidance behavior. A significant reduction (EC10) in number of cocoons and juvenile earthworms occurred at a concentration of 53 g kg−1 and 97 g kg−1, respectively; while no significant effect was found for survival of earthworm until levels of 500 g kg−1. Overall, the two biodegradable materials (PLA and PPC), appeared to be no more biofriendly than PE. Based on reported levels of plastic contamination in soil of up to 67 g kg−1, we conclude that microplastics are now starting to pose a threat to earthworm population. To better evaluate the risk posed by biodegradable and nondegradable plastics, further mechanistic studies on how microplastics affect earthworm behavior and the potential long-term impacts of this on soil functioning are required.

‘One film for 2 years’ (PM2) has been proposed as a practice to control the residual film pollution; however, its effects on grain-yield, water-use-efficiency and cost-benefit balance in dryland sp...

Understanding the potential drought characteristics under climate change is essential to reduce vulnerability and establish adaptation strategies, especially in the Huang-Huai-Hai Plain (3H Plain), which is a major grain production area in China. In this paper, we investigated the variations in drought characteristics (drought event frequency, duration, severity, and intensity) for the past 50 years (1961–2010) and under future scenarios (2010–2099), based on the observed meteorological data and the Representative Concentration Pathway (RCP) 8.5 scenario, respectively. First, we compared the applicability of three climatic drought indices: the standardized precipitation index (SPI), the standardized precipitation evapotranspiration index based on the Penman-Monteith equation (SPEI-PM) and the same index based on the Thornthwaite equation (SPEI-TH) to correlate the recorded agricultural drought areas. Then, we analyzed the drought characteristics using ‘run theory’ for both historical and the future RCP 8.5 scenario based on the best performing index. Correlation analyses between drought indices and agricultural drought areas showed that SPEI-PM performed better than SPI and SPEI-TH in the 3H Plain. Based on the results of SPEI-PM, drought risks including duration, severity and intensity during 1961–2010 showed an decreasing trend. However, under the RCP 8.5 scenario, drought is expected to rise in frequency, duration, severity, and intensity from 2010–2099, although drought components during the 2010–2039 are predicted to be milder compared with historical conditions. This study highlights that the estimations for atmospheric evaporative demand would create differences in the prediction of long-term drought trends by different drought indices. The results of this study can help inform researchers and local policy makers to establish drought management strategies.

The dynamics of soil organic carbon (SOC) is imperative for maintaining soil quality. Our objective was to investigate the effects of tillage practices on SOC and its fractions at the depth (0–60 c...

The response of ecosystems to different magnitudes of climate warming and corresponding precipitation changes during the last few decades may provide an important reference for predicting the magnitude and trajectory of net primary productivity (NPP) in the future. In this study, a process‐based ecosystem model, Carbon Exchange between Vegetation, Soil and Atmosphere (CEVSA), was used to investigate the response of NPP to warming at both national and subregional scales during 1961–2010. The results suggest that a 1.3°C increase in temperature stimulated the positive changing trend in NPP at national scale during the past 50 years. Regardless of the magnitude of temperature increase, warming enhanced the increase in NPP; however, the positive trend of NPP decreased when warming exceeded 2°C. The largest increase in NPP was found in regions where temperature increased by 1–2°C, and this rate of increase also contributed the most to the total increase in NPP in China's terrestrial ecosystems. Decreasing precipitation depressed the positive trend in NPP that was stimulated by warming. In northern China, warming depressed the increasing trend of NPP and warming that was accompanied by decreasing precipitation led to negative changing trends in NPP in large parts of northern China, especially when warming exceeded 2°C. However, warming stimulated the increase in NPP until warming was greater than 2°C, and decreased precipitation helped to increase the NPP in southern China.

High-purity cellulose nanofibers were isolated from wheat straw through an environmentally friendly, multistep treatment process that combined steam explosion, microwave-assisted hydrolysis, and microfluidization. The cellulose content of the processed nanofibers increased from 44.81% to 94.23%, whereas the hemicellulose and lignin contents significantly decreased. Scanning electron microscopy revealed the effects of the isolation treatments on fiber morphology and width. Atomic force microscopy was used to observe the changes in the components, surface roughness, and crystallinity of the fibers. Transmission electron microscopy showed long, loose nanofiber bundles that were 10–40 nm wide with an average individual diameter of 5.42 nm. Fourier transform infrared spectroscopy showed that noncellulosic components were effectively removed. X-ray diffraction analysis revealed the improved crystallinity of the processed fibers, as well as the partial crystalline transformation of cellulose I to cellulose II. T...

A comprehensive evaluation of the impacts of different tillage managements on bacterial community structure is fundamental to better understand their roles in maintaining soil health. The objective of this study was to assess the impact of no tillage (NT) vs. conventional tillage (CT) management on soil properties, bacterial community structure in a 22-year experiment established on the Loess Plateau of China, under a winter wheat cropping succession. Our results showed that the long-term application of NT caused a significant increase in bacterial alpha-diversity as indicated by the significantly greater number of unique operational taxonomic units (OTUs), richness (Chao), evenness (ACE), and Shannon index and a lower Simpson index compared to CT. Moreover, the NT treatment changed certain soil physicochemical properties, e.g., soil organic carbon (SOC), total nitrogen (TN), dissolved organic carbon (DOC), microbial biomass C (MBC), microbial biomass N (MBN) and nitrate nitrogen (NO3-N) were greater under CT. The bacterial communities differed significantly between the different tillage treatments, and NT harboured relatively higher abundances of the dominant genera Sphingomonas and Pseudomonas and a lower abundance of Acidobacteria than CT. A redundancy analysis (RDA) revealed that the bacterial community structure was strongly correlated with variations of SOC, DOC and TN. Thus, based on these findings, it is concluded that NT management is a more sustainable faming practice to improve soil properties and bacterial diversity.

Climate change is widely accepted to be one of the most critical problems faced by the Huang-Huai-Hai Plain (3H Plain), which is a region in which there is an over-exploitation of groundwater and where future warmer and drought conditions might intensify crop water demand. In this study, the spatiotemporal patterns of ET0 and primary driving meteorological variables were investigated based on a historical and RCP 8.5 scenario daily data set from 40 weather stations over the 3H Plain using linear regression, spline interpolation method, a partial derivative analysis, and multivariate regression. The results indicated a negative trend in all the analysed periods (except spring) of the past 54 years of which only summer and the entire year were statistically significant (p

A comprehensive comparison about microbial community (bacterial, archaeal and fungal) response to different tillage managements in Northern China remain little studied, in this study we compared no-tillage (NT) versus conventional tillage (CT) management on topsoil microbial community diversity and composition in field experiment. We found that NT practice significantly increased the soil moisture content (SMC), bulk density, stocks of soil organic carbon (SOC), total nitrogen (TN), and microbial biomass carbon and nitrogen (P

Plastic mulching is suspected to be a significant source of microplastics in terrestrial environments owing to its intensive application and improper disposal. However, there has been a comparative lack of studies examining this hypothesis. In this study, the occurrence of macroplastics in agricultural soils was investigated by analysing 384 soil samples collected from 19 provinces across China. Additionally, the abundance of microplastics was investigated in potential hotspots that have carried out plastic mulching for over 30 years. Macroplastic concentrations in the soil samples ranged from 0.1 to 324.5 kg/ha, with an average of 83.6 kg/ha; the concentrations were higher in western China than in eastern China. A highly significant linear correlation (R2 = 0.61) was found between the consumption of mulching film and the plastic residue in soils, indicating plastic film mulching may be a major source of macroplastics. The abundances of microplastic particles increased over time in the locations where plastic mulching was continuously employed, with concentrations of 80.3 ± 49.3, 308 ± 138.1, and 1075.6 ± 346.8 pieces/kg soil in fields with 5, 15, and 24 y of continuous mulching, respectively. Fourier transform infrared analyses revealed that the composition of the microplastics matched that of the mulching films, suggesting the microplastic particles originated from the mulching films. These findings confirm that plastic mulching is an important source of macroplastic and microplastic contamination in terrestrial environments. Further studies to investigate the microplastic hazards in soils are thus necessary.

Studying changes in soil organic carbon (SOC) pools and soil microbial C substrate utilization under plastic mulching in different seasons is of great significance for improving soil fertility and sustainable agricultural development. Based on a 2-year plastic film mulching experiment in northeastern China, we investigated the SOC, labile SOC fractions under three treatments: non-mulching (NM), autumn mulching (AM) and spring mulching (SM). The results showed that SOC decreased with soil depth under the AM and SM treatments compared with the NM treatment. The microbial biomass carbon (MBC) and dissolved organic carbon (DOC) under the AM treatment increased significantly in the 0–10 cm soil layer, by 31.2% and 27.2% (p

Vegetable waste causes resource waste and environmental pollution, giving rise to the spread of harmful organisms and causing disease in normal vegetable cultivation. Random distribution of vegetable waste can increase the risk of non-point agricultural pollution and explore the feasibility of its resource utilization. This study was designed to evaluate the effects of different doses of exogenous microbial agents on soil microbial communities after in situ composting of cucumber straw on plots with biodegradable mulch films. The cucumber straw and chicken manure were used as the base materials, and the next generation sequencing was used to analyze changes in the microbiome following composting. The results demonstrate that the addition of exogenous microbial agents had prolonged the high-temperature duration, reduced the total organic carbon (TOC) content, and accelerated the decline in the C/N ratio, ensuring compost maturity and effectively shortening the composting time. The predominant bacterial phyla of the four treatment groups were Proteobacteria and Firmicutes, while among fungal phyla, these treatments decreased the relative abundance of Ascomycota. The treatment of 300 t/ha microbial agents significantly increased the richness and diversity of both the bacterial and fungal communities. Redundancy analysis suggested that soil total nitrogen (TN) content had a significant effect on the bacterial community, while TN content, pH, and temperature influenced the fungal community in these samples. Collectively, the treatment of 300 t/ha exogenous microbial agents improved the quality of composting and promoted microbiome diversity.

Knowledge about the changes in soil nitrogen pools under different tillage managements is necessary to assess the feasibility of adoption of conservation practices for sustaining productivity and protecting the environment in dryland farming in northern China. We investigated the long-term effects (22 years) of no-till with residue retention (NTR) on total soil N and its fractions in a dry-land winter wheat ( Triticum aestivum L.) cropping system in northern China. Compared with conventional tillage without residue retention (CT), significantly higher soil total N (STN) concentrations were observed in the surface soil layer (0–10 cm) under NTR. Meanwhile, more soil N accumulated for the whole soil profile (0 to 60 cm) in the NTR (3.38 Mg ha − 1 ) treatment relative to the CT (3.17 Mg ha − 1 ) treatment. The particulate organic matter N (PON), microbial biomass N (MBN), and water extractable organic N (WEON) levels in the NTR treatments were 52.3%, 116%, and 69.4% greater at a depth of 0–5 cm and 41.6%, 108%, and 44.9% greater at a depth of 5–10 cm, respectively, compared with the CT treatment. However, no differences were observed below the 10 cm layer. At a depth of 0–60 cm, the soil NH 4 -N content under CT was higher than that under NTR. However, the soil NO 3 -N contents in the NTR treatments were significantly greater at a depth of 0–10 cm and were not significantly different at a depth of 10–60 cm, relative to the CT treatment. Significantly positive correlations were observed between the STN and the labile organic N fractions. Overall, the results show that no-till coupled with residue retention is an effective management method for improving soil N stocks and increasing soil fertility. Nonetheless, other benefits associated with NT and residue retention present greater challenges regarding their popularization and application in the dryland farming areas in northern China.

It is now widely acknowledged that microplastic pollution represents one of the greatest anthropogenically mediated threats to Earth-system functioning. In freshwater and marine ecosystems the presence of large amounts of microplastic appears almost ubiquitous, with frequent reports of negative impacts on aquatic health. In contrast, however, the impact of plastic in terrestrial environments remains poorly understood. In agroecosystems, microplastics (particles 5 mm) can enter the soil environment either directly (e.g. from biosolids application, irrigation water, atmospheric deposition), or indirectly through the in situ degradation of large pieces of plastic (e.g. from plastic mulch films). Although we have encouraged the use of plastics over the last 50 years in agriculture to promote greater resource use efficiency and food security, the legacy of this is that many soils are now contaminated with large amounts of plastic residue (ca. 50-250 kg ha

Crop consumptive water use is recognized as a key element to understand regional water management performance. This study documents an attempt to apply a regional evapotranspiration model (SEBAL) and crop information for assessment of regional crop (summer maize and winter wheat) actual evapotranspiration (ETa) in Huang-Huai-Hai (3H) Plain, China. The average seasonal ETa of summer maize and winter wheat were 354.8 and 521.5 mm respectively in 3H Plain. A high-ETa belt of summer maize occurs in piedmont plain, while a low ETa area was found in the hill-irrigable land and dry land area. For winter wheat, a high-ETa area was located in the middle part of 3H Plain, including low plain-hydropenia irrigable land and dry land, hill-irrigable land and dry land, and basin-irrigable land and dry land. Spatial analysis demonstrated a linear relationship between crop ETa, normalized difference vegetation index (NDVI), and the land surface temperature (LST). A stronger relationship between ETa and NDVI was found in the metaphase and last phase than other crop growing phase, as indicated by higher correlation coefficient values. Additionally, higher correlation coefficients were detected between ETa and LST than that between ETa and NDVI, and this significant relationship ran through the entire crop growing season. ETa in the summer maize growing season showed a significant relationship with longitude, while ETa in the winter wheat growing season showed a significant relationship with latitude. The results of this study will serve as baseline information for water resources management of 3H Plain.

Knowledge about the changes in soil aggregate stability and soil organic carbon (SOC) under different tillage treatments is necessary to assess the feasibility of adoption of conservation practices for sustaining productivity and protecting the environment in dryland farming in northern China. In this study, four treatments, no-till with straw mulching (NTSM), all straw return tillage (ASRT), shallow rotary treatment (SRT) and conventional tillage (CT) were set and a 5 years field experiment was carried out to study the effects of different tillage practices on soil aggregates stability and organic carbon distribution. We found that macro-aggregate (> 2 mm and 0.25–2 mm) proportion, mean weight diameter, total amount, content of SOC in macro-aggregate and proportion of SOC in macro-aggregate were significantly improved by NTSM, ASRT and SRT. In all treatments, soil ability to sequester carbon was improved more prominently in NTSM, and macro-aggregate proportion, mean weight diameter, total amount SOC in macro-aggregate and proportion of SOC in macro-aggregate were improve by 29.4%,30.9%,84.9% and 30.7% respectively by NTSM. In addition, improvement effects on soil aggregates stability and carbon sequestration ability in ASRT were all higher than in SRT, and compared to NTSM, macro-aggregate proportion was slightly higher (1.7%) in ASRT, but SOC content and amount in aggregates were remarkably lower. Our results revealed that reducing soil disturbance, increasing straw returning and especially their combined application (i.e. NTSM in this study) can effectively be used to reduce soil erosion and improve carbon sequestration in dryland farming in northern China.

Plastic film has become an important agriculture production material in recent years. Over the past three decades, the amount and application area of plastic film have increased steadily, and in 2014, which are 1.4 million tons and more than 180 million hm² respectively. It plays a key role for ensuring the supply of agricultural goods in China. Meanwhile, plastic film residual pollution becomes more and more serious, and in some regions, the amount of plastic film residues has reached over 250 kg/hm². In part of the Northwest region, soil structure of farmland has been destroyed by plastic film residues and then crop growth and farming operations were suppressed. It is recognized as a good choice to replace plastic film with biodegradable plastic film, an effective measure to solve the plastic film residue pollution. Now, it is in a critical stage of study and assessment of biodegradable plastic film in China and fortunately some biodegradable plastic films show effects in the production of potatoes, peanuts and tobacco. Overall, a series of challenges has still been faced by the biodegradable plastic film, mainly including improving the quality of biodegradable plastic products, such as tensile strength, flexibility, improving the controllability of rupture and degradation, enhancing the ability of increasing soil temperature and preserving soil moisture, and to satisfy the demand of crops production with mulching. In addition, it is essential to reduce the cost of the biodegradable film and promote the application of biodegradable film on large-scale. With the development of biodegradable plastic technology and agricultural production environment, the application of the biodegradable film will have a good future.地膜是农业生产中重要的生产资料之一，过去30 多年，地膜用量和农作物覆膜面积一直稳定增长，2014 年地膜用量达到了144 万t，覆膜面积超过1 800 万hm²，该技术对保障我国农产品安全供给作出了重大贡献。与此同时，地膜残留污染问题越来越严重，一些农田的地膜残留量超过250 kg/hm²，在我国西北的局部区域，地膜残留已经对农田土壤、作物生长发育、农事作业等造成严重影响和危害。生物降解地膜成为替代普通PE 地膜、解决地膜残留污染的一种有效措施和手段，目前生物降解地膜正处于产品研发和评价试验的关键阶段，部分生物降解地膜产品在马铃薯、花生、烟草生产上显示出良好的效果，但总体上还面临巨大挑战，主要包括需要进一步提高地膜产品质量，提高地膜产品破裂和降解可控性，改善地膜的增温保墒能力，实现满足农作物对地膜覆盖功能的要求；此外，需要降低生物降解地膜综合成本，促进生物降解地膜规模化应用。总体上，随着技术进步和农业生产环境的变化，生物降解地膜应用将具有良好的前景。.

Information about the effect of plastic film mulching (PFM) on the soil microbial communities of rainfed regions remains scarce. In the present study, Illumina Hiseq sequencer was employed to compare the soil bacterial and fungal communities under three treatments: no mulching (NM), spring mulching (SM) and autumn mulching (AM) in two layers (0–10 and, 10–20 cm). Our results demonstrated that the plastic film mulching (PFM) application had positive effects on soil physicochemical properties as compared to no-mulching (NM): higher soil temperature (ST), greater soil moisture content (SMC) and better soil nutrients. Moreover, mulching application (especially AM) caused a significant increase of bacterial and fungal richness and diversity and played important roles in shaping microbial community composition. These effects were mainly explained by the ST and SMC induced by the PFM application. The positive effects of AM and SM on species abundances were very similar, while the AM harbored relatively more beneficial microbial taxa than the SM, e.g., taxa related to higher degrading capacity and nutrient cycling. According to the overall effects of AM application on ST, SMC, soil nutrients and microbial diversity, AM is recommended during maize cultivation in rain-fed region of northeast China.