Search Results (162)

Conservation tillage can improve soil health and carbon sequestration and is helpful for sustainable agricultural development. However, its effect on crop yields and nitrous oxide (N₂O) emissions is still controversial. In this study, a two-year field experiment of spring maize was conducted from 2019 to 2020 in the Phaeozems region of Northeast China, involving two tillage practices (strip tillage and conventional tillage) and two nitrogen inhibitors (N-butylthiophosphorotriamine, NBPT and 3,4-Dimethylpyrazole phosphate, DMPP). The WHCNS (Soil Water Heat Carbon Nitrogen Simulator) model was calibrated and validated with field observations, and the effects of different tillage practices and nitrification inhibitors on spring maize yield, N₂O emissions, water use efficiency (WUE), and nitrogen use efficiency (NUE) were simulated using the WHCNS model. Precipitation scenarios were set up to simulate and analyze the changes in patterns of crop yield and N₂O emissions under long-term conservation tillage for 30 years (1991–2020). The results showed that concerning maize yield, under conservation tillage, the type of straw and nitrogen fertilizer inhibitor could explain 72.1% and 7.1%, respectively, of the total variance in maize yield, while precipitation explained only 14.1% of the total variance, with a 28.5% increase in crop yield in a humid year compared to a dry year. N₂O emissions were principally influenced by precipitation, which could explain 46.4% of the total variance in N₂O emissions. Furthermore, N₂O emissions were 385% higher in humid years than in dry years. Straw under conservation tillage and inhibitor type explained 8.1% and 19.4% of the total variance in N₂O emissions, respectively. Conservation tillage with nitrification inhibitors is recommended to increase crop yields, improve soil quality and reduce greenhouse gas emissions in the Phaeozems region of Northeast China, thus ensuring sustainable agricultural development in the region. Full article

The combined application of chemical fertilizers with organic materials contributes to higher contents of bioavailable phosphorus. However, the underlying mechanism remains poorly understood. A field experiment including four treatments, chemical fertilizer (CF), chemical fertilizer with biochar (CB), chemical fertilizer with organic fertilizer (CO), and chemical fertilizer with biochar and organic fertilizer (CBO), was conducted to explore how the combination of fertilizer applications enhanced soil phosphorus bioavailability using metagenomic sequencing technology. The results showed that chemical fertilizers combined with organic materials (CB, CO, and CBO) significantly increased citrate-extractable phosphorus by 34.61–138.92% and hydrochloric acid-extractable phosphorus contents by 72.85–131.07% compared to CF. In addition, the combined applications altered the microbial community structure and increased the abundance of phoR, spoT, and ppnK genes, but decreased those of gcd, phoD, and ppk1 genes. A partial least squares path model indicated that the combined applications regulated the microbial community composition and gene abundance of phosphorus-cycling microorganisms by influencing soil physicochemical properties, thereby enhancing soil phosphorus cycling. Correlation analysis indicated that pH, total phosphorus, and available phosphorus were the key factors influencing microbial communities, while available nitrogen and total nitrogen primarily regulated phosphorus cycling gene abundance. In addition, the CO and CBO treatments significantly increased maize yield by 14.60% and 21.04%, respectively. Overall, CBO most effectively enhanced bioavailable phosphorus content and maize yield. This study provides a foundation for developing rational fertilization strategies and improving soil phosphorus use efficiency. Full article

Replacing partial chemical fertilizers with organic fertilizer can increase organic carbon input, change soil nutrient stoichiometry and microbial metabolism, and then affect soil organic carbon (SOC) storage. A 6-year field experiment was used to explore the mechanism of SOC storage under different ratios of manure substitution in northeast China, with treatments including chemical fertilizer application alone (nitrogen, phosphorus, and potassium, NPK) and replacing 1/4 (1/4M), 2/4 (2/4M), 3/4 (3/4M), and 4/4 (4/4M) of chemical fertilizer N with manure N. Soil nutrients, enzymatic activity, and SOC fractions were analyzed to evaluate the effect of different manure substitution ratios on SOC storage. A high ratio of manure substitution (>1/4) significantly increased soil total N, total P, total K, and available nutrients (NO₃⁻-N, available P, and available K), and the 4/4M greatly decreased the C/N ratio compared to the NPK. Manure incorporation increased microbial biomass carbon (MBC) by 18.3–53.0%. Treatments with 50%, 75%, and 100% manure substitution (2/4M, 3/4M, and 4/4M) enhanced bacterial necromass carbon (BNC), fungal necromass carbon (FNC), and total microbial necromass carbon (MNC) by 31.9–63.5%, 25.5–107.1%, and 27.4–94.2%, respectively, compared to the NPK treatment. Notably, the increase in FNC was greater than that of BNC as the manure substitution ratio increased. The increasing manure substitution significantly enhanced particulate organic C (POC) and total SOC but did not affect mineral-associated organic C (MAOC). High soil N and P supplies decreased leucine aminopeptidases (LAPs) and alkaline phosphatase activities but increased the activity ratio of β-glucosidase (BG)/(N-acetyl-glucosaminidase (NAG) + LAP). Treatments with 25% manure substitution (1/4M) maintained maize and soybean yield, but with increasing manure rate, the maize yield decreased gradually. Overall, the high ratio of manure substitution enhanced SOC storage via increasing POC and MNC, and decreasing the decomposition potential of manure C and soil C resulting from low N- and P-requiring enzyme activities under high nutrient supplies. This study provides empirical evidence that the rational substitution of chemical fertilizers with manure is an effective measure to improve the availability of nutrients, and its effect on increasing crop yields still needs to be continuously observed, which is still a beneficial choice for enhancing black soil fertility. Full article

In this study, a method for creating networked macropores through tillage using Eisenia fetida attracted by food sources derived from decomposing straw was proposed. The effects of Eisenia fetida activity and corn stalk addition, as well as the synergistic effects of Bacillus subtilis, on macropore formation were systematically studied. A 3D visualization technique was used to render the pore network model. When compared with undisturbed soil, the results demonstrate that cultivation using earthworms attracted by food sources from decomposing straw creates a soil pore structure with the most significant effect. The 3D porosity of the soil increased 6.90-fold, its average pore volume increased 5.49-fold, and its equivalent diameter increased 4.88-fold. Cylindrical pores, which accounted for the largest proportion (4.38%), had a channel radius of 1–5 mm and comprised approximately 86.7% of all macropores. The channel length increased by 28.5%, the average roundness decreased by 2.5%, and the average coordination number increased by 33.3%. The macroporous network structure formed by these earthworm-generated pores was more beneficial for improving the structure of phaeozem, offering technical support for the field application of earthworm farming. Full article

Northeast China is a key grain production region yet achieving coordinated improvements in maize yield and quality across diverse environments remains challenging. This study conducted a meta-analysis to evaluate maize yield and quality responses to chemical fertilizer inputs under varying natural (climate, soil) and anthropogenic (fertilization, planting) conditions. The results indicated that fertilizer application increased yield by 20.0%, and protein, fat, and starch contents by 12.6, 1.4, and 1.2%, respectively, compared to no fertilization. Yield response was highest under precipitation <450 mm and temperatures >7 °C, while protein and fat gains were favored by >600 mm precipitation and 5–7 °C temperatures. Soils with pH <6.5 and saline–alkaline properties supported greater yield gains, while brown and black soils promoted protein and fat accumulation, respectively. Moderate nutrient inputs (N 180–240, P₂O₅ 75–120, K₂O 90–135 kg ha⁻¹) outperformed lower or higher levels in improving both traits, with planting density also affecting response magnitude. Yield gains were primarily driven by soil fertility, whereas quality improvements were influenced by climate and management. Moderate fertilization facilitated the simultaneous enhancement of yield and quality. Tailored nutrient strategies based on soil and climate conditions can support regional maize productivity and contribute to food security. Full article

Fertilization management constitutes a critical determinant of agroecosystem productivity. Reasonable fertilization can increase the organic matter content in soil; however, the potential mechanism of how different fertilization regimes impact soil carbon sequestration is unclear. We hypothesized that the combined application of biochar and organic fertilizer would enhance soil carbon sequestration by improving soil physicochemical conditions, increasing microbial activity, and promoting the accumulation of stable forms of carbon. This study systematically investigated different regimes, including the application of chemical fertilizer alone (SCN), chemical fertilizer with biochar (SCB), chemical fertilizer with organic fertilizer (SCO), and chemical fertilizer with both biochar and organic fertilizer (SCBO), on soil physiochemical properties, enzyme activities, labile organic carbon fractions, microbial carbon fixation gene expression, and community composition. The results demonstrated that (1) the application of organic materials significantly enhanced soil nutrient levels and enzyme activities, with the best performance from SCBO; (2) the organic materials increased the labile soil organic carbon (SOC) content and the carbon pool management index, with SCO showing the highest at 69.82%; (3) SCB and SCBO improved the stability of soil carbon components by increasing the proportion of Aromatic C; and (4) the carbon fixation genes ACAT and sdhA exhibited the highest abundance in SCBO. In parallel, the relative abundance of Actinomycetota increased with the application of organic materials, reaching its peak in SCBO. Mantel testing revealed a strong correlation between microbial community composition and SOC, emphasizing the importance of SOC in microbial growth and metabolism. Moreover, the strong correlation between carbon fixation genes and aromatic carbon suggested that specific carbon forms, particularly aromatic structures, played a critical role in driving microbial carbon fixation processes. Full article

Sustainable cropland management is essential in maintaining national food security. In the black soil regions of China, which are key areas for commercial grain production, sustainable land use must be achieved urgently. To address the absence of integrated, large-scale, remote sensing-based sustainability frameworks in China’s black soil zones, we developed a comprehensive evaluation system with 13 indicators from four dimensions: the soil capacity, the natural capacity, the management level, and crop productivity. With this system and the entropy weight method, we systematically analyzed the spatiotemporal patterns of cropland sustainability in the selected black soil regions from 2010 to 2020. Additionally, a diagnostic model was applied to identify the key limiting factors constraining improvements in cropland sustainability. The results revealed that cropland sustainability in Heilongjiang Province has increased by 7% over the past decade, largely in the central and northeastern regions of the study area, with notable gains in soil capacity (+15.6%), crop productivity (+22.4%), and the management level (+4.8%). While the natural geographical characteristics show no obvious improvement in the overall score, they display significant spatial heterogeneity (with better conditions in the central/eastern regions than in the west). Sustainability increased the most in sloping dry farmland and paddy fields, followed by plain dry farmland and arid windy farmland areas. The soil organic carbon content and effective irrigation amount were the main obstacles affecting improvements in cropland sustainability in black soil regions. Promoting the implementation of technical models, strengthening investment in cropland infrastructure, and enhancing farmer engagement in black soil conservation are essential in ensuring long-term cropland sustainability. These findings provide a solid foundation for sustainable agricultural development, contributing to global food security and aligning with SDG 2 (zero hunger). Full article

Rice is a primary food source for nearly half of the global population. In Northeast China, paddy soils are mainly classified into two distinct types: fertile mollisol and nutrient-deficient saline–sodic soil. Soil microbial communities play a critical role in maintaining the stability of rice agroecosystems; however, comparative studies on microbial diversity and functional systems across these soil types remain limited. This study aimed to systematically investigate the bacterial diversity, community structure, and functional characteristics of mollisol and saline–sodic paddy soils during the rice heading and harvest stages and to elucidate the differences between them. High-throughput sequencing technology was used to delineate the differences in bacterial communities and their functional attributes between these soil types. The results indicated that distinct variations occur in the alpha diversity and community structures of bacterial populations in both soil types during the rice heading and harvest stages. Typically, the alpha diversity indices were higher in mollisol paddy soil than that in saline–sodic soil. Notably, Actinomycetota showed a significantly higher relative abundance in saline–sodic paddy soil at the harvest stage, whereas Bacteroidota were more abundant in saline–sodic soil at both stages examined. A functional gene analysis via KEGG pathways revealed that carbon fixation pathways were more prevalent in mollisol paddy soil during the rice heading stage. Conversely, genes related to nitrogen metabolism were more abundant under saline–sodic conditions, suggesting a greater need for nitrogen in nutrient absorption by rice in these soils. Overall, bacteria in mollisol paddy soil appear to play more pivotal roles than those in saline–sodic paddy soil. This study not only sheds light on the functional dynamics of bacterial communities but also holds practical implications for soil management strategies in these contrasting environments. Full article

Albi-boric argosols, mainly distributed in the Sanjiang Plain of Heilongjiang Province, China, accounting for over 80% of the total cultivated land area, is characterized by a nutrient-deficient layer beneath black soil. This study addresses the challenges of modern agriculture by investigating the impact of straw incorporation on soil dissolved organic carbon (DOC) and its structures in albi-boric argosols, profiles, using fluorescence excitation–emission spectroscopy and parallel factor analysis (PARAFAC). Three treatments were applied: undisturbed albi-boric argosols (C), mixed albic and illuvium layers (M), and mixed albic and illuvium layers with straw (MS). Results showed that the yield of M and MS increased by 9.9% and 13.0%, respectively. There was a significant increase in DOC content, particularly in the MS treatment. Fluorescence index (FI) values ranged from 1.65 to 1.86, biological index (BIX) values were less than 1, and humification index (HIX) values were below 0.75, indicating a mix of plant and microbial sources for DOC, autochthonous characteristics, and weaker humification degree. PARAFAC identified two/three individual fluorophore moieties that were attributed to fulvic acid substances, soluble microbial products, and tyrosine-like substances, with microbial products as the dominant component. This study demonstrates the effect of improving barrier soil and maintaining sustainable agriculture by enhancing soil quality. Full article

Phosphorus is essential for crop growth, but excessive use of chemical fertilizers can lead to environmental issues. The incorporation of organic materials has the potential to enhance phosphorus availability and promote soil phosphorus cycling. This study investigated the effects of chemical fertilizer co-application with two organic materials on soil properties and functions. Four treatments were established: (1) chemical fertilizer alone (SC, consisting of urea, ammonium phosphate, and potassium sulfate), (2) chemical fertilizer with corn-straw-derived biochar (SCB), (3) chemical fertilizer with composted manure-based organic fertilizer (SCF), and (4) chemical fertilizer with both biochar and organic fertilizer (SCBF). This study focused on changes in soil properties, bioavailable phosphorus, phosphorus cycling functional genes, and related microbial communities. Compared to SC, the combined application of organic materials significantly increased available phosphorus (AP), alkaline hydrolysis nitrogen (AN), and available potassium (AK), with the SCBF exhibiting the highest increases of 78.76%, 47.47%, and 336.61%, respectively. However, applying organic materials reduced alkaline phosphatase (ALP) and acid phosphatase (ACP) activities, except for the increase in ACP in SCBF. Additionally, bioavailable phosphorus increased by up to 157.00% in SCBF. Adding organic materials significantly decreased organic phosphorus mineralization genes (phoA, phoD, phnP) and phosphate degradation genes (ppk2), while increasing inorganic phosphorus solubilization genes (pqqC, gcd), which subsequently increased CaCl₂-P and Citrate-P contents in SCB and in SCBF. In summary, organic material application significantly enhances phosphorus bioavailability by improving soil physicochemical properties and phosphorus-related gene abundance. These findings provide new insights into sustainable soil fertility management and highlight the potential of integrating organic materials with chemical fertilizers to improve soil nutrient availability, thereby contributing to increased soybean yield. Moreover, this study advances our understanding of the underlying mechanisms driving phosphorus cycling under combined fertilization strategies, offering a scientific basis for optimizing fertilization practices in agroecosystems. Full article

Rice serves as the staple food for half of the world’s population. Given the expanding global population, the urgency to allocate land for rice cultivation is paramount. In Northeast China, saline–sodic and black soils represent two distinct soil types used in rice production. During rice growth, soil microorganisms, including arbuscular mycorrhizal fungi (AMF), play pivotal roles in nutrient uptake and resistance to biotic and abiotic stressors. While numerous studies have elucidated the role of AMF in enhancing rice growth and its adaptation to stress, the differences in AMF communities within paddy fields between different soil types have been largely overlooked. In this study, high-throughput sequencing technology was employed to analyze the diversity and community structure of AMF, and metagenomic sequencing was employed to analyze AMF functional gene differences between the two soil types (black and saline–sodic soils). At the same time, the commonalities and differences of the soil characteristics (nitrogen, phosphorus, potassium, pH, etc.) were verified in influencing AMF communities. The results indicated that Glomus was the predominant genus in both soil types, followed by Paraglomus. The overall abundance of AMF was higher at the heading stage than at the harvest stage, with Paraglomus showing greater adaptation to the saline–sodic soil environment. Total phosphorus (TP) was identified as the primary factor influencing AMF diversity at the heading stage. In the harvest stage, AMF community diversity was greater in saline–sodic paddy soil compared to black soil, a reversal from the heading stage. Further analysis of the functional genes of Rhizophagus intraradices revealed that gene activity in the heading stage of saline soils significantly surpassed that in black soils, suggesting that R. intraradices plays a more crucial role in saline environments. Additionally, spore density and the content of easily extractable glomalin-related soil protein were relatively higher in saline–sodic soil than in black soil. Thus, it may be inferred that AMFs are more vital in saline–sodic soils than in black soils of the paddy fields in Northeast China. This study may offer valuable insights into the utilization of AMF in paddy fields in Northeast China. Full article

Microbes colonizing cultural artifacts are a ubiquitous phenomenon which may occur during burial, post-excavation, and storage periods, thereby seriously affecting sustainable heritage conservation. In this study, high-throughput sequencing technology was applied to analyze the microbial community structure in ancient mural paintings and the surrounding air, as well as to identify the most characteristic taxa causing black spot contamination. The results showed that members of the genera Gliomastix and Ochroconis were highly abundant in black-spots-contaminated areas and rarely detected in the air and uncontaminated mural paintings. Air samples of the two tombs showed no significant difference in Chao1 and Shannon indices, whereas statistically significant differences were observed compared to those samples collected from black spots. The taxonomic diversity of the microbial community in the soil-covered mural paintings and air exhibited similar structures at the genus level. Moreover, when compared to other areas of the two tombs, the samples from black spots differed not only in microbial community composition but also in microbial assembly processes and the co-occurrence patterns, such as much less network complexity in the black spots area. Functional predictions uncover the presence of microbial functional profiles involved in nitrogen cycling, organic matter degradation, and animal and human pathogens, representing a potential threat to cultural relics and public health. These results advance our understanding of the impacts of archeological excavations on the microbial community variation in tomb mural paintings. Full article

As a pivotal region for safeguarding China’s food security, Northeast China requires a quantitative evaluation of crop yield dynamics, planting structure shifts, and their interdependent mechanisms. Leveraging MODIS NPP data and remote sensing-derived crop classification data from 2001 to 2021, this study established a crop yield estimation model. By integrating the Theil–Sen median slope estimator and Mann–Kendall trend analysis, we systematically investigated the spatiotemporal characteristics of maize, rice, and soybean yields. Phased attribution analysis was further employed to quantify the effects of crop type conversions on total regional yield. The results revealed: (1) strong consistency between estimated yields and statistical yearbook data, with validation R² values of 0.76 (maize), 0.69 (rice), and 0.81 (soybean), confirming high model accuracy; (2) significant yield growth areas that spatially coincided with the core black soil zone, underscoring the productivity-enhancing role of conservation tillage practices; (3) all three crops exhibited upward yield trends, with annual growth rates of 1.33% (maize), 1.20% (rice), and 1.68% (soybean). Spatially, high-yield maize areas were concentrated in the southeast, rice productivity peaked along river basins, and soybean yields displayed a distinct north-high-south-low gradient; (4) crop type transitions contributed to a net yield increase of 35.9177 million tons, dominated by soybean-to-maize conversions (50.41% contribution), while maize-to-soybean shifts led to a 2.61% yield reduction. This study offers actionable insights for optimizing planting structures and tailoring grain production strategies in Northeast China, while providing a methodological framework for crop yield estimation in analogous regions. Full article

Soil biodiversity is profoundly affected by variations in climate conditions and land use practices. As one of the major grain-producing areas in China, the belowground biodiversity of the black soil region of the Northeast is also affected by the variations in climate conditions and land use types. However, most of the previous studies have focused on aboveground biodiversity, and the research of soil biodiversity is limited. The main aim of this study was to investigate the effects of variations in climate conditions and land use practices on Collembola communities of different life forms in the black soil region of Northeast China. Here, we selected three climatic areas from high to low latitudes in the black soil region of the Northeast, with three variations in land use practices (soybean, maize, and rice) sampled in each area. We found that higher temperatures and higher humidity and land use practices from rice to soybean and maize are associated with a higher Collembola density and species richness. Specifically, the density and species richness of euedaphic Colmbola are higher in climate conditions with higher temperatures and humidity, while the density and species richness of all three life forms of Collembola are higher in land use practices from rice to soybean and maize. Additionally, we discovered that environmental factors and feeding resources (soil microorganisms) both have significant effects on Collembola communities, with environmental factors exerting a more substantial influence. Our results suggest that euedaphic Collembola are more vulnerable to climate differences than epedaphic and hemiedaphic Collembola. Consequently, this may alter the vertical distribution characteristics of soil fauna (e.g., increasing soil-dwelling fauna) as well as the ecological processes associated with soil fauna in different agricultural environments. Full article

Fertilization is a key management practice for maintaining or improving soil fertility and ensuring grain yield in agro-ecosystems. Nevertheless, as a low-yield soil, how fertilization strategies impact the status of albic soil physical and chemical properties, biological activity, and crop yield are poorly understood. Through a two-year positioning experiment, the albic soil fertility characteristics (physical, chemical, and biological) and changes in maize yield under different fertilization were studied. Three treatments were established: (1) conventional fertilization (chemical fertilizer) (T1), (2) optimized fertilization 1 (low amount of organic fertilizer + chemical fertilizer) (T2), and (3) optimized fertilization 2 (high amount of organic fertilizer + chemical fertilizer) (T3). The results indicated that, compared with T1, the soil bulk density of T2 and T3 treatments decreased, the average solid phase ratio of soil decreased by 8.2%, and the average liquid and gas phase ratios increased by 7.2% and 10.2%, respectively. The soil organic matter (SOM) and soil organic carbon storage (SOCS) under treatment of optimized fertilization were significantly higher than under T1, with an average increase of 10.1% for SOM and 8.8% for SOCS, respectively. T3 significantly increased the contents of alkali-hydrolyzable nitrogen, available phosphorus, and available potassium, while different fertilizations had little effect on soil pH. T2 and T3 significantly increased activities of soil urease, sucrase, phosphatase, and catalase, with an average increase of 33.7%, 56.9%, 32.0%, and 6.7%, respectively. The numbers of soil bacteria and actinomycetes under T3 increased significantly by 30.2% and 22.0% compared to T1, while the number of fungi decreased by 6.7%. The total number of soil microorganisms increased significantly by 29.0% of T3, and the proportion of soil bacteria to the total number of microorganisms increased, while the proportion of fungi and actinomycetes decreased. The maize yield of T3 was significantly higher than under other treatments, with an increase of 2368.5 kg/ha compared to T1. Correlation analysis showed that the contents of available nutrients and organic matter, the numbers of soil bacteria and actinomycetes, and the activities of soil urease and phosphatase had the most significant impact on maize yield. The optimized fertilization, which was the organic fertilizer combined with chemical fertilizer, can improve the physical properties of albic soil, increase soil organic matter content, organic carbon storage, available nutrient content, and soil biological activity, also for maize yield. Therefore, the optimized fertilization in albic soil of Northeast China is a promising and important management option for improved soil quality and grain yield. This work provides a theoretical basis and technical reference for efficient fertilization. Full article