Investigating the effects of organic amendments on soil microbial composition and its linkage to soil organic carbon: A global meta-analysis.

Understanding the dynamics of soil microbial communities responsible for soil element cycling is vital to understanding organic amendments' mechanisms in agricultural soil. However, several studies show inconsistencies in whether and how organic amendments affect the taxonomic composition of soil microbial communities compared to the application of sole chemical fertilizers. This first global meta-analysis demonstrated that organic amendments increased the bacterial diversity indices (Shannon and Chao1) but had no significant effect on fungal diversity indices. When considering both bulk and rhizosphere soils, only copiotrophic strategies such as Proteobacteria, Bacteroidetes, and Zygomycota phylum demonstrated a significant increase in response to organic amendments, mainly because the environment with a significant increase in nutrients content preferentially supports the growth of copiotrophic species after the use of organic amendments. Additionally, the factors influencing the response of different dominant microbial phyla to organic amendments varied. Besides soil pH, the effect of organic amendments on different microbial phyla was significantly influenced by soil texture, organic fertilizer type, crop type, and climate type, providing insights into the diverse responses of microbial communities to organic amendments under varying conditions. Organic amendments significantly increased soil organic carbon (SOC) content and enzyme activities related to nitrogen (N) and phosphorus (P) decomposition but had no significant effect on enzymes related to carbon (C) decomposition. Notably, the effect of organic amendments on the relative abundance of three dominant phyla (Mortierellomycota, Nitrospirae, and Firmicutes) was related to the effect on SOC, where the increase in the relative abundance of Firmicutes was significantly positively associated with the increase in SOC. This result has implications for understanding the relationship between the dynamics of microbial community composition and C turnover in agroecosystems.

Combined physiological and metabolomic analysis reveals the effects of different biostimulants on maize production and reproduction.

Plant biostimulants (PBs) are a potential strategy to improve crop growth and grain quality. In the present study, 100 mg/L trehalose, chitosan, humic acid and gamma-aminobutyric acid treatments were applied to analyze the effects of maize production and reproductive characteristics. The contents of nitrogen, phosphorus and potassium and grain quality were significantly affected by the PBs, but not yield. The seed germination rate of all PB treatments was significantly reduced, but the drought resistance of progeny seedlings was significantly improved, with humic acid having the strongest effect. Liquid chromatography mass spectrometry analysis indicated that the disruption of the tricarboxylic acid cycle, probably due to the blockage of intermediate anabolism, reduced the supply of energy and nutrients in the early stages of germination, thus inhibiting seed germination, while the increased resistance of the offspring seedlings may be due to the up-regulation of the synthesis of unsaturated fatty acids and alkaloids by humic acid treatment. This study revealed the similarity and heterogeneity of the effects of different PBs on nutrient accumulation, yield characteristics and grain quality of maize, providing guidance for the application of PBs in intensive and sustainable agricultural production.

Living and Dead Microorganisms in Mediating Soil Carbon Stocks Under Long-Term Fertilization in a Rice-Wheat Rotation.

Although soil microorganism is an active area of research, we are still in the early stages of understanding how living microorganisms influence the accumulations of soil microbial residues under different agricultural practices. Based on a 39-year fertilization experiment, we characterized the soil microbiota and correlated their compositions to soil microbial residues, which are indicated by amino sugars under a rice-wheat rotation. In the present study, fertilization regimes and crop season all exerted significant impacts on the compositions of soil microbial communities and their residues, although no significant difference in the microbial residues was found between soil depth (0-10 cm vs. 10-20 cm). Compared within fertilization regimes, the long-term fertilization, especially the application of organic manure, stimulated the accumulations of carbon (C) and nitrogen in soils and microbial residues. Upland soils in wheat season accumulated more microbial residues, particularly in fungal residues, than paddy soils in rice season. Our results suggested that the long-term application of organic manure favored the growth of soil microbial communities, and then increased the contents of microbial residues, particularly in fungal residues, leading to an enlargement of soil C pools. The keystone taxa Pseudaleuria identified by network analysis showed a significantly positive potential in soil C sequestration by increasing the accumulation of fungal residues. Thus, this study revealed the strong and close connections between microbial communities and their residues, and provided evidence about the critical role of keystone taxa in regulating C sequestration.

Soil Aggregation Shaped the Distribution and Interaction of Bacterial-Fungal Community Based on a 38-Year Fertilization Experiment in China.

Soil aggregates provide different ecological niches for microorganisms, and in turn, the microbial interactions affect soil aggregation process. The response of the microbial community in bulk soil to different fertilization regimes has been well studied; however, the co-occurrence patterns of bacteria and fungi in different aggregates under various fertilization regimes remain unclear. Based on the long-term field experiment, we found that fertilization regimes contributed more to fungal than to bacterial community composition. Long-term fertilization decreased microbial interactions in large macroaggregates (LM), macroaggregates (MA) and silt and clay (SC) fractions, but increased in microaggregates (MI). The application of manure with inorganic fertilizers (NPKM) significantly increased the intensive cooperation between bacteria and fungi in LM and MA. Microbial communities in LM and MA were well separated and showed strong competition against microbes in MI and SC; hence, we concluded that the microbial habitat could be divided into two groups, large fractions (LM and MA) and small fractions (MI and SC). The bacterial genera Anaerolinea, Nocardioides, Ohtaekwangia, Geoalkalibacter, Lysobacter, Pedomicrobium, and Flavisolibacter were keystone taxa in inorganic fertilization, and Roseiflexus, Nitrospira, and Blastocatella were keystone taxa in NPKM, which were all sensitive to soil aggregation. In this study, we demonstrated that the NPKM decreased the microbial interactions within and between kingdoms in LM, MA, and SC, but enhanced nutrient availability and microbial interactions in MI, leading to the formation of biofilms and the strengthening of stress tolerance, which finally stimulated the formation and stabilization of soil aggregates. Thus, this study revealed how soil microbial competition or cooperation responded to different fertilization regimes at aggregate scales, and provided evidence for the stimulation of soil stability.

How Do Soil Bacterial Diversity and Community Composition Respond under Recommended and Conventional Nitrogen Fertilization Regimes?

Shifts in soil bacterial diversity and community composition are suggested to be induced by elevated input of nitrogen (N) fertilization with implications for soil quality, and consequently production. In this study, we evaluated the impacts of recommended fertilization (RF) and conventional fertilization (CF) on soil chemical properties, crop yield, bacterial diversity, and community composition from two long-term experiments conducted in fluvo-aquic soil and black soil of China. Each site comprised of four treatments, i.e., RF N-, RF N+, CF N-, CF N+. No N fertilization was indicated by N- and N fertilization was indicated by N+. Across both sites, N fertilization significantly increased crop yield compared with no N fertilization and RF successfully enhanced crop yield over CF. Interestingly, the RF maintained bacterial diversity, while CF depressed bacterial diversity in the two soils. Microbial taxa performing important ecological roles such as order Rhodospirillales and Bacillales were significantly enhanced in the RF approach, while Rhizobiales declined under CF. Furthermore, the results of partial least square path modeling revealed that soil available phosphorus (AP) negatively affected bacterial diversity while it positively affected bacterial community structure in fluvo-aquic soils. In contrast, soil pH was positively linked with both bacterial diversity and community structure in black soil. Overall, our study demonstrated that RF is an environmentally friendly approach which not only maintained above ground plant productivity, but also preserved belowground microbial populations and important soil variables regulating bacterial communities varied in different soil types.

High adsorption capacity of Mg-Al-modified biochar for phosphate and its potential for phosphate interception in soil.

In this study, Mg and/or Al modified biochars (MABC1, MBC2, ABC3) prepared by co-precipitation were to explore their phosphate adsorption capacity from aqueous solution and the potential for soil phosphate interception. The results revealed that MABC composites contained more functional groups than MBC and showed a higher surface area than ABC. The surface of MABC contained dispersed MgAl2O4, Mg(OH)2, AlOOH and Al2O3 crystals that were associated with its enhanced maximum phosphate adsorption capacity (153.40 mg g-1). According to Langmuir model, the maximum adsorption capacity of MABC was 15.91, 1.85, and 93.54 times the capacity of MBC, ABC, and raw biochar (BC4), respectively. The addition of MABC in red soil could significantly slow down the release of soil phosphorus, and MABC also had a stronger phosphate interception capacity (59.89%) than other BCs. In summary, MABC exhibits superior phosphate adsorption and interception capacity, making it ideal for treatment and prevention of phosphorus-polluted water.

Soil nutrient and microbial activity responses to two years after maize straw biochar application in a calcareous soil.

Biochar (BC) addition to soil is a strategy to enhance soil fertility, which may also affect microbial activity. However, little information is available on the responses of soil nutrients and microbial activities to BC in a calcareous soil. This study investigated the changes of soil nutrient contents and microbial activities in a calcareous soil two years after application of biochar at rate of 0, 2.5, 7.5 and 22.5 t/ha. The results showed that the contents of soil organic carbon (SOC), total nitrogen (TN), dissolved organic carbon (DOC), total dissolved nitrogen (TDN), and available phosphorus and potassium increased significantly with increasing BC addition rate, but no significant effect on soil pH. Soil microbial biomass carbon and nitrogen (MBC and MBN) had an increased and then decreased trend. BC amendment increased microbial biomass and promoted soil carbon- and nitrogen-cycling enzyme activities, the ratios of ß-glucosaminidase/phosphomonoesterase, N-acetyl-ß-glucosaminidase plus leucine aminopeptidase/phosphomonoesterase increased significantly with increasing BC addition rate. Redundancy analysis confirmed that DOC and MBN were dominant factors affecting soil microbial biomass, and soil pH, TDN, DOC, MBN and SOC were main factors regulating soil enzyme activities. Besides, principal component analysis revealed that difference in microbial community composition in one year after BC addition was mainly associated with the relative abundance of bacteria and fungi, the relative abundance of bacteria increased, while the ratios of Gram-negative/Gram-positive bacteria and fungi/bacteria, and relative abundance of fungi and arbuscular mycorrhizal fungi decreased in BC-amended soils with control. However, BC had no significant effect on microbial community composition after two years. These results suggest that application of maize BC to calcareous soils may have a great potential for improvements in the soil nutrients and enzyme activity, the changes in soil microbial composition deserve further studies.

Short-Term Responses of Soil Respiration and C-Cycle Enzyme Activities to Additions of Biochar and Urea in a Calcareous Soil.

Biochar (BC) addition to soil is a proposed strategy to enhance soil fertility and crop productivity. However, there is limited knowledge regarding responses of soil respiration and C-cycle enzyme activities to BC and nitrogen (N) additions in a calcareous soil. A 56-day incubation experiment was conducted to investigate the combined effects of BC addition rates (0, 0.5, 1.0, 2.5 and 5.0% by mass) and urea (U) application on soil nutrients, soil respiration and C-cycle enzyme activities in a calcareous soil in the North China Plain. Our results showed soil pH values in both U-only and U plus BC treatments significantly decreased within the first 14 days and then stabilized, and CO2emission rate in all U plus BC soils decreased exponentially, while there was no significant difference in the contents of soil total organic carbon (TOC), dissolved organic carbon (DOC), total nitrogen (TN), and C/N ratio in each treatment over time. At each incubation time, soil pH, electrical conductivity (EC), TOC, TN, C/N ratio, DOC and cumulative CO2 emission significantly increased with increasing BC addition rate, while soil potential activities of the four hydrolytic enzymes increased first and then decreased with increasing BC addition rate, with the largest values in the U + 1.0%BC treatment. However, phenol oxidase activity in all U plus BC soils showed a decreasing trend with the increase of BC addition rate. Our results suggest that U plus BC application at a rate of 1% promotes increases in hydrolytic enzymes, does not highly increase C/N and C mineralization, and can improve in soil fertility.

Evaluation of the Transverse Displacement of the Proximal Segment After Bilateral Sagittal Split Ramus Osteotomy With Different Lingual Split Patterns and Advancement Amounts Using the Finite Element Method.

PURPOSE: To evaluate transverse displacement of the proximal segment after bilateral sagittal split ramus osteotomy (BSSO) advancement with different lingual split patterns and advancement amounts and to determine the influential factors related to mandibular width. MATERIALS AND METHODS: A 3-dimensional finite element model of the mandible including the temporomandibular joint was created for a presurgical simulation and for BSSO with lingual split patterns I (T1; Hunsuck split) and II (T2; Obwegeser split). The mandible was advanced 3 mm (A3) and 8 mm (A8) and fixated with a conventional titanium plate. Ansys software was used to measure the linear distances of the interproximal segments and to analyze the transverse displacement distribution of proximal segments after applying the load of masticatory muscle force groups. RESULTS: After surgical simulation, T1A3, T1A8, T2A3, and T2A8 showed increased transverse widths (mean, 2.99, 4.70, 2.36, and 4.42 mm, respectively). For transverse augmentation, there was a statistically significant difference between the 2 different mandibular advancement amounts in T1 and in T2 (P ≤ .000), but no significant differences was observed between T1 and T2 (P ≥ .058). The maximum transverse displacement distribution in the proximal segment was measured around the gonial area, and the early contact area was found near the border between the horizontal and sagittal osteotomy lines. CONCLUSION: Transverse displacements of proximal segments occur after BSSO advancement with T1 and T2 and transverse augmentation has statistically meaningful effects depending on the amount of advancement; however, no differences in transverse augmentation between T1 and T2 were identified. The fulcrum caused by the early contact between the proximal and distal segments could be an influential factor related to mandibular width.

Characteristics of maize biochar with different pyrolysis temperatures and its effects on organic carbon, nitrogen and enzymatic activities after addition to fluvo-aquic soil.

In this study, the characteristics of maize biochar produced at different pyrolysis temperatures (300, 450 and 600°C) and its effects on organic carbon, nitrogen and enzymatic activities after addition to fluvo-aquic soil were investigated. As pyrolysis temperature increased, ash content, pH, electrical conductivity, surface area, pore volume and aromatic carbon content of biochar increased while yield, ratios of oxygen:carbon and hydrogen: carbon and alkyl carbon content decreased. During incubation, SOC, total N, and ammonium-N contents increased in all biochar-amended treatments compared with the urea treatment; however, soil nitrate-N content first increased and then decreased with increasing pyrolysis temperature of the applied biochar. Extracellular enzyme activities associated with carbon transformation first increased and then decreased with biochars pyrolyzed at 450 and 600°C. Protease activity markedly increased with increased pyrolysis temperatures, whereas pyrolysis temperature had limited effect on soil urease activity. The results indicated that the responses of extracellular enzymes to biochar were dependent on the pyrolysis temperature, the enzyme itself and incubation time as well.

[The research of SurgiCase CMF software in surgical simulation and prediction for mandibular asymmetry].

OBJECTIVE: To evaluate the predictive accuracy of the SurgiCase CMF software in surgical simulation and prediction for mandibular asymmetry with 3-dimensional simulation and measurement. METHODS: CBCT data of 27 patients with mandibular asymmetry were observed in CMF, and postoperative soft tissue physiognomy were predicted by simulating sagittal ramus osteotomy with or without genioplasty. The measurement parameters representing the symmetry of soft tissue were selected and the horizontal, coronal and sagittal planes were established. The results were analyzed by SPSS 19. 0. The overlap compared color grading charts were observed. RESULTS: Angles between cheilions and the horizonta plane (Ch-Ch-FH) in the simulation and postoperative soft tissues are (2. 35 ± 1. 81)° and (1. 44 ± 1. 13)°. The angles constructed among subnasale, upper lip and lower lip (Sn-UL-LL) are (4. 02 ± 3. 05)° and (2. 59 ± 1. 64)°, showing statistically different (P < 0. 01, P < 0. 05), which means that predictive accuracy of the lip canting and lip vertical deviation is relatively low. Distance between gonioi and sagittal plane (Go'-MS), distance between gonion and pogonion (Go'-Pog') and angle betweer subnasale to menton and the horizontal plane (Sn-Me'-MS) are not statistically different, which mean! high predictive accuracy of mandibular angle and chin. By observing the overlap compared color gradin-) charts, the predictive accuracy is not good in the cheek, especially in the deviate side. CONCLUSIONS: The predictive accuracy of CMF system for patients with mandibular asymmetry is relatively high, but it is not good in the lip and cheek. The software improvement is still necessary.

[Application of the cone beam computed tomography (CBCT) in Le Fort I osteotomy].

OBJECTIVE: To improve the accuracy and safety of the Le Fort I osteotomy. METHODS: Eighty-four patients underwent CBCT scan before maxillary orthognathic surgery. The anatomic structures of maxilla were marked and measured. RESULTS: In 84 cases, there were 3 cases with severe hypoplasia of maxillary sinus, 11 cases with impacted third molar, 8 cases with separation in maxillary sinus, 4 cases with the deviation of nasal septum, and 3 cases with cysts in maxillary sinus. Form CBCT images, the position of the pterygopalatine canal, the thickness of maxillary wall, hidden lesion of maxillary sinus, the location of Impacted molar, the deviation of nasal septum, and other anatomic structure could be accurately localized. CBCT could provide sufficient and valuable information in diagnosis and design for Le Fort I osteotomy. CONCLUSIONS: CBCT imaging technology could provide precise anatomic images for Le Fort I osteotomy. It improves the accuracy and safety of the Le Fort I osteotomy.

[Biomechanical study of internal midface distraction after different types of maxillary osteotomy in patients with cleft lip and palate].

OBJECTIVE: To investigate the biomechanical changes of internal midface distraction after different types of maxillary osteotomy in patients with cleft lip and palate (CLP). METHODS: 3-D finite element (FEM) analysis was used. 3-D models of Le Fort I, II, III osteotomy and soft tissue were established. Based on the new pattern of internal midface distractor, the distraction of maxillary complex was simulated to advance 10 mm anteriorly. The mechanical change was studied. RESULTS: The maxillary complex in CLP were advanced after distraction. Constriction of alveolar crest and palate occurred in Le Fort I osteotomy, but not in Le Fort II and III osteotomy. The maxillary complex was moved anteriorly en bloc after Le Fort III osteotomy, but some degree of rotation of maxillary complex was observed during the distraction after Le Fort I and II osteotomy. In vertical direction, the maxillary complex had more counterclockwise rotation after Le Fort II osteotomy. CONCLUSION: 3-D FEM analysis can be used for the study of internal distraction. It can reflect the maxillary movement and provide the theory basis for preoperative design.