Nitrous oxide emission from a transplanted rice field in alluvial soil as influenced by management of nitrogen fertiliser

We investigated nitrous oxide (N₂O) emission from an irrigated rice field over two years to evaluate the management of nitrogenous fertiliser and its effect on reducing emissions. Four forms of nitrogenous fertilisers: NPK at the recommended application rate, starch–urea matrix (SUM) + PK, neem‐coated urea + PK and urea alone (urea without coating) were used. Gas samples were collected from the field at weekly intervals with the static chamber technique. N₂O emissions from different treatments ranged from 11.58 to 215.81 N₂O‐N μg/m²/h, and seasonal N₂O emissions from 2.83 to 3.89 kg N₂O‐N/ha. Compared with other fertilisers, N₂O emissions were greatest after the application of the conventional NPK fertiliser. Moreover, SUM + PK reduced total N₂O emissions by 22.33% (P < 0.05) compared with NPK during the rice‐growing period (P < 0.05). The results indicate a strong correlation between N₂O emissions and soil organic carbon, nitrate, ammonium, above‐ and below‐ground plant biomass and photosynthesis (P < 0.05). The application of SUM + PK in rice fields is suitable as a means of reducing N₂O emissions without affecting grain production.     

呼伦贝尔地区苜蓿人工草地CO_2通量变化特征

试验采用密闭箱技术对呼伦贝尔地区种植的苜蓿人工草地进行碳通量研究,采用反硝化-分解作用模型(DNDC)进行模拟。试验结果表明:对苜蓿人工草地CO2通量24h连续观测发现,CO2通量全天变化的平均值(238.15mg/(m2·h)与11∶00(245.32mg/(m2·h)的通量变化值接近,试验从早上9∶00~11∶00进行温室气体的采集方法合理、可行;在整个生长季变化表明,7、8月CO2通量变化较显著(P0.05),且受到降水的影响较大,伴随降水的发生,CO2通量会发生不同幅度的变化,土壤温度和含水量对CO2通量有一定的影响(r0.45,P0.05);通过DNDC模型的模拟,能较好的反映苜蓿人工草地CO2通量的变化情况,但模拟结果数值普遍有些偏高。     

Managing soil quality for humanity and the planet

Rather than a human-centric, the basic strategy of achieving Sustainable Development Goals must be focused on restoring and sustaining planetary processes. The urgency of meeting the demands of the humanity must be reconciled with the necessity of enhancing the environment. Increasing and restoring soil organic matter content of the degraded and depleted soils is critical to strengthening planetary processes.     

原子吸收光谱法检测大蒜制品中微量元素锗

[目的]研究不同大蒜制品中锗元素含量的差别。[方法]采用马弗炉灰化样品,火焰原子吸收光谱法测定以金乡紫皮蒜为原料加工而成的黑蒜、蒜蓉辣酱、脱水蒜片、蒜粉、糖醋蒜5种制品中锗的含量。[结果]试验表明,黑蒜中锗含量为1.384 mg/g,蒜蓉辣酱中锗含量为0.784 mg/g,脱水蒜片中锗含量为0.913 mg/g,蒜粉中锗含量为0.956 mg/g,糖醋蒜中锗含量为0.827 mg/g。5种蒜制品中均含有锗元素,其含量由多到少依次为黑蒜、蒜粉、脱水蒜片、糖醋蒜、蒜蓉辣酱。[结论]研究可为大蒜及大蒜制品的开发利用提供参考依据。     

Exogenous CaCl2 reduces salt stress in sour jujube by reducing Na+ and increasing K+, Ca2+, and Mg2+ in different plant organs

In this study, we investigated the effects of 10 mM CaCl₂ on membrane permeability, malondialdehyde (MDA), reactive oxygen species (ROS), and Na⁺, K⁺, Ca²⁺, and Mg²⁺ concentrations in different organs of sour jujube grown under 150 mM NaCl stress. Our results showed 73% leaf wilting in the Na treatment. The Na treatment significantly increased leaf superoxide (O₂^.?) production rates, hydrogen peroxide (H₂O₂) concentrations, cell membrane permeability, MDA concentrations, and Na⁺ concentrations in roots, stems, and leaves. The Na treatment significantly reduced K⁺, Ca²⁺,and Mg²⁺ concentrations in roots, but increased K⁺ concentrations in stems. Compared with the Na treatment, 39% of the leaves showed wilting symptoms in the Na+Ca treatment. The Na+Ca treatment significantly decreased leaf O₂^.? production rates, H₂O₂ concentrations, cell membrane permeability, and MDA concentrations. Moreover, the Na+Ca treatment (1) significantly reduced Na⁺ concentrations in roots, stems, and leaves; (2) significantly increased root K⁺ concentrations; (3) significantly increased K⁺/Na⁺ ratios in roots; (4) significantly increased Ca²⁺ concentrations in stems and leaves, and Mg²⁺ concentrations in roots. In conclusion, exogenous CaCl₂ reduces NaCl stress in sour jujube by reducing Na+ concentrations and increasing K⁺, Ca²⁺, and Mg²⁺ concentrations in various plant organs.     

Effects of cover crop growth and decomposition on the distribution of aggregate size fractions and soil microbial carbon dynamics

Although the effects of cover crops (CC) on various soil parameters have been fully investigated, less is known about the impacts at different stages in CC cultivation. The objective of this study was to quantify the influence of CC cultivation stages and residue placement on aggregates and microbial carbon (C_mic). Additionally, the influence of residue location and crop species on CO₂ emissions and leached mineralized nitrogen (N_min) during the plant degradation period was also investigated. Within an incubation experiment, four CC species were sown in soil columns, with additional columns being kept plant‐free. After plant growth, the columns were frozen (as occurs in winter under field conditions) and then incubated with the plant material either incorporated or surface‐applied. With CC, concentrations of large and medium macroaggregates were twice that of the fallow, confirming positive effects of root growth. Freezing led to a decrease in these aggregate size classes. In the subsequent incubation, the large macroaggregates decreased far more in the samples with CC than in the fallow, leading to similar aggregate size distributions. No difference in C_mic concentration was found among the CC cultivation stages. CO₂ emissions were roughly equivalent to the carbon amounts added as plant residues. Comparison of columns with incorporated or surface‐applied residues indicated no consistent pattern of aggregate distribution, CO₂ emission or C_mic and N_min concentrations. Our results suggest that positive effects of CC cultivation are only short term and that a large amount of organic material in the soil could have a greater influence than CC cultivation.     

基质分散萃取-高效液相色谱法对菠菜中噻虫胺残留的检测

研究确立了乙腈为分散萃取溶剂,以羧基化双壁碳纳米管(DWCNTs-COOH)和石墨化碳黑(GCB)为基质分散材料的菠菜(Spinacia oleracea L.)样品中噻虫胺残留基质分散萃取前处理方法,建立并优化了乙腈等度洗脱的HPLC残留样品外标定量方法。结果表明,优化色谱条件下,噻虫胺标准样品的色谱保留时间为6.258 min,在0.05~100 mg/L范围内与对应色谱峰积分面积线性响应良好,回归方程为y=4.948 2x-1.316 9(R~2=0.999 7),噻虫胺在菠菜样品中0.1、0.5和5.0 mg/kg 3个水平的添加回收率均在85%以上,各添加水平的相对标准偏差均小于7%,该色谱条件下仪器检出限为0.052 7μg/L,方法的最低检测量为0.015 mg/kg。表明该残留样本前处理方法和样品检测方法简便、高效、经济、可靠,可满足噻虫胺在菠菜中的残留定量检测要求。     

Efficacy of chlorine dioxide gas in reducing Escherichia coli and Salmonella from broiler house environments

Escherichia coli and Salmonella spp. are considered to be the major pathogens associated with human transmissible infectious diseases in the air of poultry houses. Chlorine dioxide (ClO₂) is an effective biocide against a wide range of microorganisms. Accordingly, this study investigated the efficiency of gaseous ClO₂ application for disinfecting broiler houses by collecting air samples before and after fumigation using a passive method. Fumigation was performed with 125 mL or 250 mL of ClO₂ liquid (containing 2,000 ppm of ClO₂) and 3 trials were conducted for each dose. A total of 27 petri dishes were used for each trial (for each type of bacteria: E. coli or Salmonella) and placed in 3 different locations (front, middle and back) and 3 different positions (top, middle and floor) of the broiler shed. Air samples were collected at 10 min, 1 h, 3 h, 6 h, and 12 h before and after fumigation to evaluate the air quality in terms of the concentration of E. coli and Salmonella. Both levels of ClO₂ were capable of reducing the concentration of E. coli from broiler house air during all measuring periods except 10 min, with highest disinfection rate being observed at 6 h. With the exception of 1 h, the concentration of Salmonella was also reduced after fumigation with ClO₂ in all measuring period; with the highest disinfection rate occurring at 6 h. Fumigation with ClO₂ had no negative effect on birds’ health condition. Taken together, these results suggest that the application of gaseous ClO₂ at the investigated levels can be an effective option for reducing bacterial load from broiler house environments.     

基于SVM的CFRW导电性建模预测研究

针对碳纤维增强木质复合材料（CFRW）导电性具有非线性的特点，采用基于支持向量回归机（SVM）的机器学习方法建立碳纤维增强木质复合材料导电性预测模型。结果表明，所建模型的预测精度高、泛化能力强.