氮营养水平对烤烟根际土壤酶活性及烟叶内在品质的影响

田间试验研究了不同时期烤烟根际各土层土壤酶活性变化规律及其不同施氮量对烟叶品质的影响。结果表明:0~20 cm土层范围内,施氮可以提高圆顶期、采烤期及采烤结束后土壤脲酶、转化酶的活性,但当施氮量超过52.5 kg hm-2时,脲酶、转化酶的活性反而降低;土壤蛋白酶活性均在37.5 kg hm-2处理达到最大值,且随着施氮量的增多大都呈现降低的趋势。20~80 cm土层范围内,土壤脲酶、转化酶、蛋白酶活性变化规律并不一致。对于烤后烟叶,施氮量为52.5 kg hm-2的烟叶,糖碱比、氮碱比、钾氯比均比较适宜,化学成分较为协调,燃烧性较好,有利于优质烟叶品质的形成。说明在该地区的试验条件下,水稻土种植烤烟最适宜的施氮量为52.5 kg hm-2。     

基于自然灾害系统理论的辽宁省玉米干旱风险分析

为了减轻旱灾对辽宁地区玉米生产的影响,该文通过对辽宁省23个气象站点46 a气象数据和气象站点所在县玉米产量、种植面积的分析,用实际干旱发生频率、农业气象干旱发生频率、玉米生产相对暴露率和单产水平等4个因素构建了辽宁地区玉米干旱风险指数,用社会科学统计程序(statistical program for social sciences)和地理信息系统(geographic information system)对辽宁地区玉米干旱进行了风险分析和风险区划。结果表明,辽宁省有30%的站点处于玉米干旱较高或高风险区,主要分布于辽西山地丘陵和辽南沿海地区;玉米干旱中等风险区主要分布在辽西走廊和辽中平原及渤海湾附近地区;玉米干旱低风险区主要分布在辽东山地丘陵地带。经检验50%以上站点的干旱风险指数与玉米相对气象产量显著相关。所构建的辽宁地区玉米干旱风险指数能客观地反应干旱对玉米生产的影响。该研究为玉米避灾和减灾管理提供科学依据。     

Exploring National Veterinary Information Outreach

The Medical Sciences Library at Texas A&M University (MSL) participates in the National Library of Medicine (NLM) National Network of Libraries of Medicine South Central Region (NN/LM) Regional Resource Library outreach initiative. This program generally funds regional outreach activities promoting NLM information resources. The MSL and veterinary library community recognized practicing clinical veterinarians as an underserved population. The 2013–2014 MSL outreach proposal combined traditional activities with the development of materials to assist veterinarians with NLM resources, and exhibit to a national audience. This article provides an overview of the NN/LM SCR Resource Library Outreach Awards, an overview of MSL outreach activities for the year, and lessons learned.     

Comparing the value of Southern Oscillation Index-based climate forecast methods for Canadian and US wheat producers

Southern Oscillation Index (SOI) based forecasting methods are compared to determine which method is more valuable to Canadian and US wheat producers. Using decision theory approach to valuing information, the more commonly used three-phase method of El Niño, La Niña, and other is compared to a five-phase system. Because of differences in growing season and yearly SOI classification schemes, two different three-phase methods are used. The five-phase system is based on the level and rate of change of the SOI over a 2 month period. Phases are consistently negative, consistently positive, rapidly falling, rapidly rising, and near zero. As expected, results vary by the method used. Winter wheat producers in Illinois place no value on either of the SOI-based forecasting systems. Producers at seven of the 13 sites prefer the five-phase method over either of the three-phase method (spring wheat producers in Manitoba, Alberta, North Dakota and South Dakota, along with winter wheat producers in Oklahoma, Texas, and Washington). The value of the five-phase approach is up to 70 times more valuable than the three-phase approach. Producers growing spring wheat in Saskatchewan and Montana, along with winter wheat producers in Ohio and Kansas value the three-phase approach more than the five-phase. In this case, the value of the three-phase system is up to two times more valuable than the five-phase system. Depending on expected price and region, the values of the SOI-based forecasts range from 0 to 22% of the value of perfect forecasts. In both absolute and percentage of perfect forecasts, producers in Oklahoma, Texas, Manitoba, Saskatchewan, and South Dakota value either system more than producers in the remaining regions. Economic value and distributional aspects of the value of climate forecasts have implications for producers, policy makers, and meteorologists. Finally, the results clearly suggest all producers will not prefer one forecast type. Forecasts need to be tailored to specific regions.     

A GIS based approach to modelling the effects of land-use change on soil erosion in New Zealand

Abstract. The problem of soil erosion is particularly evident in New Zealand, given the combination of coarse-textured soils, steep relief, high rainfall, and intensification of agriculture. A study was undertaken to assess the effects of land use change on soil erosion and sediment transport for the Ngongotaha catchment in New Zealand's North Island, using a GIS based decision support and modelling system. Model simulations considered the effect of increased catchment area under deer farming and forestry on the amount of sediment delivered to the catchment outlet, averaged over a period of six years. The simulations predicted that sediment loss from land under deer farming was considerably greater than from land under other livestock or forestry. Further model simulations testing best management practices demonstrated that sediment yield could be halved if deer farming was restricted to slopes under 20%.     

基于ARIS的农业信息采集平台需求分析方法

需求分析是信息系统工程的关键,随着农业信息化的发展,农业信息系统工程的需求定义和分析也逐渐得到重视。该文针对农业软件系统研制中经常发生的需求无法得到准确描述的问题,在农业信息采集平台的研制过程中引入ARIS需求分析建模方法。通过对农业信息采集平台的需求建模,研究了ARIS 5种视图在农业信息系统建模中的应用,采用EPC建立流程模型。最后结合软件研制实例分析了ARIS需求分析建模方法在农业领域应用软件研制中的优势。     

基于关联规则面向对象的海岸带海水养殖模式遥感识别

针对目前海水养殖模式遥感识别中的效率低,"同物异谱"、"异物同谱"和"椒盐"噪声等问题,该文研究了关联规则分类和面向对象相结合的养殖模式遥感识别方法,通过不同养殖模式的对象分割和关联规则的自动和智能获取,来构建海水养殖模式分类器。以高分一号PMS1卫星影像为数据源,把不同养殖模式对象的光谱、空间形态和纹理特征及其关联关系作为事务数据,使用Apriori算法挖掘类别作为后件的强规则,对粤东柘林湾养殖核心区内4种海水养殖模式(池塘养殖、网箱养殖、滩涂插养、浮筏吊养)水面信息进行提取。结果表明:基于关联规则面向对象的海水养殖模式分类精度能达到88.65%,比K-近邻法面向对象法精度提高了14.38个百分点,比关联规则挖掘分类法精度提高了12.16个百分点。关联规则分类和面向对象结合方法拓宽了传统逻辑推理分类方法中获取信息的途径,使分类更加自动化和智能化,且分类精度得到显著提高,可以成为海岸带海水养殖复杂模式识别的有效支持手段。     

科尔沁沙坨地-草甸地冻融期地温与最大冻结深度的变化规律

[目的]探究科尔沁沙坨地—草甸地土壤温度与冻结深度的变化规律,为合理指导该区农工生产和建设提供支持。[方法]基于2007—2015年冻融期人工观测数据,对比分析科尔沁沙坨地与草甸地冻融期多年土壤温度与最大冻结深度变化规律。[结果]研究区100cm处沙坨地与草甸地多年土壤温度的标准差变化规律基本一致,草甸地要小于沙坨地,但融解后期由于草甸地融解期历时较长,其标准差大于沙坨地;同时考虑土壤温度和土壤水分对最大冻结深度的影响时,沙坨地在200cm处和草甸地在140cm处的R2分别为0.959和0.788。[结论]研究区内沙坨地先冻结与先融解,沙坨地最大冻结深度较草甸地深,同时考虑土壤温度与土壤水分的最大冻结深度的拟合优度最好,沙坨地与草甸地中最大冻结深度与土壤温度和土壤水分均呈负相关关系。     

Characterizing Farmer Users and Nonusers of Mass Media as Channels of Agricultural Information in Benue State,Nigeria

This study characterized farmer users and nonusers of mass media as channels of agricultural information. A structured interview was used to obtain data from 316 randomly selected farmers in Benue State, Nigeria. The data were subjected to discriminant analysis and the following socioeconomic characteristics significantly differed at a 5% level of probability between users and nonusers of mass media (and their F-ratio values): education (6.30), income (5.12), gender (4.84), and socioeconomic status (4.83). Farmer users of mass media are therefore those who have good level of education, belong to a relatively high income bracket, and are typically male and of a relatively high socioeconomic status. Farmers’ socioeconomic characteristics should be considered in planning mass media usage in agricultural information dissemination.     

外文农业科技期刊时效性信息的开发利用

外文农业科技期刊在经二次文献数据加工后,存在着部分时效性信息未得到有效地利用的情况。对时效性信息进行开发利用,满足读者对外文期刊信息的多方面需求,是国家农业图书馆亟待解决的问题。在分析该馆馆藏外文期刊的时效性信息含量的基础上,提出了通过建立时效性信息数据库,同时结合网络揭示,个性化定制推送服务等方式对外文期刊的时效性信息进行开发利用,以期进一步提高国家农业图书馆馆藏外文期刊的利用效率。