化除宿营法建立人工草地研究

化除宿营法建植人工草地产草量高,建植第2年最高干物质产量达到23 270 kg/hm2。化除宿营法与化除免耕法建立人工草地在建植当年没有显著差异,但第2年化除宿营法比化除免耕法增产7 353 kg/hm2(P<0.01)。在草地建植当年和第2年,施肥对地上生物量没有明显影响。化除宿营法建立人工草地宿营强度达到4羊夜即可,第2年平均干物质产量达15 483 kg/hm2。在无人为干预的情况下,蒿类等不可食杂草迅速侵入,土壤肥力越高,扩散速度越快;不可食杂草比例超过50%后,草地基本没有利用价值,地上生物量也不再急剧下降。     

Nitrogen pools and turnover in arable soils under different durations of organic farming: II: Source‐and‐sink function of the soil microbial biomass or competition with growing plants?

The following parameters were measured on seven field plots at 3 sites which had been under organic farming for different periods of time: mineral nitrogen (N _min) contents, in situ net nitrogen mineralization (N _net), soil microbial biomass carbon (C _mic), and nitrogen (N _mic) contents, and extractable organic N contents. The measurements were conducted every three weeks from spring 1995/1996 to autumn 1997. The objective was to test whether, under organic farming: 1) temporal fluctuations of N_mic contents over the course of the year are indicative for a source‐and‐sink function for plant‐available N of the soil microbial biomass, and 2) temporal variations in N_mic content can be related with in situ N_net or plant N uptake. N_min contents gradually increased after ploughing in autumn until late winter. During intensive plant growth in spring, values rapidly declined. In situ N_net fluctuated only moderately and reached high values during intensive plant growth (May—July) as well as after soil cultivation in autumn. The C_mic and N_mic contents generally were low in winter, increased in spring and reached maxima in late spring or summer. In spring, the increase in C_mic contents preceded the increase in N_mic contents, resulting in elevated C_mic:N_mic ratios until shooting of winter wheat. This corresponds to an uptake of available soil nitrogen by the plants at the expense of soil micro‐organisms. The subsequent increase in N_mic contents, coinciding with high plant N uptake rates, indicates an enhanced, plant‐induced N mobilization at that time. Possible mobilization mechanisms are discussed. Soil microbial biomass exerted a source‐and‐sink function for extractable organic N on some of the field plots. Estimates of in situ N_net measurements were neither correlated significantly with soil microbial biomass N, N_mic flux, N_mic turnover, nor with plant N uptake. Lower N_mic turnover rates on 41 years versus 3 years organically managed fields indicate a stabilizing effect of organic farming on soil microflora.     

Decomposition of peat,biogenic municipal waste compost,and shrub/grass compost added in different rates to a silt loam

An incubation experiment was carried out to test the effects of biogenic municipal waste (compost I) and shrub/grass (compost II) composts in comparison to peat on respiration and microbial biomass in soil. The amounts of these three substrates added were linearly increased in the range of field application rates (0.5%, 1.0%, 1.5%, 2.0%). The sum of CO₂ evolved during the incubation was markedly raised by the three substrates and increased with the rate of substrate concentration. However, the percentage of substrate mineralized to CO₂ decreased with the addition rate from 103 to 56% for compost I, from 81 to 56% for compost II, and from 21 to 8% for peat. During the first 25 days of incubation, compost I enlarged the biomass C content, which remained constant until the end. In contrast, compost II did not raise biomass C initially. But at the end of the incubation, the biomass C content of all 4 compost II treatments almost reached the level of the respective compost I treatment. The increase was significantly larger the more of the two composts was added. In contrast to the two composts, the addition of peat did not have any significant effect on microbial biomass C. The average qCO₂ values at day 25 declined in the order compost I > compost II > peat, at day 92 the order was changed to compost II > peat > compost 1. This change in the order was caused by a significant decrease in qCO₂ values of the compost I treatments, a significant increase in qCO₂ values of the peat treatments and constant qCO₂ values in the compost II treatments.     

Distribution of Microorganisms,Biomass ATP,and Enzyme Activities in Organic and Mineral Particles of a Long‐Term Wastewater Irrigated Soil

The aim of the study was to elucidate the spatial distribution of soil microorganisms and enyzme activities in a long‐term wastewater treated soil. Soil was sampled from a plough layer of the Ah horizon of a sandy Haplic Luvisol which was either (1) irrigated with municipal wastewater for almost 100 years, or (2) no more irrigated since 20 years, or (3) never received wastewater. The samples were fractionated by wet sieving to obtain seven size fractions of organic and mineral soil particles, and a separate silt+clay fraction. The individual soil samples contained between 1.2% (never irrigated) and 4.1% (long‐term irrigated) organic particles by weight, but these particles harboured up to 47.8% of the total soil carbon and 41.7% of nitrogen, and thus represented an important storage of energy and nutrient for microorganisms. In total, however, the highest C and N amounts were accumulated in the silt+clay fraction, whereas coarser mineral particles which dominanted by weight in the Haplic Luvisol were low in C and N. The highest numbers of bacteria, actinomycetes and fungi per gram of the individual soil fractions were found in organic particles of the long‐term irrigated soil. Less nutrient‐dependent oligotrophic bacteria were for the most part associated with the silt+clay fraction, irrespective of the soil treatment with wastewater. Similar to microbial counts, also the ATP content, as a measure of active microbial biomass, and the activities of β‐glucosidase, β‐acetylglucosaminidase, and proteinase were higher in the long‐term irrigated soil than in that which was never irrigated. In most cases slightly enhanced values of microbiological and biochemical parameters were still detectable 20 years after the wastewater irrigation was terminated. The values of the individual parameters decreased in all soil samples under testing in general gradually with decrease in size of the organic soil particles. In conclusion, the coarse soil organic particles > 5 mm and the silt+clay fraction < 0.05 mm represent the sites with the highest microbial inhabitance, ATP contents and enzyme activities in the Ah horizon of an Haplic Luvisol. Long‐term wastewater irrigation resulted in an increase of microbial counts, total biomass and soil enzyme activities.     

A microplate assay to measure soil microbial biomass phosphorus

Quantification of phosphorus (P) concentrations in microbial biomass is required to better understand how P immobilization and turnover in soils are controlled by environmental and anthropogenic factors. Soil microbial biomass P (MBP) is generally extracted using the chloroform fumigation-direct extraction procedure and then analysed for P using the ammonium molybdate-ascorbic acid method on a flow injection analysis (FIA) system. Our objective was to determine whether a microscale malachite green method on a microplate system would provide as accurate MBP analysis as the ascorbic acid method on an FIA system. Twelve soils were collected from agricultural fields in southwestern Quebec, fumigated with chloroform and extracted with 0.5 M NaHCO₃ (pH 8.5). The dissolved inorganic phosphorus (DIP) concentration in fumigated soils was not affected by the method of analysis, and results from the two systems of analysis were significantly correlated (r =0.998, P <0.05). The MBP concentrations in these agricultural soils were between 0.36 and 60.05 g P g^–1, consistent with other published values. Our results indicate that MBP can be assessed equally well with the malachite green method using a microplate system as with the ascorbic acid method on an FIA system. The microplate system is rapid and requires smaller volumes of samples and reagents than the FIA system, thus reducing the quantity of waste produced. We conclude that the microscale malachite green method could be applied to measure the MBP concentration in a wide range of soils with good sensitivity, reproducibility and accuracy.     

小球藻粉水热催化液化制备生物油

为探索新型生物质燃油的开发,该文以小球藻粉为原料,采用水热催化液化方法制备生物油。研究了液化温度,液化时间,催化剂等因素对液化率的影响,在此基础上采用正交试验,以液化率为指标,探讨了生物油优化的制备工艺;利用傅里叶红外光谱(FTIR)和气相色谱-质谱联用(GC/MS)技术分析了小球藻粉生物油的基团结构与组成。结果表明,小球藻粉优化的液化反应条件为:采用质量分数5%的Ce/HZSM-5为催化剂,在300°C水热条件下催化液化20min,小球藻粉和溶剂料液比为1:10g/mL,液化率达39.87%。在此条件下制备的小球藻粉生物油的主要成分为醇类,酯类以及部分碳氢化合物,热值达26.09MJ/kg。和传统木质纤维素类生物质相比,小球藻粉制备的生物油成分更接近传统化石燃油且热值更高,显示了良好的应用前景,为微藻生物质液体燃料的制备提供参考。     

生物质固化成型制品表面裂纹试验研究

针对目前生物质热压成型制品表面易出现裂纹及变形现象,通过试验研究了裂纹形成的影响因素,并结合相关研究成果探讨了裂纹形成的根本原因。结果表明:含水率和进料速度等因素影响裂纹的形成;挤压中材料屈服强度后的塑性流动过程产生的剪应力是裂纹形成的根本原因;保型筒对于减少裂纹的功用主要作用于成型过程的塑性流动阶段。     

甘南草地地上生物量的高光谱遥感估算研究

为了促进高光谱分辨率遥感技术在草地畜牧业动态监测和遥感估产中的应用,选择甘南草原为研究区,通过野外观测,测量了天然牧草的冠层高光谱和地上生物量数据,分析了4种主要草地类型的冠层光谱曲线特征,并分析了地上鲜生物量与冠层反射光谱和一阶微分光谱之间的相关关系,构建了光谱特征参数作为变量,建立了甘南草原牧草地上鲜生物量的高光谱估算模型,并对模型进行检验,结果表明：特征参数D723的对数回归模型,不仅相关系数较高,而且均方根和相对误差都较小,因此,估算精度较高,可作为甘南草地地上鲜生物量的最佳高光谱估算模型。     

大力发展“第二代生物燃料”

办为满足国民经济高速持续发展对新型能源日益增长的需求,适应改善我国能源消费结构、节能减排、发展低碳经济的需要,加快发展生物质能源是一项战略选择。文章阐述了大力发展新兴生物燃料产业具有的重大经济社会意义,提出以大批粮食、食用油为原料生产生物燃料,是第一代生物燃料,在我国发展中遭遇到不可逾越的障碍。认为大力发展第二代生物燃料,即纤维素燃料乙醇和木本油料生物柴油具有多种优越性,将开辟我国生物燃料持续发展的广阔途径,特别是开发利用广袤的“边际性土地”,即开辟最普遍、最丰富的生产生物燃料的资源,既可改善生态脆弱地区的生产与生活环境,还可点燃农业农村新经济增长点,有利于解决“三农”问题,效用重大。最后提出我国发展生物燃料的五条必要措施,包括：大力开发广袤的“边际性土地”;尽快攻克纤维素燃料乙醇的技术难关;建立健全生物燃料能源市场体系,以市场机制优化资源配置;建立专业生物能源资源产销合作社,建立社会化服务体系;加大财政扶持力度,把发展第二代生物燃料列入国家“十二五”经济社会发展规划。     

锡林郭勒不同草原类型群落生物量及多样性研究

物种多样性和生物量是表征草地生态系统数量特征的两个重要指标,深入探讨物种多样性和生物量的变化,为草原生态系统的物种保护和生产力维持提供理论依据.本文以锡林郭勒草原为研究对象,利用样方法对草甸草原、典型草原和荒漠草原三种草原类型的植被特征进行调查,分析不同草原类型植被的地上生物量和物种多样性变化及二者与环境因子之间的关联...