Fluxes of nitrous oxide and nitric oxide from experimental excreta patches in boreal agricultural soil

Nitric oxide (NO) and nitrous oxide (N₂O) emissions were measured from experimental dung and urine patches placed on boreal pasture soil during two growing seasons and one autumn period until soil freezing. N₂O emissions in situ were studied by a static chamber method. NO was measured with a dynamic chamber method using a NO analyser in situ. Mean emissions from the control plots were 47.6±4.5 μg N₂ON m⁻² h⁻¹ and 12.6±1.6 μg NON m⁻² h⁻¹. N₂O and NO emissions from urine plots (132±21.2 μg N₂ON m⁻² h⁻¹ and 51.9±7.6 μg NON m⁻² h⁻¹) were higher than those from dung plots (110.0±20.1 μg N₂ON m⁻² h⁻¹ and 14.7±2.1 μg NON m⁻² h⁻¹). There was a large temporal variation in N₂O and NO emissions. Maximum N₂O emissions were measured a few weeks after dung or urine application, whereas the maximum NO emissions were detected the following year. NO was responsible on average 14% (autumn) and 34% (summer) of total (NO+N₂O)N emissions from the pasture soil. NO emissions increased with increasing soil temperature and with decreasing soil moisture. N₂O emissions increased with increasing soil moisture, but did not correlate with soil temperature. Therefore we propose that N₂O and NO were produced mainly during different microbial processes, i.e., nitrification and denitrification, respectively. The results show that the overall conditions and mechanism especially for emissions of NO are still poorly understood but that there are differences in the mechanisms regulating N₂O and NO production.     

和田市近30年来气温的变化及其对农业的影响

选取中国地面气候资料日值数据集中的和田地区1975--2005年的日平均气温数据资料,分析近30来和田市平均气温的年、季线性趋势变化和周期性的变化特征以及对农业生产的影响。近30年的气温总体呈现上升趋势,其变化率为0．48℃/10a,气温变化具有3年、22年和30年较稳定的周期。     

我国农副产品进入现代市场的问题与对策

针对我国目前农副产品流通渠道不畅和价格不稳的现实问题,分析了我国农副产品进入现代市场的关键制约因素。借鉴国外的经验和做法,提出了我国农副产品进入现代市场的相应对策。     

健全信息服务网络提高农业经济效益

文章简述了冀州市农业信息化建设中有关基础设施建设、网络延伸、开展信息服务方面的做法和体会.通过信息引导,推动了冀州市农业结构调整,提高了农业经济效益.     

产业融合与农业产业化的路径转换

近年来,伴随着数字技术的迅猛发展,不同产业的技术关联越来越紧密,跨产业企业间的大规模兼并与合作事件越来越多,产业边界逐渐变得模糊或消失,产业发展呈现出融合化趋势。农业与其他产业的融合化发展不仅拓展了农业经营理念,而且改变了农业经济的属性,使农业也具备了与其融合产业的功能和特征。大力推进农业与其他产业的融合,是实现农业产业化的新路径。     

论农业产业化的根本出路在于农业企业化

农业产业化是当前“三农”问题研究的重要内容之一。分析了农业产业化中存在的问题,即缺少企业家资源、缺少组织生产体系、缺少严格的质量控制体系、缺少品牌策划与市场营销、缺少竞争力、缺少科学发展观的指导、缺少企业化,最根本的是缺少价值链的链接;指出农业企业化的核心就是形成以利益为中心的产业链,在各个环节之间要形成以利润为润滑剂的产业链,也就是使产业链转化为价值链,这样的产业化才会有长远的生命力,而利润的来源在于市场、技术、管理、制度。结合南京远望富硒农产品有限责任公司案例,提出了8项对策,核心是农业产业化的根本出路在于农业企业化。     

基于ASP.NET的农情数据管理系统设计与实现

介绍了基于ASP.NET技术农情数据管理系统的需求分析、功能设计、数据设计、系统结构设计及开发过程。系统以.NET为技术平台,后台数据库为SQL Server 2000,开发语言为Visual C#.NET,实现包括自然条件、经济状况、社会情况、土地利用、植被信息等的管理与维护功能,可为农业生产管理与决策提供定量化的共享信息平台。     

对发挥农产品批发市场价格中心作用的探析

从国际经验来看,农产品批发市场不但是辐射面广、凝聚力强的产销中心,更是农产品价格形成中心.农产品批发市场的规范、有序运行对稳定农产品市场供求,引导农业生产顺利进行具有关键性的作用.而我国农产品批发市场由于发展滞后,运作方式原始、粗放,应有功能没有得到充分发挥.因此,加强基础设施建设,强化制度建设并实行农业产业化是进一步发挥农产品批发市场价格中心作用的关键措施.     

河北省主要农产品比较优势研究

针对新时期河北省农业结构调整的需要,选用规模优势、效率优势和综合比较优势等指数,运用要素比例分析法,对河北省主要农产品的比较优势进行了分析研究.结果表明,河北省的小麦和玉米等粮食作物以及花生、棉花等经济作物具有一定的比较优势;蔬菜和水果效益优势明显,综合比较优势高.河北省农业结构调整应稳定小麦和玉米面积,大力推广优质专用品种,缩减稻谷种植;油料生产应重点扩大花生种植面积,提高胡麻籽生产效率;稳定发展比较优势高的蔬菜和瓜果,开发稀特菜和绿色无公害特色产品,注重比较优势,提高经济效益.     

Soil erosion and redistribution on cultivated and uncultivated land near las bardenas in the central Ebro river Basin,Spain

The semiarid regions of Spain, including the central part of the Ebro River basin, are under threat due to desertification. Severe erosion, as a result of poor land management, has led to degradation of the soil resource, and there is a clear need for quantitative erosion rate data to evaluate the problem. This study aimed to examine the potential for using caesium-137 to identify the patterns and rates of soil erosion and redistribution within this semiarid environment. Samples for the determination of caesium-137 were collected from uncultivated slopes and cultivated valley floor sites near the head and outlet of a small representative basin in the Las Bardenas area. The measured patterns of caesium-137 mobilization, redistribution and export provide a semiquantitative indication of the variation in erosion within the study site. Calibration of the caesium-137 measurements, taking account of the differing behaviour of radiocaesium on cultivated and uncultivated land, allows estimation of the actual rates of erosion and deposition involved. The results show (1) the erosion rates on the cultivated land (1.6–2.5 kg m⁻² yr⁻¹) are typically more than five times those seen on the uncultivated land (0.2–0.4 kg m⁻² yr⁻¹), and (2) erosion on the uncultivated land is significantly less severe at the head of the basin than at the outlet. Study of the vegetation cover suggests that lower growing shrubs and grasses may be more effective in reducing erosion in this environment than trees.