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Alternate wetting and drying irrigation (IAWD) is one type of water-saving technology to repeatedly dry and re-flood the fields. However, the frequent alternate aerobic and anaerobic environment under IAWD has increased the reactive nitrogen gas emission in rice fields. Fortunately, biochar has been widely used to improve land productivity (including crop production, carbon sequestration, mitigation of GHG, and remediation of heavy metal pollution) in agricultural soil amendment. However, little information is available on the effects of biochar on NH3 volatilization, N2O emissions, and reactive nitrogen gas emissions in paddy rice systems, especially under IAWD. This study aims to explore the response mechanism of reactive nitrogen gas emissions to the biochar application under IAWD conditions. A two-year field split-plot experiment was conducted with the biochar application rates (0 and 20 t/hm² ) under two irrigation regimes (continuously flooded irrigation, ICF and IAWD). Two irrigation regimes were used as the main plots, whereas, two biochar additions were the subplots. Each plot was in the size of 3 m (width) × 6 m (length) that separated by the PVC barrier at a depth of 30 cm. in order to avoid the lateral flow of nutrients and water. The results showed that the IAWD increased yields by 1.7% to 5.1% (P>0.05), NH3 volatilization by 6.6% to 11.6%, and N2O emissions by 157.1% to 116.7%, compared with the ICF (P>0.05). Biochar addition at the rate of 20 t ha−1 significantly reduced the NH3 volatilization by 10.8% to 25.2% and N2O emissions by 21.6% to 24.2% (P>0.05). There was an increase in the yield by 0.2% to 12.5% and a reduction in the reactive nitrogen gas emissions by 6.1% to 11.7% in biochar combined with the IAWD, compared with the control (ICFB0). Furthermore, the inorganic nitrogen existed mainly in the form of NH4 + -N in the soil environment of rice fields, accounting for 80% to 90%. The IAWD had no significant impact on the soil NH4 + -N, compared with the ICF, whereas, a significant increase was found in the content of surface soil NO3 − -N by 50.3% to 74% and the oxidationreduction potential by 47.6% to 54.1% (P>0.05). Moreover, the biochar addition increased the soil NH4 + -N by 25.9% to 52.41% (P>0.05), and pH by 0.6% to 1%, compared with the biochar-free treatment. Principal component analysis showed a strong negative correlation between NH3 volatilization and soil NH4+ -N content, yield, and aboveground nitrogen accumulation. It indicated that the biochar addition significantly improved the soil adsorption capacity for the inorganic nitrogen, thereby reducing the NH3 volatilization losses and increasing aboveground nitrogen accumulation, ultimately leading to an increase in the yield. N2O emissions were strongly positively correlated with the oxidation-reduction potential and soil NO3 − -N. Therefore, the frequent alternate aerobic and anaerobic environment under IAWD increased the concentration of soil NO3 − -N and the oxidation-reduction potential, thereby increasing denitrification substrates and N2O emissions. Anyway, the biochar addition coupled with alternate wetting and drying can be expected to promote rice production with water saving, carbon sequestration and emission reduction, while reducing the environmental costs associated with the reactive nitrogen emissions in the paddy field. [ABSTRACT FROM AUTHOR]

Alternate wetting and drying irrigation (IAWD) is one types of water-saving technologies to repeatedly dry and re-flood the fields. However, the frequent alternate aerobic and anaerobic environment under IAWD has increased the reactive nitrogen gases emission in rice fields. Fortunately, biochar has been widely used to improve the land productivity (including the crop production, carbon sequestration, mitigation of GHG, and remediation of heavy metal pollution) in the agricultural soil amendment. However, little information is available on the effects of biochar on the NH3 volatilization, N2O emissions, and reactive nitrogen gas emissions in paddy rice systems, especially under IAWD. This study aims to explore the response mechanism of reactive nitrogen gas emissions to the biochar application under IAWD conditions. A two-year field split-plot experiment was conducted with the biochar application rates (0 and 20 t/hm²) under two irrigation regimes (continuously flooded irrigation, ICF and IAWD). Two irrigation regimes were used as the main plots, whereas, two biochar additions were the subplots. Each plot was in the size of 3 m (width) × 6 m (length) that separated by the PVC barrier at a depth of 30 cm. in order to avoid the lateral flow of nutrients and water. The results showed that the IAWD increased yields by 1.7% to 5.1% (P>0.05), NH3 volatilization 8.9%（only in 2020）, and N2O emissions by 105.0% to 115.0%, compared with the ICF (P<0.05). Biochar addition at the rate of 20 t/hm² was significantly reduced the NH3 volatilization by 8.7% to 20.5% and N2O emissions by 21.6% to 24.2% (P<0.05). There was an increase in the yield by 0.2% to 12.5% and a reduction in the reactive nitrogen gas emissions by 6.1% to 11.7% in biochar combined with the IAWD, compared with the control (ICFB0). Furthermore, the inorganic nitrogen existed mainly in the form of NH4+-N in the soil environment of rice field, accounting for 88.6% to 94.7%. The IAWD had no significant some impact on the soil NH4+-N, compared with the ICF, whereas, the significant increase was found in the content of surface soil NO3−-N by 50.3% to 74.0% and the oxidation-reduction potential by 47.6% to 54.1% (P<0.05). Moreover, the biochar addition increased the soil NH4+-N by 25.9% to 52.41% (P<0.05), and pH by 0.6% to 1.0%, compared with the biochar free treatment. Principal component analysis showed a strong negative correlation between NH3 volatilization and soil NH4+-N content, yield, and aboveground nitrogen accumulation. It indicated that the biochar addition was significantly improved the soil adsorption capacity for the inorganic nitrogen, thereby reducing the NH3 volatilization losses and increasing aboveground nitrogen accumulation, ultimately leading to increase the yield. N2O emissions were strongly positively correlated with the oxidation-reduction potential and soil NO3−-N. Therefore, the frequent alternate aerobic and anaerobic environment under IAWD increased the concentration of soil NO3−-N and the oxidation-reduction potential, thereby increasing denitrification substrates and N2O emissions. Anyway, the biochar addition coupled with alternate wetting and drying can be expected to promote the rice production with water saving, carbon sequestration and emission reduction, while reduce the environmental costs associated with the reactive nitrogen emissions in the paddy field. [ABSTRACT FROM AUTHOR]

Biochar is widely used as one type of soil amendment to enhance soil properties and carbon sequestration in croplands. But it is still unclear on the influence of rice straw biochar application on CH4 and N2O emissions from paddy fields, especially in Northeast China. The typical rice monoculture region is often used under the alternate regime of wetting and drying (IAWD) with the aging of biochar in soil. This study aims to further investigate the potential of biochar application in IAWD paddy fields. A split-plot field was designed with two irrigation regimes, two biochar additions, and three replications in 2019- 2021. Among them, the irrigation regimes (I) included continuous flooding irrigation (ICF) and IAWD. The sub-plots within each main plot were subjected to two biochar (B) additions (biochar-free control and 20 t ha-1 biochar, represented by B0 and B20, respectively). Prior to the experiment, the surface soil was first sampled in the rice fields and then air-dried to measure the basic physicochemical parameters of the soil. Biochar was applied one day before transplanting in 2019. After that, there was no additional biochar in 2020 and 2021. The opaque static chamber was used to collect the CH4 and N2O emissions over 3-4 days after topdressing, and 7-10 days between rice transplanting and harvesting. Gas samples were finally obtained to measure the CH4 and N2O concentration using gas chromatograph (Agilent 7890B, Agilent Technologies, Inc., USA). Results showed that the IAWD significantly reduced the CH4 emission by 63.03%-78.89%, global warming potential (GWP) by 62.02%-75.21%, greenhouse gas inventory (GHGI) by 62.31%-75.28%, compared with the ICF, although there was an increase in the N2O emission of 100%-122.67%. The B20 treatment reduced the CH4 emission by 21.99% in 2020, and 38.21% in 2021, whereas, there was an increase in the soil organic carbon by 24.03%-28.88%, and N2O emission by 28.26%-33.10% over three years. Moreover, biochar was used to inhibit the negative effect of IAWD on the increase of N2O emissions. A correlation analysis showed that there was a significant negative correlation in the cumulative CH4 emissions with the soil redox potential (Eh) value, and soil organic carbon (SOC), whereas a significant positive correlation was found with the soil temperature. There was a significant negative correlation between the cumulative N2O emission and soil temperature, whereas, a significant positive correlation was between the soil Eh value. A positive effect of rice production was found in the second and third years, although there was a slight decrease in the first year of biochar application. The main reason was that the early straw biochar was more alkaline with a limited effect. A synergy effect was found in the biochar adsorption emission reduction and slow release with the pH value to the normal, indicating the increasing production. Especially, the B20 treatment significantly reduced GWP by 37.50% and GHGI by 42.86% in 2021, whereas there was an increase of 11.02%, compared with the B0. The IAWD B20 treatment reduced the CH4 cumulative emissions by 83.78%, GWP by 77.98%, and GHGI by 78.95%, compared with the ICF B0. It infers that the biochar combined with IAWD can be used to effectively reduce the GWP and GHGI. Anyway, biochar can be expected to reduce carbon sequestration and CH4 and N2O emissions in paddy fields. The finding can also provide a strong theoretical reference to mitigate the CH4 and N2O emissions after the biochar application in rice fields. [ABSTRACT FROM AUTHOR]

Pyrolysis characteristics of biogas residue can provide some ideas for resource utilization. In this study, the industrial and elemental analyses were conducted on five types of biogas residue raw materials, in order to explore the basic properties of biogas residue. The results showed that there was a high ash content of CMBR, whereas, the volatile content reached over 60% in the other types of biogas residue, except for CMBR. It infers that a higher proportion of biological oil and pyrolysis gas generated during the pyrolysis process. Then, TG-FTIR-MS was used to further evaluate the characteristics of different types of biogas residue raw materials. The experimental results show that the pyrolysis was divided into three stages: adsorption water evaporation (25-220 ℃), volatile evaporation (220-450 ℃), and carbonization (450 to 800 ℃). The weight loss rate was ranked in the order of STBR, SBR, FTBR, PTBR, CMBR, and the maximum weight loss rate was STBR, SBR, PTBR, FTBR, CMBR, due to the different internal components of five types of biogas residues. The comprehensive pyrolysis characteristic index D value demonstrated that the thermal stability was ranked as the CMBR, PTBR, FTBR, SBR, STBR. The STBR presented the lower thermal stability more conducive to the preparation of carbon materials as some soil amendments and heavy metal adsorbents. The volatile matter was gradually precipitated after 220 ℃ to reach the peak at the highest pyrolysis weight loss rate. Then, the volatile matter content decreased to the lowest, as the temperature gradually increased to the final temperature. There was a relatively complex composition of volatile components generated by pyrolysis, particularly with the multiple peaks within the range of 1 000-4 000 cm−1. Volatility analysis showed that most of them occurred within about 10 minutes of pyrolysis. The pyrolysis range of the five types of biogas residues was between 220 and 450 ℃, indicating the highest production of H2O. The other types of small molecule gases were also produced, depending on the type of material. The SBR contained a large amount of cellulose, hemicellulose, and lignin. The pyrolysis of cellulose first underwent depolymerization and dehydration reactions to form dehydrated sugar, and then decompose to form the other compounds after a series of reactions. As a result, the output of released gases was followed by the output of CO2, CO, H2 . The output was reduced in turn, while the output of CH4 was the smallest. The remaining part was non-biodegradable material, and the pyrolysis process mainly involved a decarbonization reaction, as most of the organic matter was consumed in the anaerobic fermentation process of CMBR. There was no hydrogen and methane that generated throughout the entire pyrolysis process. Kitchen waste PTBR, FTBR, and STBR produced a certain amount of CH4, due to the high proportion of C and H in organic substances, such as protein, fat, and starch in the substrate after anaerobic fermentation. Interestingly, there was a relatively high production in the total available gas of food and kitchen waste PTBR, FTBR and STBR. Therefore, the food and kitchen waste can still be used for secondary gas production and secondary utilization after anaerobic fermentation. [ABSTRACT FROM AUTHOR]

Our objective was to investigate the effect of different biochar soil amendments on soil fertility and the fruit yield of yellow peach, to provide a scientific basis for biochar use in peach cultivation. We conducted a field experiment to investigate the effect of biochar amendments on the soil physicochemical properties, soil enzyme activity, and leaf and fruit nutrients of peach trees at different growth stages, and on the yellow peach yield and quality in an orchard. We designed four fertilization treatments including the conventional fertilization regime in the local area as the control (CK) and the application of three biochars from rice straw (RB), wheat straw (WB), and Chinese fir (FB), separately. In the biochar treatments, we applied the biochar at the rate of 20 t·hm-2 with conventional fertilizers. The results showed that all biochar amendments significantly increased soil organic matter content, whereas they significantly decreased ammonium nitrogen, nitrate nitrogen, and available phosphorus contents. Compared with the CK treatment, the WB treatment significantly increased soil pH, cation exchange capacity, and total nitrogen content by 6.7%, 15.4% and 17.6%, respectively. Biochar amendment significantly increased normalized enzyme activity by 80.0%-96.0%. The responses of soil fertility varied among the biochars. Compared with the CK treatment, the WB treatment significantly increased the soil fertility index by 17.8%. In addition to RB treatment significantly decreased the fruit nitrogen content at the hard-core stage compared with CK treatment, WB and FB treatment promoted the uptake of nutrients by the trees. Compared with the CK treatment, the WB treatment significantly increased the leaf potassium content at the mature stage, fruit phosphorus content at the first expanding stage, and fruit potassium content at the first expanding and hard-core stages. The FB treatment significantly increased leaf phosphorus content at the second expanding stage, leaf potassium content at the mature stage, fruit nitrogen and phosphorus contents at the first expanding stage, and fruit phosphorus content at the mature stage. Compared with the CK treatment, the WB treatment significantly reduced single fruit mass by 12.7% and titratable acid content by 13.8%, but had no significant effect on fruit production, soluble sugar content, or sugar-to-acid ratio of yellow peaches. In conclusion, biochar amendments can improve soil properties through increasing the pH, organic matter content, and enzyme activity, and by promoting nutrient uptake; however they have little effect on peach yield and quality in the short term. [ABSTRACT FROM AUTHOR]

To study the effects of different organic amendments on the molecular characteristics of dissolved organic matter（DOM）and the environmental behavior of heavy metals in contaminated soil, three organic amendments and lead（Pb）-contaminated soils from the Changhua mining area in Hainan Province were selected as research materials. Incubation experiments were carried out on soils treated with three different organic amendments（5% sheep manure, seaweed organic fertilizer, and wheat straw biochar）, and blank control without organic amendments. The results showed that dissolved organic carbon（DOC）content in the soil was significantly increased using organic amendments, and the DOC content gradually decreased at the later stage of incubation. Except biochar, the proportion of high molecular weight aromatic carbons（C2）in the other three treatments decreased with the increase of incubation time, and the proportion of oxidized quinones with lower molecular weight（C3）increased. The infrared spectrum showed that the functional groups of DOM in soil after the application of organic amendments were mainly N H and hydroxyl OH. With the increase of incubation time, all the four treatments showed an increase in the water-soluble Pb content in the soil. Among them, the seaweed treatment showed the highest content of watersoluble Pb, reaching 1.91 mg · kg-1 . The reducible state / iron-manganese oxide binding state was the main form of Pb（48% - 54%）. Redundancy analysis at different incubation time showed a correlation between soil DOC content and related functional groups and soil Pb content and form. Pb in the soil solution was mainly controlled by DOM in the soil solution. Seaweed and sheep manure treatments increased the content of water-soluble Pb and EDTA-Pb in the soil. The application of organic amendments changed the properties of DOM in soil and affected the contents of water-soluble and available Pb in soil, which provided a theoretical basis for the remediation of heavy metal-contaminated soil by organic amendments. [ABSTRACT FROM AUTHOR]

This study aimed to understand the content changes of different protected soil organic carbon (SOC) fractions in upland red soil that have been affected by long-term fertilization management, and to explore the equilibrium or saturation for SOC pools with varying protection methods. Surface (0~20 cm) samples of upland red soil that were subjected to six different treatments were collected from a longterm fertilization experiment. Treatments included no fertilizer application (CK); chemical nitrogen fertilizer alone (N); conventional usage amount of chemical N, phosphorus (P), and potassium (K) fertilizers (NPK), double usage amount of chemical NPK fertilizers (HNPK), chemical NPK fertilizers plus organic manure (NPKM), and organic manure alone (M) . The total organic carbon (TOC) of soil was then separated into six different functional pools by the recently developed physical-chemical fractionation method, which included unprotected SOC, physically protected SOC, physical-chemically protected SOC, physical-biochemically protected SOC, chemically protected SOC, and biochemically protected SOC pools. The responses of the contents of SOC fractions with varying protection mechanisms to long-term fertilization were assessed, and the relationships between the contents of different protected SOC fractions and TOC, as well as between storages of different protected SOC pools and accumulated C input were investigated. The results showed that there was no significant (P> 0.05) difference in the contents of all the separated SOC fractions between CK and N treatments. The TOC content, the contents of unprotected SOC and physically protected SOC fractions in NPK, HNPK, M, and NPKM, however, were significantly increased by 13.3%– 48.0%, 39.2%-221.5%, 41.9%-132.3% respectively, compared with CK treatment. The proportions of unprotected SOC and physically protected SOC in TOC were significantly (P<0.05) increased under all the fertilization treatments with an exception of N treatment by 1.9- 10.0 and 2.5-5.5 percentage points respectively as compared with CK treatment. Organic amendment treatments (such as M and NPKM treatments) caused the best increase of the content of TOC and its unprotected and physically protected fractions. The contents of all the SOC fractions have shown linear positive correlations with the TOC content, according to the slope of the fitted equation. With the increase of TOC content per unit, the increase rates of the content for the unprotected coarse particle SOC and physically protected particle SOC were up to 44.3% and 28.0% (P<0.001), respectively. With the exception of biochemically protected SOC, the storages of the other separated SOC pools showed significant (P<0.01) linear correlations with the accumulated C input. Therefore, the increased TOC in upland red soil due to fertilization is preferentially sequestered in the form of unprotected coarse particle and physically protected SOC. Application of chemical fertilizer, through either single or combined application, has less effect on improving TOC sequestration, SOC lability, and its physical protection than organic amendments. The results of this study also indicated that the biochemically protected SOC pool in upland red soil reached an equilibrium status under the current condition of accumulated C input level; however, further work is needed to assess SOC saturation characteristics, which rely on lengthier experiments. [ABSTRACT FROM AUTHOR]

The unique black soil resources and natural environment of Jilin province provide the proper conditions for the growth of ginseng-the king of herb. Ginseng industry has effectively promoted the development of medical and health industry, and brought considerable economic income for ginseng farmers. However, long-term continuous cropping of ginseng causes the chemical, biological, and physical properties deterioration of soil, which influences the yield and the quanlity of ginseng, and results in the occurrence of replant obstacle. Identifying the malignant soil factors in continuous cropping obstacles, then analyzing the evolution process, and putting forward the improvement strategies is the primary task of ginseng research at present. This paper reviews the influence of ginseng cultivation on the physicochemical property, nutrient, enzyme activity, microecology and ecotoxicity of the soil, and the achievements of improving ginseng soil by chemical and biological techniques and methods in recent 10 years. [ABSTRACT FROM AUTHOR]

Phosphorus has been one of the most limiting factors in the nonrenewable natural resource to the food security in modern agriculture. The availability of phosphorus is reduced in coastal saline soil, due to the influence of pH value and salt. Biochar can be expected to serve as a coastal saline soil amendment for better soil properties. However, a new slow-release fertilizer, ammonium polyphosphate cannot be easy to be fixed in the soil. Therefore, this study aims to clarify the effects of ammonium polyphosphate combined with biochar and straw on the transformation characteristics of available phosphorus and inorganic phosphorus in the coastal saline soil. An indoor culture experiment was conducted. Five treatments were set as the blank (CK), ammonium polyphosphate (OA), ammonium polyphosphate with biochar (AB), ammonium polyphosphate with straw (AS), and ammonium polyphosphate with biochar and straw (ABS). The improved Hedley phosphorus grading method with a 100-mesh sieve was used to grind the soil in the different culture periods. A total of six inorganic phosphorus and forms content were obtained after continuous extraction, such as resin-exchanged phosphorus (Resin-P), NaHCO3-extracted phosphorus (NaHCO3-P), NaOH-extracted phosphorus (NaOH-P), 1mol/L HCl-extracted phosphorus (D. HCl-P), concentrated hydrochloric acid-extracted phosphorus (C. HCl-P), and residual phosphorus (Residue-P). The correlation was analyzed between the pH, available phosphorus, and inorganic phosphorus forms. The results showed that: 1) The available phosphorus content of ammonium polyphosphate treatment significantly increased by 2.46-4.02 times (P<0.05), compared with the CK, during the incubation period. The ABS treatment significantly increased by 15.01% and 19.20% at the end of culture, compared with the AB and AS (P<0.05). 2) There were different trends in the content of Resin-P under different treatments with the prolongation of culture time. The OA and AB treatments showed an increasing trend, whereas, the AS and ABS treatments showed a decreasing trend. At the end of the culture, the content of Resin-P in the AS and ABS treatments was significantly lower than that in the OA treatment by 39.98% and 31.06%, respectively. The content of NaHCO3-P increased first and then decreased with time, reaching the maximum on the 28th day of culture. The maximum was found in the ABS treatment. The content of NaOH-P and D. HCl-P increased with the prolongation of culture time. The content of NaOH-P in the ABS treatment was significantly higher than that in the OA by 54.07% (P<0.05) at the end of the culture. The contents of C. HCl-P and Residue-P decreased as a whole. The contents of Residue-P in the AB and ABS treatments significantly increased by 34.01% and 26.12%, compared with the OA (P<0.05). 3) Phosphorus in the coastal saline soil mainly existed in the form of HCl-P and Residue-P, accounting for 88.60%-92.20%. Correlation analysis showed that the correlation coefficients between different phosphorus forms and soil-available phosphorus were in the order of D. HCl-P> Resin-P> NaOH-P> NaHCO3-P> Residue-P>C. HCl-P. Except for the C. HCl-P, there was a significant positive correlation between other inorganic phosphorus forms. In summary, the ammonium polyphosphate combined with the biochar and straw (ABS) is superior to improve the effectiveness of phosphorus literacy in the coastal saline soil, while, the Resin-P and D. HCl-P contributed the most to the available phosphorus. This finding can provide an important theoretical reference for the phosphorus availability and utilization rate in coastal saline soil. [ABSTRACT FROM AUTHOR]

[Objectives]This article aimed to explore the influence mechanism of bio-based compound amendments composed of vermicompost, active enzyme conditioner and endophytic mycorrhizal fungus agent on the root growth and physiology of alfalfa grown in saline soil in different regions, in order to provide theoretical guidance for the improvement, rational utilization of saline-alkali land and reducing crop salt stress damage. [Methods]The alfalfa pot experiment was used, and conventional fertilization(without amendments)was used as the control(C). Bio-based compound amendments(E)was added to the saline soil of northern Jiangsu tidal flat(J)and the saline soil of the Yellow River delta(S), respectively. There were 4 treatments in total:the northern Jiangsu tidal flat saline soil without amendments(JC)and with amendments(JE); the Yellow River Delta saline soil without amendments(SC)and with amendments(SE). Samples were collected during the budding stage and the effects of bio-based compound amendments on the physical and chemical properties of the rhizosphere soil, root growth characteristics, root vigor, nutrients, antioxidant systems of alfalfa cultivated in saline soils were analyzed. [Results]The addition of bio-based compound amendments could effectively reduce the pH value and soluble salt content of the rhizosphere soil of cultivated alfalfa in saline soils in northern Jiangsu tidal flat and the Yellow River Delta, and increase available nutrients; it was beneficial to the growth and development of salt-tolerant alfalfa roots. The total root length, total root surface area, number of tips, number of forks and root dry weight significantly increased. The total root length of JE treatment reached 460.1 cm, which was an increase of 40.54% compared with JC treatment(P<0.05), and the total root length of SE treatment reached 438.6 cm, which was higher than that of SC treatment by 59.05%(P<0.05), and the root phenotypic parameters of alfalfa cultivated in saline soil in northern Jiangsu tidal flat were significantly better than those cultivated in saline soil in the Yellow River Delta. It effectively increased the total phosphorus, total potassium content and root vigor of the root system. The root vigor of JE treatment was 0.69 times that of JC treatment(P<0.05), and the root vigor of SE treatment was 0.50 times that of SC treatment(P<0.05). It inhibited the accumulation of root hydrogen peroxide(H2O2), superoxide anion(O·-2), and malondialdehyde(MDA)contents, up-regulated superoxide dismutase(SOD), peroxidase(POD)and catalase(CAT)activities, and promoted proline production. The results of correlation analysis showed that root vigor and root phenotypic parameters were significantly positively correlated with antioxidant enzyme activity, root nutrients, and significantly negatively correlated with membrane lipid peroxidation and reactive oxygen species. [Conclusion]The bio-based compound amendments were beneficial to reducing rhizosphere soil salinity, improving soil fertility, enhancing the active oxygen scavenging ability of alfalfa roots, accelerating the biosynthesis of osmotic adjustment substances, increasing root vigor, and promoting nutrients absorption and root system development, thereby promoting the growth of the above ground. [ABSTRACT FROM AUTHOR]

As a kind of agricultural waste, rice straw can be prepared as adsorbent, which has a good application prospect in soil remediation field. The preparation and modification methods of rice straw biochar were reviewed, and the influence of pyrolysis temperature on the physicochemical properties of biochar was analyzed. The research achievements in physical, chemical and biological modification of biochar were summarized. The adsorption capacity and mechanism of rice straw biochar for cadmium in soil were analyzed, and the current research status was reviewed. Finally, a series of prospects were made for the feasibility and research direction of rice straw biochar as soil amendment in the future. [ABSTRACT FROM AUTHOR]

Animal manure treatment can be widely used a promising pyrolysis technology, due to the complete destruction of pathogens, full decomposition of antibiotics, the value-added energy, and biochar products, heavy metal immobilization, as well as the remarkable reduction in the waste stream volume. Biochar is one type of solid carbon-rich by-product of the animal manure pyrolysis (<800 ), indicating the abundant porous structure and high levels of mineral elements. Th ℃ e biochar can be used as the soil amendment and fertilizer, in order to improve the uptake of nitrogen, phosphorus, and potassium for the better water-holding capacity and the less susceptibility to erosion. Extensive research has indicated that the biochar can be an efective adsorbent for the contaminants, such as heavy metals and pesticide residues. However, the high levels of heavy metals were the key limiting factor for the application of animal manure. Fortunately, pyrolysis can be expected to concentrate the heavy metals in biochars. In addition, the animal manure biochar can also be alkaline to generally improve the acid soil with high ash contents. Previous studies have demonstrated that the biochar application for the remediation of soils can reduce the bioavailability of heavy metals, thus reducing the potential for the heavy metals to be uptaken by agricultural crops. However, acid soil can increase the bioavailability of heavy metals in biochar. The long-term application of animal manure biochar to the cropland can also increase the heavy metal accumulation in soil, and even enter the food chain as a threat to human health. Therefore, it is essential to evaluate the ecotoxicity of heavy metals in the biochar for scientific utilization. More importantly, the pig production was approximately 0.5 billion heads annually in China, accounting for nearly 1/2 of the global production. The concentrations of heavy metals, especially Cu and Zn in pig manure were significantly higher than those in other animal manure. Taking the pig manure biochar as the research object, this study aims to explore the interfacial behavior of heavy metals at the surface of biochar and soil particles. A pot experiment was conducted using biochar and acid soil in the laboratory. Scanning Electronic Microscope (SEM), physical absorption, X-ray Diffraction Pattern (XRD), X-ray Photoelectron Spectroscopy (XPS) and Inductively Coupled Plasma Mass Spectrometry (ICP-MS) were utilized to identify the morphology, pore structure, crystal composition and elements of acid soil and biochars, respectively. The basic properties (pH, EC, Cu, Zn, and PO4 3-) of soil pore water were characterized after the experiment. Results showed that the main fraction of Cu and Zn in the pig manure biochar was the oxidizable extraction, accounting for 79.37% and 53.43%, respectively. Mineral elements of biochar were found on the surface of biochar particles as the oxides. The specific surface area and pore volume of biochar increased after incubated with the acid soil. The contents of Cu, P, K on the surface of biochar decreased. There was a significant increase in the pH and EC values, as well as the concentration of Cu, Zn, and PO4 3- of soil pore water, after the biochar was applied to the acid soil. The concentrations of PO4 3- and Cu were in the range of 2.26-298.00 mg/L and 1.81-2.86 μg/L, respectively. Consequently, the carbonate and phosphate alkaline salt in the biochar neutralized the H + in the acid soil, and then released into the acid soil, leading to the release of Cu that precipitated and adsorbed by carbonate, phosphate in biochar. Some Cu was released into the soil solution, while another Cu was formed from the mineral compounds (Cu4(SO4(OH)6H2O)H2O,Cu(SiO3)H2O) that combined with the soil components. The smaller particle size of biochar greatly contributed to facilitating the release of Cu. The largest release amounts of PO4- 3 and Cu in the biochar were achieved on the 30th day incubated with acid soil. However, the Zn in the biochar was difficult to release in the acidic soil environment, where the biochar adsorbed Zn to reduce the bioavailability after being applied to the acidic soil. The finding can provide a strong reference to better understand the transformation and potential environmental risk of heavy metals in pig manure biochars. [ABSTRACT FROM AUTHOR]

It is necessary to generate a sustainable strategy for evaluation of carbon leaching risk and organic fertilizer application by studying the effects of different fertilization practices on dissolved carbon leaching along soil profile in the area of lime concretion black soils. Aiming to analyze the contents and distribution of physicochemical, microbial properties, dissolved organic carbon (DOC), and dissolved inorganic carbon (DIC) contents in soil profile based on a 33-year long-term fertilization experiment to select an environmentally friendly organic amendments, five treatments were designed, including mineral fertilization (MF), mineral fertilization combined with low amount wheat straw (MFL), mineral fertilization combined with high amount wheat straw (MFH), mineral fertilization combined with pig manure (MFP), and mineral fertilization combined with cattle manure (MFC), respectively. Results showed that the contents of soil organic carbon, microbial biomass carbon (MBC), and microbial biomass nitrogen (MBN) in the profile at 0-60 cm soil depth were substantiality increased, whereas the values of soil total nitrogen, bulk density and pH value were mainly influenced at 0-20 cm soil depth in the organic amendments treatments compared with MF treatment. Compared with the MF treatment, soil DOC contents at 0-20 cm and >20-40 cm soil depths under long-term organic amendments application treatments were significantly (P<0.05) increased, whereas the values were not significantly increased at >40-60 cm soil depths. In contrast, soil DIC contents under long-term organic amendments application treatments at 0-60 cm depth were significantly (P<0.05) increased compared with the MF treatment. Both the values of UV280 absorption and aromaticity index (AI) at 0-60 cm soil depth were significantly (P<0.05) increased under long-term organic amendments application treatments, especially for the MFC treatment. The values of AI at the 0-20, >20-40, and >40-60 cm soil depths under the MFC treatment were significantly increased by 71.2%, 153.3%, and 38.1%, respectively. It was indicated that soil DOC chemical structure in the whole profile at 0-60 cm soil depth under long-term organic amendments application was greatly influenced and the contents of aromatic compound were increased, which suggested that soil DOC chemical structure under long-term organic amendments application were more complex. Furthermore, stepwise lineal regression showed that the DOC and DIC contents in the profile at 0-60 cm soil depth were regulated by soil pH value and MBC, and the strength of influence soil pH value was larger than soil MBC. Soil DOC chemical structure in the soil profile were mainly influenced by soil MBC. Generally, the type and amount of exogenous organic amendments were the two major factors influencing the characteristics of soil dissolved carbon distribution. The risk of dissolved carbon leaching was aggravated after long-term organic amendments application, especially for pig and cattle manure. Crop straw application is a recommended organic agricultural practice deceasing dissolved carbon leaching risk. [ABSTRACT FROM AUTHOR]

Severe soil compaction often occurs with heavy traffic during mining, particularly for a large number of large-scale opencast mines in the Loess Plateau. An important indicator, the soil hydraulic property can be widely used to measure the soil pore conditions of compacted soils. Biochar can also be added to improve the land quality for higher crop yields in farmland in recent years. The environmental soil amendment has presented higher ecological and economic benefits, due to the specific properties from the special porous structure of biochar, including the large surface area, high porosity, low bulk density, and high organic carbon contents. As such, the soil bulk density can be reduced to increase the water holding capacity in the coarse texture soil. However, only a few studies focused on the biochar addition in the soil improvement in the mining areas, especially the hydraulic characteristics of compacted soil. The purpose of this study is to evaluate the impact of addition rates and particle sizes of biochar on the soil hydraulic conductivity under various compaction conditions in a mining dump. The soil sample was collected from Datong City in Shanxi Province of China. The experiment was then carried out under the four particle sizes of biochar (1-2, 0.25-1, 0.10-0.25, and <0.10 mm) with four addition rates (0, 4, 8, and 16 g/kg) and five compaction conditions (1.3, 1.4, 1.5, 1.6, and 1.7 g/cm3). A modified van Genuchten (VG) model was also established to determine the characteristic curve of soil water. The results show that all the correlation coefficients were above 0.960, and the standard deviations were below 0.015, indicating this model suitable for the characteristic curve of soil water after the biochar addition. Most macropores and mesopores with larger pore sizes were distributed to significantly improve the water holding capacity in the field. The specific values increased from the lowest 22.74% (1.3 g/cm3, 1-2 mm, 0 g/kg) to 37.56% (1.4 /cm3, 0.25-1 mm, 16 g/kg) with the amount of biochar addition. Furthermore, the initial soil water content increased from 0.135 cm3/cm3 (1.3 g/cm3, 1-2 mm, 0 g/kg) to 0.166 cm3/cm3 (1.3 g/cm3, 1-2 mm, 8 g/kg), where the maximum increase was 0.031 cm3/cm3 in an initial soil water content. Therefore, the biochar addition greatly contributed to the water holding capacity of compacted soil with less air entry for the better use of soil water. Correspondingly, the higher capacity of water holding was obtained at the lower bulk densities (1.3 and 1.4 g/cm3), and the larger particle sizes (0.25-2 mm). A combination of parameters was achieved for the optimal water holding at the high bulk density (1.5, 1.6, and 1.7 g/cm3), lower particle sizes (<0.25 mm), and higher addition (8, 16 g/kg). Consequently, the targeted application of biochar can be widely expected to effectively improve the water holding and water retention capacity of the soils with various compaction in the mining areas. This finding can also provide a promising basis for recovery the low-quality soil. [ABSTRACT FROM AUTHOR]

Anaerobic digestion can be widely used to convert the lignocellulosic biomass into biogas, particularly with the by-product digestates. A large amount of digestate discharge has been one of the most limiting factors for the promotion and application of anaerobic digestion, with the development of large-scale biogas engineering in recent years. It is highly urgent to rapidly and effectively treat the digestate. Alternatively, the thermochemical conversion can be selected to realize the harmless treatment and resource utilization of lignocellulosic digestates. The digestates still retain most of the carbon elements and energy in the original material before digestion. The content of lignocellulosic is also very considerable for a large potential of thermochemical conversion. Therefore, this review aims to focus on the digestates forming fuel, pyrolysis, and hydrothermal carbonization. The forming performance of digestates was better than that before digestion, but the NOx emission and slagging phenomenon during the combustion were outstanding to be monitored and controlled. In pyrolysis, the lignocellulosic digestates presented the application potential in the preparation of liquid fuels, phenolic compounds, carbon-based adsorbents, soil amendments, and syngas synthesis. Specifically, the digestate derived bio-oil behaved a much higher calorific value while a lower acid content, where the relative content of 4-vinylphenol reached 60.9%. The pore structure of the biochar was also developed to contain more nutrients, such as P and K. The gaseous product presented a more suitable H2 to CO molar ratio with less tar. However, the conversion application in the combustion and pyrolysis was confined to the drying energy consumption caused by the high water content of digestates. In comparison, the drying energy consumption was ignored before hydrothermal carbonization. At the same time, hydrothermal carbonization was used to improve the quality of digestates fuel, including the removal of alkali and alkaline earth metals, the higher calorific value, as well as the improved hydrophobicity, grindability, and fluidizability. Another potential was to prepare the functionalized carbon materials for soil improvement. But, there were still some challenges to the disposal of water phase products after hydrothermal carbonization. In addition, the potential ecological hazards of biochar and hydrochar derived from digestates for farmland application also needed to be paid enough attention, including heavy metals, and polycyclic aromatic hydrocarbons. Overall, the anaerobic digestion and thermochemical conversion presented complementary advantages in energy utilization efficiency, large-scale treatment, and the removal of biotoxicity. Additionally, the thermochemical conversion products of digestates also showed great potential for recycling in anaerobic digestion processes. For instance, the high-temperature flue gas produced by combustion can be recycled to the insulation of the biogas engineering, while the ash residue and biochar can be used to purify the biogas slurry, and the water-phase by-products also have a certain methane production potential. Consequently, a combination of lignocellulosic biomass anaerobic digestion and digestates thermochemical conversion can greatly contribute to the promotion and application of large-scale biogas engineering. [ABSTRACT FROM AUTHOR]

Soil fumigation is currently an effective and rapid method to prevent soil-borne diseases, insects, and weeds. However, some pathogens may reproduce again as crops are planted, leading to the continuous development of diseases. After soil fumigation treatment, it will cause the soil microenvironment to be in a state of imbalance. Soil amendments can improve the soil environment, reduce crop root diseases, reduce nutrient loss and improve the quality of agricultural products. Soil fumigation combined with amendments can repair or improve the soil to a certain extent, restore the microbial community affected by the fumigants or increase the relative abundance of beneficial microorganisms, prevent soil pathogenic bacteria from reinfecting, which will make the soil more conducive to the growth of crops. This article briefly summarizes the classification information of commonly used fumigants and soil amendments, focusing on the combined use of soil amendments and fumigants to affect the physical and chemical properties, enzyme activities, microbial communities and crop growth of the soil after fumigation. Therefore, this study has provided the reference for the prevention and control of disease-borne diseases, the combined use of fumigants and soil amendments, and related mechanisms. [ABSTRACT FROM AUTHOR]

For the purpose of exploring the effect of various soil amelioration measures on the facility agriculture soil and the physical and chemical properties of tomato grown through facility agriculture and screen the most suitable amelioration method for the local degraded soils in facility agriculture. The greenhouse of Qinxi vegetable planting demonstration garden was chosen as the study site and soil from greenhouse and tomato were used as materials to implement this study. Three soil ameliorants, i.e. plant ash, biochar and EM fungi, were selected for this study, and various singular and combined application of the ameliorants were set up as treatments. In total, there were seven treatments, i.e. EM fungi treatment (E), biochar treatment (S), biochar + EM fungi treatment (SE), plant ash (C) treatment, plant ash + biochar treatment, plant ash + biochar + EM fungi treatment (CSE) and the control treatment (CK), in this study. The results indicated that all the treatments can improve the soil physical and chemical properties and among the seven treatments, and CSE treatment showed the most significant effect on soil properties in comparison with the CK treatment. Specifically, CSE treatment significantly increased soil pH, soil organic matter, soil total nitrogen, soil alkali nitrogen, soil total phosphorous, soil available phosphorous, soil total potassium and soil available potassium by 23.06%, 130.94%, 44.34%, 52.78%, 67.72%, 127.35%, 16.24% and 119.48%, respectively. In terms of the effect on tomato, in comparison with CK treatment, the combined application of ameliorants was much more significant than singular application in increasing total nitrogen of whole plant, and CSE treatment increased the most by 25.16%; regarding total phosphorous of tomato plant, the same effect was observed and the total phosphorous of CSE treatment was 2.09 folds higher than that of CK treatment. For total potassium of the tomato plant, except for E treatment, all the rest five ameliorant treatments can significantly increase the total potassium, and the total potassium of CSE treatment was 1.44 folds higher than that of CK treatments. The effect of ameliorant application on plant ash was little. However, the sugar/acid ratio of tomato increased significantly and CSE treatment increased the sugar/acid ratio by 69.3% in comparison with CK treatment. The application of soil ameliorants showed positive effect on soil fertility. The result of soil integrated fertility index of each treatment showed soil ameliorant increased the soil fertility in comparison with CK treatment, and again the CSE was observed with the best effect on improving soil fertility. When comparing the integrated score obtained by principal analysis, CSE treatment received the highest score in comparison with the rest treatments in this study. From the aforementioned results, and after a comprehensive analysis of the results, we can conclude that the simultaneous application of plant ash, biochar and EM fungi is able to effectively mitigate the soil acidification, improve the soil fertility and increase the tomato quality of alpine facility agriculture in Tai Bai County, Shaanxi. The simultaneous application of plant ash, biochar and EM fungi can be a promising method to mitigate the soil problems of facility agriculture. In order to screen an effective method for the remediation of degraded soil. [ABSTRACT FROM AUTHOR]

Soil structure is a key factor to determine the different functions of soil, such as water infiltration and retention, soil permeability, and nutrients availability. The dynamic behavior of soil also depends mainly on the tillage, crop roots, and soil organic matter return. Black soil is one of the most important arable soil with high clay content, but hard soil structure is one of the main factors limiting crop growth. It is still lacking on the effect of organic amendment on soil pore structure in the black soil. In this study, a field experiment was carried out in the black soil region located in Hailun City, Heilongjiang Province of China, in order to clarify the effects of organic amendment and depths on soil physical properties and pore structure before maize sowing in 2019. Four treatments were conducted using random block design with four replicates, including shallow tillage with maize straw return in 0-15 cm soil layer (T1), deep tillage with maize straw return (T2), or combined maize straw and organic manure return (T3) in 0-35 cm soil layer, conventional tillage without organic amendment as control. Maize straw and organic manure were also incorporated into the soil layers by shovel using manual work, where the application rates were 10 000 and 30 000 kg/hm2, respectively. CT scanning was adopted to visualize and quantify soil pore structure after maize harvesting. The constant head method was used to measure the saturated hydraulic conductivity. The results demonstrated that the bulk density under T1, T2, and T3 treatments significantly decreased 3.77%-5.66%, compared with CK, while the saturated hydraulic conductivity increased by 2.2-5.00 times, and the field water capacity increased by 6.91%-11.01% within 0-15 cm soil layer (P<0.05). T2 and T3 treatments also improved the bulk density, saturated hydraulic conductivity, and field water capacity within >15-35 cm soil layer after one maize growing season. Furthermore, the number of soil pores and porosity of >500 μm aperture under T1, T2, and T3 treatments significantly increased by 18.1%-180% and 69.2%-256% (P<0.05) in 0-15 cm soil layer, respectively, compared with CK treatment (P<0.05). Specifically, the soil pore number and porosity of >1 000 μm aperture were more 6.06%-150% and 17.4%-196% under T2 treatment than the rest. It infers that the treatments with organic amendment increased the number of soil pores with optimal distribution. In addition, the complexity and connectivity of soil pore also increased significantly, in presence of connected and sender pore. The Euler number values under T1, T2, and T3 treatments were decreased by 21.7%-54.3%, whereas, the fractal dimension under T1 treatment increased by 1.5% in 0-15 cm soil layer (P<0.05), compared with CK treatment. T2 and T3 treatments improved the soil pore structure in >15-35 cm soil layer, as shown in that the Euler decreased by 65.9%-70.5%, anisotropy, fractal dimension, and circularity increased by 50.0%-110%, 12.8%-13.9%, and 12.2%-14.9%, respectively, compared with CK treatment (P<0.05). The Euler and porosity of >1 000 μm aperture presented the largest contribution both for the bulk density and saturated hydraulic conductivity in 0-35 cm soil layer, whereas, the anisotropy and Euler presented the largest contribution for the field capacity in 0-15 cm and >15-35 cm soil layers. Pearson correlation analysis indicated that the extremely significant negative relationship was found between bulk density and saturated hydraulic conductivity, field water capacity, soil porosity within 0-15 cm soil layer (P<0.01), while the extremely significant or significant correlation was found between bulk density and all indicators, excepting for the anisotropy and Euler. Consequently, the improved physical properties of soil were attributed to the fact that the organic amendment regulated soil structure, including optimal distribution of soil pore, complex, and connectivity of pore structure. Correspondingly, the organic amendment can be expected to serve as an effective approach for the pore structure of black soil. It is also necessary to consider the response of soil pore structure in the decomposition of returned organic manure in the future. [ABSTRACT FROM AUTHOR]

[Objectives]In order to explore the effects of bio, organic fertilizer(BIO)or its combined application of silicon, potassium, calcium amendment(SOA)on the soil fertility and yield of pear orchards in acid red soil, an experiment based on BIO and its combined application of SOA were carried out for three consecutive years. Soil nutrient content, microbial biomass and soil enzyme activity were studied to provide a theoretical basis for the rational application of bioorganic fertilizers and soil amendments in pear orchards. [Methods]With local custom fertilization as the control(CK), local custom fertilization with SOA(CK+SOA), only appli, cation of BIO, and mixed application of BIO and SOA(BIO+SOA), a total of 4 treatments were thus formed. The soil pH value, soil nutrient content, soil microbial activity, yield and economic benefits were measured under the four different treatments. [Results]The results showed that BIO and BIO + SOA treatments improved soil pH value, increased soil organic matter (SOM) content, and decreased ammonium nitrogen, nitrate nitrogen and available phosphorus content. Compared with CK, the microbial biomass carbon and microbial biomass nitrogen in the rhizosphere soil of pear trees under the BIO+SOA treatment significantly increased by 87.8% and 110. 1% (P < 0. 05), respectively. Compared with CK, BIO treatment significantly increased cellobiohydrolase ( CBH) and N, acetyl, ß, D, glucosaminidase(NAG)activities in rhizosphere, while BIO+SOA significantly increased the L, leucine aminopeptidase (LAP)and NAG activities in bulk soil(P<0.05). Obviously, BIO and BIO+SOA significantly improved the pear yield about 56% to 85%(P<0.05)compared to CK and CK+SOA treatments, respectively. RDA analysis showed that the effects of different treatments on soil physical and chemical properties could explain about 87% of the changes in soil microbial activities and yield. SOM content was positively correlated with LAP, CBH and NAG activities, and NO-3, N and NH+4, N were also positively correlated with acid phosphatase(ACP)activity. [Conclusions]Bio, organic fertilizer and its combined application of silicon, potassium, calcium amendment could improve soil pH value, increase organic matter content, and activate soil microbial activities, thereby increasing pear yield. [ABSTRACT FROM AUTHOR]

This study aims to propose a feasible production technology for the organic fertilizer or soil amendments using the small-scale compost decomposing with local straws and livestock manure. The technical procedure included the straw silkization, material mixing, compression molding, and small-scale compost decomposing. The compost production was transformed from transporting materials to moving equipment, from decomposing and then forming to bagging and then decomposing. The fertilizer production technology can contribute to enhance the local utilization rate of agricultural wastes from small and medium-sized scattered farmers, as well as the mechanization during composting and decomposing effects. The appropriate fertilizer source material ratio and compression ratio were selected under the different material moisture content to prevent water pollution of livestock manure. The special microbial compound agents were added to control the maturity time, and thereby regulate the release of odorous gases. The corn stalks and cow dung were used as fertilizer sources. The seed germination index (GI) was selected as the detection index for the maturity effect of composting. The experimental factors were set for the small-scale compost production, where the key process parameters included the ratio of fertilizer source materials, material moisture content, compression ratio, application amount of microbial agents, and maturity time. A single factor experiment was conducted to determine the appropriate range of experimental factors. A better maturity effect of small-scale compost fertilizer was achieved, where the critical value of applied microbial agent was 0.5‰, the fertilizer source material ratio was 15% to 35%, the material moisture content was 45% to 60%, the compression ratio was 25% to 50%, and the maturity time reached 24 days. A combination experiment of ternary quadratic regression and orthogonal rotation was performed to optimize the influence of key process parameters on the maturity effect of compost fertilizer. A regression model was established between the seed germination index and various factors. The analysis showed that the primary and secondary order for the influence of various factors on the seed germination index was: material moisture content > compression ratio > fertilizer source material ratio. There were significant effects on seed germination index (P<0.05) in the correlation of fertilizer source material ratio and compression ratio, and the correlation of material moisture content and compression ratio. The optimized process parameters were verified by the field experiments. An optimal combination of process parameters was determined to be the application of 1.5‰ microbial bacteria dosage, maturity for 32 days, material moisture content of 60%, compression ratio of 39.50%, and the material ratio of 23%. In this case, the seed germination index of small-scale compost fertilizer reached 96.52%, where the detection of indicators can meet the national standards for organic fertilizer and the requirements of agricultural production, while, the local straw and livestock manure can be nearby used conveniently. The findings can provide a theoretical basis for the local compost of organic fertilizer in small scale, further to design the supporting equipment in low-carbon agriculture. [ABSTRACT FROM AUTHOR]

A field experiment with four treatments（control（CK）, organic manure（OM）, microbial fertilizer（MF）, and silicon–calcium– potassium–magnesium fertilizer（SCPM））was conducted to investigate the effects of three amendments on the growth and rhizospheric soil biochemical properties of Codonopsis tangshen in a continuous cropping system to provide scientific basis and technical support for alleviating the continuous cropping obstacle of C. tangshen. Results showed that the SPAD values of the C. tangshen leaf under the OM, MF, and SCPM treatments were enhanced by 41.2%, 20.7%, and 47.4%, respectively, compared with the control. The OM and SCPM treatments significantly increased C. tangshen yield by 20.2% and 13.8%, respectively. The OM and MF treatments remarkably increased the polysaccharide content by 9.3 and 6.2 percent points, and the MF treatment significantly increased the lobetyolin content by 18.3%. The three amendments had different effects on the rhizospheric soil biochemical properties of C. tangshen. After the application of OM and SCPM, the soil pH was increased by 0.28，0.14 units, and the exchangeable aluminum content of the soil was decreased by 8.7% and 19.9%, respectively, compared with the control. The MF treatment significantly decreased the soil organic matter content by 12.0% compared with the control. The available potassium content of the soil was increased by 107.5%, 23.2%, and 32.6% under the OM, MF, and SCPM treatments, respectively, compared with the control. The SCPM treatment remarkably increased bacterial abundance and decreased fungal abundance of the rhizospheric soil of C. tangshen; the ratio of bacteria/fungi abundance was increased by 5038 times compared with the control. All the three amendments generally enhanced the photosynthetic capacity of C. tangshen and had different effects on plant growth and rhizospheric soil biochemical properties. The OM and SCPM treatments improved C. tangshen yield, whereas the MF treatment increased the lobetyolin content of C. tangshen. The comprehensive analysis showed that the improvement effect of the three amendments on C. tangshen growth followed the order of OM（4500 kg·hm-2）> MF（750 kg·hm-2）> SCPM（750 kg·hm-2）. [ABSTRACT FROM AUTHOR]

This study explored the effects of different soil amendments—a calcium preparation（GZJ）, furfural residue（KQZ）, and weathered coal（FHM）on the improvement of moderately saline-alkali coastal soil and maize growth therein. The effects of the treatments on the physicochemical properties of the soil and on maize plant height, chlorophyll content（SPAD）, and yield were studied via pot experiments, and the experimental dosage of each treatment was as follows：GZJ1（15 t·hm-2）, GZJ2（22.5 t·hm-2）, KQZ1（30 t·hm-2）, KQZ2（45 t·hm-2）, FHM1（30 t·hm-2）, and FHM2（45 t·hm-2）. The results showed that the three amendments significantly increased the cation exchange capacity（CEC） of saline-alkali soil by 17.53%~49.45%, compared to when no amendments were added. Three amendments reduced soil bulk density and salt content while two different doses of furfural slag and high levels of weathered coal reduced soil bulk density significantly by 7.80%~12.06%. Two different doses of weathered coal and a low dose of the calcium preparation reduced the soil salt content significantly by 13.19%~19.33%. In addition, the calcium preparation and furfural residue significantly increased the quantity of water-stable aggregates（0.25~0.5 mm and 0.5~1 mm, respectively）, increasing these by 5.36~6.59 percentage points and 1.92~ 2.81 percentage points, respectively. The quantity of micro-aggregates（<0.25 mm）was decreased by 9.93~11.52 percentage points. The best treatment to improve the physicochemical properties of saline-alkali soil was KQZ1（30 t·hm-2 of furfural residue）. Furfural slag and weathered coal significantly increased the plant height and SPAD of maize at different stages. The height of the maize plant at maturity increased by 9.71%~13.09% and the SPAD at jointing stage increased by 10.13%~16.44%. The three amendments increased the number of grains per ear and yield per plant by 15.97%~37.43% and 25.86%~49.65%, respectively; Once again, treatment KQZ1 had the best effect. The calcium preparation, furfural slag, and weathered coal all improved the moderately saline-alkali coastal soil and the kernel number and yield of maize. However, there was no significant difference between the three kinds of amendments in different dosages. The comprehensive effect of improvement with the use of furfural slag was better than those with the use of weathered coal and the calcium preparation; and treatment KQZ1（30 t·hm-2）had the best comprehensive improvement effect among the furfural slag treatments. [ABSTRACT FROM AUTHOR]

Soil erosion on sloping farmland has posed a great challenge on land productivity and crop yield, resulting coarse soil and less arable area due to the losing of fine soil particles. Moreover, N and P in soil that migrated with runoff and sediment can also affect the quality of downstream water. Therefore, it is highly demanding to control soil erosion on sloping farmland. Currently, various measures are being taken in the long run, covering from biological, tillage, and engineering. Soil amendments can be used to greatly reduce soil erosion and increase cohesion between surface soil particles, which can maintain surface soil structure to prevent soil crust, resulting the increase in soil infiltration rate, while the decrease in the surface runoff. Therefore, a new material related to soil amendments has drawn much attention. In recent years, the Changjiang River Sciences Research Institute has developed a new seaweed polysaccharide Anti-erosion Material SA-01. This study aims to explore the effect of SA-01 concentration on runoff and sediment yield of red soil, in order to verify the new polysaccharide corrosion inhibitor (SA-01) from the seaweed in controlling soil and water loss on a slope. Taking the typical red soil in southern China as an example, a series of artificial rainfall experiments were carried out, where the rainfall intensity of 90 mm/h, and the slope of 5°, 10°, and 15° under various concentrations of 0, 0.25%, 0.50%, 0.75%, and 1.00%. The mechanism of SA-01 on soil erosion was analyzed in a combination of soil water repellency and aggregate stability experiments. The results show that under the same slope, the runoff yield on the slope with SA-01 was higher than that on the control slope. The runoff yield on the slope decreased first and then increased, while the cumulative runoff on the slope decreased first and then increased with the increase of applied concentration. The increment ratio of surface flow increased as the SA-01 concentration increased, indicating that SA-01 can significantly reduce sediment yield on a slope. In the initial runoff yield stage, SA-01 can significantly reduce the slope sediment yield. In the stage of surface erosion, the slope without SA-01 reached the maximum, then fell rapidly, and eventually became stable. Compared with the control slope, the sediment yield of SA-01 slope fluctuated slightly in the early stage of runoff yield, and the time to reach stable sediment yield was earlier than that of the control slope. With the increase of applied concentration, the sediment yield decreased significantly. SA-01 can significantly increase the runoff while reduce the sediment yield of different slopes, due mainly to the change of soil hydrophilic to water repellency, and the decrease of infiltration rate. Soil water repellency was improved after SA-01 was applied. When the concentration was 0.25%, the sample retained the same hydrophilicity as the original soil. When the concentration was more than 0.25%, the soil began to change from hydrophilicity to repulsion. Due to the soil Ca2+ cation chelation with SA-01, the soil particles generated on the surface of a layer with a certain intensity. The presence of preservation layer increased soil water repellency, while reduced the soil aggregate dispersion, and thereby to improve the stability of soil aggregates at different levels. SA-01 can provide a new idea for soil and water conservation of red soil on a slope. [ABSTRACT FROM AUTHOR]

[Objective] To study the effects of soil amendments and grafting cultivation on the soil properties of the solar greenhouse and tomato yield and quality, and to provide a reference for soil and vegetables. [Method] Experiment to set up soil amendments (no application of (Fl), biochar (F2)), Desulfurized gypsum (F3)) and cultivation mode (self-root seedling cultivation (S1), grafted seedling cultivation (S2)) 2 factors, random block design, a total of 6 treatments, respectively F1S1 (CK), F1F2, F2S1 F2S2, F3S1, F3S2. [Result] Compared with CK, the tomato plant height, stem thickness, chlorophyll and leaf area of ​​each treatment were significantly increased, and the increase of F2S2 treatment was the largest; F2S2 treatment can significantly reduce soil EC and increase pH. F1S2, F2S1, F3S1, and F3S2 can significantly increase soil EC and lower pH; the membership function method is used to evaluate soil nutrients and quality, and finally it is concluded that F2S2 treatment has the fastest increase in soil nutrients, and F3S2 treatment has the best nutritional quality; photosynthesis of each treatment The effect and yield have been improved, and the photosynthesis and yield increase in F2S2 treatment is the largest. [Conclusion] The application of biochar (10 t/hm2) per 667 m2 of soil and the treatment of grafting cultivation (F2S2) have the best effect and can be effective Improve soil fertility, promote plant photosynthesis, and increase fruit yield and quality. [ABSTRACT FROM AUTHOR]

The aim of this study was to determine the effect of biochar application on soil fertility and enzyme activity. The soil nitrogen （N）, phosphorus（P）, and potassium（K）contents and enzyme activity were measured in 12 treatments, including 3 fertilizer application rates: 100%, 80% and 60% of full recommended fertilization, marked as F1, F2, F3, and 4 biochar application rates：CK：0 t·hm-2, B1：2.6 t·hm-2·a-1, B2：13 t·hm-2, B3：26 t·hm-2. The results showed that biochar amendment compensated soil N decline by reducing 40% of N fertilizer inputs. In detail, biochar caused 23.08%~52.25% increase of soil total N content and 39.39%~85.76% increase of soil ammonium （NH+4 -N）concentration when compared with control soil. Meanwhile, soil nitrate（NO-3 -N）concentration was 1.80~2.46 times of control. The soil P availability was elevated by biochar addition at F3 fertilization rate, e.g., the available P content in B2×F3, B3×F3 were 84.98% and 159.23% higher than their corresponding control. Furthermore, although soil total K content was not affected by biochar, the soil avail able K content was 18.99%~61.24% higher than in the control. Soil enzyme activity was mainly affected by biochar application pattern：One-time biochar application（B2 and B3）improved soil urease activity, and when biochar was applied annually（B1）, it enhanced acid phosphatase activity, but soil urease and catalase activity was inhibited, implying that labile fraction in fresh biochar was the main substances affecting soil enzyme activity. Our results indicated that biochar application is an effective measure for soil fertility improvement and its application pattern has a great influence on soil enzyme activity. [ABSTRACT FROM AUTHOR]

BACKGROUND: Rice is the staple food of about half of the world's population, and the dependence of Asian staple food on rice exceeds 90%. There are varying degrees of arsenic (As) pollution all over the world. As can accumulate in rice and enter the human body, causing health problems. OBJECTIVES: To reveal the mechanism of As absorption in rice. METHODS: The content and species characteristics of As absorbed by rice and the species analysis techniques were reviewed. The mechanisms of As absorption, tolerance and detoxification by rice were summarized. RESULTS: The content of As in rice ranged from a few to several hundred ng/g. The process of As entering the rice from the soil involved complex physical and chemical changes and species transformation. Arsenic mainly existed in the form of arsenate, arsenite, thiol and methyl coordination in rice. Field water management, fertilization and soil amendments controlled the absorption of As in rice. Each technique had their advantages and disadvantages. Soil pH, redox conditions, organic matter and coexisting elements were the key factors affecting As absorption by rice. Agronomic methods can control the absorption of As by rice. Many factors such as arsenic biogeochemistry and the absorption and metabolism of arsenic in rice agroecosystems affect the concentration of arsenic in rice and grain. Comprehensive consideration of the effects of agronomic activities on soil pH, redox conditions, organic matter structure and coexisting elements, and different geographic factors such as soil characteristics and economic factors were the keys to realize the control of arsenic absorption by rice in production practice. CONCLUSIONS: Comprehensive use of multiple agronomic methods for rice farming is an important way to control the absorption of arsenic in rice in the future. Application of new agronomic methods in the control of arsenic absorption by rice, the impact of climate change on arsenic absorption by rice, and application of non-destructive in situ and in vivo analysis techniques for As speciation analysis, are keys for more scientifically and effectively controlling the arsenic content in rice and reducing the risk of human As exposure on the global scale in the future. These are also the key development directions and challenges in the future. [ABSTRACT FROM AUTHOR]

【Objective】Rational fertilization and adoption of soil amendment is one of the ways to improve acidic soil and reduce fertilizer.By studying the effects of phosphorus potassium nitrate compound fertilizer combined with Calcium oxide conditioner on vegetable yield,nutrient absorption and utilization and soil pH,so as to determine the optimal fertilization scheme for acidified vegetables.【Method】Four treatments were set up in the experiment:(i)Conventional fertilization(CK);(ii)Tianji Conditioner(CT);(iii)Tianji Phosphate Potassium Nitrate Compound Fertilizer(CY);(iv)Tianji NPK Compound Fertilizer + Conditioner(CYT),the changes of yield,biomass,nutrient absorption and utilization and soil pH value of cauliflower and pickled mustard tuber were studied under different fertilization treatments.【Result】Compared with CK,under the condition that CYT treatment reduces the fertilizer application amount by 25 %-33.3 %,the yield and biomass of cauliflower and mustard tuber were increased significantly(P<0.05); The cumulative uptake of nitrogen,phosphorus and potassium in cauliflower was significantly increased by 20.19 %,28.38 % and 25.93 % respectively.(P<0.05); The apparent utilization rate of nitrogen,phosphorus and potassium was significantly increased by 15.77 %,18 % and 64.06 %,respectively(P<0.05); The cumulative uptake of nitrogen,phosphorus and potassium in mustard tuber products increased significantly by 19.17 %,28.82 % and 20.1 %,respectively(P<0.05); In addition,the soil pH was increased by 0.7 and 0.3 units when mixed with potassium phosphate nitrate compound fertilizer and conditioner; The content of exchangeable calcium in soil increased by 28.9 % and 42.6 % respectively; The exchangeable acid content of pickled mustard decreased by 2.13 % and soil acidification was improved.【Conclusion】Phosphorus potassium nitrate compound fertilizer combined with calcium oxide conditioner can increase vegetable yield,fertilizer apparent utilization rate,soil pH and exchangeable calcium content,and reduce soil exchangeable acid content.Therefore,the application of calcium oxide conditioner in the compound fertilizer of phosphorus and potassium nitrate in purple soil area of Chongqing is an effective way to reduce the amount of fertilizer applied in farmland and adjust soil acidification. [ABSTRACT FROM AUTHOR]

In a land-sea transitional zone, various technologies are used to reduce the accumulation of water-soluble salts for the efficient utilization of saline soils in coastal reclaimed areas. In the conventional processes of salt-washing and fertilizing, the emission of the agricultural non-point pollutants has posed a threat to the offshore ecological environment. Therefore, it is necessary to explore new environmentally friendly methods for the improvement of soils quality. In microbial amendments, soils was fermented by adding Bacillus amyloliquefaciens IAE (7.2×1010 cfu/g) in the matrix at percentage of 1% (w:w), while the substrate was prepared in the combination of Flammulina velutipes residues, scoria of bentonite, vinegar production residues and humus acid, at the ratio of 6:2:1:1 (w:w). The matrix that fermented without the inoculation of B. amyloliquefaciens IAE, generally named as soil amendment. To investigate the effect of the soil amendment and microbial soil amendment on coastal reclaimed saline soils, three treatments were set in this study: 1) control, soil without any treatment; 2) soil amendment treatment (SAT), soil added with soil amendment at 30 t·ha-1; 3) microbial soil amendment treatment (MSAT), soil added with microbial soil amendment at 30 t·ha-1. The pilot field was located at Tiaozini coastal reclamation area in Dongtai, Jiangsu Province, China. The contents of soluble salt in soils were ranged from 3.57 to 10.66 g/kg. Water saving irrigation and traditional paddy planting methods were also selected in three treatments. The quantified data have been recorded including the irrigation quantity, biological characteristics of paddy, physical and chemical features and microbial properties of the soils. The results showed that both SAT and MSAT improved paddy soil properties, and MSAT did better than that. Compared to those in the control treatment, the accumulative irrigation quantity in MSAT decreased by 35.2% (P<0.05), while the plant height, number of grains per ear, thousand grains weight, effective ear yield, and rice yield in the MSAT treatment increased by 31.4%, 30.3%, 29.7%, 17.5%, and 83.2%, respectively. The contents of saturation moisture, water holding capacity, total porosity, capillary porosity, organic matter content, total nitrogen content, and content of available potassium in soils in MSAT increased by 13.8%, 20.0%, 6.80%, 9.79%, 2.30 times, 53.0%, 31.0%, respectively, compared to those in the control treatment. Populations of the soil microorganisms of bacteria, fungi and actinomyces in MSAT increased by 10.3, 11.2 and 3.18 times, respectively (P<0.05). Meanwhile, the bulk density of soils in MSAT decreased by 6.90% (P<0.05), compared to that in the control treatment. The contents of soluble salts in the soil depth of 0-60 cm in MSAT were significantly lower than those in control treatment, and those in tillage layer of 0-10cm and 10-20cm decreased by 61.1% and 54.4%, respectively. This finding demonstrates that microbial amendment can contribute to physical structure and microbial properties of soils, thereby to increase in the water conductivity while decrease in salt content in soils. This study can also provide a promising and feasible method to improve the quality of saline soils in coastal reclaimed zone. [ABSTRACT FROM AUTHOR]

Cd-polluted field soil was collected from a greenhouse in Beijing and a pot experiment was conducted to investigate the uptake and accumulation of Cd by leek and rape. The bioavailability of Cd in human gastric juice and human health risk of Cd in vegetables grown on Cd-polluted soil and soil remediated with amendments（zeolite+earthworm manure, attapulgite+earthworm manure）were determined us⁃ ing an in-vitro simulation test and by health risk assessment, respectively. The results indicated that the Cd content in the both vegetables exceeded the National Food Safety Standard and that there was a significant difference in the uptake content of Cd between the vegetables. The Cd content in rape was 1.04 times higher than that in leek. According to the in-vitro simulation test, the bioavailable Cd content in leek and rape reached 0.027, 0.039 mg·kg-1 fresh weight, indicating that Cd in leek is more available for human than that in rape. The carcinogenic risk of Cd to human body was observed for the both vegetables based on the health risk assessment. Moreover, the carcinogenicrisk to children aged 0~6 years was higher than that to adults aged >18 years. The maximum decrease in the Cd content in leek and rape grown on soil treated with amendments was 65.2% and 72.3%, respectively, compared with that in the corresponding controls. Further, the bioavailability and carcinogenic risk of Cd in leek and rape decreased significantly with different soil amendment treatments, and the carcinogenic risk value of Cd approached the safety level in the both vegetables grown on soil treated with a mixture of attapulgite and earth⁃ worm manure. [ABSTRACT FROM AUTHOR]

BACKGROUND:The total selenium content in the selenium-rich red soils in Fengcheng City of Jiangxi Province was relatively high, but the available selenium content directly absorbed and utilized by plants was low. The bioavailability of selenium in soils is a key factor affecting selenium in crops. OBJECTIVES:To find safe and effective ameliorants for improving the availability of selenium in selenium-rich soils. METHODS:Biomass carbon and steel slag were used as modifiers, and 8 different experiments were set up. Through indoor soil test and pot experiment, the content of available selenium in the selenium-rich red soils in Fengcheng was determined by atomic fluorescence spectrometry, and the regulation effect of two kinds of ameliorants on available selenium under different treatment levels was investigated. RESULTS:The results of the soil tests show that different amounts of biomass carbon and steel slag can increase the soil pH in the study area by 0.1-3.79 units. The results of elemental speciation analysis indicate that the ameliorant mainly controlled the soil available selenium by affecting the organically bound selenium. The soil organic matter content increased significantly after the application of biochar in the soil, but the organic matter showed a fixed effect on selenium. The available selenium content decreased by 8.4%-15.1%, resulted in the overall lower available selenium content in soils. The significant effect of steel slag on soil pH is beneficial to the activation of selenium in soils, and the soil available selenium content can be increased by 1.4 to 2.0 times. The results of the pot experiment showed that the selenium content of Chinese cabbage increased by more than 30% after treatment with steel slag, while the selenium content of Chinese cabbage decreased by 7.14%-42.8% after treatment with biochar. CONCLUSIONS:This study shows that biochar is not suitable for regulating the availability of selenium in the soil of the study area. Steel slag can be used as a control material for soil selenium availability in the study area, which not only realizes solid waste recycling, but also improves the availability of selenium in soil. [ABSTRACT FROM AUTHOR]

In order to solve the problems existing in the production of flue-cured tobacco at Meizhou of Guangdong about sowing time discom fort and soil acidification, a variety (Yunyan87) was used as tested material, the field experiment by a split plot design was conducted, including four sowing time as main treatments and three different concentrations of soil amendment as vice treatments, to investigate the effects of sowing time and amendment dosage on the growth period and agronomic of flue-cured tobacco plants and analyze their yield and quality. The results showed that: (i) with the postponement of the sowing time, the growth peak period and baked period tended to shorten, while amendments had no significant effects on the processes of tobacco plant development. (ii) Sowing time had effects on the plant height, stem and leaf area of flue-cured tobacco and decreased along with sowing date postponed, and Mosaic disease morbidity increased with the delay of sowing date; Soil amendments had no effects on morbidity and leaf area, but it could improve flue-cured tobacco plant height, stem. (iii) The yield and quality of the earlier planting were better than that of later planting, adding modifier could improve the inner quality of tobacco leaves, make flue-cured tobacco trace element content in coordination and enhance flue-cured tobacco quality. When soil amendment dosage was 450 kg/hm2 , flue-cured tobacco could achieved better quality, and when 900 kg/hm2 , flue-cured tobacco could obtained higher yield. Combined with local actual production and test results, it was suggested that local sowing time should be in advance, and the dosage of the soil amendment could be 450 kg/hm2. [ABSTRACT FROM AUTHOR]