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Carbon and nitrogen leaching and seepage with subsurface flow is one of the main paths of soil carbon and nitrogen loss. However, as great challenges lie in direct observation, soil carbon and nitrogen leaching related research is relatively lagging behind. Especially due to the complexity of the soil subsurface flow, some problems have not been fully elucidated. In this paper, the characteristics and observation methodologies of soil carbon and nitrogen leaching under the influence of soil, environment and subsurface flow were first summarized, and numerous complicated factors demonstrated to affect carbon and nitrogen leaching, where the influence of rainfall and soil properties were pre-dominant. Field measurement could reflect the natural process of leaching, the indoor experiment could effectively quantify the influential factors on leaching, and the mathematical model could help understand the physical mechanism of carbon and nitrogen leaching by simulating water flow and matter transport in porous media. Future research could combine these methods to achieve a better research effect. The aim of this paper was to provide a certain understanding of the role of carbon and nitrogen in the process of matter cycling and nutrient transfer, and to provide a scientific basis for better regulation of the dynamics of carbon and nitrogen mineralisation, sequestration, leaching and plant uptake in future ecosystems. [ABSTRACT FROM AUTHOR]

Carbon and nitrogen leaching and seepage with subsurface flow is one of the main paths of soil carbon and nitrogen loss. However, as great challenges lie in direct observation, soil carbon and nitrogen leaching related research is relatively lagging behind. Especially due to the complexity of the soil subsurface flow, some problems have not been fully elucidated. In this paper, the characteristics and observation methodologies of soil carbon and nitrogen leaching under the influence of soil, environment and subsurface flow were first summarized, and numerous complicated factors demonstrated to affect carbon and nitrogen leaching, where the influence of rainfall and soil properties were pre-dominant. Field measurement could reflect the natural process of leaching, the indoor experiment could effectively quantify the influential factors on leaching, and the mathematical model could help understand the physical mechanism of carbon and nitrogen leaching by simulating water flow and matter transport in porous media. Future research could combine these methods to achieve a better research effect. The aim of this paper was to provide a certain understanding of the role of carbon and nitrogen in the process of matter cycling and nutrient transfer, and to provide a scientific basis for better regulation of the dynamics of carbon and nitrogen mineralisation, sequestration, leaching and plant uptake in future ecosystems. [ABSTRACT FROM AUTHOR]

【Objective】The paper aimed to explore the impact of different years of abandonment in tropical regions on soil carbon fixing bacterial communities in farmland, and provide theoretical basis and data support for sustainable agricultural management. 【Method】Real time quantitative PCR and high-throughput sequencing technology were used to analyze the gene abundance, community diversity, and differences of soil carbon fixing bacteria in farmland, short-term abandoned land (2＜abandoned years＜5), and long-term abandoned land (abandoned years＞5) in the central region of Hainan Island. 【Result】The abundance of cbbL gene in the soil within the region ranged from 3.11×107-2.84×108 copies/g of dry soil, showing a trend of farmland＞short-term abandoned land＞long-term abandoned land. Compared with the control farmland, long-term abandoned land reduced the Chao1 index, Observed Specifications index and Shannon index of soil carbon fixing bacteria. The dominant phyla of carbon fixing bacteria in tropical farmland soils with different abandonment years were Pseudomonadota and Actinomycetota, and the dominant genera were Bradyrhizobium, Mycobacterium, Rhodopseudomonas, Rubrivivax, Blastochlolis, Nocardia, Mesorhizobium, Dokdonella and Azospirillum, and most of them were facultative autotrophic bacteria. The overall changes in the community structure of soil carbon fixing bacteria with different abandonment years showed clustering according to each abandonment year. A total of 33 differential markers were analyzed for three different abandonment years of soil, including 17 in farmland, 5 in short-term abandonment land, and 11 in long-term abandonment land. The RDA results showed that the community structure of soil carbon fixing bacteria was significantly influenced by SOC, SWC, ROC, TP, TN, Coarse sand, pH and Fine sand. 【Conclusion】The increase in abandoned years has reduced the gene abundance of soil carbon fixing bacteria, and the community structure has also changed. Environmental factors such as SOC, SWC, ROC, TP and TN have a significant impact on the community structure of soil carbon fixing bacteria. [ABSTRACT FROM AUTHOR]

[Objective] The present paper aimed to study the effects of exogenous straw carbon addition on the organic carbon composition and rice growth characteristics of calcareous paddy soil in karst area, providing reference basis for exploring the changes in carbon composition of alcareous paddy soil in karst areas. 【Method】The rice pot experiment was carried out in the greenhouse of Yanshan Campus of Guilin University of Technology in March 2023, and the experiment period was 120 d. A total of 19 treatments were set up in the pot experiment. In the treatment that only added straw carbon, 0.5%, 1.0% and 3.0% （dry soil mass ratio） crushed straw, straw compost and straw biochar were added, respectively. In the treatment of adding straw carbon and calcium carbonate, the carbon content of the three kinds of straw was 1.0%, and on this basis, 0, 10.0% and 20.0% （dry soil mass ratio） calcium carbonate were added, respectively. At the same time, the control （CK） treatment without adding any substances was set up. The growth characteristics of rice and the changes of soil organic carbon components microbial biomass carbon （MBC), dissolved organic carbon （DOC), granular organic carbon （POC） and their influencing factors were analyzed.【Result】The type and amount of straw carbon had an impact on the content of organic carbon components in the soil. Adding 0.5% straw compost resulted in the highest MBC content in soil （235.73 mg/kg), while adding 1.0% straw compost resulted in the highest DOC content in soil （221.50 mg/kg). The soil treated with 3.0% straw biochar had the highest POC content （36.20 mg/kg). The content of calcium carbonate in soil also affected the composition of soil organic carbon. When the content of calcium carbonate was 20.0%, the soil MBC contents in the treatments adding three straw carbons were the highest. The soil with 10.0% calcium carbonate+1.0% straw compost had the highest DOC content （195.60 mg/kg). The effects of adding three kinds of straw carbon on the growth of rice were as follows: straw biochar ＞ straw compost ＞ broken straw. Among them, the rice with 0.5% straw biochar added had the best growth, with an average plant height of 102 cm and root length of 50 cm. Addition 3.0% crushed straw had the strongest inhibitory effect on rice growth. With the increase of calcium carbonate addition, the rice plant height treated by straw compost increased first and then decreased, and the addition of 10.0% calcium carbonate had a stronger effect on plant height. The correlation analysis results showed that the amount of straw biochar was significantly negatively correlated with soil DOC content （P ＜ 0.05, the same below), and extremely significantly positively correlated with soil POC content （P ＜ 0.01). There was a significant positive correlation between calcium carbonate addition and soil DOC content.【Conclusion】Exogenous straw carbon has a positive excitation effect on the active organic carbon components in calcareous paddy soil, which can greatly increase the contents of MBC, DOC and POC in soil, and the addition of straw carbon and calcium carbonate has a synergistic effect on the increase of soil active carbon components. Adding low amount of straw carbon can promote rice growth, and straw biochar has the most obvious promoting effect. Adding straw compost and straw biochar to soils with 10.0% and 20.0% calcium carbonate concentrations can promote rice growth [ABSTRACT FROM AUTHOR]

In order to investigate the effects of vegetation restoration on soil aggregates and organic carbon in severe burning sites in Greater Khingan Mountains, this paper used larch plantations of different stand ages (11, 21 and 32 years) planted on heavy fire sites as the research object, and conducted a study on the stability of soil aggregates and organic carbon characteristics of soil aggregates by measuring the percentage content of each particle size and the organic carbon content of soil aggregates. The results showed that: 1)After vegetation restoration of burned areas, the mechanical stability and water stability of soil aggregates in larch plantations of different stand ages were dominated by the content of >0. 25 mm particle size, accounting for 85. 57%-89. 42% and 62. 86%-83. 19%, respectively. With the increase of stand age, the content of soil mechanical stability aggregates >2 mm particle size in 0-10 cm layer of larch plantation decreased significantly and the content of 0. 25-2 mm particle size increased significantly, while the water stability aggregates showed a trend that the content of >2 mm particle size decreased significantly and the content of 0. 5-2 mm particle size increased significantly (P < 0. 05). 2)32 years of larch plantation soil mechanical stability aggregates mean weight diameter (MWD) and geometric mean diameter (GMD) of the upper soil water-stable aggregates were significantly smaller than 11 years, and the MWD of the upper soil water-stable aggregates was consistent with the characteristics of the mechanically stable aggregates. Water-stable macroaggregate content (WSA 0. 25 ) gradually increased with the increase of restoration years, and the percentage of aggregate destruction (PAD) of the 32 years old larch plantation decreased significantly. 3)With the increase of forest age, the organic carbon content of soil aggregates in larch plantation forest increased, and the increase was more in the upper layer. The organic carbon contribution of large aggregates (>0. 25 mm fraction) dominated. The results could provide scientific basis for vegetation restoration of burned areas in Greater Khingan Mountains. [ABSTRACT FROM AUTHOR]

[Objective] The present paper aimed to study the impact of organic and inorganic combined application on the organic carbon composition, carbon bank management index and organic carbon functional group of tobacco planting soil in Wuxi county, so as to provide reference for improving the quality of tobacco planting soil and reasonable fertilization. [Method] Four treatments were set up under the condition of constant nitrogen input in field experiment: chemical fertilizer（CF）, chemical fertilizer with mushroom slag organic fertilizer（CMO）, chemical fertilizer with high carbon-based fertilizer（CHB）, and chemical fertilizer with biological organic fertilizer（CBO）. The effect of organic and inorganic application on soil carbon reservoir was studied by measuring total organic carbon and active carbon functional group structure using Fourier infrared spectrometry（FTIR）. [Result] （i） Compared with single organic fertilizer, the soil supplemented with organic fertilizer was slightly increased, and there was no significant difference between the treatments, significantly increased the output value on flue-cured tobacco leaf;（ii） The DOC, MBC content of the soil active carbon bank treated with organic fertilizer was significantly higher than that of single chemical fertilizer treatment. Among them, CMO treatment showed the largest increase in soil DOC content, thus being 67. 13%, 12. 84%, and 28. 54% higher than CF, CHB, CBO, respectively. CBO treatment showed the most increase in soil MBC content, with soil MBC content increasing 42. 32% compared to CF and CHB treatment showing 11. 43% higher soil EOC compared to CF;（iii）Among the three organic fertilizers, the DOC distribution of DOC, CMO, CBO, EOC, and the carbon bank management index of CHB treatment was significantly greater than CF and CMO;（iv） The structure difference of each treated organic carbon functional group was small, which mainly included phenols, aromatic hydrocarbons, olefins and mesamides. The relative peak area at 1634 cm-1 was associated significantly positively with soil MBC content, and that at 468 cm-1 was associated significantly negatively with soil TOC content. [Conclusion] Compared with single organic fertilizer, soil organic residue organic fertilizer significantly improved soil DOC and MBC content and high carbon-based fertilizer significantly improved soil EOC content and carbon bank management index. Short-term organic and inorganic distribution had little impact on organic carbon functional groups. However, the peaks at 1634 and 468 cm-1 were significantly associated with the soil TOC and MBC content. At the same time, organic-inorganic fertilizer significantly increased the yield and output value of flue-cured tobacco. [ABSTRACT FROM AUTHOR]

To explore the differences and change rules of soil nutrients and enzyme activities in Larix gmelinii forest in the cold temperate zone, so as to provide scientific basis and data basis for in-depth understanding of forest ecosystem functions and future development trends in the cold temperate forest ecotone in China. In this paper, four different types of larch forest (Betula platyphylla -Larix gmelinii, Rhododendron dauricum-Larix gmelinii, Larix gmelinii, and Larix gmelinii plantation) in Heilongjiang Zhongyangzhan Black-Billed Capercaillie Nature Reserve were selected as the research objects. Sampling was carried out by season, and the soil. chemical properties and enzyme activities ( catalase, acid phosphatase, urease, sucrase and cellulase) were determined in different seasons, and the dynamic changes with seasons were also explored. Results showed that: (1) Soil chemical properties and enzyme activities were significantly different in different forest types and seasons, and the changing trends were also different to some extent. (2)Soil acid phosphatase was significantly affected by the contents of soil total P, total N and available K. Soil catalase was significantly positively correlated with the contents of total N, available N, available K and available P. Soil sucrase was mainly affected by the contents of available P and available N. Soil urease and cellulase were most affected by soil organic carbon content. (3)The principal component analysis showed that there were significant differences in soil enzyme activities and soil chemical properties among the four forest types, and first principal component 1 could explain more than 50% of the variance variables. The soil chemical properties and enzyme activities in different Larix gmelinii were significantly different with the seasons, which were related to the accumulation of litter and the difference of vegetation types. Soil enzyme activities were correlated with soil chemical properties to varying degrees. [ABSTRACT FROM AUTHOR]

[Objective] Alpine wetland ecological environment is fragile and sensitive to global change. The present paper aimed to explore the response mechanism of soil physical and chemical properties to nitrogen deposition in alpine wetland. [Method] Four levels of CK（0 g/m2）,N2（2 g/m2）,N5（5 g/m2） and N10（10 g/m2） nitrogen addition tests were set in Xiaopo Lake Wetland in Qinghai Lake basin as the research object. Simulated nitrogen deposition test was conducted from June to October 2019.Samples were taken in October 2019 to determine soil water content, pH, organic carbon, total carbon, total nitrogen and inorganic nitrogen, and analyze the influence of nitrogen deposition test on soil physical and chemical properties.[Result]（i）Nitrogen deposition reduced soil moisture content and increased soil pH, and the influence reached extremely significant level（P<0.01）.(ii)Nitrogen deposition made soil carbon nitrogen content change. Total carbon organic nitrogen and ammonia nitrogen decreased with the increase of nitrogen concentration, and the influence on total carbon content was significant(P<0.05).The effect of nitrate nitrogen in the two soil layers was different. In the 0-15 cm soil layer, it increased with the increase of nitrogen concentration, and reached a significant level under the treatment of N10（P<0.05）,decreased with the increase of nitrogen concentration in the 15-30 cm soil layer.(iii) Soil moisture content was the main factor affecting soil organic carbon and total nitrogen.Soil inorganic nitrogen was not closely related to other factors, but there was a very significant correlation between soil organic carbon and total nitrogen(P<0.01).[Conclusion]The present study provides reference for the change of soil environment and the protection and utilization of wetland under the global change. [ABSTRACT FROM AUTHOR]

[Objective] The objective of the paper is to discuss soil carbon, nitrogen, phosphorous content and their ecological stoichiometric characteristics, to explore ecological stoichiometric characteristics of soil nutrient elements and to provide the scientific basis for improvement of soil nutrient content in Guizhou province. [Method] The ecological stoichiometric characteristics of topsoil in Guizhou province are analyzed by using literature collection and ANO VA methods. [Result] The average value of SOC, TN and TP in soil of the research area was 27. 34, 2. 11 and 0. 7 4 g ·kg-1, respectively. C N, C: P and N: P was 14. 27, SO. 92 and 3. 75, respectively. The variance coefficient of SOC, TN, TP, C N, C P and N: P was 71. 22 %, 61. 61 %, 79. 73 %, 7S. S4 %, 90. 67 % and 78. 93 %,respectively. The spatial variability in TP and C P was the maximum. Soil SOC, TN, TP and their ecological stoichiometric characteristics were correlated significantly. [Conclusion] SOC, TP and C N in soil of Guizhou province is higher than SOC (17. 12 g ·kg-1), TP (0. S6 g ·kg-1) and C N (12. 30) of national land soil. The variance coefficient of soil SOC, IN, TP and their stoichiometric ratio ranges from 0. 1 to 1l. SOC is the main factor affecting TN, C N and C: P. [ABSTRACT FROM AUTHOR]

【Objective】The objective of the paper is to provide a reference for soil nutrient management and sustainable operation in Karst areas.【Method】The soil samples were collected from woodland and dry land in Baiduo Village(dolomite areas) and Shiqiao Village(limestone areas) in Shibing County,Guizhou Province,and then the soil nutrient was analyzed.【Result】The soil developed from dolomite was featured with higher organic matters,total N,available P,available K and hydrolysable N.The soil developed from limestone was featured with higher total P and total K.Total N was positively and very significantly related to hydrolysable N and organic carbon in soil developed from limestone and dolomite.Hydrolysable N was positively and significantly related to organic carbon in limestone areas.Hydrolysable N was positively and very significantly related to organic carbon in dolomite areas.Land use patterns had obvious effects on nutrient content in soil developed from limestone and dolomite.Soil total K,total N,hydrolysable N and organic carbon content in limestone woodland was higher than dry land,and available K,total P,available P and pH was lower than dry land.Soil total P and available P in dolomite woodland are lower than dry land,and other indexes are higher than dry land.The organic matter,total N,total P and total K content in dolomite-developed soil was Grade II,Grade I,Grade VI and Grade III respectively.The organic matter,total N,total P and total K content in limestone-developed soil was Grade II,Grade I,Grade V and Grade I separately.【Conclusion】Soil nutrient was not only affected by soil forming rock,but also affected by land use pattern. [ABSTRACT FROM AUTHOR]

Conservation tillage has numerous ecological benefits. For example, it is conducive to the sustainable development of agricultural ecosystems. This paper compared and analyzed various studies on the effects of conventional and protective tillage measures on soil aggregates, soil organic carbon, soil microorganisms, and soil nematodes at home and abroad. The effects of conservation tillage on soil aggregates and biological characteristics were largely manifested as follows：Conservation tillage reduced the damage of large soil aggregates, reduced aggregate turnover rates, and improved the stability of soil structures. Conservation tillage increased the total surface soil contents of organic carbon and active organic carbon. Conservation tillage could increase the microbial biomass in cultivated layers, with a particularly significant impact on fungal biomass. Conservation tillage increased the microbial biomass and microbial diversity in aggregates to varying degrees, but did not change the microbial population distribution patterns in aggregates. Conservation tillage increased soil nematode abundance. It also increased the maturity and structure indexes of nematode communities in undisturbed soil and soil aggregates of all sizes, but does not change the total number of nematodes, nutritional groups, functional groups, or ecological distribution patterns of indexes in agglomerates. Based on the current research status at home and abroad, this article looks forward to the future research focus of conservation tillage with the goal of providing theoretical support for selecting conservation tillage measures in accordance with local conditions and promoting the sustainable development of agriculture in China. [ABSTRACT FROM AUTHOR]

This paper studies and discusses the changes of soil chemical indexes in different recovery years of XingJ an larch forest in Daxinganling, Inner Mongolia, in order to evaluate the self recovery of natural forest and provide basis for the management of Daxin- ganling forest in Inner Mongolia. The pH, C content, whole nitrogen, whole phosphorus and whole potassium content of the soil used in the experiment were calculated according to the Forest Soil Experiment Tutorial and the Soil Agroization Analysis. The effects of logging interference on the chemical properties of soil were studied using a single - factor variance ( ANOVA) analysis ( SPPS 13. 0 software). Results showed that ： ® comparing the differences in soil pH, soil C and other nutrients in Xing * an larch natural forest and two differ¬ent interference plots of clear cut and gradual cut, it is found that clear cut and gradual cut have significant differences in soil chemical properties (P<0.05). Clear cut has an extreme significant positive correlation with soil total nitrogen (P<0.01) , and a significant positive correlation with soil carbon content and pH ( P < 0. 05 ). (2) Comparing the significance of different cutting methods on soil physical and chemical properties in different years, there is a certain gap between the logging sites in 1987 and 2014, while the differ¬ences between the logging sites in 2009, 1987 and 2014 are not significant. Conclusion ： deforestation interference can reduce the pH of soil, objectively increase soil nutrients, and may be conducive to the natural renewal of forests. Logging interference significantly af¬fects the balance of soil carbon and other nutrients [ABSTRACT FROM AUTHOR]

The long-term dynamic of soil organic carbon in the mesoscale range is critical to the concentration of atmospheric greenhouse gases and the ecological effects of the local environment. Taking twelve soil types and seven types of land use in the Loess Tableland in Shaanxi Province as the research object, this paper studied the spatial distribution characteristics of soil organic carbon density (0- 20 cm) in the past three decades. The relationships between soil temperature, topographic factor, soil type, land use type and soil organic carbon density and storage are discussed. The results show: 1) In the past three decades, the soil organic carbon density and storage in the Loess Tableland have increased, and the increase rates were bigger and bigger. The increments of soil organic carbon density and storage were 0.14 kg/m2 and 2.04×106 t during 1985-2000, and the increments were 0.80 kg/m2 and 10.10×106 t during 2000-2015. 2) From 1985 to 2015, with the increases of temperature and precipitation, the soil organic carbon density showed an increasing trend. With the increases of elevation and slope, the organic carbon density increased first and then decreased, reaching the maximum in the ranges of 679-779 m and 10°-20°. 3) The organic carbon density and storages in most soil types increased with time, among which the soil organic carbon density of the black loam increased the most (1.59 kg/m2) and the storage capacity of the yellow soil increased the most (5.64×106 t). The organic carbon density and storage in different land use types increased with time. The organic carbon density in forest grassland is obvious higher than that in cultivated land. 4) Surface soil organic carbon density is significantly correlated with temperature, soil type and land use type with P <0.001, and significantly correlate with precipitation with P <0.05. Regardless of which factor is the controlling factor, both soil type and land use type are significantly related to the organic carbon density of the topsoil (P <0.001), indicating that these two factors are the dominant factors affecting the organic carbon density. [ABSTRACT FROM AUTHOR]