2014年辽宁省猪瘟和蓝耳病疫苗临床使用效果调查

调查辽宁省养殖场常用猪瘟和猪蓝耳病疫苗临床使用效果,其中猪瘟脾淋苗和弱毒疫苗生产厂家共14家,猪蓝耳病疫苗生产厂家15家。调查内容:疫苗注射的安全性、疫苗免疫期内的有效性和抗体合格率。调查结果表明,各种疫苗的安全性和有效性良好,猪瘟疫苗免疫抗体合格率均在80%以上,猪蓝耳病疫苗免疫抗体合格率均在78%以上。     

地面机械系统的混沌学研究初探

分析了地面机械系统中相互作用过程的非线性特征，并对典型作业部件推土机铲刀所受法向力的混沌特性进行了量化分析。研究表明，地面机械系统中存在混沌现象。文中最后阐述了地面机械系统混沌学研究的意义及发展前景。     

新型曲柄连杆机构运动学模型的研究

提出一种用于内燃机的新型曲柄连杆机构,建立了该机构的运动学数学模型,并编制了计算机程序。根据程序输出结果对新型曲柄连杆机构的活塞运动规律进行了重点分析。结果发现,经过改进的新型曲柄连杆机构具有明显的活塞运动的非对称性,并简析了这种新特性有可能对内燃机工作过程产生的影响。     

The validation of a gully headcut retreat model in short-term scale based on an in-situ experiment in dry-hot valley

Purpose

How to predict gully erosion rates was one of the most important issues at present. A model implemented in the Channel Hillslope Integrated Landscape Development (CHILD) model based on the shape factor (S_f) of the plunge pools, which successfully predicted the headcut retreat rates over a long timescale. But whether this model was also valid in the short-term scale? What factors affected the prediction effects of the model? These issues still need evaluation.

Material and method

Four gully head plots with consistent initial topography and soil types were constructed for conducting in-situ scouring experiments with different flow discharges. Eighteen tests were conducted in each plot to monitor the plunge pool growth and headcut retreat rates using an unmanned aerial vehicle (UAV) to create high-precision topographic data.

Results and discussion

The topographic parameters of the plunge pools generally increased with scouring duration and were strongly correlated with the total runoff energy consumption (0.55 < R² < 0.92, P < 0.01). In contrast, headcut retreat was an intermittent process that suddenly migrated in a short time after relatively long stable periods lasting from 20 to 130 min. The relationships between the headcut retreat rates and total energy consumption were weaker than those with the plunge pools.

Conclusion

As the timescale shortened, the contribution of mass failure due to gravity to headcut migration significantly increased, leading to the pool effects of the model to influence the prediction of the gully headcut retreat rates, which assumed that flow hydraulics were the key dynamics.

     

Potential N mineralization and availability to maize in black soils in response to soil fertility improvement in Northeast China

Purpose

Understanding the soil nitrogen (N) mineralization potential (N₀) and crop N availability during the growing season is essential for improving nitrogen use efficiency (NUE) and preventing over-fertilization, which lead to negative environmental impacts.

Methods

Five black soils with different levels of fertility were selected in Northeast China. The N₀ and kinetics of these soils were estimated through laboratory experiments at different incubation temperatures (15, 25, and 35 °C). N mineralization dynamics were simulated using field soil temperature according to the incubation results. Moreover, the N uptake dynamics of maize were simulated according to the literature.

Results

Compared with the very low-fertility soils, the cumulative mineralized nitrogen increased under all incubation temperatures (15, 25, and 35 °C), by 48–136%, 8–61%, and 24–59%, respectively, in the medium- and high-fertility soils. The highest N₀ values (96.90, 115.31, and 121.33 mg/kg at the three different temperatures) were recorded in the very high-fertility soils. The soil N mineralization dynamics and N uptake of maize in the growing season were highly consistent over time, although the soil N supply could not meet the maize growth requirements. The higher the soil fertility, the lower the N fertilizer requirement.

Conclusions

Different fertilizer strategies were developed based on the cumulative mineralized N, N uptake by maize, and NUE in soils with different fertility levels. We suggested a reduction of 50–65 kg N/ha in N fertilizer in the two highest fertility soils. This study provided basic data to reduce chemical N fertilizer to improve NUE and reduce negative environmental impacts.

     

关于构建现代农业科研院所和谐劳动关系的几点思考

文章围绕构建现代农业科研院所和谐劳动关系进行研究,阐述了构建和谐劳动关系的基本内涵, 指出了构建和谐劳动关系对于农业科研单位的重要意义,重点说明了构建和谐劳动关系对于该院创新工程 顺利实施的重要意义。通过大量数据分析出中国农业科学院劳动关系及其调整的现状和发展趋势,指出多 元化、契约化、市场化、法制化、国际化的趋势为中国农业科学院和谐劳动关系的构建提出了更高的要求。 在综合分析的基础上,进而提出构建农业科研院所和谐劳动关系的基本思路和构建农业科研院所和谐劳动 关系的具体措施。     

精确农业背景下我国农业机械发展趋势

精确农业是世界农业发展的新潮流,是传统农业发展的必然趋势。为此,讲述了我国发展精确农业的必要性,并简单说明了国外智能农业机械的发展现状及趋势;分析了我国精确农业背景下的农业机械化发展存在的问题,对比国外精确农业的发展并结合我国基本国情,对我国新形势下的智能农业机械发展提出意见。     

环模式秸秆压块机的设计与性能试验

介绍了环模式秸秆压块机工作原理、结构设计及其性能试验。通过对环模式秸秆压块机关键部件进行设计,在不同的磨辊间隙下进行主轴转速与生产率、成型率以及单位能耗试验研究。结果表明：主轴转速增大,生产率增大,吨料能耗减小;但转速进一步提高,生产率会变小,吨料电耗增大;磨辊间隙过大,生产率减小,间隙过小,模辊磨损加剧。当磨辊间隙为5 mm、主轴转速为165 r/min时,压块机的生产率、吨料电耗和关键部件耐磨性都最优。     

可溶性盐对土壤pH测定的影响及消除初探

在我国大量施肥的背景下,最近几十年农田土壤酸化速率加快,尤其是设施栽培体系土壤。在淋洗强度较弱的情况下,土壤可伴随有次生盐渍化现象,而可溶性盐的存在对土壤p H(H2O)(用水浸提土壤测得的p H)的测定有显著影响。由于p H是酸化评估的重要指标之一,有必要深入探究农田土壤常见可溶性盐对p H(H2O)测定的影响。本研究中,为精确评估积盐农田土壤的酸化状况,以潮土、褐土、水稻土和红壤为研究对象,研究了农田土壤尤其是设施土壤中常见六种可溶性盐(Ca(NO3)2、KNO3、Mg SO4、K2SO4、Ca Cl2、KCl)对土壤p H测定的影响;并以硝酸钾为研究对象,对比分析了四种消除可溶性盐对p H(H2O)测定影响的方法,这四种方法分别为:用石灰位代替p H(H2O);用0.01 mol L-1Ca Cl2浸提代替水浸提;先用模型计算出盐分对p H(H2O)测定的影响,然后从p H(H2O)中减去;用蒸馏水或50℃的50%酒精溶液将土壤中可溶性盐洗除后风干再测定p H(H2O)。结果表明:10 g kg-1可溶性盐的存在可使土壤p H下降0.09~0.87个单位,可溶性盐浓度及土壤电导率(EC)均与p H、△p H(p H的下降程度)之间具有显著的自然对数相关性。同种土壤,不同盐类对p H测定的影响程度不同,强弱顺序因离子组成和土壤类型而异,总体表现为硝酸盐和氯化物对p H测定的影响高于硫酸盐,氯化钙的影响程度高于钾盐及硝酸钙和硫酸镁,三种钾盐之间差异不明显;同种盐类,四种土壤受盐分影响的程度强弱顺序为:褐土水稻土潮土红壤。四种方法均可以减弱或消除硝酸钾对p H测定的影响,6.9 g kg-1硝酸钾施入土壤中可使土壤p H下降0.24~0.71个单位,消除影响后,硝酸钾仅可使土壤p H下降-0.38~0.19个单位。四种方法的简单有效程度为:石灰位0.01 mol L-1Ca Cl2浸提测定p H模型拟合计算洗盐处理。消除可溶性盐对p H测定的影响可以使积盐的农田土壤酸化评估更为精确,使土壤酸化风险预测更为准确,有利于制定合理有效的风险应对措施。     

Ammonia oxidizers and denitrifiers in response to reciprocal elevation translocation in an alpine meadow on the Tibetan Plateau

Purpose

Global climate change, in particular temperature variation, is likely to alter soil microbial abundance and composition, with consequent impacts on soil biogeochemical cycling and ecosystem functioning. However, responses of belowground nitrogen transformation microorganisms to temperature changes in high-elevation terrestrial ecosystems are not well understood.

Materials and methods

Here, the effects of simulated cooling and warming on the abundance and community composition of ammonia-oxidizing archaea (AOA) and bacteria (AOB), as well as the abundance of denitrifiers, were investigated using quantitative polymerase chain reaction and clone library approaches, on the basis of a 2-year reciprocal elevation translocation experiment along an elevation gradient from 3,200 to 3,800 m above sea level on the Tibetan Plateau.

Results and discussion

We found that, compared with the temperature variations caused by elevation translocation, the soil origin exerted a much stronger influence on AOA abundance. There were significant effects of both soil origin and elevation translocation on AOB abundance, which was particularly decreased by elevation-enhanced (simulated cooling) and increased by elevation-decreased (simulated warming) treatments. Altered temperature affected the abundance of nirK rather than nirS and nosZ genes, and the latter two seemed to be associated tightly with the soil origin. Furthermore, the results showed that temperature changes had obvious influences on the community structure and diversity of AOB, but not AOA. More apparent response of AOB to warming than in other studies on grassland and forest ecosystems may be attributed to higher elevation and lower mean annual temperature in this study.

Conclusions

Our findings thus suggest that, in comparison with AOA and denitrifying populations, AOB may respond more sensitively to natural temperature variation caused by elevation translocation in this alpine grassland ecosystem on the Tibetan Plateau.