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As one of the four major black soil distribution areas in the world, the black soil region in northeastern China has shown a trend of nutrient degradation under excessive development. Understanding its nutrient changes and the factors affecting them is of great significance to the sustainable development of black soil. Soil nutrient profiles are influenced by several anthropogenic management patterns, including fertilizer application methods and tillage practices. A comprehensive analysis of the influencing factors can help to understand the mechanisms of nutrient changes in black soil cropland. Therefore, using soil organic carbon (SOC) as a proxy for nutrients, this study applied a meta-analysis based on 1138 observations from 60 papers to reveal the effects of anthropogenic management practices (application of organic fertilizers (OF), straw back (SB), application of chemical fertilizers (CF) and conservational tillage (CT)) on soil nutrients. The results showed that the most of soil nutrients increased significantly under management model. The application of chemical fertilizers decreased soil pH by 4.55% and increased soil available phosphorus (AP) content by 112.14%. Compared to the conventional model, application of organic fertilizers significantly increased SOC content, total nitrogen (TN) content and microbial biomass carbon (MBC) content by, 16.75%, 20.10% and 31.15% (p < .05), respectively. The effect values of SOC content were positively correlated with those of most soil nutrient contents under different anthropogenic management. This study helps to understand the response of nutrient content of northeastern black soils to different anthropogenic management models and provides reasonable references for sustainable farming patterns. [ABSTRACT FROM AUTHOR]

Abstract: In order to explore the effect of organic matter on phosphorus (P) adsorption and availability in northeast black soil, 3 types of black soil with different levels of organic matter including high organic matter black soil (T1), medium organic matter black soil (T2) and low organic matter black soil (T3) were selected to explore whether the adsorption-desorption of phosphorus was influenced by endogenous organic matter by removing the organic matter. In addition, black soil with high organic matter was selected as the material, and 4 treatments with different organic fertilizer addition rates were set, including 0% (CK), 1% (C1), 2% (C2), 3% (C3), respectively. The effects of different organic fertilizer addition rates on soil physicochemical properties and phosphorus availability were analyzed. The results showed that with the increase of organic matter, the black soil adsorption affinity constant (K), maximum adsorption capacity (qm), and soil maximum buffer content increased, while the soil phosphorus saturation (DPS) decreased, indicating that phosphorus was less likely to be lost in soils with high organic matter. The higher the organic matter, the stronger the soil's ability to adsorb phosphorus. When the equilibrium content was 100 mg·L-1, the phosphorus adsorption capacities of T1, T2 and T3 treatments were 754.83, 722.58 and 660.65 mg·kg-1, respectively. The lower the organic matter, the stronger the soil's ability to desorb phosphorus, and the higher the phosphorus availability. Removing organic matter reduced the phosphorus adsorption capacity of black soil with different levels of organic matter by 5.90% to 17.33%, enhancing soil phosphorus availability. The determination coefficient (R2) of the phosphorus isothermal adsorption equation was higher for the Langmuir equation than for the Freundlich equation, indicating a better fit; soil phosphorus adsorption was mainly dominated by chemical adsorption. Different doses of organic fertilizer application could reduce the adsorption rate of phosphorus by black soil, and the adsorption rate significantly decreased with the increase of organic fertilizer dosage. When the maximum phosphorus equilibrium concentration was reached, the C3 treatment had the greatest reduction in soil phosphorus adsorption and the highest soil phosphorus availability. The pseudo-second-order kinetic equation could well express the kinetic characteristics of soil phosphorus adsorption with organic fertilizer application. The addition of organic fertilizer significantly increased soil pH, available phosphorus, effective phosphorus and acid phosphatase activity by 1.05%~3.97%, 121.43%~251.35%, 8.38%~12.65% and 42.96%~57.77%, respectively. Above results provided scientific theoretical support for scientific management of black soil in different regions, rational application of organic fertilizer and improvement of phosphorus availability. [ABSTRACT FROM AUTHOR]

In order to solve the problem of low and poor straw degradation in typical black soil areas of Northeast China, the present study was carried out to screen the potential of in situ strains with cellulose degradation ability from black soils of Northeast China to play a role in the resourceful utilization of straw and the development of sustainable agriculture. The straw degradation potential of the strains was evaluated by combining sodium carboxymethyl cellulose plate screening and cellulase viability assay; the species identification of the strains was carried out by morphology, physiology, biochemistry, and molecular biology; and the basic medium formulation of the strains was optimized by Box–Behnken response surface methodology. Ten cellulose-degrading strains were identified: ZL-5, ZL-69, ZL-88, ZL-95, ZL-111, ZL-137, ZL-139, ZL-140, ZL-187, and ZL-216, of which ZL-139 had the highest cellulase production capacity, with a cellulase secretion of 7.8781 U/mL in the enzyme-producing medium. ZL-139 was identified as Bacillus cereus; the optimized best formulation was glucose—4.284 g/L, yeast extract—1.454 g/L, MgSO4—0.417 g/L, KH2PO4—0.5 g/L, KH2PO4—0.5 g/L, K2HPO4—1.5 g/L, and NaCl—1.0 g/L. In conclusion, strain ZL-139 has good potential for crop straw degradation and can be a candidate strain for a straw-rotting agent in northeast China, with promising prospects for development and utilization. [ABSTRACT FROM AUTHOR]

An aerobic, Gram-stain-negative, motile rod bacterium, designated as SYSU BS000021T, was isolated from a black soil sample in Harbin, Heilongjiang province, China. Phylogenetic analysis based on 16S rRNA gene sequences indicated that the isolate belongs to the genus Methylobacterium, and showed the highest sequence similarity to Methylobacterium segetis KCTC 62267 T (98.51%) and Methylobacterium oxalidis DSM 24028 T (97.79%). Growth occurred at 20–37℃ (optimum, 28 °C), pH 6.0–8.0 (optimum, pH 7.0) and in the presence of 0% (w/v) NaCl. Polar lipids comprised of phosphatidylcholine, phosphatidylethanolamine, phosphatidylglycerol, diphosphatidylglycerol, one unidentified aminolipid and one unidentified polar lipid. The major cellular fatty acids (> 5%) were C18:0 and C18:1ω7c and/or C18:1ω6c. The predominant respiratory quinone was Q-10. The genomic G + C content was 68.36% based on the whole genome analysis. The average nucleotide identity (≤ 83.5%) and digital DNA–DNA hybridization (≤ 27.3%) values between strain SYSU BS000021T and other members of the genus Methylobacterium were all lower than the threshold values recommended for distinguishing novel prokaryotic species. Based on the results of phenotypic, chemotaxonomic and phylogenetic analyses, strain SYSU BS000021T represents a novel species of the genus Methylobacterium, for which the name Methylobacterium nigriterrae sp. nov. is proposed. The type strain of the proposed novel species is SYSU BS000021T (= GDMCC 1.3814 T = KCTC 8051 T). [ABSTRACT FROM AUTHOR]

[Objective] To investigate the impact of intermittent rainfall on the amount and sorting characteristics of black soil splash erosion. Methods］ This study is based on artificial simulated rainfall experiments, with two rainfall intensities (40, 70 mm/h) designed, each with 5 rainfall events, to analyze the splashing erosion amount and particle size distribution characteristics of black soil under different rainfall conditions. Results］ Under two different rainfall intensities, there is a dynamic development process of alternating strength between "no crust weak crust strong crust weak crust new crust" in the soil surface layer of different rainfall sites. Under two different rainfall intensities, the maximum values of splashed aggregate MWD and GMT) appeared in the fourth rainfall, and the minimum values appeared in the first rainfall. The agglomerates with a particle size of 5 〜2 mm did not migrate in each rainfall, and the splashed agglomerates were mainly composed of particles with a size of 2〜().25 mm, accounting for 36.49% 〜58.61 % and 49.1()% 〜 60.09% of the splashed erosion amounts of the two rainfall intensities, respectively. The erosion amount of the five rainfall events showed a trend of first increasing and then decreasing with the decrease of particle size, while the mass percentage with particle size <1 ().053 mm showed a trend of first decreasing and then increasing with the increase of intermittent frequency. The mass percentage with particle size ().053 mm all showed the minimum value in the third rainfall event, which was 1&21% and 17.63%，respectively. Conclusion] Rainfall can lead to the formation of soil crust, and the thickness of soil crust shows dynamic changes with the increase of rainfall frequency. Tn the third rainfall, the soil crust thickness is the highest, and at this time, the splash erosion amount has the minimum value, mainly greater than ().053 mm. The research results provide reference for the study of soil water erosion mechanism in the black soil area of Northeast China. [ABSTRACT FROM AUTHOR]

Soil organic matter (SOM) is an important carbon pool in terrestrial ecosystems and plays a key role in soil functions. Nevertheless, the effects of fertilization practices on the physical, chemical, biological, and comprehensive stability of SOM are still unclear. We carried out a long-term field experiment in the northeast black soil region in China with four different fertilization practices: no fertilizer (CK), single chemical fertilizer (NPK), chemical fertilizer + straw (NPKJ), and chemical fertilizer + organic manure (NPKM). The content of particulate organic matter (POM) and mineral-associated organic matter (MAOM), compound composition of SOM, carbon mineralization characteristics, active soil organic matter (ASOM), and inert soil organic matter (ISOM) were tested. The results showed that the application of fertilizers significantly increased the contents of POM and MAOM to 2.59–4.65 g kg−1 and 32.69–34.65 g kg−1 (p < 0.05), but decreased the MAOM/POM values by 37.8–42.4%, indicating reduced the physical stability of SOM. Fertilization practices increased the contents of aromatic, nitrogen-containing compounds and decreased the oxygen compounds of SOM, representing enhancement of the chemical stability. The contents of ASOM and ISOM increased in fertilization practices, while the biological stability index (BSI) under the NPKJ and NPKM treatments was lower than the CK treatment, suggesting that the biological stability decreased under the manure and straw application. In addition, the comprehensive stability of SOM increased by 26–116% through a reduction in the physical and biological stability, coupled with an increase in the chemical stability. Collectively, our study demonstrated that the application of manure and straw enhanced both the comprehensive stability and content of SOM and reduced the physical and biological stabilities while increasing the chemical stability, which made the largest contribution to the comprehensive stability. [ABSTRACT FROM AUTHOR]

The hydrothermal properties of black soils in seasonal frozen regions are more complex during the freezing process. In the context of the freezing and thawing cycles of black soil within seasonal freeze–thaw regions, there is a limited application of mathematical models to characterize the interplay between water and thermal dynamics. Therefore, existing models for analyzing water and heat in black soil in seasonal frozen regions may not be applicable or accurate. The application of existing models to the water and heat problems of black soil in seasonal frozen regions is important and innovative. This study is grounded in Darcy's law pertaining to unsaturated soil water flow and is informed by principles of mass conservation, energy conservation, and conduction theory. The research begins with the establishment of definitions for relative saturation and the solid–liquid ratio through mathematical transformations. Subsequently, a theoretical model is developed to represent the water–heat coupling in black soil, utilizing relative saturation and temperature as field functions. The model's validity is confirmed through its integration with experimental data from a black soil freezing and thawing model test. Furthermore, the analysis delves into the distribution of the temperature field, water field, and ice content that arise from the phase change processes occurring during the freezing and thawing of black soil roadbed slopes. There is a theoretical basis for the prevention and control of disasters associated with black soil roadbed slopes in seasonal frozen areas. [ABSTRACT FROM AUTHOR]

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[Objective] Soil respiration occupies an important proportion in the annual total soil respiration during freeze-thaw process. The effects of water content, freezing temperature and freeze-thaw cycles on soil carbon mineralization dynamics during soil freeze-thaw process were studied. [Methods] The study focuses on chernozem soil from the Nenjiang County Heshan Farm Jiusan Soil and Water Experimental Station in Heilongjiang Province, China was used as the research object to carry out an indoor freeze-thaw degree simulation test. Seven freeze-thaw cycles were carried out, and three soil moisture content were set 100% field water holding capacity (100% WHC), 60% field water holding capacity (60% WHC), and 30% field water holding capacity (30% WHC). Additionally, three environmental temperatures were used a constant 10 °C (control), -5 °C (mild freezing) and -15 °C (severe freezing). [Results] The number of freeze-thaw cycles, moisture content and freezing temperature had significant effects on CO2 emissions and the impact degrees were -0.63, 0.21 and 0.14, respectively. The thawing process notably increased soil carbon mineralization. The soil carbon mineralization of 60% WHC in the first three freeze-thaw cycles increased 33.0% and 35.2%, respectively, compared with 100% WHC and 30% WHC in the last 4 freeze-thaw cycles. In the case of severe freezing, the carbon mineralization of 100% WHC soil in the first 2 freeze-thaw cycles increased by 25.2% and 68.0% respectively, compared with 60% WHC and 30% WHC soil in the last 5 freeze-thaw cycles. [Conclusion] The number of freeze-thaw cycles had the greatest effect on soil CO2 emission, followed by moisture content, and the least freezing temperature. The freeze-thaw effect increased the cumulative CO2 emissions of soil with low water content. The cumulative CO2 emission of soil with high water content was reduced. For soils with medium moisture content, mild freezing increased CO2 cumulative emissions, while severe freezing decreased them. The first-order kinetic equation fitted the CO2 emissions from freeze-thaw soil well (R2 > 0.997), both moisture content and freezing temperature significantly influenced the potential for organic carbon mineralization (C0 value).

[Objective] The impact of soil erosion on nutrient content and stoichiometric ratios in soil is crucial for further comprehending and effective control of quality degradation in the sloping farmlands of black soil regions. [Methods] Selecting straight slopes cultivated for over a century and a convex slope cultivated for more than five decades in the typical black soil area of Keshan County as the research objects, utilizing 137Cs tracing method to estimate soil erosion rates on the slopes. Quantitative analysis was conducted on the relationship between soil erosion and key parameters such as soil organic carbon (SOC), total nitrogen (TN), and total phosphorus (TP) contents, along with the stoichiometric ratio in the ecological chemistry. [Results] (1) Using 137Cs tracing technique, the average annual erosion rate of the whole slope was 4 428.56 t/(km2·a), the average erosion rates of the linear and convex slopes were 3 284.53, 5 884.59 t/(km2·a), and the total erosion volumes were calculated at 3.21×105, 2.94×105 t/km2, respectively. (2) The overall carbon/nitrogen ratio (C/N) on the slopes showed a highly significant positive correlation with SOC (p0.05). [Conclusion] Ultimately, soil erosion redistributed SOC, TN and TP on the slopes, affecting the stoichiometric ratios of soil nutrients and leading to substantial nutrient loss on the slopes.

[Objective] To investigate the effects of different straw returning methods on the temperature of black soil during seasonal freeze-thaw period. [Methods] By monitoring the field temperature, the soybean field was selected as the research object, and two types of returning methods were set, namely, straw mulching (FG) and straw mixing(FH). The amount of returned straw was 30% (59 670 kg/hm2), 60% (119 340 kg/hm2) and 90% (179 010 kg/hm2), respectively, and the bare land was designated as the control treatment (CK) in a total of seven treatments. Four soil depths of 5, 10, 20 and 30 cm below the surface along the vertical profile of soil were set to analyze the characteristics of soil temperature changes during the freezing and thawing period under different straw return methods and amounts. [Results] (1) Straw returning to the field resulted in the soil entering various freeze-thaw stages at a time lagging behind that of the bare land, and effectively raised the range of the minimum soil temperature and lowered the maximum temperature, of which both the maximum temperature raising and lowering occurred in the FG90 treatment, which were 3.0~6.1 ℃ and 1.5~5.2 ℃, respectively. (2) Straw returning weakened the soil temperature variability and correlation with air temperature. The maximum coefficient of variation and coefficient of variation and correlation occurred in the bare soil layer of 5 cm, which were 6.54 and 0.82, respectively. The minimum occurred in the 30 cm soil layer of the FG90 treatment, with values of 0.82 and 0.26, respectively. The relationship between soil temperature variability was CK>FG30>FH30>FH60>FG60> FH90>FG90, and the relationship between soil temperature and air temperature was CK>FH30>FG30>FH60>FH90>FG60>FG90>FG90. (3) The freezing and thawing rates of bare land were the highest and the freezing-thawing periods were the shortest, with a freezing rate of 0.19 ℃/h and thawing rate of 0.60 ℃/h. The minimum freezing rate occurred in FH90 treatment (0.04 ℃/h) and the minimum thawing rate occurred in FG90 treatment (0.05 ℃/h). (4) With the increase of soil depth, the soil freezing stage and thawing stage gradually increased, but the freezing duration gradually decreased. The effect of delaying freeze-thawing was most obvious in the FG90 treatment, with the freezing stage and thawing stage of 8 and 10 days, respectively. [Conclusion] The results of the research quantitatively described the temperature characteristics of black soil under different straw return measures during freezing and thawing periods, and clarified the differences in soil temperature effects between different straw return measures, which is of great significance in guiding the rational use of straw resources and conservation tillage in black soil areas.

[Objective] To delve deeper into the spatiotemporal characteristics and pivotal driving factors underlying the hardness of black soil in eroded sloping farmlands. [Methods] Based on the dynamic monitoring of soil penetration resistance across 110 sample points in typical water erosion sloping farmlands, coupled with measurements of pertinent factors, the factors affecting soil penetration resistance were analyzed by multivariate linear regression (MLR) and random forest (RFR) models, and its transfer function was further construct. [Results] The spatiotemporal variability of soil penetration resistance was influenced by a combination of soil depth, moisture conditions, and agricultural practices. Notably, the spatial heterogeneity was significantly lower in the topsoil layer compared to the sub-surface layer, with coefficients of variation of 17.4% and 26.3%, respectively. As the soil dried out and the duration since the last tillage increases, spatial heterogeneity tended to intensify. Soil erosion played a significant role, with higher soil penetration resistance observed in areas of intense erosion compared to deposition zones, particularly under wet conditions where the difference is most pronounced (p

[Objective] In order to grasp the current situation and spatial variability pattern of black soil layer thickness in the typical black soil region within a small watershed, and realize dynamic monitoring of black soil layer thickness in such areas. [Methods] This study selected a small watershed of Heshan Farm in Nenjiang City, Heilongjiang Province. Soil sampling points were uniformly distributed at intervals of 100 meters, and undisturbed soil samples were collected from surface to parent material using soil augers to determine the thickness of the black soil layer. Meanwhile, terrain and land use data were extracted based on UAV aerial photography data. The study analyzed the thickness of black soil layer in the small watershed and its influencing factors. [Results] Among the 295 sampling points in the small watershed, the thickness of black soil layer varied from 0 to 160 cm, with an average of 44.1 cm. “Popihuang” (black soil layer thickness ≤20 cm) accounted for 17.63%, thin black soil (60 cm) accounted for 20.34%. Thick layer black soil was primarily distributed in the lower slopes, in the vicinity of gullies, and other gently sloping areas of the watershed, while thin layer black soil was predominantly found in steep slopes and areas with sandy gravel parent material, and medium layer black soil was predominant in other regions. Terrain indices such as topographic position index, curvature, slope exhibited significant correlations with the black soil layer thickness. The thickness of black soil layers in cultivated land was significantly lower compared to grassland and forest land. [Conclusion] The thickness of black soil layer exhibits significant spatial heterogeneity within the small watershed, which is primarily influenced by terrain characteristic, parent material and landuse. The research findings can be used as one of the bases for dynamic monitoring of regional black soil layer thickness, and can provide data support for the formulation of soil and water conservation measures in small watershed.

[Objective] In the context of significant breakthroughs in black soil protection technologies, this study explored the impact of agricultural machinery services on farmers’ black soil protection behavior, to provide a theoretical support for mobilizing the enthusiasm of farmers in protecting land in the black soil region, promoting the sustainable use of black soil land resources, and building a solid foundation for food security. [Methods] Based on the survey data of farmers in typical black soil areas of Jilin Province in 2021, this study used the Oprobit model, conditional mixed process, and Sobel test to analyze and test the impact and mechanism of agricultural machinery services on farmers’ black soil protection behavior. [Results] (1) Agricultural machinery services had a positive incentive effect on farmers’ black soil protection behavior, which was still true after correcting for potential endogenous errors and selective errors, and was consistent using different variables and methods. (2) The impact of agricultural machinery services on different types of farmers’ black soil protection behavior had asymmetric characteristics. The incentive effect of agricultural machinery services outsourcing on the black soil protection behavior of large-scale farmers, professional farmers, and non-elderly farmers was greater than that of small farmers, part-time farmers, and elderly farmers. (3) Agricultural machinery services had a positive incentive effect on farmers’ black soil protection behavior. From the external objective level, agricultural machinery services promoted farmers’ adoption of black soil protection behavior by improving the availability of black soil protection technology. From the internal subjective level, agricultural machinery services promoted farmers’ adoption of black soil protection behavior by improving farmers’ value perception of black soil protection. [Conclusion] Therefore, agricultural machinery services and their organizations should be used as the media to leverage the external driving force of technology supply and the internal motivating effect of value perception, which will help to stimulate the enthusiasm of farmers for black soil protection.

The manure–compost–soil process is the main avenue for using agricultural livestock waste. Biochar not only impacts the composting process but also enhances the soil's organic matter and nitrogen content when applied with compost. This paper explores the profound impact of biochar as an additive on the manure–compost–soil process, uncovering novel mechanisms driving enhanced soil health and bacterial succession. The basic physicochemical properties (organic matter, total nitrogen, etc.) and microbial structure of the composting and soil samples were analyzed. Biochar additive increased the C/N ratio and the total carbon content of the compost. Biochar, compost, and biochar-based compost improved the total carbon and organic matter of the soil. After high-temperature composting, Saccharomonospora (from 2.68% to 0.80%), Atopostipes (from 5.71% to 0.13%), and Lactobacillus (from 5.27% to 0.04%) were almost eliminated. Lysobacter, Glutamicibacter, and Streptomyces were the dominant genera in the soil samples, promoting plant growth. Nocardiopsis, Saccharomonospora, Bacillus, and Oceanobacillus dominated the genera in the whole manure–compost–soil process. Thus, composting could eliminate the toxic or negative bacteria directly deposited into soil by manure. Those genera arising from compost or biochar-based compost in the soil could contribute to organic matter's cycle. [ABSTRACT FROM AUTHOR]

Understanding the spatiotemporal patterns and driving mechanisms of cropping patterns' evolution tailored to local conditions is crucial for the effective allocation of black soil in northeast China and the advancement of agricultural development. This study utilized the Google Earth Engine platform to extract the spatial distribution data of major grain crops in northeast China for the year 2022. Using crop classification data from 2000 to 2022, the spatial overlay analysis method identified cropping pattern types based on spatial and temporal changes. The primary cropping patterns identified were continuous maize cropping, maize–soybean rotation, mixed cropping, and continuous soybean cropping. Simultaneously, this research constructed three distinct crop periods: Period I (2000–2002), Period II (2010–2012), and Period III (2020–2022). Over three periods, these patterns covered 94.73%, 88.76%, and 86.39% of the area, respectively. The evolution of the dominant cropping pattern from Period I to Period II involved the transition from continuous soybean cropping to continuous maize cropping, while from Period II to Period III, the main shift was from continuous maize cropping to maize–soybean mixed cropping. From a spatial perspective, since Period I, maize has increasingly replaced soybean as the dominant crop, with continuous maize cropping expanding northward and continuous soybean cropping contracting. The maize–soybean rotation area also migrated northward, particularly in the core area of the Songnen Plain, evolving mostly into continuous maize cropping. Maize cropping areas exhibited significant regional characteristics, being densely distributed in the Sanjiang Plain and Liaohe Plain, and along major tributaries in northeast China. Consequently, the interplay of the natural environment, economic policies, and agricultural technologies drove these changes. The findings offer valuable insights for optimizing cropping patterns and developing rotation systems in northeast China. [ABSTRACT FROM AUTHOR]

This study assessed the presence of potentially toxic elements (PTEs) in China's northeastern black soil belt, an area with limited prior research. We collected 304 soil samples (0–20 cm) from Gonghe Town, Hailun City, and analyzed the PTE contamination degree using the single-factor pollution index and Nemerow pollution index. The results demonstrated that the mean concentrations of arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), mercury (Hg), nickel (Ni), lead (Pb), and zinc (Zn) were 11.16, 0.11, 65.29, 22.56, 0.03, 27.07, 26.09, and 66.01 mg/kg, respectively. Source apportionment was conducted via correlation analysis, principal component analysis, and positive matrix factorization, identifying four main sources: natural (33.2%), irrigation (29.5%), fuel (23.4%), and fertilizer (13.2%). The ecological risk index indicated a slight ecological risk, while the human health risk showed that non-carcinogenic risks were negligible and carcinogenic risks were acceptable. Our findings emphasize the need to prioritize controlling PTEs from fertilizer, particularly cadmium, and to a lesser extent, irrigation and fuel sources, focusing on As, Pband Hg. This research provides critical insights for policymakers aiming to manage PTE contamination in black soils. [ABSTRACT FROM AUTHOR]

Black soil erosion gullies pose a significant risk to the food security in the northeast of China, and the vast majority of them located in the cold environment. As a universal method of erosion gully control, the check dam faces the complex environmental threats of the freezing area. Confronting the issue of check dams in colder regions being unstable due to various factors like freezing, thawing, snowmelt and rainfall, a novel technology is introduced for managing black soil erosion gullies in cold regions, named ecological flexible gangue soil check dam. This check dam is composed of soil, soil filtering and anti-washout geosynthetics, gangue articulated blocks and plant protection, and offers benefits such as local materials, time efficiency, flexibility, stability, solid waste utilization, stone replacement, and advantageous cuttings,et al. This paper gives the design concept, the key parameters of the check dam and the crucial technologies for practical application, which constitutes a complete set of procedures. The results of field tests reveal that the deformation capacity of the ecological flexible gangue soil check dam is concentrated between -0.051 8 m and 0.030 7 m, within the acceptable range. Neither the channel before nor after the check dam widened, and the sediment deposition depth ranged between 17 cm and 67 cm. The soil erosion is significantly reduced. The vegetation coverage increased by 30% over the course of one year. This suggests the robust stability, governance effect, and substantial ecological advantages of the dam. The innovative ecological flexible gangue soil check dam surpasses the conventional check dam design by integrating eco-technology with organic engineering, offering fresh concepts and methods to manage erosion gully. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Soil & Water Conservation (1009-2242) is the property of Institute of Soil & Water Conservation and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Soil & Water Conservation (1009-2242) is the property of Institute of Soil & Water Conservation and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Soil & Water Conservation (1009-2242) is the property of Institute of Soil & Water Conservation and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Soil & Water Conservation (1009-2242) is the property of Institute of Soil & Water Conservation and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Soil & Water Conservation (1009-2242) is the property of Institute of Soil & Water Conservation and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Composite erosion caused by snowmelt and rainfall causes considerable soil loss during spring thawing. However, research on the impact of frozen soil layers (FSL) on composite erosion is lacking. Therefore, indoor simulation experiments were conducted on soil conditions of 0 cm (unfrozen soil, FSLUN) and 3 cm thawing depths to explore the influence of FSL on composite erosion in the black soil region of Northeast China. Three snowmelt runoff (SR) discharges (0.34 L min−1, 0.5 L min−1, and 0.67 L min−1), three rainfall (RF) intensities (80 mm h−1, 120 mm h−1, and 160 mm h−1), and three snowmelt–rainfall interactions (SRI; 0.34 L min−1–80 mm h−1, 0.5 L min−1–120 mm h−1, and 0.67 L min−1–160 mm h−1) were used in this study. The results indicate that FSL advanced the initial erosion times of SR, RF, and SRI by 42.06%, 43.33%, and 45.83%, respectively. FSL increased the soil erosion rate (SER) of SRI by 1.2 (1.0–1.6) times that of unfrozen soil, which was smaller than that of SR (16.3, 5.6–25.0) and RF (1.7, 1.6–1.9), indicating that the interaction had an inhibitory effect on the increase in water erosion in the frozen layer. Under FSL and FSLUN conditions, RF erosion was 1.5–4.1 times and 14.5–24.3 times greater than SR erosion. The SRI erosion was not a simple linear superposition of multiple types of single-phase erosion; it had a significant nonlinear superposition amplification effect (SAE), with SAE of ~100% and ~300% under frozen and unfrozen soil conditions. Flow velocity (0.11 < R2 < 0.68), stream power (0.28 < R2 < 0.88), and energy consumption (0.21 < R2 < 0.87) exhibited significant (p < 0.05) linear relationships with SER in both FSL and FSLUN. The research results deepen our understanding of the composite erosion process during the spring thawing period in the black soil region of Northeast China and provide a basis for the prevention and control of soil erosion in the region. [ABSTRACT FROM AUTHOR]

The implementation of ridge-furrow with plastic film mulching has the potential to enhance crop yields and water productivity, particularly in black soil regions. However, the synergistic impacts of combining ridge-furrow with plastic mulching alongside with various organic amendments on maize yield and nitrogen fertilizer utilization efficiency remain unclear. Using 15N-labeled tracing technology, we investigated fertilizer-N recovery of maize, distribution, fertilizer-N residual in soil, and nitrogen fertilizer loss across six treatments: nonmulched flat with non-organic amendment (FN), non-mulched flat with straw amendment (FS), non-mulched flat with biochar amendment (FBC), ridge-furrow with plastic mulching without organic amendment (RN), ridge-furrow with plastic mulching with straw amendment (RS), and ridge-furrow with plastic mulching with biochar amendment (RBC). The results revealed that ridge-furrow with plastic mulching in comparison to non-mulched flat, led to a significant increase in maize dry biomass accumulation, yield, and the rate of fertilizer-N recovery in maize (NRE) by 8.57%–12.36%, 10.08%–15.13%, and 2.22%–3.18%, respectively. The rate of fertilizer-N residual in soil (NSR) and fertilizer-N loss (NLS) decreased by 0.5%–2.04% and 0.78%–3.21%, respectively. In addition, the straw and biochar amendments under different planting methods promoted NRE in plants and NSR in soil, reducing NLS. Compared with non-organic amendment treatments, the inclusion of straw and biochar amendments resulted in increased NRE and NRS by 1.64%–6.20% and 0.12%–2.18%, while NLS decreased by 1.76%– 7.78%. Biochar amendment treatment exhibited significantly higher nitrogen accumulation and NRE compared to the straw amendment treatment. Overall, ridge-furrow with plastic mulching combined with biochar amendment proved to be an effective method to enhance nitrogen fertilizer utilization of maize in the black soil regions, improving both yield and nitrogen fertilizer utilization efficiency. [ABSTRACT FROM AUTHOR]

Although black soil in northeast China undergoes severe erosion, the contribution of parent materials, mainly Quaternary loess and non-loess sediments, to soil erodibility remains unclear. Considering the inheritance of ferromagnetic materials by parent materials, changes in magnetic parameters can successfully determine soil erodibility on a regional scale with a close climatic background. Here, we analysed the magnetic indicators of 142 samples from the black soil horizon formed on loess and non-loess sediments, covering areas of severe and slight erosion in the region to determine the effects of parent materials on the erodibility of black soil in northeast China. Both low-frequency magnetic susceptibility and frequency magnetic susceptibility (χfd) were proportional to the decrease in erosion rate due to erosion-induced leaching of ferromagnetic materials, and the change in χfd was narrow for black soil with loess parent materials, corresponding to relatively low soil erodibility. Compared with loess, the addition of soil organic matter could stabilise soils against erosion, thereby inducing a decrease in the erodibility of black soil formed on loess. Additionally, sustainable soil management policies to protect black soil from further erosion are necessary and urgent under the pressure of maintaining high grain yields and preventing erosion in northeast China. [ABSTRACT FROM AUTHOR]

This study used a potted experiment to apply biochar to black soil (BCS) and saline-alkali soil (BSAS) in Northeast China, with a dosage of 0 and 300 g biochar/pot applied, respectively. The original black soil (CS) and saline-alkali soil (SAS) were used as controls to investigate the effects of different particle sizes of soil aggregates on the activity of enzymes related to carbon, nitrogen, and phosphorus cycle. Compared with CS and SAS, the soil organic matter (SOM) values for biochar added into the black soil (BCS) and saline-alkali soil (BSAS) treatments were increased significantly by 41.86 % and 31.98 %. Compared with CS, BCS significantly increased the polyphenol oxidase and ß-1,4-glucosidase activity. Polyphenol oxidation activity, endo-1,4-ß-D-glucanohydrolase activity, ß-1,4-glucosidase activity and xylanase activity are more active in particles with a diameter of >2 mm. The alkaline phase activity and Coenzyme activity with BCS treatment was highest in soil aggregates with sizes of 1~2 mm and >5 mm, respectively. Mantel test analysis shows a highly significant effects between SOM and total nitrogen content (TN) with soil nitrogen, phosphorus, and potassium cycling. Therefore, from the perspective of soil enzyme activities, application of biochar is more effective in promoting soil bio-fertility in northeastern soil of China. Biochar to the soil is more likely to promote the improvement of soil biological fertility. [ABSTRACT FROM AUTHOR]

The northeastern part of China is a traditional sugar beet cultivation area where the soils are classified generally as the black and albic soil types with low boron (B) availability. Boron fertilizer can increase soil B content and significantly improve crop yield and quality. At present, the effects of slow-release B fertilizer on beet root yield and quality remain unclear. Two sugar beet varieties KWS1197 and KWS0143 were selected as the research materials; and biologically evaluated with three dosage rates of 0, 15, and 30 kg ha-1 in two soil types. Results showed that slow-release B fertilizer (30 kg ha-1) improved sugar beet net photosynthetic rate (13.6%) and transpiration rate (9.8%), as well as enhanced dry matter accumulation and the transfer to underground parts (23.1%) for higher root yield (1.4 to 9.7% in black soil and 3.5-14.2% in albic soil). Specifically, boron fertilizer greatly increased root B accumulation, as evidenced by decreasing amino N and Na contents alongside increasing surose (Pol) content. Slow-release B fertilizer increased white sugar yield by 3.5 to 35.7% in black soil and 5.8 to 20.8% in albic soil. In conclusion, applying slow-release B fertilizer is an effective strategy to increase sugar beet yield and quality in northeast China, with a recommended application rate of 30 kg ha-1. These findings established a baseline for formulating effective and futristic fertilizer for sugar beet.

Human-environment interactions in agroecosystems are frequently mirrored by land-use changes. Clarifying the conflict between land use and ecological health in agricultural production regions is essential for achieving sustainable agricultural development and maintaining ecosystem services. Therefore, we chose the Northeast Black Soil Zone, a major grain producing area, to explore the impacts of land use change on ecosystem services from 2000 to 2030. The results show that: During the 30-year period, 1) Under any of the simulated scenarios, the level of ecosystem services in the NBSR tends to increase overall. 2) Rapid conversion between land use types and reduction of forest land area lead to weakening of synergies and increasing of trade-offs among ecosystem services. 3) Conversion and intensity of land use types significantly impacted on the level of ecosystem services under different scenarios (p

Gully erosion can lead to the destruction of farmland and the reduction in crop yield. Gully mapping from remote sensing images is critical for quickly obtaining the distribution of gullies at regional scales and arranging corresponding prevention and control measures. The narrow and irregular shapes and similar colors to the surrounding farmland make mapping erosion gullies in sloping farmland from remote sensing images challenging. To implement gully erosion mapping, we developed a small training samples-oriented lightweight deep leaning model, called asymmetric non-local LinkNet (ASNL-LinkNet). The ASNL-LinkNet integrates global context information through an asymmetric non-local operation and conducts multilayer feature fusion to improve the robustness of the extracted features. Experiment results show that the proposed ASNL-LinkNet achieves the best performance when compared with other deep learning methods. The quantitative evaluation results in the three test areas show that the F1-score of erosion gully recognition varies from 0.62 to 0.72. This study provides theoretical reference and practical guidance for monitoring erosion gullies on slope farmland in the black soil region of Northeast China.

Straw mulching is a widespread practice for reducing the soil carbon loss caused by erosion. However, the effects of straw mulching on dissolved organic matter (DOM) runoff loss from black soil are not well studied. How straw mulching affects the composition and loss of runoff DOM by changing soil aggregates remains largely unclear. Here, a straw mulching treatment was compared to a no mulching treatment (as a control) on sloping farmland with black soil erosion in Northeast China. We divided the soil into large macroaggregates (>2 mm), small macroaggregates (0.25–2 mm), and microaggregates (

【Objective】 Black soil is widely distributed in northeastern China and other countries. Machinery operations in agricultural production in these regions has resulted in soil compaction. In this paper, we investigated the impact of soil compaction on growth, yield, and nitrogen use efficiency of maize in the black soil. 【Method】 The field experiment compared three soil compactions: low compaction (C1), moderate compaction (C2) and high compaction (C3). For each compaction, there were two fertilization treatments: nitrogen fertilization (F) and no fertilization (F0). In each treatment, we measured the growth, yield and nitrogen use efficiency of the maize. 【Result】 Increasing soil compaction significantly reduced leaf area index (LAI) and plant height of the maize. Nitrogen fertilization affected plant height significantly but did not impact LAI at significant levels. Soil compaction also impacted grain yield significantly, with the high and moderate soil compaction reducing grain yield by 24% and 10%, respectively, compared to the light compaction. Soil compaction and nitrogen fertilization combined to impact nitrate in the soil. Elaborated soil compaction inhibited maize growth, reduced nitrogen absorption, leading to an increase in residual nitrate nitrogen in soil as a result. Soil compaction also influenced nitrogen uptake and its subsequent translocation in the above-ground part of the maize. Nitrogen fertilization increased nitrogen absorption by the crop significantly, but reduced nitrogen use efficiency, especially in the high compaction treatment. 【Conclusion】 Elaborated compaction of the black soil due to machinery operations severely inhibited growth, absorption and use of nitrogen of the maize, thereby leading to an increase in residual nitrate nitrogen in the soil and reducing grain yield as a result.

[Objective] To evaluate the contribution of freeze-thaw cycle (FTCs) to gully erosion by measuring the collapse volume of gully wall collapse during FTCs. [Methods] From 2016 to 2018, a total of 463 collapse points in 36 gullies were selected for field investigation. Based on the investigation results, there were two types of wall collapse: massive collapse and loose accumulation. The morphology parameters of two kinds of accumulations were measured at each collapse point, including the volume of the collapsed soil, the width and depth of the gull coross-section, and the shear force and hardness of soil of the corresponding gully wall soil. [Results] (1) The average collapse strength of gully wall collapse caused by FTCs during the three-year study period is 16.12 m3/(km·a). The two types of collapse occurred randomly within the gully, and the single point freeze-thaw collapse mainly concentrated in 0~3 m3, but the amount of soil caused by massive collapse was larger. (2) The transverse width and depth of the gully were the main factors affecting the collapse of the gully wall, and the collapse amount increased with the increase of the width-depth ratio. When the width-depth ratio>2.71, the collapse amount increased rapidly. (3) The amount of gully collapse was closely related to the shear force and hardness of the soil on the gully wall. [Conclusion] The freeze-thaw collapse of the gully wall was closely related to the width and depth of the gully cross-section, the freeze-thaw collapse accounted for 3.28% to 23.68% of the sediment yield of the gully erosion, and its influence was equivalent to that of the headward erosion of gully head. The research results provide data support for quantitatively evaluating the contribution of FTCs to gully erosion.

Growing evidence suggests that the use of manure containing residual antibiotics universally leads to an increase in soil antibiotic resistance genes (ARGs). However, there is limited understanding of the influence of long-term antibiotic-free fertilization and the differences between antibiotic-free manure and chemical fertilizer on soil ARGs. This study aimed to quantify the assembly patterns of the antibiotic resistome by in situ probing bacterial community and environmental variations in field soils that have been subjected to long-term exposure to chemical fertilizer and/or manure from animals without antibiotic amendments. Long-term fertilization slightly impacts the diversity of antibiotic resistomes, with 85.5 % of total ARGs and mobile genetic elements (MGEs) being common across all treatment types, while significantly increasing their abundances from 0.68 to a maximum of 0.90 copies/16S rRNA. The rise in ARG abundances was less pronounced when using antibiotic-free manure compared to chemical fertilizer, particularly for Rank Ⅱ ARGs. However, when antibiotic-free manure and chemical fertilizer were combined, a significant increase in nutrients (such as available nitrogen and organic matter) and MGEs occurred, leading to the enrichment of soil microbial populations, especially in certain resistant species, and Rank Ⅰ and Ⅱ ARGs. Despite the influence of various factors like bacterial communities, soil properties, heavy metals, and MGEs, the MGEs had the most significant standardized effects on shaping ARGs through both direct and indirect pathways. Our findings indicates that while of antibiotic-free manure can lower the risk of antibiotic residues and promote sustainable farming practices, it may not fully eliminate the prevalence of ARGs, highlighting the need for more comprehensive strategies to address antibiotic resistance in agriculture rather than simply prohibiting the use of antibiotics.

In the context of the carbon peak and carbon-neutral era, it is crucial to effectively utilize maize straw as a resource for achieving carbon (C) sequestration and emission reduction in rural agriculture. Maize straw carbon undergoes two processes after being added to the soil: mineralization (decomposition) and humification (synthesis) by soil animals and microorganisms. These processes contribute to the reintegration of carbon into the agroecosystem's carbon cycle. However, understanding of the transformation and stabilization of straw carbon, as well as the differences in C fixation capacity in soils with various fertilization treatments in black soils, remains limited. This study aims to quantify the relationship between straw carbon input and organic carbon sequestration in various fertilization treatments of black soil. Based on a long-term positional fertilization trial (45 years) in black soil, 13C-labeled maize straw (1.5 g in 120 g of dry soil) was applied and combined with an in situ incubation method using carborundum tubes. Throughout the 360-day trial, we observed the influence of fertilization on soil total organic C levels, organic carbon δ13C values, maize straw addition rate, and straw C fixation capacity. The decomposition of straw was most prominent during the initial 60 days of the incubation period, followed by a gradual decrease in the rate of decomposition. Compared with day 0, the SOC δ13C value and straw C residue rate were highest in the no-fertilization treatment (CK) after 360 days of incubation. The amount of organic carbon transformed and fixed in the soil was significantly higher in the organic fertilizer treatment (M) compared to other treatments, highlighting the stronger decomposition, transformation, and carbon fixation capacity of straw carbon in the M treatment. Moreover, the highest carbon storage of 43.23 Mg·ha−1 was observed in the M fertilization treatment after 360 days, which was significantly different from other treatments (p < 0.05). The study demonstrates that soil with low fertility exhibits increased sequestration potential for straw carbon. Additionally, organic fertilizer input would increase soil organic carbon storage and facilitate straw carbon conversion. [ABSTRACT FROM AUTHOR]

Accurately predicting the feedback mechanisms between forest ecosystem carbon cycling and climate change is crucial for effective climate mitigation. Understanding soil organic carbon (SOC) responses to the combined impacts of plant biomass, litter, and nitrogen deposition, especially regarding temperature sensitivity, is essential but remains poorly understood. We conducted incubation experiments using buried black soil from a cool temperate deciduous broad-leaved forest in Japan, which has high C content and a highly stable molecular structure. The stepwise addition of glucose and a temperature increase from 15 to 35 °C accelerated SOC mineralization by 74.0 mg C kg−1 with a positive priming effect (PE) during the 49-day incubation period, while the simultaneous addition of nitrogen had no significant effect on this phenomenon, with SOC mineralization measured at 75.5 mg C kg−1. Conversely, glucose mineralization was significantly accelerated by 10%, from 241.0 to 261.3 mg C kg−1, by stepwise nitrogen addition and temperature increase. Under the combined impacts, the Q10 value of the soil increased significantly from 1.6 to 2.0 compared to that in the unmodified conditions, primarily due to the stepwise addition of glucose. We also found a strong positive correlation between activation energy (Ea) and Q10. This result strongly supports the carbon quality–temperature (CQT) hypothesis. These results likely stem from interactions between SOC quality and carbon availability, suggesting that, in the future, climate change is likely to have a positive feedback effect, especially on buried black soils. [ABSTRACT FROM AUTHOR]

Snowmelt runoff and soil freezing have been combined to seriously exert on the rill networks and soil erosion intensity in the black soil region of northeastern China. The dynamic development of rill networks can be used to quantitatively extract the parameters of erosion. Previous studies have focused primarily on the runoff erosion caused by rainfall. Only a few studies were to consider the combined effects of snowmelt runoff and freezing. Currently, available methods cannot fully meet the high precision of rill morphology. Therefore, it is very necessary to systematically investigate the rill erosion under combined effects using high-precision extraction. This study aims to simulate the snowmelt runoff scouring on the frozen (-20°C freezing) and non-frozen slopes (10°C), refilled with black soil from northeastern China. A 0°C ice-water mixture was used to simulate the snowmelt runoff scouring. Meanwhile, three-dimensional laser scanning was employed to obtain the point cloud data of the slope surface after different times of scouring, until the eroded surface stabilized. The Digital Surface Model (DSM) of Difference (DoD) with point cloud reverse engineering was used to detect and parameterize the micro-topographic pattern (e.g., development of rill networks and erosion area, erosion volume, rill length, and rill density). The results show that there was a significant impact of freezing-induced temperature on the development of rill networks: (1) The frozen slope was more prone to develop the rill networks. The erosion rate after each scouring was significantly higher than that on the nonfrozen slopes. Upon reaching stability, the erosion area, erosion volume, and rill length were 291%, 557%, and 437% of those on the non-frozen slopes, respectively; (2) The cumulative erosion volume of the frozen and non-frozen slopes showed similar patterns during the rill development. But there were noticeable differences along the cross-sectional direction of the rills. On the frozen slopes, the width-depth ratio (RW/D) of the rill cross-sections decreased rapidly at the rill intersections with accelerated downcutting, whereas, the width and depth of rills increased linearly and stably. On the non-frozen slopes, the RW/D at the midslope cross-sections increased with the number of scouring events, thus accelerating lateral erosion, while the RW/D at other sections decreased with the number of scouring events with accelerated downcutting; (3) The relative error range was -12.70% to 4.42% for the Differential Digital Surface Model (DoD) with ArcGIS hydrological processing and GeoMagic point cloud reverse engineering models for the frozen slopes, with an absolute mean relative error of 5.48%, and an extraction accuracy of over 94%. The combined extraction with GeoMagic and ArcGIS showed a great contribution to obtain the rill parameters on the freeze-treated slopes. The finding can serve as a promising potential to the rill development under complex eroding settings. [ABSTRACT FROM AUTHOR]

Black soils, which play an important role in agricultural production and food security, are well known for their relatively high content of soil organic matter (SOM). SOM has a significant impact on the sustainability of farmland and provides nutrients for plants. Hyperspectral imaging (HSI) in the visible and near-infrared region has shown the potential to detect soil nutrient levels in the laboratory. However, using portable spectrometers directly in the field remains challenging due to variations in soil moisture (SM). The current study used spectral data captured by a handheld spectrometer outdoors to predict SOM, available nitrogen (AN), available phosphorus (AP) and available potassium (AK) with different SM levels. Partial least squares regression (PLSR) models were established to compare the predictive performance of air-dried soil samples with SMs around 20%, 30% and 40%. The results showed that the model established using dry sample data had the best performance (RMSE = 4.47 g/kg) for the prediction of SOM, followed by AN (RMSE = 20.92 mg/kg) and AK (RMSE = 22.67 mg/kg). The AP was better predicted by the model based on 30% SM (RMSE = 8.04 mg/kg). In general, model performance deteriorated with an increase in SM, except for the case of AP. Feature wavelengths for predicting four kinds of soil properties were recommended based on variable importance in the projection (VIP), which offered useful guidance for the development of portable hyperspectral sensors based on discrete wavebands to reduce cost and save time for on-site data collection. [ABSTRACT FROM AUTHOR]

Knowledge of long-term phosphorus behavior is essential to improve soil structure, nutrient supply potential, and the sustainability of cropping systems. A 45-year long-term experimental trial was used to observe organic phosphorus fractionation and its effects on soil aggregation and nutrient distribution at three depths (0–20, 20–40, and 40–60 cm) in Vojvodina Province, Serbia, under maize monoculture and maize/barley rotation. Five fertilizing systems were studied, including Control, NPK, NPK + maize remains, NPK + manure, and NPK + manure in rotation. Soil aggregates were fractionated into four size categories (>2000, 2000–250, 250–53, and <53 μm) using a wet sieving method. The samples were analyzed for main indicators, including different forms of phosphorus, total and available (PT and PA), as well as its organic forms (Labile Po, Biomass Po, Mod. Labile Po, Fulvic acid Po, Humic acid Po, and Resistant Po), and other fertility parameters. Significant differences in total and available phosphorus as well as all observed organic phosphorus fractions were evident between treatments with and without organic amendments, particularly in the 0–20 and 20–40 cm soil layers. Moderately labile P forms were dominant across all treatments, while labile forms constituted a smaller proportion. The most notable differences between treatments were observed in the labile and moderately labile forms, as well as in the resistant form of organic phosphorus. Manure application led to increased nutrient content in macroaggregates (>250 μm) compared to microaggregates. Microaggregates (<250 μm) were predominant across all depths, while stable structural aggregates did not show a significant increase after manure application. PCA highlighted significant correlations between soil characteristics, including total and available P, total organic carbon, clay content, and enzyme activity, across different aggregate sizes and organic P fractions. Overall, long-term mineral fertilization combined with organic amendment application induced variations in phosphorus fractions and the content of carbon, nitrogen, and phosphorus associated with aggregates in the first two soil layers, except for aggregate size classes. [ABSTRACT FROM AUTHOR]

Copyright of Chinese Journal of Applied Ecology / Yingyong Shengtai Xuebao is the property of Chinese Journal of Applied Ecology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The biological degradation of plant residues in the soil or on the soil surface is an integral part of the natural life cycle of annual plants and does not have adverse effects on the environment. Crop straw is characterized by a complex structure and exhibits stability and resistance to rapid microbial decomposition. In this study, we conducted a microcosm experiment to investigate the dynamic succession of the soil microbial community and the functional characteristics associated with lignocellulose-degrading pathways. Additionally, we aimed to identify lignocellulose-degrading microorganisms from the straw of three crop species prevalent in Northeast China: soybean (Glycine max Merr.), rice (Oryza sativa L.), and maize (Zea mays L.). Our findings revealed that both the type of straw and the degradation time influenced the bacterial and fungal community structure and composition. Metagenome sequencing results demonstrated that during degradation, different straw types assembled carbohydrate-active enzymes (CAZymes) and KEGG pathways in distinct manners, contributing to lignocellulose and hemicellulose degradation. Furthermore, isolation of lignocellulose-degrading microbes yielded 59 bacterial and 14 fungal strains contributing to straw degradation, with fungi generally exhibiting superior lignocellulose-degrading enzyme production compared to bacteria. Experiments were conducted to assess the potential synergistic effects of synthetic microbial communities (SynComs) comprising both fungi and bacteria. These SynComs resulted in a straw weight loss of 42% at 15 days post-inoculation, representing a 22% increase compared to conditions without any SynComs. In summary, our study provides novel ecological insights into crop straw degradation by microbes. [ABSTRACT FROM AUTHOR]

Degradation of black soil areas is a serious threat to national food security and ecological safety; nevertheless, the current lack of information on the location, size, and condition of black soil farmland productivity is a major obstacle to the development of strategies for the sustainable utilization of black soil resources. We synthesized remote sensing data and geospatial thematic data to construct a farmland productivity assessment indicator system to assess the productivity of black soil cropland at the regional scale. Furthermore, we conducted research on the spatial differentiation patterns and a spatial autocorrelation analysis of the assessment results. We found that farmland productivity within this region exhibited a decline pattern from south to north, with superior productivity in the east as opposed to the west, and the distribution follows a "spindle-shaped" pattern. Notably, the Songnen and Sanjiang typical black soil subregions centrally hosted about 46.17% of high-quality farmland and 53.51% of medium-quality farmland, while the Mondong typical black soil subregion in the west predominantly consisted of relatively low-quality farmland productivity. Additionally, farmland productivity displayed a significant positive spatial correlation and spatial clustering, with more pronounced fluctuations in the northeast–southwest direction. The developed indicator system for farmland productivity can illustrate the spatial differentiation and thereby offer a valuable reference for the sustainable management of farmland resources. [ABSTRACT FROM AUTHOR]

Lime concretion black soil in the southern region of the Huang-Huai-Hai plain is known for its poor physical structure as a typical low-yield field. Although measures of deep tillage and straw return have been proved to be able to improve soil physical properties and soil fertility, there are still problems such as shallow tillage soil, weak fertility, high bulk density of the deeper soil, poor aggregate structural properties, serious stratification of the deeper soil, low crop yields and other problems, due to the long-term use of rotary tillage of wheat before sowing and no-tillage of maize and straw return tillage. It is important to adopt reasonable tillage practices and organic matter addition to improve the quality of lime concretion black soil. Therefore, in order to investigate the effects of the tillage practices, straw return to the field and biochar addition on the particle size structure distribution of soil aggregates, nutrient characteristics of aggregates, nutrient storage capacity and annual yield of wheat and maize, a long term localization experiment was set up with tillage and straw treatment at the Henan Province Agro ecosystem Field Observation and Research Station since 2014. After the year of 2020, the soils were supplemented with biochar. A three-factor, two-level experimental design was adopted, which consisted of tillage practices (conventional rotary tillage (CT), deep tillage (DT)), straw treatments (straw returned to the field (S), straw not returned to the field (NS)) and biochar addition (biochar addition (B), and no biochar addition (NB)), with a total of eight treatments. The results showed that rotary tillage without biochar addition significantly improved the stability of soil aggregates and soil nutrient stocks in the 0-15 cm soil layer, whereas deep tillage with straw significantly improved the composition of soil aggregates in the >15-30 cm soil layer, which enhanced soil fertility and promoted the increase of crop yield. The correlation analysis showed that the crop yield increase in the lime concretion black soil was more dependent on the improvement of soil physical structure and soil fertility in the deep layer (>15-30 cm). compared with CT-NS-NB (rotary tillage straw no return without biochar) treatment, Biochar addition, such as DT-S-B (deep tillage straw return with biochar addition) especially increased the stability of aggregates in the >15-30 cm layer, and increased the proportion of >2 mm aggregates, MWD and GMD values by 165.88%, 62.37% and 119.81%, respectively. DT-S-B treatment increased the organic carbon and nutrient preservation capacity of >2 mm aggregates and decreased the organic carbon and nutrient preservation capacity of <2 mm aggregates, and significantly increased the organic carbon storage, total nitrogen, total phosphorus and total potassium pools in the >15-30 cm soil layer 22.87%-23.03%. The treatment of DT-S-B contributed to an average increase of 22.96% in 2-year annual crop yield. Although the increased application of biochar was presented as having the function of improving soil structural properties and promoting soil fertility, it did not show a significant increase in crop yield, probably due to the short application time and small amount of addition. In sum, the application of biochar with deep tillage straw returned to the field significantly improved the particle size distribution and stability of deep soil aggregates in the lime concretion black soil of the southern Huang-Huai-Hai Plain, enhanced the soil fertility and the annual yield of wheat and maize, and ensured the efficient green and sustainable production of farmland. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Shenyang Agricultural University is the property of Journal of Shenyang Agricultural University Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The elucidation of the influence of soil erosion on crop yields is of paramount importance to ensure food security. Remote sensing data has facilitated the acquisition of long‐term spatially‐distributed information on soil erosion modulus and crop yields. The Revised Universal Soil Loss Equation (RUSLE) model was employed to estimate the soil erosion modulus, while the Carnegie‐Ames‐Stanford Approach (CASA) model has been utilized to calculate the net primary productivity (NPP). This study integrated models to assess the impact of soil erosion on dryland crop yields in the Songnen Plain from 2000 to 2020. The findings reveal that the annual average soil erosion modulus for dry cropland in black soil region (BSR) of the Songnen Plain is 4.2 (t ha−1 yr−1), which is 1.5 times greater than that of the other region (OR). The greater cropland erosion within the BSR limited the trend for increasing crop yields, whereas the impact of erosion on crop yield dynamics in the OR was not significant. The areas where dryland crop yields diminished in the Songnen Plain because of soil erosion were predominantly concentrated within the BSR. Advancements in agricultural technology have partially mitigated the adverse consequences of erosion on yields. [ABSTRACT FROM AUTHOR]

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Background: Previous research on whole-soil measurements has failed to explain the spatial distribution of soil carbon transformations, which is essential for a precise understanding of the microorganisms responsible for carbon transformations. The microorganisms involved in the transformation of soil carbon were investigated at the microscopic scale by combining 16S rDNA sequencing technology with particle-level soil classification. Methods: In this experiment,16S rDNA sequencing analysis was used to evaluate the variations in the microbial community structure of different aggregates in no-tillage black soil. The prokaryotic microorganisms involved in carbon transformation were measured before and after the freezing and thawing of various aggregates in no-tillage black soil. Each sample was divided into six categories based on aggregate grain size: >5, 2-5, 1-2, 0.5-1, 0.25-0.5, <0.25 mm, and bulk soil. Results: The relative abundance of Actinobacteria phylum in <0.25 mm aggregates was significantly higher compared to that in other aggregates. The Chao1 index, Shannon index, and phylogenetic diversity (PD) whole tree index of <0.25 mm aggregates were significantly smaller than those of in bulk soil and >5 mm aggregates. Orthogonal partial least-squares discrimination analysis showed that the microbial community composition of black soil aggregates was significantly different between <1 and >1 mm. The redundancy analysis (RDA) showed that the organic carbon conversion rate of 0.25--0.5 mm agglomerates had a significantly greater effect on their bacterial community structure. Moreover, humic acid conversion rates on aggregates <0.5 mm had a greater impact on community structure. The linear discriminant analysis effect size (LEfSe) analysis and RDA analysis were combined. Bradyrhizobium, Actinoplane, Streptomyces, Dactylosporangium, Yonghaparkia, Fleivirga, and Xiangella in <0.25 mm aggregates were positively correlated with soil organic carbon conversion rates. Blastococcus and Pseudarthrobacter were positively correlated with soil organic carbon conversion rates in 0.25--0.5 mm aggregates. In aggregates smaller than 1 mm, the higher the abundance of functional bacteria that contributed to the soil's ability to fix carbon and nitrogen. Discussion: There were large differences in prokaryotic microbial community composition between <1 and >1 mm aggregates. The <1 mm aggregates play an important role in soil carbon transformation and carbon fixation. The 0.25-0.5 mm aggregates had the fastest organic carbon conversion rate and increased significantly more than the other aggregates. Some genus or species of Actinobacteria and Proteobacteria play a positive role in the carbon transformation of <1 mmaggregates. Such analyses may help to identify microbial partners that play an important role in carbon transformation at the micro scale of no-till black soils. [ABSTRACT FROM AUTHOR]