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Biochar addition to soil has been proposed as a strategy to enhance soil quality and crop productivity. However, little is known about responses of soil nutrients and microbial activities to additions of chemical fertilizer and biochar with different pyrolysis temperatures. To investigate the effects of control (CK), chemical fertilizer (NPK), and NPK with maize straw biochar (MC) produced at 300, 450, and 600 °C (NPK + MC300, NPK + MC450, and NPK + MC600) on crop yield, soil nutrients, soil enzyme activities, and microbial attributes in a calcareous soil, we conducted a pot experiment. The results showed that the NPK + MC450 treatment obtained the highest wheat yield and N, P, and K uptakes. The NPK + MC300 and NPK + MC450 treatments decreased significantly the soil available K content and increased the C/N ratio, contents of soil organic carbon (SOC) and available P compared to the NPK + MC600 treatment. The NPK + MC450 treatment promoted the increases in soil C- and N-cycling enzyme activities. The total N content, soil MBC and MBN were the main driving factors affecting soil enzyme activities. All the NPK plus MC soils significantly reduced the relative abundance of soil fungi and enhanced soil nutrient contents (excluding soil inorganic nitrogen) and total phospholipid fatty acid concentrations. A redundancy analysis revealed that the changes in soil microbial community depended mainly on the contents of MBC, MBN and available K as well as the C/N ratio. This study provides clear evidence that the co-application of NPK fertilizers and MC produced at 450 °C was more efficient for improving soil quality and potential crop productivity.

Retaining carbon in cultivated soils is an important mechanism to mitigate climate change and to maintain the sustainability of agricultural ecosystems. Characterization of the soil microbial community was an early means to quantify the increase in soil organic carbon (SOC) content and stability under different cropping systems. However, the effects of different cropping systems on the soil microbial community and enzyme activity and the driving force for increasing the SOC content remain unclear, especially the differences between continuous maize (Zea mays L.) cropping and rotation systems containing legumes. We used a long-term field experiment (30 years) in the Mollisol region of Northeast China. The field experiment was undertaken in split-plot design comprised of four treatments: i) farmland fallow (FALL), ii) continuous soybean cropping (CSC), iii) maize-soybean rotation (MSR), iv) continuous maize cropping (CMC). Fluorometric assays and phospholipid fatty acid analysis (PLFA) were used to determine the biological characteristics of the soil. The SOC chemical composition was characterized using Cross Polarization/Magic Angle Spinning solid-state 13C-nuclear magnetic resonance (13C NMR) spectroscopy. Principal component analysis (PCA), redundancy analysis (RDA) and the partial least squares path model (PLS-PM) were used to explore the coupling mediation of these parameters further. Our results suggested that soil microbes in the four systems were not limited by C and N, but co-limited by P. But compared with the FALL system, the CMC system significantly alleviated the phosphorus limitation of the microorganisms. The CMC system also significantly increased soil nutrient content, especially SOC content (40.8%), available phosphorus (117%), available potassium (30.3%), NO3−-N (148%), and increased microbial community abundance and enzyme activities. Compared with the CMC system, the MSR system held relatively lower Gram-positive: Gram-negative ratio and higher fungi: bacteria ratio, which indicated that the soil microbial community structure is more conducive to improving the SOC stability. Meanwhile, more evidence supporting data that SOC stability was enhanced in MSR soils was provided by the 13C NMR spectra and higher-quality indices (A / AO, AI, HI and LCI). Moreover, strong correlations and RDA analysis confirmed that SOC is the main factor affecting microbial communities and enzyme activities.

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 β-glucosaminidase/phosphomonoesterase, N-acetyl-β-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.

Free-living nitrogen fixation (FLNF) by diazotrophs is a ubiquitous renewable resource and may constitute an attractive viable solution to the problem of environmental degradation caused by nitrogen over-fertilization. However, the biotic and abiotic control mechanisms of free-living nitrogen fixation are poorly understood. Moreover, there is rare information to link the composition and functions of diazotrophic communities; additionally, there are insufficient or inadequate predictors of the potential N fixation rate (PNFR) to help improve fertilization strategies. Here, through high-throughput sequencing, network analysis, and 15N2 labelling methods, we investigated the long-term effects of partial substitution of mineral N by organic fertilizers on diazotroph abundance and composition in double rice cropping systems. The field trial was conducted for 34 years and included five treatments: control without fertilizer (CK); only mineral NPK fertilizer (NPK); 70% inorganic N + 30% organic N + PK (NPKM1); 50% inorganic N + 50% organic N + PK (NPKM2); 30% inorganic N + 70% organic N + PK (NPKM3). Our results revealed that at the same nutrient input level, increasing the percentage of organic N substitution reduced diazotrophic abundance. Compared with the CK and NPK treatments, the organic substitution regimes reduced the fluctuation range of the PNFR between the early and late rice growing seasons. NH4+-N was the primary factor that negatively correlated (p

Ammonia oxidation in the soil is related to nitrogen (N) availability for plants, nitrate loss, and N fertilizer use efficiency, which is important for studies on the N cycle of paddy field ecosystems. Substitution of partial mineral N fertilizer with organic amendments is commonly considered to optimize fertilization practices and reduce the application of mineral N fertilizer in the paddy fields. However, little is known about the effects of this type of fertilization on the relative contribution of ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) to soil nitrification. Therefore, a 34-year field trial including five fertilization regimes (CK, without fertilizer; NPK, mineral NPK fertilizer; NPKM1, 70% inorganic N + 30% organic N + PK; NPKM2, 50% inorganic N + 50% organic N + PK; NPKM3, 30% inorganic N + 70% organic N + PK; P: phosphorus, K: potassium) was conducted. AOA and AOB abundance and community structures were determined by quantitative PCR and high-throughput sequencing analyses. Although the abundance of AOA and AOB increased with the increase in the percentage (30%–70%) of organic N substitution, the abundance ratio of AOA to AOB (133.9–84.7) decreased. Soil potential nitrification rate (PNR) increased dramatically (p

Substitution of chemical fertilizers with organic amendments recycle organic wastes and minimizes adverse environmental effects of mineral-fertilizer overuse. In China, cropping systems which utilize two rice plantings per year are the most important planting pattern for ensuring food security. To date, few studies have comprehensively evaluated the responses of soil fertility and rice performance in double rice cropping systems to the partial substitution of chemical nitrogen (N) with organic N under the same input rates of N, P and K. In addition, the influences of the mineral-to-organic substitution ratio and season on these responses remain poorly understood. Here, a 34-year field fertilizer trial was sampled to determine the impacts of organic substitution regime and growing season on soil biochemical properties and rice yield. Compared with the mineral NPK fertilizer regime, the replacement of 30 %, 50 % and 70 % of total N with organic N increased the yield of early rice by 4.5 %–8.3 %, respectively and that of late rice by 6.7 %–9.6 %. Moreover, the organic substitution regimes significantly improved soil biochemical indicators. The higher organic N substitution percentage resulted in higher values of many soil properties with the exception of TC:TN, fungi:bacteria and G+:G−, which tended to decrease with increasing substitution. Both fertilizer regime and growing season affected soil nutrient contents, enzyme activity and microbial community structure. The relative abundances of identified PLFA biomarkers 16:1ω5c, 16:1ω7c and 18:1ω7c were markedly higher (p ≤ 0.05) in the organic alternative treated soils than the NPK-treated soils in both seasons. Our results suggest that the substitution of 70 % chemical N with organic N is the most effective fertilizer practice for improving soil fertility and rice yield in double rice cropping systems.

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.

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.

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&minus, RF N+, CF N&minus, CF N+. No N fertilization was indicated by N&minus, 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.

Treating soil with a combination of nitrogen (N) and biochar (BC) has often been suggested as an approach to enhancing soil quality. In the present study, we therefore conducted a two -year randomized two-factorial field experiment in order to explore optimal N fertilizer management strategies in the context of BC application to calcareous soil, with a focus on both microbial activities and soil nutrient levels. Maize straw BC (0 or 22.5 t ha−1) was applied to the soil once prior to the planting of wheat, with four different N fertilizer concentrations (0, 150, 225, and 300 kg ha−1) being applied to experimental plots. We found that N fertilizer addition resulted in significant reductions in soil pH and available phosphorus (AP) levels, whereas soil phosphatase activity was increased by such treatment. Relative to treatment with only BC or N in isolation, the combined application of both N and BC led to significant increases in soil organic carbon (SOC), total nitrogen (TN), dissolved organic carbon (DOC), total dissolved nitrogen (TDN), and available potassium (AK) levels, while also enhancing the activity of C- and N-cycling enzymes. In contrast, this combination treatment did not impact soil pH or phosphatase activity. The application of BC did not significantly affect microbial biomass, but it was associated with changes in overall microbial community structure, including a decrease in the fungi/bacteria ratio and the Gram-negative/Gram-positive bacteria ratio. These changes were also linked to increases in relative actinomycetes abundance and an elevated cy19:0/18:1ω7c ratio. These results suggested that combined N and BC application is thus not conducive to rapid fungal growth, with soil AK, pH, TN, and TDN being the primary factors that affected soil microbial community structure. While BC did significantly increase the βG:(NAG LAM) ratio, this was not associated with any N-mediated microbial restriction. Overall, our findings conclusively demonstrate that combined BC and N fertilizer application can enhance soil quality while supporting a more stable microbial community structure and more active soil biological activity.

There is global concern about the adverse impacts of conventional agricultural practices on the environment. Recent evidence has shown that ecological intensification (EI) of agriculture can safeguard the environment from negative impacts of agricultural practices and simultaneously produce substantially higher crop productivity. Here, we employed the concept of EI and compared it with conventional agriculture or farmer’s practice (FP). We explored the effects of EI and FP treatments on maize yield, N losses via potential nitrification activity (PNA), potential denitrification activity (PDA), N2O emissions, greenhouse gas (GHG) emissions, and nitrogen (N) cycling microbial populations associated with nitrification and denitrification in fluvo-aquic soil and black soil of North China. There were four treatments, i.e., EI N-, FP N-, EI N+, FP N + at each site, - and + indicate no N addition and N addition, respectively. The results revealed that across the two soils, N addition increased PNA and PDA; however, compared with the FP N + treatment, lower PNA and PDA were observed in the EI N + treatment. Similarly, the abundance of N cycling genes, including AOA amoA and AOB amoA, for nitrification and nirS, nirK, and nosZ for denitrification were significantly increased under N addition, and compared with the FP N + treatment, reduced abundance was noted in the EI N + treatment. N2O and GHG emissions were quantified, and it was observed that, in comparison to the FP treatment, reduced N2O and GHG emissions occurred in EI treatments in the two locations. EI with best management practices also increased crop yield relative to FP. Owing to higher N rates in FP treatments, substantial soil acidification was noted in FP plots but not in EI plots. In addition, PNA and PDA were significantly positively linked with soil nitrifying and denitrifying communities, particularly in the black soil. Moreover, the N availability pathway rather than soil acidification mainly regulated N cycling microbial communities. Our results suggest that EI could be a sustainable and environmentally friendly approach due to higher crop productivity and lower N losses via PNA, PDA, N2O, and GHG emissions, thus preventing the negative impact of agricultural practices, especially N fertilization, on the environment.

Biochar addition to soil has been proposed as a strategy to enhance soil quality and crop productivity, which may also affect microbial activity. However, the response of soil enzymes and microbial community composition to biochar addition and the main factors that drive their consequent behavior have rarely been studied. Therefore, to investigate the combined effect of different amounts of biochar (0, 0.5, 1.0, 2.5 and 5.0% by mass) and urea application on soil nutrients, enzymatic activities and microbial community in a fluvo-aquic soil, we conducted a 90-day laboratory study. Increased maize biochar addition led to significantly increased soil organic carbon (SOC), total N, and exchangeable K and reduced soil exchangeable Ca. Soil total N and exchangeable Ca were dominant factors affecting soil enzyme activities. Activities of soil extracellular enzymes involved in C and S cycling (except β-xylosidase) suggested lower amounts of biochar addition (0.5% by mass) could increase soil enzyme activities, while higher amounts of biochar addition reduce soil enzyme activities. However, the activities of l -leucine aminopeptidase and urease, both of which are involved in N cycling, increased with the increase of biochar addition rate. Total phospholipid fatty acid content and the relative abundance of bacteria were significantly reduced with increasing biochar addition rate. The relative abundance of fungi in the urea-amended soil was significantly higher than that in the other treated soils, and abundance of actinomycetes did not show a clear response to biochar addition. The changes in the microbial community composition were mainly related to SOC and total N contents, with a significant negative correlation. We concluded that the effect of biochar addition on soil enzymes and microbial community composition was highly variable. There is an urgent need to further estimate both the positive and negative long-term effects of biochar on the soil quality and crop productivity in this region.

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.

To evaluate the predictive accuracy of the SurgiCase CMF software in surgical simulation and prediction for mandibular asymmetry with 3-dimensional simulation and measurement.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.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 (P0. 01, P0. 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.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.

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.