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Background: The COVID‐19 pandemic is an unprecedented health crisis that has affected in vitro fertilization practices globally. Previous studies have shown that SARS‐CoV‐2 impacts the quality of embryos by inducing an immunological response in infertile patients. In this study, the early embryonic development of SARS‐CoV‐2‐infected infertile patients was investigated. Methods: Sixty‐five SARS‐CoV‐2 infected infertile patients and 258 controls were involved in this study. The major outcome parameters for the cycle were analyzed, including the number of oocytes, maturation oocytes, available embryos per cycle, and embryo morpho kinetic characteristics. Results: From SARS‐CoV‐2 infection until oocyte retrieval, it took an average of 6.63 days. The results revealed that the number of oocytes and high‐quality embryos on day 3 dramatically reduced in SARS‐CoV‐2‐infected infertile patients. SARS‐CoV‐2 was detected in the follicular fluid of three infertile patients. SARS‐CoV‐2 infection had negatively impacted the number of oocytes in multivariate linear regression models. The early embryonic development in the SARS‐CoV‐2 infection group had a noticeable delay from the six‐cell stage to blastocyst stage. Conclusions: SARS‐CoV‐2 infection reduced the number of oocytes and high‐quality embryos on day 3. It delays the early embryonic development from the six‐cell stage to blastocyst stage and has a negative impact on the quality of embryos. [ABSTRACT FROM AUTHOR]

Aims: Cropland revegetation is an effective measure to curb soil erosion on eroding hillslopes and increase farmers' income at depositional check dams. However, how soil microbial metabolic limitation responds to cropland revegetation in erosion and deposition landscapes remains poorly understood, which has substantial implications for carbon (C) retention and nutrient cycling in the eroding environment. Methods: We sampled 0–2 m soils in cropland and revegetated forest and grassland at upslopes and check dams in the hilly-gully region of the Loess Plateau, China. The activities of soil C-, nitrogen (N)-, and phosphorus (P)-acquiring enzymes were analyzed. The improved enzyme vector model (V-T model) based on balance points was used to quantify microbial metabolic limitations based on ecoenzymatic stoichiometry. Results: Microorganisms suffered from no energy (C) limitation, but the relative microbial C limitation was greater in revegetated forest than in cropland. At upslopes, the revegetated forest was primarily limited by P, while the revegetated grassland and cropland were limited by N, which was indicated by the VTN/P limitation values of 4.35, -2.74, and − 1.87, respectively. Microbial P limitation was greater in deep soils of revegetated forest due to the assimilation of P by the root system. At check dams, land-use change had no significant influence on microbial N/P limitations owing to abundant soil C and nutrients and a wet environment. Conclusion: Concludingly, cropland revegetation had a weaker influence on microbial metabolic limitation at the lower-lying topography, which compensates for the current understanding of resource restrictions on microorganisms at slopes or flat areas. [ABSTRACT FROM AUTHOR]

To improve the performances of AlGaN solar‐blind ultraviolet (UV) avalanche photodetectors (APDs), we propose a separate absorption and multiplication (SAM) AlGaN APD with a gradually doped charge layer. The calculation results indicate that the designed APD can significantly increase the maximum gain by almost 40%, and reduce the breakdown voltage by about 9% compared with the conventional AlGaN APD. The parameters of multiplication layer and p‐type layer are optimized, and the physical mechanism is described in detail, which provides theoretical guidance for high‐performance device structure design and experimental preparation. [ABSTRACT FROM AUTHOR]

Soil erosion is a major form of land degradation, especially in agroecosystems, which has been effectively controlled by vegetation restoration. However, the interactive role of erosion and cropland revegetation on soil enzyme activities and microbial nutrient limitations is less understood. To address this issue, we examined carbon (C), nitrogen (N), and phosphorus (P) in bulk soils and microbial biomass, enzyme activities, and microbial nutrient limitations in the 0–200 cm soils in eroded and deposited landscapes occupied by cropland, revegetated forest, and grassland. The results showed that the activities of C-, N-, and P-acquiring enzymes were larger in the deposited landscape than in the eroded landscape for 0–20 cm soils in forest and grassland but not in cropland. Microbial metabolism was co-limited by N and P, and the threshold element ratio (TERL) indicated that P was the most limiting factor. Microbial N limitation was lower in the deposited than the eroded zone, especially in surface soils in revegetated forest and grassland. The TERL value was larger at the deposited than at the eroded zone, and a greater difference was found in the surface soils of forest and grassland. Microbial nutrient limitations were mostly explained by C/P and N/P. Conclusively, the deposited areas were characterized by ameliorated enzyme activities, decreased microbial N limitation but relatively strengthened microbial P limitation compared to the eroded area, and such variations existed in the revegetated forest and grassland but not in the cropland, which thus contributes to a better understanding of C and nutrient cycling for agroecosystems and revegetation ecosystems in eroded environments. [ABSTRACT FROM AUTHOR]

Electrical treeing is one of the main causes of crosslinked polyethylene (XLPE) cable failure. The current methods for locating electrical trees are mainly based on the partial discharge (PD) signal. However, PD signals are easily attenuated in the long cable and the PD test voltage may cause damage to the insulation. This work proposes an improved broadband impedance spectrum (BIS) method to locate electrical trees in XLPE cable. A mathematical model of a long cable containing local electrical tree degradation is established. The Gaussian signal is chosen as the simulated incident signal to reduce the spectral leakage. The location spectrum is obtained by multiplying the frequency domain function of the single-ended reflection coefficient and the Gaussian pulse. It has been found that the location spectrum of the local capacitance change can be characterized as a typical double-peak waveform and the spectrum of the local conductance change can be regarded as a typical single-peak waveform. Electrical tree experiments at different temperatures were carried out to initiate different types of electrical trees. A vector network analyzer (VNA) was used to test the high frequency capacitance characteristics in the treeing process. The location spectra of the 20 m long cable containing different types of electrical trees was calculated by the improved location algorithm. The results show that the location error of local electrical tree degradation is less than 3%. The capacitance of the sliced sample decreases with treeing time. The effect of the bush-pine tree on capacitance parameters is greater than that of the branch-pine tree. A typical double-peak is found in the bush-pine tree location spectrum and a single-peak is found in the branch-pine tree spectrum. [ABSTRACT FROM AUTHOR]

Abstract The agro-pastoral ecotone is an ecologically fragile transition zone and suffers from extensive human-induced land-use changes. To understand how soil organic carbon (OC) and nutrients will respond to re-vegetation practices in such an ecotone zone, we present the response of OC, nitrogen (N) and phosphorus (P) in both bulk soils and water-stable aggregates to typical re-vegetation patterns in an agro-pastoral ecotone of northern China. Three re-vegetation patterns, i.e., cropland converted to natural grassland, woodland and artificial grassland at different times (6 to 40 years), were selected. The paired croplands were also selected as the control for each re-vegetation pattern. The measured soil metrics include the proportions of each type of water-stable aggregate, the mean weight diameter and geometric mean diameter of the aggregates, and the concentrations of OC, N and P in bulk soils and each aggregate fraction. The results showed that the three re-vegetation patterns significantly increased the mass proportion of macro-aggregates, the values of mean weight diameter and geometric mean diameter, and the concentrations of OC and N in topsoils (0–10 cm). The accumulation of OC and N in bulk soils was mainly due to the accumulation in macro-aggregates. Furthermore, increases in OC and N were greater after conversion to legume vegetation than to non-legume vegetation, and were highest at approximately 20 years after the conversion. However, concentrations of P in bulk soils and aggregates were similar among the three re-vegetation patterns and the three aggregate fractions, and were minimally affected by the conversion. These results highlighted the potential of legume vegetation to increase OC and N in surface soils and aggregates, and indicated no response of soil P to re-vegetation in an agro-pastoral ecotone of northern China. Highlights • Re-vegetation improved soil structure and increased OC and N in agro-pastoral ecotone. • The increases in OC and N were highest approximately 20 years after conversion. • The increases were greater after conversion to legume than non-legume vegetation. • Changes in soil OC and N after re-vegetation mainly occurred in macroaggregates. • Soil P was not affected by re-vegetation in bulk soil and aggregates. [ABSTRACT FROM AUTHOR]

Highlights • Converting grassland to shrubland increased soil N availability and mineralization. • The positive effect on soil mineral N was higher in lower slope than upper slope. • The positive effect on soil mineral N was similar across soil textures. • The effect on net N mineralization varied with slope position and soil texture. Abstract Grassland afforestation, which is a major form of land-use change, has expanded considerably in the last few decades. However, the effect of conversion from grassland to shrubland on soil nitrogen (N) cycling and availability with regard to soil textures and slope positions is unclear. This lack of clarity has hindered our understanding of how grassland afforestation influences soil N availability and transformation on a larger spatial scale. In this study, we compared the net N mineralization rates and mineral N concentrations in soils from native grassland and under legume shrub (Caragana korshinskii Kom.) with contrasting soil textures (sandy-loam vs. loamy-sand) and slope positions (upper vs. lower) in the northern region of China's Loess Plateau. The objective of this study is to understand how soil texture and slope position regulate the response of soil N cycling to grassland afforestation. The results showed that the concentrations of soil nitrate and total mineral N and the rates of net nitrification and mineralization were higher in soils under shrub (0.64 ± 0.10 g N m−2, 1.01 ± 0.11 g N m−2, 23.19 ± 5.22 mg N m−2 d-1 and 22.07 ± 5.44 mg N m−2 d-1) than in grassland (0.22 ± 0.03 g N m−2, 0.56 ± 0.04 g N m−2, 1.48 ± 1.51 mg N m−2 d-1 and 1.36 ± 1.96 mg N m−2 d-1). However, soil ammonium concentration and net ammonification rate were not affected by grassland afforestation. The effect of afforestation on nitrate and total mineral N concentrations was greater in the lower slope than in the upper slope but was similar between the sandy-loam and loamy-sand soils. The effect of this land-use change on net nitrification and mineralization rates varied with soil texture and slope position, with greater effects in the upper slope than in the lower slope in more clayey soils, but with the opposite influencing pattern in more sandy soils. These results suggested that planting C. korshinskii in grassland ecosystems increased soil N mineralization and availability. More importantly, soil texture and slope position should be considered when assessing the effects of grassland afforestation in complex landscape conditions. [ABSTRACT FROM AUTHOR]

Abstract The creation of "fertile islands" beneath shrubs in dryland ecosystems has been widely reported worldwide and is the major factor influencing ecosystem structure and function. However, studies investigating whether and how shrubs affect soil biogeochemical cycles in deep soil layers are relatively limited. In this study, we examined the vertical distribution of the soil nutrient contents and enzymatic activities at the 0–100 cm soil profiles beneath three common xerophytic shrubs (Artemisia ordosica , Caragana korshinskii and Salix psammophila) and in interspace bare soils in a transition zone from desert to loess in the north of China. The soil metrics included the contents of organic carbon, total nitrogen, total phosphorus, nitrate and ammonium nitrogen, available phosphorus and potassium, and the activities of saccharase, urease, alkaline phosphatase and amylase. We found that the contents of organic carbon, total nitrogen and available potassium, and the activities of saccharase, urease and alkaline phosphatase were higher in the soils beneath shrubs than in the interspace bare areas, but these differences only occurred in the 0–10 cm soil profile but not in the soils below the depth of 10 cm. The soil quality index was consistently improved among the three shrub species in the topsoil. In addition, the soil nutrients were positively correlated with enzymatic activities, and the organic carbon content explained approximately 50% of the variations in the enzymatic activities. Collectively, our results demonstrated that the establishment of xerophytic shrubs improved the soil chemical and biological conditions in the desert-loess transition region, and the effect was restricted to the 0–10 cm soil layer. Highlights • Xerophytic shrubs significantly increased soil nutrient contents and enzymatic activities. • Effects of shrubs on soil nutrients and enzyme activities occurred at 0–10 cm depth. • Soil quality index was similar among A. ordosica , C. korshinskii and S. psammophila. • Soil nutrient contents were positively correlated with enzymatic activities. • Organic carbon explained ~50% of the variations in enzymatic activities. [ABSTRACT FROM AUTHOR]

Abstract Shrubs play a vital role in ecosystem restoration in the desert transition zone, which suffers intensive desertification, land degradation, and nitrogen (N) limitation. To evaluate the effects of different shrub species on soil N availability, transformation, and their seasonal dynamics, we determined mineral N contents and mineralization rates in soils under three common shrub species (Artemisia ordosica Krasch., Caragana korshinskii Kom., and Salix psammophila C.) and in bare land during the growing season in the desert-loess transition zone in northwestern China. The average contents of soil nitrate N and mineral N were 153% and 55% greater, respectively, and cumulative net N nitrification and mineralization were 101.2 and 121.0 mg N m−2 higher, respectively, in soils beneath C. korshinskii than in bare land (P < 0.05) at the 0–10 cm depth over the growing season. The net N mineralization rate in 0–10 cm depth was significantly higher in soils under C. korshinskii than that in bare land during 21 Jun-23 Jul and 23 Aug-15 Oct of the growing season. However, C. korshinskii did not influence soil N metrics at the 10–20 cm depth. The incorporation of A. ordosica and S. psammophila into bare land did not influence soil N availability or transformation rates. Our results demonstrated that C. korshinskii was more preferable than A. ordosica and S. psammophila in ameliorating soil N cycling in the desert-loess transition zone. Highlights • Xeric shrub species: Artemisia ordosica , Caragana korshinskii , Salix psammophila • The fragile transition zone between the desert and the Loess Plateau of China • C. korshinskii increased mineral N content and net N mineralization rate • Effects of C. korshinskii were greater in dry and cold period and the 0–10 cm soil. • A. ordosica and S. psammophila did not influence soil N mineralization. [ABSTRACT FROM AUTHOR]

Abstract The presence of vegetation has significant effects on soil nitrogen (N) turnover. However, whether these effects vary with slope aspect, vegetation type and time of season were not understood in previous studies, precluding our ability to understand how vegetation affects soil N cycling in sloping land. In this study, we investigated the effects of vegetation presence (plots with vs. without vegetation), vegetation type (grassland vs. woodland) and slope aspect (east vs. west slope) on soil N turnover during the growing season in sloping lands of the Loess Plateau, China. Soil metrics measured included concentrations of ammonium (NH 4 +), nitrate (NO 3 −) and total mineral N (Min-N) in soil solution and rates of ammonification (R a), nitrification (R n) and net N mineralization (R m). We hypothesized that the presence of vegetation would deplete the soil Min-N pool and decrease R m and that these effects would be greater in east slopes and woodlands than in west slopes and grasslands. In partial support of these hypotheses, vegetation presence decreased soil Min-N concentration but did not affect R m. NH 4 + and NO 3 − contributed similarly to Min-N, while R n dominated R m. The effects of vegetation presence on soil mineral N and N mineralization varied with the time of the season but were not related to the vegetation type and slope aspect. The soil Min-N and R m were significantly higher in woodlands, east slopes and 0–10 cm depth than grasslands, west slopes and 10–20 cm depth, respectively. The R a and NH 4 + increased, while the R n , R m , NO 3 − and Min-N decreased with increasing soil moisture. These results indicated that soil Min-N and R m in the sloping lands of the Loess Plateau consistently respond to vegetation presence across slope aspect and vegetation type, and were regulated by soil moisture. Highlights • Vegetation decreased soil inorganic N pool because of plant uptake. • Effects of vegetation presence (plots with vs. without vegetation) on soil mineral N and N mineralization varied with season. • Effects of vegetation presence on N turnover were irrespective to vegetation type and slope aspect. • Soil mineral N pool and mineralization rate were higher in woodland and east than grassland and west slope. [ABSTRACT FROM AUTHOR]

• Eroding soils and sediments were collected at 0–2 m depth across the Loess Plateau. • Sediments had higher clay than eroding soils at sites with higher erosion modulus. • Sediments had higher BD, lower Ks, FC, porosity than soils at sites with higher MAP. • Reaggregation of deposited sediments occurred, which were enriched in clay and SOC. • Spatial heterogeneity in deposition zone was not lower than that in erosion zone. Soil erosion, the most widespread form of soil degradation worldwide, has been acknowledged to cause onsite soil physical deterioration. However, the off-site impact of erosion on the soil physical and hydraulic properties of deposited sediments remains unclear, especially at catchment or larger scales. Here, we measured soil physical and hydraulic properties in erosion topography (hillslopes) and deposition topography (check dams) at 0–2 m depth in five eroding catchments across China's Loess Plateau. Results indicated that the deposition zone exhibited a higher clay content (+13%) at the southern sites with a finer texture and a higher erosion modulus, while the same zone exhibited a higher sand content (+25%) at the northern sites with a coarser texture and a higher extreme rainfall erosivity. The deposition zone exhibited a higher bulk density (+9%) and a lower saturated hydraulic conductivity (-13%), field capacity (−9%), and porosity (-5%) than those of the erosion zone, which was strengthened by a higher mean annual precipitation. Soil macroaggregate proportion and mean weight diameter of aggregates were significantly lower in the deposition zone (14.36% and 0.69 mm, respectively) than those in the erosion zone (15.71% and 0.75 mm, respectively), and the differences were larger at sites with higher rainfall erosivity levels and in surface 20 cm soils. However, sediment reaggregation occurred due to the accumulation of binding agents such as clay and organic carbon at sites with lower rainfall erosivity levels. The spatial heterogeneities of sediment physical and hydraulic properties were greater than or similar to those of soils in the erosion zone. Results of our study highlight the dependence of variations in soil physical and hydraulic properties driven by erosion and deposition on erosion factors, which contributes to a better understanding of the hydrology cycle and carbon stability in erosion and deposition topographies. [ABSTRACT FROM AUTHOR]

• WDOM parameters in erosion and deposition zone were tested across Loess Plateau. • Sediment below 20 cm had higher WEOC, aromaticity, hydrophobicity, humic components. • Eroded soils above 20 m had higher WEOC and exogenous features with plant inputs. • WEOM variations were higher in deep soils and in sites with higher erosion modulus. • WEOM variations were mostly driven by vegetation in top and by ΔSOC in deep soils. Water-extractable organic matter (WEOM) is the most active and mobile fraction of soil organic matter and responds sensitively to soil erosion. However, previous studies on the chemical nature of WEOM in the erosion and deposition landscapes were controversial at site-level studies and mainly focused on surface soils, limiting our assessment of WEOM's environmental fate at larger and deeper scales. Here, we collected eroded soils and deposited sediments from a depth of 0–200 cm in five eroding catchments with an erosion intensity gradient across the Loess Plateau. We examined the concentration, composition, and potential sources of WEOM using UV–visible absorption and fluorescence excitation-emission matrix-parallel factor analysis. Soil WEOM quantity and quality varied significantly in the erosion and deposition landscapes, with greater variations in soils below 20 cm, where WEOM in the deposition zone was characterized by higher concentration, aromaticity, hydrophobicity, and UVA and UVC humic-like components derived from terrestrial and soil organic matter. WEOM variations in deep soils increased with increasing erosion modulus among sites, and were mainly driven by changes in soil organic carbon concentration, aggregate stability, and carbon to nitrogen ratio. However, the pattern of WEOM parameters between erosion and deposition zones at 0–20 cm was opposite to that in soils below 20 cm. Vegetation inputs compensated the loss of organic matter in sites with suitable climatic status and weak erosion, and led to higher concentrations and exogenous features of WEOM in the surface erosion area. Concludingly, the WEOM concentration, components, and sources differed significantly between erosion and deposition zones, and these differences, as well as their response to erosion intensity, revealed an opposing pattern in surface and deep soils. [ABSTRACT FROM AUTHOR]

The micro-discharge effect limits the development of high-frequency microwave power components to miniaturization and integration. Therefore, it has become a focus of research to effectively suppress the micro-discharge effect, increase the micro-discharge threshold, and strengthen the environmental stability of high-frequency microwave devices. In this study, different elemental ratios of carbon (C)/silver (Ag)/titanium (Ti) composite films were obtained by multi-target magnetron co-sputtering technology and then systematically analyzed for micro-discharge effects. When the doping ratio of C/Ag/Ti was 3.538/1/0.013, the corresponding maximum secondary electron emission coefficient (δmax) decreased to 1.01 owing to the suppression of secondary electron emission by the increase in the content of sp2 hybrid bond. The micro-discharge threshold of Ku band waveguide filters coated with moderate C/Ag/Ti composite films showed an optimal performance of 10 000−12 500 W, which was increased by approximately 20 times. Moreover, the microstructure of the composite films exhibited higher density and flatness with a tiny increase in the titanium doping ratio, representing good environmental stability. Thus, the effective suppression of the secondary electron emission yield, significant improvement in the micro-discharge threshold, and enhancement of the environment stability of microwave components could be realized simultaneously by reasonably controlling the content of titanium in silver and titanium co-doped carbon-based composite films. [ABSTRACT FROM AUTHOR]

• Soil in eroding zone had higher mineral N and net mineralization rates than in depositional zone. • Vegetation removal increased soil mineral N but not affected soil net N mineralization rates. • The effects of vegetation removal on mineral N pools depended on landscape position, site, and season. • The responses of net N mineralization rates to vegetation removal were consistent across landscape positions and sites, but varied with season. The soil nitrogen (N) availability is a key limiting element of terrestrial ecosystem productivity and functioning, especially in fragile ecosystems (e.g., eroding environments). However, to date, little is known about how vegetation and erosion individually or jointly affect soil N mineralization under field conditions across a range of sites varying in soil and climate properties on a long-term observational scale. In this study, we elucidated how soil net N mineralization responds to vegetation removal (plots with vs. without vegetation) and landscape position (eroding vs. depositional zones) during a two-year manipulation experiment using an in situ incubation method on the China's Loess Plateau. The results indicated that the nitrate and total mineral N concentrations and net nitrification and mineralization rates were higher in the eroding zone (2.74 ± 0.12 mg kg−1, 4.47 ± 0.13 mg kg−1, 0.046 ± 0.005 mg kg−1 d-1 and 0.046 ± 0.006 mg kg−1 d-1) than those in the depositional zone (2.01 ± 0.10 mg kg−1, 3.80 ± 0.12 mg kg−1, 0.030 ± 0.005 mg kg−1 d-1 and 0.032 ± 0.006 mg kg−1 d-1) on the China's Loess Plateau. Vegetation removal resulted in an increase in the nitrate (2.88 ± 0.13 vs. 1.87 ± 0.09 mg kg−1) and total mineral N concentrations (4.56 ± 0.14 vs. 3.71 ± 0.11 mg kg−1), but did not affect the soil net N mineralization rates on the China's Loess Plateau. The effects of vegetation removal on soil mineral N pools depended on the site, season and landscape position, with stronger effects in the eroding zone than those in the depositional zone. However, the responses of the net N mineralization rates to vegetation removal were consistent across the various landscape positions and sites, but varied with the season. Variance partitioning revealed that soil properties rather than climate and vegetation conditions were the most dominant contributors to the variations of soil N mineralization in both the eroding and depositional zones, explaining 37.6–64.6% of the variation. These results emphasized the substantial spatial (landscape position and site) and temporal (seasonal) dependence of the effects of vegetation removal on soil N mineralization at large scale. [ABSTRACT FROM AUTHOR]

Soil erosion can dramatically alter soil nitrogen (N) cycling, but it has rarely been examined under in-situ conditions due to the complicated interaction between erosion and vegetation. Comparing the effects of vegetation presence at eroding and depositional sites would provide a direct understanding of such effects. Herein, we investigated how soil N dynamics (mineral N pools and net N mineralization rates) responded to vegetation presence (plot with vs. without vegetation), landscape position (eroding vs. depositional sites) and vegetation type (grassland vs. woodland) during a two-year manipulation experiment using an in-situ incubation method in the hilly-gully region of China's Loess Plateau. The results showed that soils on eroding site had higher concentrations of nitrate (3.820 ± 0.302 vs. 2.642 ± 0.280 mg kg-1) and mineral N (5.853 ± 0.320 vs. 4.308 ± 0.287 mg kg-1) but similar rates of net nitrification (0.057 ± 0.013 vs. 0.051 ± 0.011 mg kg-1 d-1) and mineralization (0.056 ± 0.014 vs. 0.056 ± 0.013 mg kg-1 d-1) in comparison to depositional site in all grassland plots. The concentrations of soil nitrate and mineral N and rates of net nitrification and mineralization in legume woodland were 26%, 19%, 88% and 64% higher than that in grassland in all slope plots, respectively. Although vegetation presence significantly decreased soil nitrate (−57%) and total mineral N (−27%) concentrations, it did not affect the rates of net nitrification and mineralization. The effects of vegetation presence on soil net N mineralization occurred irrespective of landscape position and vegetation type(P > 0.05), but varied with season or year, with greater effects in 2017 growing season than in the non-growing season and 2018 growing season. Redundancy analysis and hierarchical partitioning indicated that the above- and blow-ground biomass accounted for most of the variation in soil N mineralization. These results suggested that the variations in soil mineral N and net N mineralization in relation to vegetation presence in this eroding watershed were consistent across different landscape positions and vegetation types, but showed intra- and inter-annual variability. • Vegetation presence decreased soil mineral N pools because of plant uptake. • Soil mineral N concentrations in eroding site were higher than deposition site for the grassland. • Soil mineral N and mineralization rates were higher in woodland than grassland for the eroding sites. • Effects of vegetation presence on soil mineral N and mineralization rates were irrespective to landscape position and vegetation type, but varied with season or year. [ABSTRACT FROM AUTHOR]

Check dams are small engineering structures. They are used worldwide for soil and water conservation, gully rehabilitation, hydrological regulation, and food supply. Eroded materials trapped and buried in check dams constitute an important carbon (C) sink. However, as a typical deposition site, systematic information about C cycling processes in check dams is relatively unknown, despite its crucial role in estimating the fate of buried C and elucidating the ongoing C sink/source debate on soil erosion. This study reviewed the stock, source, enrichment, distribution, stability, and underlying mechanisms of sediment C in check dams. Current studies have found a large amount of C stored in check dams (approximately 1–30 Mg C km−2 yr−1), and have demonstrated that C retention ability relied more on factors governing sediment production and trapping at larger scales than on check dam trapping efficiency at smaller scales. Stable isotopes, radiocarbon, geochemical properties, biomarkers, and spectroscopy methods have proven to be practical in identifying the sources of sediment C but can only be used in certain situations because of their intrinsic limitations. Both enrichment and impoverishment of sediment C compared with source soils have been reported, and have depended on soil erosion type, land-use type, sediment connectivity, and the loss of C during transportation. Sediment C generally increases from the back of the check dam to the front along the flow pathway and fluctuates vertically, depending on the clay and sand layers of the deposition couplets. Information about C mineralization and sequestration is relatively limited, and the existing studies have shown reduced C mineralization and promoted C-fixing potential in check dam sediments. Given the specific benefits of deposition couplets in reflecting information about burial period, erosion intensity, and historical land use, further studies should integrate C stability with soil erosion and deposition information for the deposit profiles. The responses of C cycling to climate change and human disturbances, such as warming, dam-break, tillage, and fertilization for check dam sediments require further research. • Check dams store significant C depending on sediment input and trapping efficiency. • Both enrichment and impoverishment of sediment C occur compared with source soils. • Sediment C raises with flow path horizontally and fluctuates with couplets vertically. • Stable C fractions dominated in the sediments and changed little with depth. • Effects of warming, tillage, fertilization, and dam-break on C stability are needed. [ABSTRACT FROM AUTHOR]

Re-vegetation of cropland is an important measure for carbon (C) sequestration, while the combined effects of land-use change, re-vegetation type and time on soil organic C (OC) turnover and temperature sensitivity have been less studied. Here, we investigated soil cumulative OC mineralization (C min), specific OC mineralization (C min /C 0 , normalized by initial OC) and temperature sensitivity (Q 10) with an 84-d incubation experiment after the conversion of cropland to artificial grassland (6, 10, 15 and 20 yr), to natural grassland (6, 10 and 20 yr) and to pea shrub woodland (10, 20 and 40 yr) in the agro-pastoral ecotone of northern China. Results showed that re-vegetation significantly increased C min (from 38.21 to 57.79 mg kg−1 soil, +51%) at the 0–10 cm depth but not the 10–20 cm depth, with greater increases after the conversion of cropland to artificial grassland (+77%) than the other two patterns but similar among different conversion years for each pattern. Variations in C min among different re-vegetation patterns and times were mostly explained by changes in total nitrogen concentration (TN) in the macro-aggregate fraction. Across all treatments, 6.20–20.29 g kg−1 OC was mineralized during the incubation and Q 10 was 1.16–2.40. The C min /C 0 and Q 10 changed not significantly during the post-agricultural re-vegetation chronosequences for each pattern, which were mostly due to the unchanged TN concentration in silt and clay fraction. Re-vegetation also changed the dependence of C min , C min /C 0 on N availability, with significant relationships in re-vegetated artificial grassland and pea shrub woodland which may due to the influence of legumes on microbes. In conclusion, OC mineralization increased with conversion, varying by re-vegetation type, while OC decomposability and temperature sensitivity were stable regardless of re-vegetation type and time, indicating the similar biodegradability and stability in face of warming. • OC mineralization and Q 10 were tested in varied re-vegetation types and times. • Cropland re-vegetation increased C min especially for artificial grassland. • •N in macro-aggregate explained about 50% of cumulative OC mineralization. • •OC biodegradability and Q 10 were similar during the post agricultural restoration. [ABSTRACT FROM AUTHOR]

• We investigated soil physical and hydraulic properties across a cultivation chronosequence. • A greater decrease in aggregate stability was found in cropland after long-term cultivation. • Long-term cultivation partially improved deep soil bulk density, porosity, field capacity and K s. • The parameters of soil water retention curve were unaffected by the cultivation time. Black soils (Mollisols) are inherently productive and fertile but are deteriorating due to long-term intensive cultivation. Understanding the changes in soil physical and hydraulic properties in topsoils and deep soils after converting forest to cropland would reveal the mechanism related to the black soil degradation. Herein, we investigated the variations in the soil water-stable aggregates, soil water content, bulk density, field capacity, total porosity, saturated hydraulic conductivity, and parameters of soil water retention curve at the 0–100 cm depth in four sampling fields. These fields included a forest as control and three croplands that were converted from forest 41, 50 and 65 years ago in the black soil region of Northeast China. We showed that converting forest to cropland decreased >2 mm aggregates and aggregate stability especially at 0–15 and 70–100 cm depths, with a greater decrease in cropland after relatively longer time of cultivation. Conversion of forest to cropland significantly decreased the soil water content at the 0–15 cm depth but increased it at the 15–100 cm depth, and the increase in the 50–100 cm soil layer was strengthened with cultivation time. The decreases in field capacity, total porosity and saturated hydraulic conductivity and increase in bulk density at the 0–50 cm depth following the conversion of forest to cropland were higher after 41 and 50 years of cultivation than those after 65 years of cultivation. However, changes in these metrics at the 50–100 cm depth increased with cultivation time. The parameters (i.e., θ r , θ s , α and n) of the soil water retention curve were not affected by the cultivation time after converting forest to cropland. These results highlighted that long-term cultivation after the conversion of forest to cropland resulted in the changes in soil physical and hydraulic properties in the 0–100 cm soil profiles, and thus, the response of deep soils should not be ignored in this black soil region. [ABSTRACT FROM AUTHOR]

Extreme precipitation regime under global change context is estimated to cause heavy rainstorms and longer drought intervals. Temporal variations of soil structure and erosion characteristics during and after heavy rainstorms were less investigated, particularly across a wide soil texture gradient. In this study, 15 soils were selected with clay content ranging in 12.9–38.2%. Soil erosion characteristics and enrichment ratios of organic carbon (ER OC) and nitrogen (ER N) were measured during 3 successive rainfall simulations at slope of 15° and intensity of 120 mm h−1. The water-stable aggregate distribution was measured for soils before and after rainfall and drying. The mean weight diameter (MWD) of water-stable aggregate remained unchanged before (1.476 ± 0.182) and after rainfall and drying (1.406 ± 0.135 mm), but decreased for soils with higher organic carbon contents. Soil erodibility (K factor) averaged in 0.018 ± 0.003, 0.011 ± 0.001 and 0.008 ± 0.001 in 3 successive rainfall events, with 42% and 27% decreases after each event, respectively (P < 0.05); and the decreases were greater for less aggregated soils or coarser textured soils. Stepwise regression showed that the <0.25 mm water-stable aggregate explained most variations of K and its dynamics. The ER OC and ER N were close to 1 and were not correlated with clay content or MWD (P > 0.05). The ER N decreased first and then remained stable, and ER OC was unchanged during successive rainfalls. These results indicated that soil texture or aggregation status affected soil erodibility and its temporal changes in successive rainstorms. Unlabelled Image • Extreme precipitation regime was simulated by successive rainstorms and drying. • Aggregate stability was not affected by rainfalls and drying regardless of texture. • Erodibility decreased in successive rainstorms especially in poorly aggregated soils. • ER OC and ER N were close to 1 regardless of texture and unaffected by sediment mass. [ABSTRACT FROM AUTHOR]

Soil carbon (C) and nitrogen (N) combining with physical and chemical properties play important roles in terrestrial C and nutrient cycling; however, how C and N in deep soils respond to land-use change is less understood, hindering the precise evaluation of soil C dynamics and budgets. Here, we present results regarding soil C, N and related soil properties at 0–500 cm depth as affected by afforestation at two sites (Fufeng and Yongshou) with contrasting soil inorganic C (SIC) levels in China's Loess Plateau. The concentrations of SIC ranged from 12.94 to 20.17 g kg−1 in Fufeng and from 0.18 to 0.36 g kg−1 in Yongshou. The objectives of this study were to examine how soil C and N in deep soils are altered following afforestation and how these effects vary with soil depth and site. We found that the establishment of woodland on cropland increased soil porosity and saturated hydraulic conductivity but decreased the bulk density in the topsoils (0–20 cm). The conversion of cropland to woodland resulted in an increase of soil electric conductivity in the topsoils and a decrease in the deep soils in Fufeng but had an opposite influence with soil depth in Yongshou. This land-use change increased organic C and total N concentrations along the 0–500 cm soils at both sites but had divergent effects on the concentrations of SIC and soil total C (STC) between the two sites. Overall, the concentrations of SIC and STC increased in Yongshou but decreased in Fufeng after woodland establishment. The results from this study indicated the determination of the initial SIC concentration on the response of C to afforestation in semiarid soils, and such determination should be considered in biogeochemical models. • Afforestation decreased pH and increased SOC and TN regardless of sites. • Effects of afforestation on soil C were dependent on initial SIC level. • Afforestation increased SIC and STC in low SIC site and reduced them in high SIC site. [ABSTRACT FROM AUTHOR]

Ferroelectric memory is one of the most attractive emerging nonvolatile memory. Conventional methods to increase storage density in ferroelectrics include reducing the storage bit size or fabricating 3D stacks. However, the former will face a physical limit finally, and the integration of single‐crystalline ferroelectric oxide following the latter still remains a great challenge. Here, a new method is introduced to construct a scroll‐like 3D memory structure by self‐rolling‐up single‐crystalline ferroelectric oxides. PbZr0.3Ti0.7O3 single‐crystalline thin film is chosen as a prototype and epitaxially grown on another oxide stressor layer with a few lattice‐mismatch. Releasing such "Pb(Zr, Ti)O3/stressor" bilayered structure from the substrate induces self‐rolling‐up due to the internal stress from the lattice‐mismatch. High‐density information can be written in the form of switched ferroelectric domains on those flat "Pb(Zr, Ti)O3/stressor" membranes via piezoelectric force microscopy. In self‐rolling‐up membranes, information density can be experimentally enhanced up to 45 times. Theoretically, the freestanding "Pb(Zr, Ti)O3/stressor" membranes have a strongly driven force to self‐rolling‐up, and the area ratio can enhance 100–450 times, corresponding to an ultra‐high density information storage of 102 Tbit In−2. This study provides a new and general method to develop compact, high‐density, and 3D memories from oxide materials. [ABSTRACT FROM AUTHOR]

Deep soil organic carbon (SOC) plays an important role in carbon cycling. Precisely predicting deep SOC at the regional scale is crucial for the accurate assessment of carbon sequestration potential in soils but has been challenging for a century. Herein, we developed a depth distribution function-based empirical approach to predict SOC in deep soils at the regional scale. We validated this approach with a dataset from four regions of the world and examined the application of this approach in China's Loess Plateau. We found that among the reported depth distribution functions describing vertical patterns of SOC, the negative exponential function performed best in fitting SOC along the soil profile in various regions. Moreover, the parameters (i.e., Ce and k) of the negative exponential function were linearly correlated to surface SOC (0–20 cm) and the changing rates of SOC within the topsoil (0–40 cm). Based on the above relationships, the empirical equations for predicting the negative exponential parameters are established. The validation results from site-specific and regional dataset showed that combining the negative exponential function and such empirical equations can precisely predict SOC concentration in soils down to 500 cm depth. Our study provides a simple, rapid and accurate method for predicting deep soil SOC at the regional scale, which could simplify the assessment of deep soil SOC in various regions. [ABSTRACT FROM AUTHOR]

The crosslinked polyethylene (XLPE) cable safety is affected by environmental factors and artificial defects during operation. This work proposes an improved locating method based on broadband impedance spectrum (BIS) to locate local defects in XLPE cables. The calculation process of the algorithm has been analyzed. The selection of the incident Gaussian signal and the peak recognition method have been discussed, where the pulse width of the Gaussian signal was found to be determined primarily by the upper limit frequency of the traveling wave transmitting in the cable. The centroid and function fitting methods were established to reduce the peak recognition error caused by the test sampling rate. This work verified the accuracy of the algorithm through experiments. A vector network analyzer (VNA) was used to test the BIS of the cable. A 20 m-long cable containing abrasion and an inserted nail with different depths was measured in the BIS test. It was found that the abrasion and the nail could be located. The locating deviation of abrasion was within ±1%, and the centroid and function fitting methods could effectively reduce the locating deviation. The locating deviation was within ±1% when the depth of the nail inserted into the cable accounted for less than 50% of the insulation thickness. When the depth exceeded 75% of the insulation thickness, the deviation of each method was more significant, and the maximum absolute value of the deviation was 4%. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ca- OC and clay + silt-OC played a vital role in the stability of MAOC. • Ca- OC and clay + silt-OC contributed to the sequestration of MAOC. • MAOC persistence was positively correlated with the MAOC sequestration. Mineral associated organic carbon (MAOC) accounts for a substantial portion of soil organic carbon (SOC) due to its tendency for physicochemical bonding with mineral surfaces. However, the mechanisms controlling MAOC stability and sequestration upon erosion and deposition remain unclear. We collected samples from topsoil (0–20 cm) and subsoil (60–80 cm) in an eroding loess landscape in Northwest China. SOC was fractionated into particulate organic carbon (POC) and MAOC, and OC retained by reactive mineral phases (calcium, iron, and aluminum) were studied. Adsorption-desorption experiments were performed to quantify the OC capture capacity, and thermogravimetric techniques were used to determine the thermal stability of MAOC. Although POC dominated in the soil mass distribution (>60 %) in both sites, the MAOC in the topsoil and subsoil in the depositional sites was characterized by 1.38–3.88 times higher OC contents than the eroding sites. Furthermore, depositional sites featured 1.19–1.45, 1.43–1.72, and 1.28–1.96 times higher maximum adsorption capacity, specific mineral surface area, and silt + clay contents, respectively, than these of the eroding sites, indicating high OC sequestration capacity in the soils of depositional sites. Erosion directly transports soil materials (e.g., OC and fine particles) to the depositional sites, when coupled with the high OC capture capacity, this leads to an increase in the OC content from 0.50 to 1.37 at the eroding sites to 2.19–3.28 mg g−1 at the depositional site. The content and chemical structure of organic-metal complexes had minor differences, however, MAOC in the depositional sites was observed to have excellent thermal stability. Calcium-, and silt + clay-associated OC (Ca-OC and CS-OC) were positively correlated with the MAOC stability and content. Overall, our findings highlight the important role of Ca-OC and CS-OC in determining the stability and sequestration of MAOC in eroding loess landscapes. [ABSTRACT FROM AUTHOR]

Deforestation can lead to severe losses of soil nutrients. However, the impacts of the slope morphology and position on the spatial distributions of soil nutrients after deforestation and their relationships are unclear, thereby limiting our understanding of the mechanism of soil degradation. In this study, we aimed to identify the relationships between the changes in soil nutrients and the slope morphology (i.e., slopes with different widths or lengths) after deforestation. Soil samples were collected from forestland slopes with different morphologies after deforestation for 28 years in the hilly area of the Loess Plateau, China. We analyzed the effects of the length, width, and position of the slope on the pH, soil organic carbon (SOC), total nitrogen (TN), total phosphorus (TP), nitrate-N (NO 3 −), ammonium-N (NH 4 +), available phosphorus (AP), and available potassium (AK) distributions after deforestation. The spatial autocorrelation analysis indicated that the Moran's I index value for soil nutrients was larger on deforested slope than that of forest land, thereby suggesting that deforestation increased the spatial heterogeneity of the soil nutrients. After deforestation, the spatial autocorrelation distances increased for the soil pH and TP, whereas they decreased for SOC, TN, NH 4 +, NO 3 −, and AK. The TN, NH 4 +, and NO 3 − contents were significantly higher on the narrow slope than the wide slope. Among the three slope lengths, the soil nutrient losses were greater on the longer slope because of the more severe erosion of the slope after deforestation. The slope position significantly affected the distributions of the soil nutrients. In the vertical direction, the soil nutrient contents decreased continuously in the 0–10, 10–20, and 20–40 cm soil layers, but then increased in the 40–60 cm soil layers, mainly due to the eluviation of nutrients to deep soil layers. These results demonstrate that the slope morphology and position should not be overlooked when predicting the responses of soil nutrients to deforestation in the hilly loess region of China. • Deforestation changed the spatial distributions of the soil nutrients on the slope. • The nutrient contents were higher on the narrow slope than the wide and medium slopes. • Among the three slope lengths, the soil nutrient losses were greater on the longer slope. • Slope morphology and position should not be overlooked when predicting the responses of soil nutrients to reclamation. [ABSTRACT FROM AUTHOR]

In the current in vitro fertilization and embryo transfer protocol, the 8 blastomeres in the day-3 embryo are selected for transfer because these embryos can produce high rates of blastocyst formation and clinical pregnancy. However, the relationship between the blastomere number in day-2 embryos and the rate of blastocyst formation or clinical pregnancy remains unclear. The purpose of this retrospective study is to explore the relationship between the blastomere number in day-2 embryos and the rate of blastocyst formation or clinical pregnancy. From January 2015 to April 2020, we collected 8126 day-3 embryos (8 blastomeres) from 2282 patients. These embryos were classified into 8 groups (1 blastomere, 2 blastomeres, 3 blastomeres, 4 blastomeres, 5 blastomeres, 6 blastomeres, 7 blastomeres, and 8 blastomeres) based on their blastomeres number on day 2 after insemination. Of these groups, the 4 blastomeres group accounted for the largest proportion (74.44%). The 1 blastomere group accounted for the smallest proportion (0.22%). A total of 3554 day-3 embryos (8 blastomeres) from 1648 patients developed into blastocysts. The rate of blastocyst formation from the 4 blastomeres group was the highest (94.06%). Finally, 800 patients received single day-3 embryos (8 blastomeres) transfer. The rate of clinical pregnancy from 4 blastomeres group was the highest (51.98%). In conclusion, our data provide evidence that the number of blastomeres in day-2 embryos affects the rate of blastocyst formation and clinical pregnancy. [ABSTRACT FROM AUTHOR]

The conversion of croplands to shrublands is a common approach used to control soil erosion in the drylands of the Loess Plateau in China and affects the soil, water, and carbon cycles. Knowledge of the soil water content (SWC) and soil organic carbon (SOC) content in response to land-use change is essential for optimizing revegetation strategies and improving ecosystem services. This study investigated the distribution characteristics of the SWC and SOC content for the 0–500 cm soil layer in 11 croplands and 39 shrublands planted on a former cropland over 50 years ago. The coupled and trade-off relationship between soil water consumption and carbon fixation in the shrubland soil was also analyzed. The results showed that the SOC content and SWC of the shrublands and croplands varied with soil depth, but their distribution patterns were similar under both land-use types. Planting shrubs on slopes reduced the SWC but did not significantly enhance the SOC content, indicating that cropland-to-shrubland conversion results in excessive soil water depletion without increasing carbon fixation in the soil. Additionally, both the SOC content and SWC of the shrublands varied significantly with slope positions (p < 0.05) and showed intermediate coordination levels across the entire slope. Moreover, the SOC content provided higher benefits than SWC, where the foot slope showing a relatively higher coupling coordination degree and a lower trade-off than other slope positions. These results suggest that shrubs provide a limited contribution to improve SOC stocks in the drylands of the Loess Plateau and that reductions in deep soil water under cropland-to-shrubland conversion require consideration when planning future ecological restoration measures. To improve ecosystem services (carbon sequestration and soil conservation) without compromising water resources in the drylands of the Loess Plateau or similar regions worldwide, it is necessary to fully consider the slope position and the trade-off between the SWC and SOC content. • Cropland-to-shrubland conversion induces soil moisture decline on the Loess Plateau. • Planting shrubs on slope land does not sequester large amounts of carbon. • SOC content has a higher relative benefit than SWC for the entire shrubland slope. • Afforestation measures in dryland areas should consider slope position. [ABSTRACT FROM AUTHOR]

Ferroelectric memories, freestanding single-crystalline oxide membranes, information storage, self-assemblies, self-rolling-up Keywords: ferroelectric memories; freestanding single-crystalline oxide membranes; information storage; self-assemblies; self-rolling-up EN ferroelectric memories freestanding single-crystalline oxide membranes information storage self-assemblies self-rolling-up 1 1 1 05/16/23 20230512 NES 230512 B Information Storage b In article number 2213668, Ming Liu, Bin Peng, and co-workers introduce a self-assembly method to fabricate scroll-like 3D architecture, which can increase the information storage density in ferroelectric memories. Self-Rolling-Up Enabled Ultrahigh-Density Information Storage in Freestanding Single-Crystalline Ferroic Oxide Films (Adv. Funct. [Extracted from the article]

Soil erosion is continually overlooked in the hilly red soil region of southern China, and there is a substantial lack of knowledge about the effects of soil and water conservation measures (SWCMs) on erosion prevention and soil carbon and nitrogen accumulation for the eroded sloping arable land in this region. Herein, based on a long-term experiment in the red soil hilly region in China, we investigated the effects of 17 years of SWCMs on soil organic carbon (SOC), total nitrogen (TN), microbial biomass carbon and nitrogen (MBC and MBN, respectively) as well as soil erodibility (K factor) at soil depths of 0–100 cm in the top, middle and bottom parts of the slope. The SWCMs included straw mulching (SM), downslope ridge cultivation (DC), downslope ridge cultivation + contour hedgerow planting (DCH), and contour ridge cultivation tillage (CC). A bare land treatment without any crops was used as a control (CK). We found that SWCMs increased SOC, TN, MBC, and MBN by 8–57%, 1–14%, 25–68%, and 17–35%, respectively, with greater increases in these variables in the CC and SM treatments and smaller increase in the DC treatment. Additionally, the effects of the SWCMs were greater at the top and middle of the slope than at the bottom of the slope, and the effects varied with soil depth. Moreover, the SWCMs decreased soil erodibility, with a lower K factor in the SWCMs treatments (0.018–0.049 t ha h ha−1 MJ−1 mm−1) than in the CK (0.042–0.068 t ha h ha−1 MJ−1 mm−1) and a greater decrease in the CC treatment. The effects of the SWCMs on soil erodibility mainly occurred through the regulation of SOC according to structural equation modeling. Overall, this study suggested that straw mulching and contour ridge cultivation tillage were the most effective strategies for restoring soil carbon and nitrogen and preventing soil erosion. • The SWCMs improved soil carbon and nitrogen levels but reduced erodibility. • The effects of the SWCMs on soil erodibility mainly through the regulation of SOC. • Straw mulching and contour ridge cultivation tillage prevent soil erosion conspicuously. [ABSTRACT FROM AUTHOR]

• Up-slope runoff and sediment increased most nutrient contents on the wide slope. • Up-slope runoff and sediment decreased most nutrient contents on the narrow slope. • Up-slope runoff and sediment reduced random spatial heterogeneity of soil nutrients. Upslope runoff and sediment critically influence soil erosion, while their impact on the subsequent downslope nutrient distribution has not been examined, consequently hindering the exact assessment of the effects of erosion on soil biogeochemical cycles. Herein we selected two groups of wide and narrow slopes on the middle Loess Plateau, with each slope group including slopes with and without upslope runoff and sediment. For each slope, we collected soil samples from topsoil along the slope at different distances from the upper slope to the lower slope, and collected samples from depths of 0–60 cm at the upper, middle and lower positions of the slope. The contents of soil organic matter and nutrients were analysed. The purpose of this study was to disentangle the effects of upslope runoff and sediment on spatial distribution of soil nutrients on slopes of different widths. We showed that compared with slopes without upslope runoff and sediment, upslope runoff and sediment increased the content of most nutrients in topsoil on the wide slope, but had a contrasting effect on the narrow slope. Upslope runoff and sediment reduced the random spatial heterogeneity of soil nutrients on both the wide and narrow slopes, with greater effects observed on the narrow slope. The influence of upslope runoff and sediment on the profile distribution of soil nutrients varied with slope position and slope width, and was nutrient type-dependent. These results indicated that slope topographical conditions interact with upslope runoff and sediment in influencing vertical and horizontal patterns of soil nutrients on slopes. [ABSTRACT FROM AUTHOR]

• Higher erosion intensity and smaller size of check dam resulted in greater variation in soil particles. • Soil OC and N in check dams decreased with the distance from the dam body to the gully head. • Silt content was more important than clay content in influencing the distribution of OC and N in check dam soils. Check dams are effective soil and water conservation structures worldwide that play an important role in preserving sediments containing carbon (C) and nitrogen (N). However, in terms of the depositional characteristics of C and N in check dams, research on the relative effects of erosion intensity and depositional area is limited, hindering our understanding of the fates of eroded C and N. This study compared the horizontal and vertical distributions of soil particles, organic C (OC), and total N (TN) in check dams of various sizes and erosion intensities in the Loess Plateau. The results showed greater variations in the horizontal and vertical patterns of soil particles of smaller check dams and highly serious erosion (erosion modulus = 15040 t km-2 a-1) than those that of larger check dams and strong erosion regions (erosion modulus = 5151 t km-2 a-1). Soil OC and TN contents decreased from the dam body to the gully head, especially in the highly serious erosion region. Notably, the effect of smaller check dam on the vertical distributions of soil OC and TN was more intense than that of the larger check dam in the strong erosion region. In contrast, a minor effect of check dam size was observed in the highly serious erosion region. Moreover, a closer relationship between the distribution of OC and TN with silt content rather than with clay content in check dams was observed, and this relationship was enhanced by an increase in erosion intensity. Overall, the synergistic effects of erosion intensity and check dam size affected the spatial patterns of OC and TN in sediments on the Loess Plateau. Careful consideration of these two factors is beneficial for accurately assessing the C and N fates in depositional areas. [ABSTRACT FROM AUTHOR]

Soil nitrogen (N) mineralization is an important ecological process influencing N availability and ecosystem functionality, and is sensitive to vegetation presence and soil erosion. However, how vegetation presence affects N mineralization and its response to erosion has not been directly examined, hindering our ability to predict N cycling in eroding environments. Herein, we compared the effect of vegetation presence on N mineralization and mineral N dynamics in two growing seasons between erosion vs. deposition sites in three sub-watersheds in the transition zone between water erosion and wind erosion of North China. We aim to examine how soil N cycling responds to erosion and vegetation presence at temporal and spatial scales. The mineral N concentration in the soil solution and mineralization rates between May 2017 and October 2018 in plots with and without vegetation were measured to assess the effects of vegetation presence. We showed that N mineralization rates did not significantly vary among the three sub-watersheds or between erosion and deposition sites. The concentrations of mineral N in the soil solution were higher in relatively larger sub-watersheds for the erosion sites and in smaller sub-watersheds for the deposition sites. Vegetation decreased soil NO 3 --N and total mineral N and increased NH 4 +-N concentrations in the early and middle periods of the growing season. The effects of vegetation presence on net N mineralization rates varied with size of sub-watersheds, with increased rates of net nitrification and mineralization at both deposition and erosion sites in relatively larger sub-watershed, but reduced rates of net nitrification and mineralization in smaller sub-watersheds. Moreover, the presence of vegetation shifted the seasonal pattern of N mineralization. Therefore, vegetation presence had important ecological regulation on soil N cycling at spatial and temporal scales in the transition zone between water erosion and wind erosion. • Soil mineral N varied with sub-watershed scales and landscape positions. • Vegetation decreased nitrate and total mineral N but increased ammonium. • The effects of vegetation on N mineralization varied with sub-watershed scales. • Vegetation presence shifted the seasonal pattern of N mineralization. [ABSTRACT FROM AUTHOR]

Cultivation after the converting natural ecosystems to agricultural land is often accompanied by accelerated soil erosion. To better understand how land-use conversion and agricultural erosion separately affect aggregate-associated nitrogen (N) and organic carbon (OC), we examined the responses of aggregate-associated N and OC to both the converting forest to agricultural land and erosion in the agricultural region of Northeast China. Non-erosion sites in forest and agricultural land converted from forestland 60 years ago were selected to address the effects of land-use change. The sites with various erosion intensities in an eroding area of sloping cropland (i.e., non-erosion, light erosion, moderate erosion and heavy erosion) were selected to compare the effects of the erosion intensity. The measured soil metrics included the soil bulk density, water-stable aggregates, and aggregate-associated OC and N along 0–70 cm soil profiles. Converting forest to agricultural land did not significantly influence the OC and N concentrations in each aggregate, while the land-use change significantly reduced the OC and N stocks in macroaggregates but increased them in microaggregates and silt+clay fraction. However, erosion significantly decreased the OC and N concentrations and stocks in each aggregate. The changes in the OC and N stocks in aggregates were mainly due to the depletion of soil aggregates in responding to the conversion of forest to agricultural land but due to decreases in OC and N concentrations in aggregates in responding to soil erosion. Our results indicated that the effects of erosion on aggregate-associated OC and N were greater compared with the effects of converting forest to agricultural land in this Mollisol region. • Land-use change didn't significantly affect OC and N concentrations in aggregates. • Erosion decreased OC and N concentrations in aggregates. • OC and N stocks in aggregates were determined by their concentrations during erosion. • OC and N stocks in aggregates were dominated by aggregates mass following land-use change. [ABSTRACT FROM AUTHOR]

• Afforestation increased significantly soil OC and N mineralization. • The increase of OC and N mineralization were larger in sites with high clay content. • The temperature sensitivity decreased in sites with relative high clay content. • Soil texture regulated OC and N mineralization and their temperature sensitivity. Afforestation on abandoned cropland has great potential to increase soil organic carbon (OC) and nitrogen (N). Identifying the effect of afforestation on mineralization of OC and N as well as their temperature sensitivity at large spatial and temporal scales is essential to understand soil OC and N dynamics. In this study, we measured mineralization of soil OC and N at standard temperatures (15 and 25 °C) by laboratory incubation, and calculated their temperature sensitivity (Q 10). Soil samples were collected from cropland (0 years, selected as a control) and adjacent woodlands with different afforestation age (10, 20 and 30 years) at five sites from north to south on China's Loess Plateau. The objectives were to understand how long-term afforestation affects OC and N mineralization and their Q 10 and whether such effects depend on afforestation age and soil texture. The results showed that afforestation increased OC and N mineralization, but this effect was not affected by afforestation age (10–30 years). The Q 10 of OC and N mineralization increased in the first 10 years of afforestation but decreased in the late stage. Furthermore, the increases of OC and N mineralization by afforestation were higher at sites with fine-textured soils than those at sites with coarse-textured soils. However, the Q 10 increased at sites with a relatively high sand content but decreased or remained unchanged at sites with a relatively high clay content. The changes in OC and N mineralization and their Q 10 were related to soil OC and N contents, pH and clay content. Overall, we concluded that long-term afforestation would contribute to the stability of soil OC and N in afforested ecosystems. Soil texture is an important factor controlling OC and N mineralization and their Q 10 , and should be considered when predicting soil OC and N dynamics in response to temperature change in different landscapes. [ABSTRACT FROM AUTHOR]

• Simulated erosion decreased mineralization of OC and N in soils • Decrease in OC and N mineralization was mainly occurred in small aggregate sizes • Changes in OC and N availability determined decrease in OC and N mineralization • The OC and N mineralization increased with OC and N contents but texture independent Soil erosion has important influence on soil processes and particularly soil nutrient dynamics, which in turn affects the terrestrial C and N cycling and greenhouse gases emission. However, the responses of carbon (C) and nitrogen (N) cycling in soils and soil fractions to erosion remain largely unclear, hindering the precise prediction of the fate of C and N in the terrestrial ecosystem. Herein, we compared the mineralization of organic carbon (OC) and N at two different temperatures (15 and 25 °C) in bulk soils and aggregate fractions of 19 soils before and after a simulated rainstorm. The temperature sensitivity (Q 10) of OC and N mineralization was calculated. Soil samples were collected from 9 sites across China, with soil types of Alfisols, Inceptisols, Mollisols, Ultisols, and land uses of croplands, grasslands, and woodlands. The soil aggregate fractions were >2, 2-1, 1-0.25 and <0.25 mm, respectively. We hypothesized that erosion will decrease OC and N mineralization due to the loss of labile organic matter from soils and that the effects of erosion would decrease with clay content and vary with different aggregate fractions. In support of these hypotheses, the cumulative mineralized OC and N (C m and N m) in the soils and aggregate fractions were decreased of 78-85% and 37-52% after erosion, and the temperature sensitivities of OC and N mineralization were decreased of 80-84% and 4-43%, respectively. The effects of erosion varied with site where the soil was collected. The decreases in C m and N m mainly occurred in small aggregate sizes (1-0.25 and <0.25 mm fractions). The C m and N m in bulk soils and aggregates increased significantly with the contents of OC, N, labile OC and mineral N but were texture independent. These results highlighted significantly reduction of OC and N mineralization at eroding sites, which should be carefully considered when assessing emissions of greenhouse gases in eroding environments. [ABSTRACT FROM AUTHOR]