耕作措施对东北黑土微生物呼吸的影响

【目的】利用东北黑土13年保护性耕作定位试验,研究耕作措施（免耕和秋翻处理）对土壤微生物的影响,从土壤微生物角度分析免耕是否有利于土壤有机碳（SOC）的固定,为合理评价农田黑土碳“源”与“汇”功能提供科学依据。【方法】以连作玉米为研究对象,采用单因素随机区组设计,耕作处理包括免耕和秋翻。免耕除播种外不扰动土壤,秸秆覆盖地表。秋翻处理的田间管理包括人工除草、中耕起垄和秋翻,秋翻时将秸秆翻于地表之下。土壤微生物呼吸速率通过PVC环在野外采用动态气室法（Li-Cor8100）直接测定（去除植物根系）,定期监测土壤微生物呼吸速率的季节变化,并在土壤微生物呼吸速率最高的季节取样分析不同处理土壤微生物量碳和数量特征。【结果】生长季节内免耕和秋翻处理下土壤微生物呼吸速率分别为0.42-3.35和0.48-3.24 μmolCO₂·m^-2·s^-1,两处理平均值差异不显著（8.8%）,但土壤累积CO₂-C释放量免耕比秋翻高10.0%（2012）和4.3%（2013）（P＜0.05）。免耕显著地增加0-5 cm表层土壤细菌、真菌和放线菌的数量,分别比秋翻高125.7%、112.4%和53.3%;还显著地增加了其他土层的真菌数量,分别为105.3%（5-10 cm）,159.4%（10-20 cm）和114.7%（20-30 cm）。耕作处理影响土壤温度,主要体现在春季,秋翻（0-5 cm,5-10 cm）春季（6月）土壤温度比免耕分别高2.8%和5.8%。土壤微生物呼吸速率表现出显著的季节变化规律,与土壤温度具有相似的动态变化,夏季（7、8月份）最高,秋季较低。尽管耕作处理没有明显地影响土壤微生物呼吸速率的季节动态格局,但秋翻的土壤微生物呼吸最高值比免耕晚半个月。土壤微生物呼吸速率随土壤温度（5 cm和10 cm）呈指数型增长,10 cm处的回归模型明显好于5 cm。耕作处理只改变了5 cm的Q₁₀值,免耕比秋翻高10.8%。土壤微生物呼吸速率与土壤温度、水分混合回归模型能更好地反应其变化规律,解释土壤微生物呼吸速率变异的65%（秋翻）和81%（免耕）。【结论】免耕增加了表层（0-5 cm）的SOC含量,从而使得该土层的土壤微生物量碳和活性增加,但是由于免耕处理增加0-30 cm 土层SOC含量的加权平均值,因此相对于传统的耕作措施（秋翻）,免耕有利于SOC含量的增加。     

Effect of temperature on below-ground N-dynamics in a weedy model ecosystem at ambient and elevated atmospheric CO2 levels

Model multispecies terrestrial communities composed of four trophic levels (plants, herbivores, parasitoids, decomposers) were established in the Ecotron controlled environment facility. Two experimental runs enabled us to investigate the effects of enhanced temperature on below-ground microbial processes (N-mineralisation, urease, arginine deaminase, protease activity and potential denitrification) in both ambient and elevated (ambient +200 ppm) CO₂ atmospheres.The enzyme activities involved in nitrogen cycling showed weak responses to elevated temperature in both experimental runs. In the Ambient CO₂ Run, protease and arginine deaminase values tended to be lower in elevated temperature; on the other hand, N-mineralisation, urease and denitrification enzyme activity (DEA) were higher. In the Elevated CO₂ Run, all microbial variables showed higher activities at elevated temperature, although only the results for DEA and arginine deaminase were statistically significant. The interaction between higher temperature and elevated CO₂ weakly affected root growth and tissue C:N ratio, limiting feedbacks into the microbial community.Besides temperature and CO₂, substrate availability, water stress and successional development regulated the response of the soil microbes. The supply of organic carbon and nitrogen in the soil allowed plant growth and maintenance of the microbial population. Nitrogen competition between vegetation and microbes restricted net microbial growth. The increase of dissolved organic carbon (DOC) at higher CO₂ and temperature levels significantly favoured DEA. The high water regime in the soil also favoured DEA and inhibited oxidation of organic compounds, as indicated by low levels of enzyme activity. Additionally, water stress decreased rooting density in the soil; this resulted in negative feedback into microbial processes. We conclude that water stress and soil nitrogen deficiency caused an early levelling-off of both microbial population growth and activity rates during the early part of the model ecosystem's development.     

典型河源区畜禽粪便农田施用的环境承载力研究

畜禽粪便作为农业面源污染的主要来源之一,对农田土壤质量及河源区水质安全存在严重威胁.本研究选取东辽河源区东辽县畜禽粪便为研究对象,通过分析其重金属与典型抗生素与产生特征,阐明了畜禽粪便农田施用的环境承载力及应对措施.结果表明:畜禽粪便中重金属Cu、Zn含量最高,四环素类抗生素中金霉素残留最高,猪粪中含量高于鸡粪和牛粪....     

Winter legume and tillage effects on cotton growth and soil ecology

Field studies were conducted at 2 locations in Alabama during 1984 and 1985 to identify cultural practices which would improve cotton (Gossypium hirsutum L.) stands when plantned no-till into winter legumes. The soils were a Decatur silt loam (Rhodic Paleudult) and a Norfolk sandy loam (Typic Paleudult). The experimental design was a randomized complete block with 4 replications. Whole plots consisted of winter annual legumes (Vicia villosa Roth or Trifolium incarnatum L.) and fallow areas. Split-plot treatments established at cotton planting included conventional and conservation tillage, and fungicide. Soil samples were collected at cotton planting for population determination of Collembola and Acari species, and for estimation of cotton-disease fungus (Rhizoctonia solani) infestation. Collembola populations were greater in the Decatur than Norfolk soils, and higher in legume-mulched than fallow soils by 39 and 72% for the Decatur and Norfolk soil, respectively. Disease infestation in the Decatur soil was 10% higher in legume than fallow plots, and 18% higher in legume than fallow plots in the Norfolk soil. Cotton populations were 19% less in legume than fallow areas, and 25% less with conservation (no-till) than with standard tillage. Bedding improved cotton stands by 21% compared to conservation tillage. Seed-cotton yields from the Decatur soil were consistently high (3798 kg ha⁻¹, and there was no yield response to treatments. Maximum seed-cotton yields at the Norfolk site were achieved with conservation tillage in the fallow area, and conventional tillage in the legume area (both receiving fungicide).     

Land snail distribution patterns within a site: The role of different calcium sources

The aims of this study were to analyse whether land snail assemblage patterns reflect the gradient of calcium content on a very small scale within a site. We chose two sites differing in their calcium richness and source of the calcium. The “Tufa site” had abundant tufa in the soil, while the “Boulder site” was on chemically inert chert bedrock where calcium originated from vegetation. On each site a set of 20 quadrats from which snails were extracted was laid down in a line from the calcium rich patch to the calcium poorer surround matrix. At the both sites, available calcium contents of topsoil decreased significantly with samples' position from the patch centre. For the Tufa site, calcium content was a strong controller not only of species composition but also species richness, total abundance, and abundances of almost all species. At the Boulder site only species composition was significantly driven by calcium. Species composition was highly nested along calcium gradient at the Tufa site contrary to the Boulder site where the species had an almost random distribution. We conclude that the best predictor of species composition was in both cases content of carbonate calcium in topsoil. Topsoil pH was positively correlated with calcium content only at the Tufa site.     

1990-2015年乌苏里江流域土地覆被变化

[目的] 分析1990—2015年乌苏里江流域内中国和俄罗斯两国区域土地覆被变化特征和差异，为该流域内人地关系研究和土地资源管理提供科学参考。[方法] 以Landsat TM/OLI遥感影像为数据源，采用基于面向对象的遥感分类方法，提取乌苏里江流域1990年和2015年的土地覆被信息，分析乌苏里江流域土地覆被变化的主要特征。[结果] 1990—2015年的26 a间，乌苏里江流域内农田、湿地面积变化较为明显。农田呈扩张趋势，面积增加6 089.69 km²，增长率18.4%。其中，5 416.7 km²农田由湿地转化而来，农田扩张主要发生在中国境内区域。湿地、林地面积分别减少了5 683.51和844.09 km²，减少率分别为56.4%和3.51%。俄罗斯境内土地覆被变化作用强度较弱，各土地覆被类型间变化率均不超过2%。[结论] 气候、地形、农业宏观政策和农业生产方式等是推动乌苏里江流域土地覆被变化的影响因素；其中，农业生产方式的转变和规模的扩大是该流域土地覆被变化的最主要驱动力。     

磷肥对紫花苜蓿生产力影响的研究概述

随着畜牧业的发展,对苜蓿的种植生产提出了更高的要求。磷肥的有效利用是影响苜蓿生产力的关键因素之一。笔者系统概述了苜蓿缺磷的主要症状,不同地区施磷量和方法对苜蓿生产力的影响,施磷提升苜蓿生产力的途径,苜蓿的磷素吸收机制以及磷素与其他养分及水分互作对苜蓿生产的影响。建议今后针对不同地区的土壤理化性质,特别是有效磷含量,测土施肥,综合不同地区的结果建立气候-土壤-施肥模型,并进一步开展磷素促进苜蓿生长的生理和分子机制的研究,以期为苜蓿研究和产业发展提供有益信息。     

Species abundance distribution of collembolan communities in forest soils polluted with heavy metals

The species frequency of collembolan communities along a gradient of heavy metal pollution in soil of pine forest soils was studied. Sampling plots were established in forests 1, 3, 5, 8, 11, 68 and 148 km from the Miasteczko Śląskie zinc smelter. At each plot the plant associations, physicochemical characteristics of soil, and collembolan species composition and abundance were examined. The structure of collembolan communities was analyzed with regard to species distribution, testing geometric series, broken-stick, logarithmic series, log-normal and negative binomial distribution models. Most of the collembolan communities occurring both in contaminated and in uncontaminated soils had structure similar to a negative binomial distribution. In the samples from the oldest forest, the species frequencies could also be fitted to a log-normal distribution. The species frequency model was independent of the degree of soil pollution. Under the assumption of a negative binomial distribution of Collembola from soil samples, it is possible to estimate the theoretical number of collembolan species in the habitats studied. The difference between estimated and empirical numbers of species (the number of species not revealed in samples) was linearly correlated with metal concentrations in soil, indicating the elimination of a number of rare species from severely polluted forests.     

农业中专图书馆为“三农”培养技能服务型人才

农业中专图书馆为发展现代农业,在开放办馆中发挥专业特色和优势,主动为"三农"培养基层农业推广人才、技能服务型和农村实用型人才服务。     

不同施肥处理对膜下滴灌玉米光合特性和产量的影响

在膜下滴灌的条件下,研究有机无机肥配施对玉米光合特性及产量的影响。结果表明:有机无机肥配施可明显增加叶片叶绿素含量、蒸腾速率和气孔导度值,进而提高叶片的净光合速率。不同肥料处理下的玉米叶片叶绿素含量、净光合速率、蒸腾速率、气孔导度从大口期到成熟期呈现先升高后降低的趋势,最高值均在抽雄吐丝期,且随着玉米生育时期的推进,有机无机肥料配施与其他处理间的光合生理指标差异逐渐增大,有机无机肥料配施呈现出明显优势。叶片胞间CO2浓度的变化呈现先降低而后在成熟期略有升高的趋势,以对照处理含量最高,有机无机肥配施最低。不同处理的产量高低为M+NPK>NPK>M>ck。