Gene-gene interaction network analysis indicates CNTN2 is a candidate gene for idiopathic generalized epilepsy.

Twin and family studies have established the genetic contribution to idiopathic generalized epilepsy (IGE). The genetic architecture of IGE is generally complex and heterogeneous, and the majority of the genetic burden in IGE remains unsolved. We hypothesize that gene-gene interactions contribute to the complex inheritance of IGE. CNTN2 (OMIM* 615,400) variants have been identified in cases with familial adult myoclonic epilepsy and other epilepsies. To explore the gene-gene interaction network in IGE, we took the CNTN2 gene as an example and investigated its co-occurrent genetic variants in IGE cases. We performed whole-exome sequencing in 114 unrelated IGE cases and 296 healthy controls. Variants were qualified with sequencing quality, minor allele frequency, in silico prediction, genetic phenotype, and recurrent case numbers. The STRING_TOP25 gene interaction network analysis was introduced with the bait gene CNTN2 (denoted as A). The gene-gene interaction pair mode was presumed to be A + c, A + d, A + e, with a leading gene A, or A + B + f, A + B + g, A + B + h, with a double-gene A + B, or other combinations. We compared the number of gene interaction pairs between the case and control groups. We identified three pairs in the case group, CNTN2 + PTPN18, CNTN2 + CNTN1 + ANK2 + ANK3 + SNTG2, and CNTN2 + PTPRZ1, while we did not discover any pairs in the control group. The number of gene interaction pairs in the case group was much more than in the control group (p = 0.021). Taking together the genetic bioinformatics, reported epilepsy cases, and statistical evidence in the study, we supposed CNTN2 as a candidate pathogenic gene for IGE. The gene interaction network analysis might help screen candidate genes for IGE or other complex genetic disorders.

[Effects of Fertilizer Application Strategy Adjustments on Nitrogen and Phosphorus Loss from Typical Crop Systems in Taihu Lake Region].

The intensity of crop farming fertilizer input is generally high in the Taihu Lake Region, with chemical fertilizer as the main form. Due to inappropriate fertilizer application, nitrogen and phosphorus loss have occurred, causing serious agricultural non-point source pollution. The Ministry of Agriculture and Rural Affairs of China has launched the "zero-growth action for chemical fertilizer use" and "replacement action with organic fertilizer" ("two actions" for short) campaigns since 2015. Local agricultural sectors adjusted fertilizer application strategies of crop farming to respond to the call of two actions. However, the current research is still focusing on reducing the total amount of fertilizer application and increasing the area of organic fertilizer application, which is mainly based on grain crops. The study of agricultural environment problems is still lacking, especially in vegetable, orchard, and tea systems. Therefore, a study was carried out in the typical agricultural area of Suzhou City Wuzhong District from 2019 to 2021. Based on the data of the amount of nitrogen and phosphorus removal by harvest crops and soil nitrogen and phosphorus residual in paddy, vegetable, orchard, and tea systems, the loss was estimated. The responses of nitrogen and phosphorus loss from typical crop systems to fertilizer application strategy adjustments were studied through analysis of different factors. The results showed that fertilizer application rate was the key to control nitrogen and phosphorus loss. Additionally, the suitable replacement ratio of organic fertilizer could further reduce the loss risk. It should be noted that the urgent demand for nutrients in crop growth should be considered to determine the timing of organic fertilizer application, and agricultural machinery should be used to assist organic fertilizer application to reduce labor output if possible. Fertilizer efficiency was the core of environmental friendliness and economic benefits of crop farming. Hence, improving fertilizer efficiency should be the guidance of fertilizer application strategy adjustment. Our suggestions on the adjustment of fertilizer application strategy in different crop systems in the study area are as follows:attention should be paid to the nitrogen, phosphorus, and potassium input ratio in paddy systems to further reduce nitrogen and phosphorus loss. Planting structure adjustment should be emphasized in vegetable systems to promote fertilizer efficiency. The strategy to satisfy both tea and orchard growth from a composite system perspective would help to build crop systems that meet the needs of green agricultural development.

[Effects of Aeration on Surface Water Nutrient Dynamics and Greenhouse Gas Emission in Different Straw Returning Paddy Fields].

Straw returning is of great significance for improving soil structure, soil fertility, crop yield, and quality. However, straw returning causes environmental problems such as increased methane emission and non-point source pollutant emission risk. How to reduce the negative effects of straw returning is an urgent problem to be solved.In this study, the effects of aerobic treatment on carbon and nitrogen concentration in surface water and greenhouse gas emissions in paddy fields with different treatments of straw returning were systematically compared.The results showed that different treatments of straw returning significantly increased chemical oxygen demand (COD) in the surface water of the paddy field and significantly promoted the methane emission of the rice field and the global warming potential (GWP), although it slightly reduced N2O emission. The increasing trends showed that wheat straw returning>rape straw>broad bean straw returning.Straw returning increased rice yield when compared with the control without straw returning, but the difference was not significant. Aerobic treatment reduced the COD in surface water by 15%-32%, the methane emission of the paddy field by 10.4%-24.8%, and the GWP of paddy field by 9.7%-24.4% under different straw returning treatments, without affecting the rice yield. The mitigation effect of aerobic treatment with wheat straw returning was the best. The results indicated the potential of oxygenation measures in greenhouse gas emission mitigation and COD emission risk reduction in straw returning paddy fields, especially in wheat straw returning paddy fields.

[Effects of Warming and Fertilization on Soil Organic Carbon and Its Labile Components in Rice-wheat Rotation].

Farmland is the important soil carbon pool of terrestrial ecosystems and organic nutrient pool for crop growth. To clarify the impact of climate warming on the soil carbon pool, this study analyzed the effects of warming and fertilization on soil organic carbon and its labile components under rice-wheat rotation using a free-air temperature increase system. The variation in soil carbon pool management index (CPMI) was also evaluated. The results showed that the combined effects of warming and fertilization on soil organic carbon content and labile organic carbon components were insignificant. Warming increased the soil organic carbon (SOC) content, and the differences between warming and the ambient control in total organic carbon (TOC) and recalcitrant organic carbon (ROC) reached a statistically significant level. Compared with those under the ambient control, the contents of TOC, ROC, and labile organic carbon (LOC) subjected to warming increased by 7.72%, 7.42%, and 10.11%, respectively. The increased microbial biomass carbon (MBC) content (20.4%) and decreased particulate organic carbon (POC) content (36.51%) may have been the main reason for the variation in SOC. Warming showed no significant effect on soil dissolved organic carbon (DOC) content, whereas it markedly reduced its soluble microbial by-product components (41.89%). The results also showed that fertilization had no significant effect on soil TOC, ROC, and LOC, but it notably reduced the contents of DOC and POC and increased the MBC content. Compared with those under the control without fertilization, the contents of DOC and POC subjected to fertilization decreased by 35.44% and 28.33%, respectively, and the MBC content increased by 33.38%. Additionally, fertilization tended to increase the anthropogenic humus component (5.13%) and soluble microbial by-product component (29.41%) in dissolved organic matter and reduce the terrestrial humus component (13.33%). Warming and fertilization both tended to improve soil CPMI. Affected by SOC and LOC, the increase in soil carbon pool index and soil lability index were the main reason for the increase in soil CPMI under warming and fertilization, respectively. Overall, the results revealed that climate warming can affect the soil carbon pool by changing soil labile carbon components, which are not affected by fertilization.

[Effect of Deep Fertilization with Slow/Controlled Release Fertilizer on N Fate in Clayey Soil Wheat Field].

Clayey soil seriously affects water-holding capacity and nutrient movement. Adopting appropriate agronomic measures to optimize the distribution of soil inorganic nitrogen (SIN) and reduce the nitrogen (N) loss in this soil is the key to agricultural sustainable development. To clarify the effect of deep fertilization of slow/controlled release fertilizer with sowing on N loss in a clayey soil wheat field, two types of fertilizers, conventional fertilizer (CN) and slow/controlled release fertilizer (RCU), were selected in this study. Here, we evaluated the effects of these two fertilizer types on wheat yield, seasonal N runoff loss, ammonia volatilization, and N2O emissions in wheat fields in two typical fertilization modes (manual surface sowing and spreading (B) and belowground fertilization of slow/controlled release urea with mechanized strip sowing (D)). The temporal and spatial distribution characteristics of SIN in topsoil were also analyzed. The results showed that under the same fertilizer type, the wheat yield of D treatment was significantly higher than that of B treatment, whereas the yield of RCU was notably higher than that of CN under the same fertilization mode. D-RCU achieved the highest yield of 6.97 t·hm-2. The seasonal N losses from runoff and ammonia volatilization were higher than that from N2O emissions, and the responses of different N loss pathways to fertilizer types and fertilization methods were diverse. Fertilizer type and runoff occurrence time were the main influencing factors of N runoff loss, and N runoff loss of the RCU treatment was higher in the non-fertilization period. Unfortunately, affected by annual rainfall pattern, the seasonal N runoff loss of the RCU treatment (20.35 kg·hm-2) was significantly higher than that of the CN treatment (10.49 kg·hm-2). The late growth period was the main phase of ammonia volatilization, and the later period was jointly affected by fertilization modes and fertilizer types. The B-CN treatment induced the highest seasonal ammonia volatilization (18.15 kg·hm-2), which was significantly higher than that of the other treatments (7.31-8.38 kg·hm-2). Additionally, the D-RCU treatment (2.41 kg·hm-2) tended to reduce the N2O emissions in comparison to that in the B-CN treatment (4.02 kg·hm-2). The results also indicated that the horizontal movement of SIN was higher than the vertical movement. Deep fertilization of RCU was conducive to optimizing the spatial and temporal distribution of SIN, which was the main reason for the increase in wheat yield and the control of N loss from wheat fields. These results suggest that RCU is a suitable alternative fertilizer for increasing yield and reducing N loss in clayey soil wheat fields; D-RCU can increase the wheat yield and reduce ammonia volatilization and N2O emissions in wheat fields by optimizing the spatial and temporal distribution of SIN, and its increasing effect on N runoff loss in the non-fertilization period deserves attention.

Perception of recurrent risk versus objective measured risk of ischemic stroke in first-ever stroke patients from a rural area in China: A cross-sectional study.

OBJECTIVE: Risk perception is critical to the formation of individual health prevention behaviors. A long-term accurate perception of stroke recurrent risks is imperative for stroke secondary prevention. This study aims to explore the level of recurrence risk perceptions and the influential factors of inaccuracy between perceived and objective risk in first-ever ischemic stroke patients from a rural area. METHODS: From May to November 2020, 284 first-ever ischemic stroke patients were conveniently recruited in a rural area of Henan Province, China. Perceived risk was measured based on self-reported using a numerical rating scale, whereas the objective risk was measured by the Essen Stroke Risk Score. Patients' perceived risk was compared with their objective risk and categorized as "Accurate," "Underestimated," and "Overestimated." The influencing factors of inaccuracy were further evaluated using multivariate regression analyses. RESULTS: 46% of the participants underestimated their stroke risk, while 15.9% overestimated their risks. Patients who were younger (≤65 years), didn't worry about recurrent stroke, and had a low actual recurrent risk were more likely to underestimate their recurrent risk. Patients who were employed, had lower independence, and had greater anxiety were more likely to overestimate their recurrent risk. CONCLUSIONS: The majority of participants were unable to accurately perceive their own risk of stroke recurrence. Patients' age, working status, worry about recurrent stroke, actual recurrent risk, level of dependence, and anxiety played a role in perception inaccuracy. PRACTICE IMPLICATIONS: The findings could help healthcare providers gain a better understanding of the level and accuracy of recurrence risk perceptions among first-ever stroke patients in the rural area. Future counseling on the perceived risk of stroke recurrence and individual objective risk assessment could be conducted to help patients better understand their risk of recurrence. Individualized risk communication and multidisciplinary teamwork can be developed to improve the accuracy of recurrence risk perceptions and health behaviors.

Efficacy and safety of sodium oligomannate in the treatment of Alzheimer's disease.

To evaluate the efficacy and safety of sodium oligomannate in the treatment of Alzheimer's disease. Patients with mild-to-moderate AD were randomly divided into three groups, the scores of ADAS-Cog, ADL, CIBIC-plus, NPI and CSDD were evaluated at the 0th, 12th, 24th, 36th and 48th weeks of medication. Comparing the mean scores of each scale in each cycle of each group. Using SPSS21.0 software for measurement data using t test, Chi-square test was used for counting data. A total of 72 patients with AD were included. The difference of CIBIC-plus score at week 12(P=0.007) and 24(P=0.005), ADAS-Cog scores (P=0.01) at week 24 in GV-971 group was statistically significant compared with that in the control group. The CIBIC-plus score at week 24(P=0.01) and week 48 (P=0.04), CSDD scores at week 48(P=0.02) of GV-971 group was statistically significant compared with that of donepezil group. There were 2 cases of adverse reaction of increased stool frequency in GV-971 (5.67%), and 2 cases of adverse reaction of nausea in donepezil group (8.33%), the difference was statistically significant. GV-971 is as effective as donepezil in the treatment of Alzheimer's disease, and may even be better. It has good safety.

[Development of Zeolite Loaded Mg-La-Fe Ternary (hydr) oxides for Treatment of Low Concentration Phosphate Wastewater].

A novel Mg-La-Fe ternary (hydr)oxide magnetic zeolite adsorbent (MLFZ) was prepared using the hydrothermal method and employed for effective phosphate removal in this study. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) indicated that the MLFZ presented an amorphous surface with Mg, Fe, and La dispersed on the surface of the zeolite. The isothermal adsorption and kinetics results showed that the adsorption behavior of the MLFZ was consistent with that of the Langmuir isothermal model and quasi-second-order kinetics model. A relatively fast adsorption of phosphate with a short equilibrium time of 30 min was observed in the kinetics experiment, and the maximum adsorption capacity of the MLFZ was 13.46 mg·g-1 in the equilibrium adsorption isotherm study. The MLFZ showed effective adsorption performance over a wide pH range from 3.0 to 9.0. Moreover, the coexisting ions had an insignificant effect on phosphate adsorption. The MLFZ could easily be recovered using a magnet. After five adsorption-desorption cycles, the phosphate removal efficiency was maintained at approximately 90%. The FTIR, XPS, and Zeta potential analysis confirmed that the adsorption mechanisms were attributed to the surface deposition, electrostatic adsorption, and the inner complex formation by ligand exchange between lanthanum and phosphate. Furthermore, the MLFZ demonstrated high efficiency in scavenging phosphate from a natural pond (phosphate concentration decreased from 0.86 mg·L-1 to 0.013 mg·L-1), indicating that the MLFZ was an ideal material for phosphate management and treatment.

Rhizosphere and Straw Return Interactively Shape Rhizosphere Bacterial Community Composition and Nitrogen Cycling in Paddy Soil.

Currently, how rice roots interact with straw return in structuring rhizosphere communities and nitrogen (N) cycling functions is relatively unexplored. In this study, paddy soil was amended with wheat straw at 1 and 2% w/w and used for rice growth. The effects of the rhizosphere, straw, and their interaction on soil bacterial community composition and N-cycling gene abundances were assessed at the rice maturity stage. For the soil without straw addition, rice growth, i.e., the rhizosphere effect, significantly altered the bacterial community composition and abundances of N-cycling genes, such as archaeal and bacterial amoA (AOA and AOB), nirK, and nosZ. The comparison of bulk soils between control and straw treatments showed a shift in bacterial community composition and decreased abundance of AOA, AOB, nirS, and nosZ, which were attributed to sole straw effects. The comparison of rhizosphere soils between control and straw treatments showed an increase in the nifH gene and a decrease in the nirK gene, which were attributed to the interaction of straw and the rhizosphere. The number of differentially abundant genera in bulk soils between control and straw treatments was 13-23, similar to the number of 16-22 genera in rhizosphere soil between control and straw treatment. However, the number of genera affected by the rhizosphere effect was much lower in soil amended with straw (3-4) than in soil without straw addition (9). Results suggest possibly more pronounced impacts of straw amendments in shaping soil bacterial community composition.

[Effects of Wheat Straw Hydrochar and Its Modified Product on Rice Yield and Ammonia Volatilization from Paddy Fields].

Hydrochar can mitigate ammonia volatilization when applied in paddy fields due to its acidity and adsorption property. To realize the recycling of agricultural biowaste as well as the control of nutrient loss from paddy fields, a simulation soil-column experiment with wheat straw hydrochar (WHC) and water-washed hydrochar (W-WHC) was conducted to evaluate the performance of rice yield and ammonia volatilization from paddy fields. The results showed that WHC and W-WHC applied in paddy fields both increased the rice yield and the increased effect at low application rate (0.5%) was higher than that at high application rate (1.5%). In comparison with the control treatment (CKU), the rice yields achieved from low application rate treatments for WHC and W-WHC increased by 17.16% and 20.20% respectively. Except for the equal emission rate between W-WHC with low application rate and CKU treatments, hydrochar (WHC, W-WHC) addition reduced the ammonia volatilization from paddy fields when compared with the CKU. Among them, the ammonia volatilization levels from low-application WHC and high-application W-WHC treatments were significantly lower than that from the CKU treatment, reduced by 31.01% and 17.40%, respectively. Based on the analysis of ammonia volatilization during different fertilization stages, the control effect of hydrochar addition on ammonia volatilization was mainly benefited from tillering and panicle fertilizer stages. The change in the nitrogen concentration of surface water at the tillering fertilizer stage and in pH at the panicle fertilizer stage with the addition of hydrochar was the main driving factor for the reduction in ammonia volatilization. The results show that sufficient amounts of hydrochar derived from wheat straw application can increase crop yield while reducing ammonia volatilization from paddy fields. This method provides an effective route for recycling agricultural biowastes.

Effects of long-term fertilization without phosphorus on greenhouse gas emissions from paddy fields.

The strategy of few or no-phosphorus fertilization in rice season but more in wheat season can effectively increase phosphorus use efficiency and reduce phosphorus loss through runoff and leaching. It remains unknown whether the lack of phosphorus will affect greenhouse gas emission in the rice season. We monitored the CH4 and N2O emission fluxes during the growth period of rice treated with normal phosphorus application (NPK) and no-phosphorus application (NK) in two long-term experimental fields in Suzhou and Yixing. The results showed that long-term no-phosphorus application promoted CH4 and N2O emission in both fields. Compared with the NPK treatment, CH4 and N2O emissions from the NK treatment significantly increased by 57% and 25% in Suzhou experi-mental field, respectively, while those in Yixing experimental field were also significantly increased by 221% and 70%, respectively. The contents of organic acid, dissolved organic carbon and available phosphorus in soil were reduced under long-term NK treatment, and they were closely related to CH4 emission. Soil available phosphorus content was significantly negatively correlated with CH4 emission (r=-0.987). The global warming potential (GWP) was greater in NK treatment than NPK treatment in both fields. Therefore, long-term no-phosphorus application could decrease the contents of organic acid, soluble organic carbon, and available phosphorus in soils, resulting in more CH4 and N2O emission in rice field.

[Effects of Film Materials on Ammonia Volatilization Emissions from a Paddy System After Reducing Nitrogen Fertilizer Application].

Ammonia volatilization emissions constitute the main pathway of nitrogen loss from paddy systems. Present control technologies are based on reducing the amount of nitrogen fertilizer applied. However, ratio of nitrogen loss through ammonia volatilization emissions has not changed, and it has become a bottleneck for promoting nitrogen use efficiency. Therefore, in order to study the effects of film materials on ammonia volatilization emissions, a two-year field plot experiment was carried out with agricultural waste powder and amphipathic molecule materials spread on surface water after nitrogen fertilizer application in paddy system. The results showed that film materials could reduce nitrogen loss through ammonia volatilization by 19%-31% in the paddy season, and this part of nitrogen was accumulated in soil or assimilated by paddy tissue. The ammonium concentration and pH in the surface water and film materials were the major control factors of ammonia volatilization emissions with nitrogen fertilizer application. Moreover, further reductions in ammonia volatilization emissions could be achieved by film materials after reducing nitrogen fertilizer application. Differences in the effect mechanisms of the film materials provide flexible options for practical agricultural production to meet demands.

[Effects of Modified Biowaste-based Hydrochar on Rice Yield and Nitrogen Uptake].

Biochar application on farmlands is an efficient way to realize agricultural/forestry biowaste recycling in parallel with carbon sequestration. Recently, hydrochar produced by hydrothermal carbonization processes has attracted attention due to the advantages over conventional pyrolytic production (i.e., easier production process, higher carbon yield, reduced energy consumption, and lower flue gas emissions). To clarify the effects of hydrochar applied in farmlands on crop production, as well as to realize the recycling of agricultural/forestry biowaste resources, this study evaluated the effects of four types of modified-hydrochar addition on rice yield and nitrogen uptake in two typical soils and the possible influencing factors through soil-column experiments and material characterization. The results showed that sawdust hydrochar and/or straw hydrochar could increase rice yield and nitrogen uptake, as well as reduce N loss, in both treated soils after physical or biological modification, an effect that was independent of the application rate (5‰, 15‰; mass fraction). In comparison to the control, the rice yield and nitrogen uptake of hydrochar-addition treatments increased by 9.2%-20.7% and 7.7%-17.0% respectively. Sawdust hydrochar, with a wider C/N material, was conducive to improving nitrogen uptake in high fertility soils; meanwhile, the nitrogen utilization in low fertility soils was less affected by the type of hydrochar due to the limitations imposed by multiple factors. The results of material characterization showed that the surface of the hydrochar was rich in nutrients; the pore structure of hydrochar after washing or biological modification was greatly improved, the relative content of C was remarkably reduced, and the relative contents of N and O notably increased, which could affect nutrient fixation and supply. Thus, the improved pore structure and increased contents of N and O of modified hydrochars may be the key drivers for the increase in rice yield and nitrogen uptake with hydrochar addition. These results suggest that modified hydrochar is beneficial to realizing agricultural/forestry biowaste recycling and improving crop yield and nitrogen utilization, as well as reducing N loss from farmlands.

[Situation Analysis and Trend Prediction of the Prevention and Control Technologies for Planting Non-Point Source Pollution].

The contribution of crop planting to agricultural non-point source pollution should not be underestimated in China. Although many modern technologies have been developed to prevent non-point source pollution in recent decades, their impacts on pollution control in farmland are far from expectation. The application of technologies for non-point source pollution control for crop farming has been delayed due to unclear technical parameters and application effectiveness. Therefore, based on studies of the non-point source pollution control for crop farming in China and abroad that were published in the last 20 years, the present research was carried out to determine the development process of planting non-point source pollution control technologies and to illuminate the framework construction. The technologies in different fields and directions were compared by their effects on fertilizer input,yield, and pollutant emission. The development trend in the field of prevention and control technologies for planting non-point source pollution was subsequently predicted. In addition, a technical framework was developed with 3 fields (pollutant source reduction, pollutant interception in the migration process, and nutrient recycling) and 14 directions. The analysis showed that the technologies for reducing pollutants from the source have attracted the most (and increasing) concern with many research directions, and that many of the studies in this field have focused on the regulation of fertilizer application. On the contrary, there is a lack of technologies in the fields of pollutant process interception and nutrient recycling. Promoting nutrient-use efficiency, regulating nutrient transformation, and using soil supplements will be the main entry points for non-point source pollution control for crop farming. Furthermore, technologies will operate better with the help of farmland infrastructure and downstream purification systems.

[Fabrication of La-MHTC Composites for Phosphate Removal: Adsorption Behavior and Mechanism].

Lanthanum (La)-based materials have shown great potential for phosphate removal owing to the strong affinity between La and phosphate. In this study, magnetic hydrothermal biochar immobilized La(OH)3 (La-MHTC) were prepared and used as phosphate adsorbents. Hydrochar was produced by the hydrothermal carbonization process (220℃, 2 h). Magnetic La-MHTC with different La-to-Fe mass ratios were synthesized by the co-precipitation method. Subsequently, La-MHTC was applied to remove phosphate from wastewater. Results indicate that La-MHTC (with a La-to-Fe mass ratio of 2:1) exhibited excellent magnetic properties for easy recovery and high phosphate adsorption capacity up to 100.25 mg·g-1. Effective phosphate removal was obtained over a wide pH range of 3-10. The absorption isotherm and kinetics were better fitted by the Langmuir model and the pseudo second-order model, respectively, which showed a fast adsorption rate and exhibited superior La utilization efficiency. The La-MHTC has strong selectivity for phosphate in the presence of coexisting ions (Cl-, NO3-, and SO42-). The adsorption-desorption experiment suggested its excellent stability and cyclic utilization. In addition, La-MHTC was applied to treat real domestic wastewater, efficiently reducing the phosphate concentration (from 0.87 mg·L-1 to 0.05 mg·L-1). Electrostatic attraction and inner-sphere complexation between La(OH)3 and P via ligand exchange were the main mechanisms of phosphate adsorption by La-MHTC.

[Effect of Applying Hydrochar for Reduction of Ammonia Volatilization and Mechanisms in Paddy Soil].

Hydrochar, as a product of the hydrothermal carbonization of biomass, has good application prospects for the NH3 volatilization reduction in rice fields due to its rich pore structure and functional surface. In this study, hydrochar was applied as a soil conditioner to paddy soil. A soil column experiment was conducted to investigate the effect of hydrochar on NH3 volatilization throughout the growth period of rice. The experiment was conducted with three treatments:CKU (control without hydrochar); SHC (sawdust hydrochar); and W-SHC (water-washed sawdust hydrochar). The application rate of SHC and W-SHC was 0.5% (w/w). The study investigated the effects of different hydrochars on the pH and concentrations of NH4+-N in floodwater, the flux and accumulation of NH3 volatilization, and the yield-scale cumulative emission of NH3 volatilization. Results show that the SHC treatment significantly reduces cumulative emissions of NH3 volatilization and the yield-scale cumulative emissions of NH3 volatilization (P<0.05), which were 32.42% and 47.61% lower than CKU, respectively. The effect of W-SHC on ammonia volatilization reduction was slightly weaker, as the cumulative emissions of NH3 volatilization and the yield-scale cumulative emissions of NH3 volatilization decreased by 10.14% and 27.71%, respectively, compared with CKU. The NH3 volatilization reduction was possibly related to the disturbance of pH and the decrease in NH4+-N concentrations in the floodwater because of the application of hydrochar. Compared with CKU, both SHC and W-SHC treatments reduced the pH and NH4+-N concentration in the floodwater. The impacts were more obvious in the rice base fertilizer period (BF) and the first supplemental fertilizer period (SF1) than in the second supplemental fertilizer period (SF2). The soil urease activity was significantly inhibited by hydrochar (P<0.05), and the abundance of soil ammonia-oxidizing gene (AOA, AOB) also significantly increased after application of SHC (P<0.05). This resulted in the enhanced efficiency of ammonia-oxidizing, which had an effect on the reduction of the NH4+-N concentrations in the floodwater. This study provides theoretical and experimental data support for the application of hydrochar in agro-environments with regard to ammonia volatilization reduction in paddy fields.

[Effect of Two Soil Synergists on Ammonia Volatilization in Paddy Fields].

Nitrification inhibitor and biochar are commonly used as soil synergists. Among them, nitrification inhibitor can increase crop yields and N use efficiency, while biochar is a relatively new way of using biomass resources and has certain adsorption characteristics. In order to reduce nitrogen loss and environmental pollution caused by ammonia volatilization in paddy fields, a pot experiment with chemical fertilizer application (CN) as a control was conducted to study the effects of biochar (B), nitrapyrin (CP), and compound application (BCP) on pH, NH4+-N concentration dynamics in the flood water, rice yields, and ammonia volatilization from paddy fields. The results showed that the application of these two synergists had no significant effect on rice yields, and the nitrification inhibitors had a tendency to increase rice yields. The two synergists significantly increased ammonia volatilization from paddy fields, accounting for 25%-35% of the total N rate. Ammonia volatilization during periods of fertilizer application accounted for 86%-91% of the total loss, representing the main period of ammonia volatilization. Compared with the CN treatment, the CP treatment increased NH4+-N concentrations in flood water and the loss of ammonia via volatilization, which was increased by 59.18% and mainly occurred during a week after the basal fertilization(138%) and spike fertilization (48%), and non-fertilization stage (78%). Biochar had a promoting effect on ammonia volatilization with typically phased characteristics. The initial increasing effect of biochar on ammonia volatilization was higher than during the later stages, when NH4+-N concentrations and the pH of flood water showed the same trend. In addition, the coupling of nitrification inhibitor and biochar significantly increased the total loss of ammonia via volatilization loss due to the promotion effect of CP and B. The problem of increased ammonia volatilization loss caused by the application of nitrification inhibitors requires further research.

[Effects of sewage irrigation on growth of rice seedlings and soil environment with straw incorporation.] / 生活污水尾水灌溉对麦秸还田水稻幼苗及土壤环境的影响.

The effects of sewage irrigation on the growth of rice seedlings and soil environment under wheat straw returning were examined with a pot experiment. Root morphology, root activity, tiller number, plant height, dry matter accumulation of rice seedling, soil ferrous ions content, organic acid content and enzyme activity were measured. The results showed that sewage irrigation significantly increased the number of tillers and root activity at 41 days after transplanting under no N fertilizer application. Under the same N input level, sewage irrigation combined with N fertilizer promoted the growth of rice seedlings and root, and increased the root length, root surface area, root volume, root activity, tiller number and dry matter accumulation. Sewage irrigation significantly reduced the contents of soil ferrous ions and organic acid, while significantly increased the activities of soil urease and catalase. These results indicated that the combination of sewage irrigation and N fertilizer could effectively reduce the negative effect of straw returning on rice seedling and thus enhance soil fertility and quality.

[Effects of Returning Nitrogen by Biochar Loading on Paddy Growth, Root Morphology, and Nitrogen Use Efficiency].

Building a nutrient channel between eutrophic water and agricultural fields could reduce nutrient input into fields and alleviate eutrophication by returning nitrogen. In order to determine the feasibility of returning nitrogen by biochar loading, a rhizobox experiment was conducted with two nitrogen applied methods, namely SN (applied nitrogen by nitrogen fertilizer solution) and BN (applied nitrogen by nitrogen-loaded biochar). The results showed that BN, in comparison with SN, decreased the biomass and nitrogen uptake of the aboveground paddy by 16% and 14%, respectively, increased biomass root-shoot ratios by 25%-27%, and reduced nitrogen recovery use efficiency. Two nitrogen application methods affected the length and volume of paddy adventitious roots. Paddy underground biomass and nitrogen uptake were positively correlated with soil ammonium content, whereas paddy aboveground nitrogen uptake was negatively correlated with root tips. It was suggested that the paddy biomass and nitrogen uptake would be influenced when nitrogen was applied solely by nitrogen-loaded biochar. However, no affinity and no significance in nitrogen use efficiency were found for plant uptake between chemical nitrogen and biochar-loaded nitrogen. Additionally, biochar promoted soil mineral nitrogen content for further plant uptake. Therefore, biochar could be used as the carrier for returning nitrogen from waterbodies to fields. The replacement rate of chemical nitrogen fertilizer is the key to influencing plant growth and needs future study.

[Control Effect of Side Deep Fertilization with Slow-release Fertilizer on Ammonia Volatilization from Paddy Fields].

In order to reduce the ammonia volatilization in paddy fields, seven treatments were evaluated. These included three slow-release nitrogen fertilizers[sulfur-coated urea (SCU); resin-coated urea (RCU); release bulk blending fertilizer (RBB)], two fertilization modes[single base fertilization (B) and combined with panicle fertilizer (BF)], and conventional split fertilization (CN). The effects of side deep fertilization for slow-release nitrogen fertilizers on ammonia volatilization and surface water nitrogen dynamics were examined using a rice transplanter with a fertilizer sowing mechanism in the Taihu Lake region. The results showed that total nitrogen and ammonium nitrogen concentration in the surface water of the SCU treatment in the base period were higher, and those for RCU and RBB were lower than in the CN treatment. The cumulative ammonia volatilization during the whole rice season varied among different types of slow-release nitrogen fertilizers from 3.84% to 28.17% of the total N applied. The nitrogen loss from ammonia volatilization using the three slow-release nitrogen fertilizers was decreased when compared with conventional split fertilization. The ammonia volatilization loss exhibited the following relationship for the treatments:CN, B-SCU > BF-SCU, BF-RBB, BF-RCU, B-RBB, and B-RCU. When the slow-release nitrogen fertilizers were applied in single base fertilization, the total ammonia volatilization for the SCU was significantly higher than those for the RCU and RBB, while no significant differences were detected when these three slow-release fertilizers were combined with panicle fertilizer. Moreover, although the ammonia volatilization of BF-SCU was lower than that of B-SCU, those of BF-RCU and BF-RBB were higher than those with the B-RCU and B-RBB treatments, respectively. There are no significant differences for nitrogen volatilization when any of these three different fertilizers are applied as B or BF. The results for the emissions during ammonia volatilization during different stages indicated that the ammonia volatilization of SCU at the basal-tillering fertilization stage (7.54%) and the tillering-panicle fertilization stage (16.04%) were higher than those of the panicle fertilization-mature stage. The N loss from ammonia volatilization for RBB in the base-tillering fertilization stage (2.91%) increased more than in the tillering-panicle fertilization stage and panicle fertilization-mature stage. For RCU treatment, the highest rate for ammonia volatilization was detected at the panicle fertilization-mature stage (2.75%). Compared with the single base fertilization mode, ammonia volatilization during the panicle fertilization-mature stage was increased when combined with panicle fertilizer (BF) for the slow-release fertilizer. There was no obvious correlation between the N loss with ammonia volatilization for the three slow-release nitrogen fertilizers and the concentration of ammonium nitrogen in surface water during the panicle fertilization-mature stage.