甘薯测土配方施肥指标体系研究

为了解决过量施肥、盲目施肥、肥料利用率偏低等问题,本文通过大量的田间肥料试验,研究施肥指标体系,旨在更好地指导当地农民科学施肥。本文根据“3414”田间试验结果,将土壤养分含量水平划分为“丰富”、“中等”和“缺乏”3个等级,建立莆田地区甘薯土壤速效氮磷钾丰缺指标。结果表明,与甘薯相对产量75%~90%相对应的土壤碱解氮、有效磷和速效钾的丰缺指标临界值分别为85~128 mg/kg、10~24 mg/kg和42~115 mg/kg。通过肥料效应函数计算出的各试验点的推荐施肥量与相对应的土壤有效氮磷钾含量测试值之间呈指数回归关系,由回归方程得出,中等肥力水平下的推荐施氮量范围为114~168 kg/hm2,推荐施磷量范围为51-62 kg/hm2,推荐施钾量范围为159~323 kg/hm2。     

舟山海域水体中指示性多氯联苯的赋存状态

[目的]监测舟山东部及南部近海海域水体中7种指示性多氯联苯(PCBs)同系物的污染水平及分布特征。[方法]在舟山东部及南部近海海域选取8个采样点,共采集海水样品40个,进行PCBs残留检测及分析。[结果]PCBs在此海域有一定的残留,其总残留水平范围为0.185~27.200 ng/L,平均值为10.200 ng/L。40个海水样品中,共有34个样品检出PCBs,检出率为85%。7种同系物中共有4种被检出,检出率从高到低依次为PCB 28(77.5%)PCB 118(50.0%)PCB 110(10.0%)PCB 138(5.0%),而其余3种同系物(PCB 52、PCB 153和PCB 180)未检出。舟山近海水体中PCBs残留量较低,水质较好。[结论]该研究可为改善舟山渔场附近的生态环境和提高水产品质量提供一定的基础数据,有利于控制近海污染及评估海域生态安全。     

福州市行道树种综合评价与分级选择

城市绿化树种的选择与评价是城市美化与建设的关键,直接影响着城市绿地系统生态效益与综合功能的发挥。本研究在广泛调查的基础上,建立了由7个抗性功能指标、6个生态功能指标、5个美学性能指标、3个经济性能指标组成的城市行道树种综合评价指标体系,运用层次分析法及模糊综合评价法对福州27种主要行道树种进行综合评价,并运用最优分割分级法对参评树种进行分级,评价分级结果显示与福州市行道树种选择有着较高的一致性,从而为城市园林绿化树种的选择和应用提供科学依据。       

Identifying indicator species for post-release monitoring of genetically modified,herbicide resistant crops

In Europe, regulations for release and placing-on-the-market of genetically modified (GM) crops require post-release monitoring of their impact on the environment. Monitoring potential adverse effects of GM crops includes direct effects as well as indirect effects, e.g. GM crop specific changes in land and pest management. Currently, there is a gap in the pre-release risk assessments conducted for regulatory approval of GM herbicide resistant (HR) crops. Since the relevant non-selective herbicides have been registered many years ago, in current dossiers requesting regulatory approval of GM HR crops, the environmental impacts of the corresponding non-selective herbicides are either entirely omitted or the applicant simply refers to the eco-toxicological safety assessments conducted for its original pesticide approval that do not address environmental issues arising in conjunction with the cultivation of GM HR crops. Since the ‘Farm-scale Evaluations’, it is clear that consequences for farmland biodiversity can be expected. The objective of this project was to identify relevant indicator species for the long-term impact of GM HR maize cultivation and the application of their corresponding non-selective herbicides, glyphosate and glufosinate. In this article, we describe the outcome of a modified Event Tree Analysis, essentially a funnel-like procedure allowing to reduce the large number of potentially affected non-target species to those with greatest ecological relevance and highest risk to be adversely affected based on a number of ecological criteria. This procedure allowed us to identify a total of 21 weed-Lepidoptera associations that we proposed for post release monitoring of GM HR maize in Germany.     

大型土壤动物作为指示生物研究的现状与展望

土壤动物指示作用的研究已成为生态学研究的热点和前沿课题。该文着重对大型土壤动物作为指示生物的目地、意义和应用进行综述。     

木质活性炭自热过程指标气体产生规律研究

[目的]研究木质活性炭受热氧化过程指标气体的产生规律。[方法]利用程序升温对3种挥发分含量不同的木质活性炭进行加热氧化和尾气在线检测,并对其受热过程中指标气体产生规律进行分析研究。[结果]木质活性炭在受热升温氧化过程中会释放出H2、CO、C2H4和C2H2,当木质活性炭的挥发分含量较高时还会放出CH4指标气体。其指标气体产生规律为:当体系温度达100℃时,样品开始释放出H2;随着温度的升高,依次检测到其他气体,各样品C2H4在140～160℃、CO在160～180℃、C2H2在190～200℃时,分别被检测到;C2H2在体系温度为230℃释放量达最大值,其余各指标气体的释放量则随体系温度增大而增大。[结论]各指标气体随着相应官能团逐步活化而释放,并且前一指标气体释放时产生的热量为后一官能团的活化提供热量。     

土壤裂缝研究进展

土壤开裂是一个复杂的物理过程,裂缝形成对土壤性状、作物生长以及水分溶质运输均有重要影响。本文介绍了目前国际上土壤裂缝的表征指标体系及指标测定方法,并讨论分析了裂缝与土壤属性、裂缝发育与植被生长、裂缝形成与土壤入渗和溶质运输等方面的最新国际研究进展,在此基础上,对我国今后的土壤裂缝研究工作的方向和重点提出了建议。     

Mapping crop diseases using survey data: The case of bacterial wilt in bananas in the East African highlands

Globally, crop diseases result in significant losses in crop yields. To properly target interventions to control crop diseases, it is important to map diseases at a high resolution. However, many surveys of crop diseases pose challenges to mapping because available observations are only proxies of the actual disease, observations often are not normally distributed and because typically convenience sampling is applied, leading to spatially clustered observations and large areas without observations. This paper addresses these challenges by applying a geostatistical methodology for disease incidence mapping. The methodology is illustrated for the case of bacterial wilt of banana (BWB) caused by Xanthomonas campestris pv. musacearum in the East African highlands. In a survey using convenience sampling, 1350 banana producing farmers were asked to estimate the percentage yield loss due to bacterial wilt. To deal with the non-normal distribution of the data, the percentages were classified into two binary variables, indicating whether or not the disease occurred and whether or not the yield loss was severe. To improve the spatial prediction of disease incidence in areas with low sampling density, the target variables were correlated in a logistic regression to a range of environmental variables, for which maps were available. Subsequently, the residuals of the regression analysis were interpolated using simple kriging. Finally, the interpolated residuals were added to the regression predictions. This so-called indicator regression kriging approach resulted in continuous maps of disease incidence. Cross-validation showed that the method yields unbiased predictions and correctly assesses the prediction accuracy. The geostatistical mapping is also more accurate than conventional mapping, which uses the mean of observations within districts as the predicted value for all locations within the district, although the accuracy improvement is not very large. The maps were also spatially aggregated to district level to support regional decision-making. The analysis showed that the disease is widespread on banana farms throughout the study area and can locally reach severe levels.     

The analysis of ranked observations of soil structure using indicator geostatistics

Structure is an important physical feature of the soil that is associated with water movement, the soil atmosphere, microorganism activity and nutrient uptake. A soil without any obvious organisation of its components is known as apedal and this state can have marked effects on several soil processes. Accurate maps of topsoil and subsoil structure are desirable for a wide range of models that aim to predict erosion, solute transport, or flow of water through the soil. Also such maps would be useful to precision farmers when deciding how to apply nutrients and pesticides in a site-specific way, and to target subsoiling and soil structure stabilization procedures.

Typically, soil structure is inferred from bulk density or penetrometer resistance measurements and more recently from soil resistivity and conductivity surveys. To measure the former is both time-consuming and costly, whereas observations made by the latter methods can be made automatically and swiftly using a vehicle-mounted penetrometer or resistivity and conductivity sensors. The results of each of these methods, however, are affected by other soil properties, in particular moisture content at the time of sampling, texture, and the presence of stones. Traditional methods of observing soil structure identify the type of ped and its degree of development. Methods of ranking such observations from good to poor for different soil textures have been developed. Indicator variograms can be computed for each category or rank of structure and these can be summed to give the sum of indicator variograms (SIV).

Observations of the topsoil and subsoil structure were made at four field sites where the soil had developed on different parent materials. The observations were ranked by four methods and indicator and the sum of indicator variograms were computed and modelled for each method of ranking. The individual indicators were then kriged with the parameters of the appropriate indicator variogram model to map the probability of encountering soil with the structure represented by that indicator. The model parameters of the SIVs for each ranking system were used with the data to krige the soil structure classes, and the results are compared with those for the individual indicators. The relations between maps of soil structure and selected wavebands from aerial photographs are examined as basis for planning surveys of soil structure.     

土壤微生物量碳氮作为土壤肥力指标的探讨

通过对不同肥力水平黑土、棕壤、黄棕壤、红壤土壤微生物量碳氮的比较,研究和探讨土壤微生物量碳氮与土壤肥力的关系。结果表明:有机肥或无机肥施入土壤均能增加土壤微生物量C、N的含量,且有机肥与无机肥配合有显著的正交互作用。土壤微生物量C、N从北到南的地带性变化规律不强。BC/BN及TC/TN从北到南逐渐减小,BC/TC及BN/TN从北到南逐渐增加。相关分析结果表明:土壤微生物量C、N与全C、全N均呈极显著相关,可以作为指示土壤肥力的重要指标。