微生物群落在团聚体中的分布及耕作的影响

对水稻土微生物群落在不同粒级土壤团聚体中的分布以及耕作的影响,结果表明:细菌和真菌主要分布在粒级＜0.053 mm的粉砂与粘粒组分中,而在各粒级团聚体中的分布无显著差异.放线菌主要分布在粒级为0.053～0.2 mm的土壤微小团聚体中,在其它各粒级团聚体中的分布无显著差异.研究认为水稻土微生物群落在土壤团聚体中的数量分布受土壤团聚体结构的影响.细菌、真菌、放线菌都主要分布于小粒级的土壤组分中.垄作免耕稻田显著提高了耕层土壤微生物的数量,但对微生物的分布模式没有影响.

Abstract：

The present paper reports the distribution patterns of microbial community in soil water-stable aggregates of different sizes and the effects of tillage methods on them in a paddy soil. The results showed that the pattern of microbes in arable layer was: bacteria ＞ fungi ＞ actinomyce, that bacteria and fungi were mainly distributed in sand and silt particles of ＜0. 053 mm with no marked difference among aggregates of different sizes and that actinomyces were mainly distributed in 0. 053～0.2 mm soil aggregates. It is concluded that the distribution pattern of microbial community within soil aggregates was restricted by the structure of soil aggregates. Bacteria, fungi and actinomyces were mainly distributed in microaggregates. No-tillage ridge culture remarkably increased the number of soil microbes in the arable layer but had no significant effect on the distribution patterns of soil microbes.     

土壤硝化作用在团聚体中的分布以及耕作的影响

土壤团聚体是最重要的一种土壤结构体.在西南大学国家紫色土肥力定位监测点,研究了长期(18 a)垄作免耕和常规轮作两种不同耕作方式下,不同大小土壤团聚体中硝化细菌及硝化作用强度的分布模式.结果表明,不同团聚体中土壤硝化作用分布不同,耕作方式对其在团聚体中分布无明显影响.＞0.053 mm各粒级中,土壤硝化作用强度随团聚体粒径的减小而减小,而＜0.053 mm的粉砂与粘粒组分中也表现出较高强度;大团聚体(2.0～0.25 mm)中的硝化细菌数量明显高于微团聚体(0.25～0.023 mm),＜0.053 mm粒级硝化细菌也呈现出较高数量;团聚体中无机氮素(NH_4~+-N和NO_3~-N)和pH对土壤硝化作用影响较小,无明显相关规律.同时,垄作免耕有利于大团聚体形成,土壤结构好,且比常规轮作具有更强的硝化能力.

Abstract：

Soil aggregates are the most important structures of soil. This paper reports a study of the distribution patterns of nitrobacteria and nitrifying intensity in soil aggregates under conventional tillage (CT)and ridge tillage (RT) in an 18-year long- term field experiment. The result indicates that nitrification distribution patterns vary in different soil aggregates whereas tillage methods have no obvious effect on aggregates. For aggregates with a diameter ＞0. 053 mm, soil nitrifying capacity reduces with the reduction of the particle size, but the nitrification of silt and the clay (＜0. 053 mm) component is also fairly strong.The nitrobacteria content of large-sized aggregates (2.0～0. 25 mm) is higher than that of the microaggregates (0.25～0. 023 mm) and the number of nitrobacteria is also fairly great for the particle size ＜0. 053 mm. Nitrogen (NH_4~+-N and NO_3~--N) and pH have no significant influence on nitrification within aggregates and no distinct regularities can be detected. Ridging with no-tillage is advantageous to big aggregate formation, improves soil structure, and shows greater nitrification ability than convention tillage.     

Soil tillage methods by years interaction for dry matter of plant yield of maize (Zea mays L.) using additive main effects and multiplicative interaction model

The objective of this study was to assess soil tillage methods by years interaction for dry matter of plant yield of maize(Zea mays L.) grown in West Poland by the additive main effects and multiplicative interaction model. The study comprised four soil tillage methods, analysed in 12 years through field trials arranged in a randomized complete block design, with four replicates. Dry matter of plant yield of the tested soil tillage methods varied from 86.7 dt ha~(–1)(for no-plough tillage in 2005) to 246.4 dt ha~(–1)(for complete conventional tillage in 2012), with an average of 146.6 dt ha~(–1). In the variance analysis, 49.07% of the total dry matter of plant yield variation was explained by years, 12.69% by differences between soil tillage methods, and 10.53% by soil tillage methods by years interaction. Dry matter of plant yield is highly influenced by soil tillage methods by years factors.     

紫色土丘陵区不同种植模式下团聚体分形特征

选择紫色土丘陵区5种种植模式,分层(0～20,20～40 cm)采集土壤样品,对土壤团聚体分布、团聚体水稳性和分形特征进行研究.结果表明:不同种植模式下团聚体分布和水稳性差异明显,＞0.25 mm水稳性团聚体含量和团聚体稳定性指数(ASI)表明团聚体水稳性从高到低依次为自然生草地,横坡玉米,南方早熟梨+苜蓿,桑基+农作物,柑橘+鸭茅草;0～20 cm土层团聚体水稳性较20～40 cm团聚体高.湿筛后团聚体的分形维数(y2)与＞5 mm(x3),＞0.25 mm(x4)水稳性团聚体含量回归方程为y2=-1.186x3+0.636x4,相关系数达极显著水平.风干土团聚体分形维数与粉粒和粘粒含量呈正相关,而水稳性团聚体分形维数则与之呈负相关;有机质含量高的土壤结构较好,分形维数较小.因此,可以通过横坡耕作和农林复合经营提高土壤团聚体稳定性,减轻和防治水土流失.

Abstract：

Soil samples from different profiles (0～20 and 20～40 cm) were collected from 5 cropping patterns, and the distribution and water stability of soil aggregates and their fractal features were studied.The results indicated that aggregate distribution and water stability were distinctly different with cropping patterns. The content of ＞0. 25 mm water stable aggregates and aggregate stability index (ASI) were in the order of natural grassland, southern precocity pear + alfalfa, mulberry hedgerow intercropping, orange + Dactylis glomerata L.; aggregates from the 0～20 cm profile were more stable than those from 20 ～40 cm. The regression equation of the fractal dimension of aggregates after wet sieve (y2) and the content of ＞5 mm (x3) and ＞0.25 mm (x4) water stable aggregates was y2 =- 1. 186x3+0. 636x4, with a highly significant correlation. The fractal dimension of air-dry aggregates was positively correlated with the contents of silt and clay, but the fractal dimension of water stable aggregates was negatively correlated with them. Soils with higher organic matter content had better structure and lower fractal dimension. Therefore, soil and water conservation could be done through horizontal cropping and agriculture-forest management for such practices can enhance water stability of aggregates.     

Changes in organic C stability within soil aggregates under different fertilization patterns in a greenhouse vegetable field

Knowledge of the stability of soil organic C(SOC) is vital for assessing SOC dynamics and cycling in agroecosystems. Studies have documented the regulatory effect of fertilization on SOC stability in bulk soils. However, how fertilization alters organic C stability at the aggregate scale in agroecosystems remains largely unclear. This study aimed to appraise the changes of organic C stability within soil aggregates after eight years of fertilization(chemical vs. organic fertilization) in a greenhouse vegetable field in Tianjin, China. Changes in the stability of organic C in soil aggregates were evaluated by four methods, i.e., the modified Walkley-Black method(chemical method), ~(13)C NMR spectroscopy(spectroscopic method), extracellular enzyme assay(biological method), and thermogravimetric analysis(thermogravimetric method). The aggregates were isolated and separated by a wet-sieving method into four fractions: large macroaggregates(2 mm), small macroaggregates(0.25–2 mm), microaggregates(0.053–0.25 mm), and silt/clay fractions(0.053 mm). The results showed that organic amendments increased the organic C content and reduced the chemical, spectroscopic, thermogravimetric, and biological stability of organic C within soil aggregates relative to chemical fertilization alone. Within soil aggregates, the content of organic C was the highest in microaggregates and decreased in the order microaggregatesmacroaggregatessilt/clay fractions. Meanwhile, organic C spectroscopic, thermogravimetric, and biological stability were the highest in silt/clay fractions, followed by macroaggregates and microaggregates. Moreover, the modified Walkley-Black method was not suitable for interpreting organic C stability at the aggregate scale due to the weak correlation between organic C chemical properties and other stability characteristics within the soil aggregates. These findings provide scientific insights at the aggregate scale into the changes of organic C properties under fertilization in greenhouse vegetable fields in China.     

Soil Organic Carbon Sequestration Potential in Nectarine Orchards under Different Reclamation Systems

The Red Soil Hilly Region in South China, where there is a high capacity of carbon(C), and the land use and vegetation cover change greatly, is an important ecological area in the world, and has an important impact on the global carbon cycle and the seasonal fluctuation of atmospheric CO_2. To better evaluate the effects of reclamation systems in orchards converted from grasslands on soil carbon sequestration, we investigated soil organic carbon(SOC) content and stable C isotope(δ~(13)C)composition in three nectarine orchards at Yuchi Experimental Station in South China. Compared with the sloping clean tillage orchard and terraced clean tillage orchard, SOC content in the terraced orchard with grass cover was increased by 14.90% to 38.49%, and 7.40% to 15.33%, respectively. During the 14 years after orchard establishment, the soil organic matter sources influenced both δ~(13)C distribution with depth and carbon replacement. SOC turnover of the upper soil layer in the terraced orchard with grass cover(a mean 63.05% of replacement in the 20 cm after 14 years) was 1.59 and 1.41 times larger than that of the sloping clean tillage orchard and terraced clean tillage orchard under subtropical conditions, respectively. The equilibrium value of soil organic carbon in the three treatments ranged from 16.067 to 25.608 g/kg under the experimental conditions. The equilibrium value of soil organic carbon in the surface layer under grass cover was 54.801 t/hm~2, and the carbon sequestration potential was 24.695 1 t/hm~2.     

Improved soil characteristics in the deeper plough layer can increase grain yield of winter wheat

In the North China Plain(NCP), soil deterioration threatens winter wheat(Triticum aestivum L.) production. Although rotary tillage or plowing tillage are two methods commonly used in this region, research characterizing the effects of mixed tillage on soil characteristics and wheat yield has been limited. A fixed-site field trial was carried out during 2011–2016 to examine the impacts of three tillage practices(5-year rotary tillage with maize straw removal(RT); 5-year rotary tillage with maize straw return(RS); and annual RS and with a deep plowing interval of 2 years(RS/DS)) on soil characteristics and root distribution in the plough layer. Straw return significantly decreased soil bulk density, increased soil organic carbon(SOC) storage and SOC content, macro-aggregate proportion(R_(0.25)) and its stability in the plough layer. The RS/DS treatment significantly increased the SOC content, total nitrogen(TN), and root length density(RLD) in the 10–40 cm layer, and enhanced the proportion of RLD in the 20–30 and 30–40 cm layers. In the 20–30 and 30–40 cm layers, an increase in SOC and TN could lead to higher grain production than commensurate increases in the surface layer, resulting in a sustainable increase in grain yield from the RS/DS treatment. Thus, the RS/DS treatment could lead to high productivity of winter wheat by improving soil characteristics and root distribution at the deeper plough layer in the NCP.     

Influence of Conservation Tillage on Soil Aggregates Features in North China Plain

Tillage greatly influences the aggregation and stability of soil aggregates. This study investigated the effects of conservation tillage on soil aggregate characteristics. During a four-year study period （2001-2005）, soils were sampled from no-tillage （NT）, rotary tillage （RT）, and conventional tillage （moldboard tillage, CT） plots at the Luancheng Agriculture and Ecology Experimental Station in Hebei Province, China, and the amount, size distribution, and fractal dimension of the aggregates were examined by dry and wet sieving methods. The results indicated that NT significantly increased the topsoil （0-5 cm） bulk density （BD）, while RT maintained a lower BD as CT. Dry sieving results showed that NT had higher macro-aggregate content （R0.25）, and a larger mean weight diameter （MWD） and geometric mean diameter （GMD） than other treatments in the 0-10 cm layer, while RT showed no difference from CT. In wet sieving, results showed that most of the aggregates were unstable, and the MWD and GMD of water-table aggregates showed the trend of NT 〉 RT 〉 CT. At 0-5 cm layer, the fractal dimension （D） of water-stable aggregates under NT was lower than it was under RT and CT. At 5-10 cm, RT yielded the highest D, and showed stability. After four years, NT increased the aggregation and the stability of soil aggregates; while due to intense disturbance, the aggregation and stability of the upper layer （0-10 cm） under RT and CT decreased.     

Soil aggregation and aggregate associated organic carbon and total nitrogen under long-term contrasting soil management regimes in loess soil

This study investigated the effects of three contrasting soil management regimes and different nutrient treatments on the distribution of water-stable aggregates(2, 1–2, 0.5–1, 0.25–0.5, and 0.25 mm) and associated soil organic carbon(SOC) and total nitrogen(TN) content in loess soil. A 21-yr long-term experiment was performed, in which soil management regimes include cropland abandonment(Abandonment), bare fallow(Fallow) and wheat-fallow cropping(Cropping). Under Cropping, the following nutrient treatments were employed: control(CK, no nutrient input), nitrogen only(N), nitrogen and potassium(NK), phosphorus and potassium(PK), NP, NPK, and manure(M) plus NPK(MNPK). Results demonstrated that Abandonment significantly increased the content of soil macro-aggregates(0.25 mm) and mean weight diameter(MWD) at 0–10 and 10–20 cm soil horizons compared with Cropping, whereas Fallow yielded lower values of above two parameters. Abandonment increased SOC and TN contents in all aggregate sizes by 17–62% and 6–60%, respectively, at 0–10 cm soil layer compared with Cropping. Conversely, Fallow decreased SOC and TN contents in all aggregates by 7–27% and 7–25%, respectively. Nevertheless, the three soil management regimes presented similar SOC contents in all aggregates at 10–20 cm soil horizon. Only Cropping showed higher TN content in 0.5 mm aggregates than the two other regimes. Consequently, Abandonment enhanced the partitioning proportions of SOC and TN in 1 mm macro-aggregates, and Fallow promoted these proportions in micro-aggregates compared with Cropping. Under Cropping, long-term fertilization did not affect the distribution of aggregates and MWD values compared with those under CK, except for NPK treatment. Fertilizer treatments enhanced SOC and TN contents in aggregates at all tested soil depths. However, fertilization did not affect the partitioning proportions of SOC and TN contents in all aggregates compared with CK. Comprehensive results showed that different soil management regimes generated varied patterns of SOC and TN sequestration in loess soil. Abandonment enhanced soil aggregation and sequestered high amounts of SOC and TN in macro-aggregates. Long-term amendment of organic manure integrated with NPK maintained soil aggregate stability and improved SOC and TN sequestration in all aggregates in loess soil subjected to dryland farming.     

Tillage and Poultry Manure Effects on Soil Physical Properties,Nutrient Status,Growth, Dry Matter and Grain Yield of Sorghum

The effects of different tillage systems and poultry manure on soil physical properties, performance and nutrients in sorghum were studied for three years at Owo, southwest Nigeria. There was factorial combinations of herbicide-based zero tillage （ZT）, manual clearing （MC）, disc ploughing （P）, ploughing plus harrowing （P＋H） and ploughing plus double harrowing （P＋2H）, and two rates of poultry manure at 0 and 7.5 Mg ha^-1. Herbicide-based zero tillage and manual clearing reduced soil temperature and conserved more water than mechanized tillage techniques. Poultry manure reduced soil bulk density and temperature and increased soil water and porosity. There was a percentage decrease of leaf N, P, K, Ca and Mg concentrations, plant height, leaf area, stem girth, root dry weight, dry matter and grain yield in ascending order for herbicide-based zero tillage, manual clearing, ploughing, ploughing plus harrowing and ploughing plus double harrowing while percentage increases were recorded in a descending order for all the various combinations of tillage with poultry manure in that order. Poultry manure in combination with tillage increased dry matter and grain yield by 33.1 and 39.5%, respectively in comparison with tillage only. The manure-zero tillage methods increased dry matter and grain yield by 8% and 15%, respectively when compared with manure-mechanized tillage methods. Zero tillage or manual clearing in combination with 7.5 Mg ha^-1 poultry manure was most suitable for sorghum cultivation.     

《河北农业大学学报》创刊年代考

清光绪二十八年(1902)河北农业大学前身—直隶农务学堂诞生,经几易其名,于1958年更名为河北农业大学至今。清光绪三十一年(1905)直隶高等农业学堂时期创办了《北直农话报》,清光绪三十四年(1908)更名为《直隶农务官报》,中华民国七年(1918)改出《农学月刊》,中华民国十七年(1928)易名为《河大农刊》,中华民国二十三年(1934)更名为《河北通俗农刊》,中华民国二十四年(1935)易名为《河北农林学刊》,1948年更名为《河北农学院研究专刊》,1959年更名为《河北农业大学学报》至今。《河北农业大学学报》前身诸刊都与现时的《河北农业大学学报》有着一脉相承的历史渊源,各刊之间联系紧密,连续性、继承性强。因此,《河北农业大学学报》的创刊时间应追溯至1905年创办的《北直农话报》。     

生态旅游潜在客源市场特征的调查研究--以湖南永州金洞森林旅游开发为例

为探明客源市场生态旅游消费的潜在特征，采用问卷调查的形式，就长沙市居民对湖南金洞生态旅游开发的意向等问题进行抽样调查．结果显示，生态旅游符合人们“回归自然”的旅游新时尚，有着极大的开发空间，指出生态旅游的开发要注重环境保护和可持续发展．开发的产品要以休闲度假类的大众产品为主，开发生态旅游都市客源市场还要多种渠道并用，尤其是要注重媒体的宣传．     

浅谈饲料中有效能的测定技术

饲料中有效能是供动物生长发育的基础.不同动物所用的有效能体系不同,目前大多数动物采用消化能、代谢能体系,但随着研究的发展与深入,发现最能反映饲料有效能的是净能体系.无论哪种体系,采用合理的测定技术准确测定饲料中的有效能值显得尤其重要,通过对饲料有效能值的准确测定可以实现动物所需能量的精确供给,减少养殖成本,使经济效益最大化.文章综述了几种有效能评价体系的测定技术.     

高校贫困生认定工作面面观

国家贫困生资助政策实施以来,对贫困生帮助很大,同时在实际运行中还存在着一些问题。本文提出贫困生认定工作仍需要进一步采取各种相关配套措施,以推动和保障贫困生资助工作更好地开展。     

水牛梭形住肉孢子虫包囊抗原的纯化技术

应用萄聚糖凝胶柱层析对水牛梭形住肉孢子虫包囊包溶性抗原进行了纯化。结果表明：纯化水牛梭形住肉孢子虫包囊抗原的最适条件为：选用萄聚糖凝胶Ｇ—１００柱层析系统；洗脱液为０３ＭＰＢＳ（ｐＨ７２），床体积为１０ｃｍ×１６５ｃｍ，上样体积为５００ＨＬ；流速为１２ｍＬ／ｈ。纯化抗原可使琼脂凝胶双扩散试验的阳性检出率提高３０％。     

黑豆不同部分馏油的体外抗氧化性比较

[目的]通过体外抗氧化体系比较黑豆不同部分馏油抗氧化性活性。[方法]通过正交试验优化索氏提取黑豆馏油的最佳工艺,提取黑豆不同部分馏油;研究黑豆不同部分馏油对羟基自由基(·OH)、DPPH自由基(DPPH·)的清除能力。[结果]在样品浓度为1.0 mg/mL时,黑豆不同部分馏油对·OH的清除率分别为全豆馏油83.9%、豆黄(黑豆去皮部分)馏油64.8%、豆皮馏油17.3%,对DPPH·的清除率分别为全豆馏油41.3%、豆黄馏油33.2%、豆皮馏油77.9%。[结论]黑豆不同部分馏油均具有较好的抗氧化性,是良好的天然抗氧化剂。黑豆不同部分馏油对·OH的清除能力从大到小依次为全豆馏油、豆黄馏油、豆皮馏油,对DPPH·的清除能力从大到小依次为豆皮馏油、全豆馏油、豆黄馏油。     

山茱萸多糖提取工艺优化及马钱苷含量测定

采用L（934）正交设计试验,对山茱萸浸提液中山茱萸多糖的酶水解法提取工艺进行了优化研究,并对浸提液的中有效成分马钱苷含量进行了HPLC法分析。结果表明,山茱萸多糖浸提的最佳工艺为：液料比1∶5,浸提时间4 h,浸提温度80℃,果胶酶添加量0.55 g/L。用HPLC法测定出的山茱萸浸提液中马钱苷平均含量为0.512 ...     

施用SODm增效剂对水稻干物质积累及肥料利用率的影响

通过设置不同SODm增效剂施肥量梯度,研究SODm增效剂对提高肥料利用率和水稻干物质积累与转换的影响,结果表明SODm增效剂分别较普通肥处理和复混肥处理可显著提高肥料利用率6.8%和5.04%。施用SODm增效剂可以显著提高水稻抽穗前后干物质生产,以及抽穗后物质转运效率,相对于普通肥处理增产8.4%。     

动物疫苗接种异常反应的处理

动物疫病是畜牧业生产的大敌,要发展畜牧业生产就要防治动物疫病。但在疫苗接种时,经常出现正常反应外的其他不利于机体的反应,如废食、皮疹、休克、死亡等,正确处理或避开这些问题,对推行动物疫病的计划免疫,实施强制免疫,保护人畜安全具有十分重要的现实意义和作用。     

增强我国水果业出口竞争力的思考

分析了入世4年来,我国水果出口在量上实现了突破,但并没有实现质变的主要原因,指出我国水果业存在的问题。论述了引进外资对发展我国水果业的意义,并提出了具体可行的对策与建议。