土壤侵蚀对生态系统的影响

每年在世界陆地生态系统中大约有750亿t的土壤被侵蚀掉。农用地土壤流失速率在13~40 t/(hm2.a)之间,因为土壤形成非常缓慢,这就意味着土壤流失速率是更新速率的13~40倍。降雨和风力是耕地或裸地的两个主要侵蚀营力,当土壤缺乏植被覆盖保护时侵蚀就发生了。土壤侵蚀造成水分、养分、土壤有机质、生物区系、土壤厚度等的流失或减少因而使土地生产力降低。土壤侵蚀加剧了由于人口的快速增长而带来的食物短缺问题的威胁。于是人们便开垦森林以弥补荒废的侵蚀农用地的损失。     

休闲农业-旅游新看点

从休闲农业产生的背景、内涵、条件和运营方式等方面分析了休闲农业发展的重要性和必然性,并介绍了休闲农业发展的前景。     

压力式谷物产量监测系统优化与试验验证

为了提高谷物收获作业过程中谷物产量在线监测的精度,研制了基于谷物流压力原理的车载谷物产量在线监测系统,该系统包括谷物流量监测装置、定位装置、割台高度控制开关、核心处理器以及人机交互装置。以谷物产量与谷物流压力间的谷物产量监测数学模型为指导,搭建了谷物产量监测试验台,采用Box-Behnken试验设计方法优化谷物流量监测装置结构参数,研究了传感器数量、传感器安装位置和监测装置水平倾角对谷物产量监测系统测产误差的影响,确定了最优参数组合为传感器数量5、传感器安装位置0.24 cm、监测装置水平倾角5°,并对最优参数组合进行了验证试验,结果表明,谷物产量监测系统测产误差为3.27%,满足谷物产量监测的精度要求。对谷物产量监测系统田间实际效果进行了试验验证,试验结果表明,田间测产误差为5.28%,生成的产量分布图为后续田间作业管理提供了决策依据。     

动定刀同轴水稻秸秆切碎还田装置结构设计与试验

针对中国南方稻田留茬高、土壤黏重,油菜栽种复式作业机耕整地作业部件易缠草、壅泥,影响作业质量和油菜出苗的难题,提出了将田间稻秸秆收集切碎并绕过耕作部件后均匀覆盖于播种行行间的种植方法,研发了多功能油菜覆草直播播种机,围绕该机器设计了一种动刀与定刀及风送叶片同轴安装的稻秸秆切碎装置,并分别对稻秸秆的"站秆"和"残茬"进行切碎台架试验。结果表明:喂入压辊转速、动刀转轴转速、动定刀间隙3个影响因素对切碎长度合格率、功耗影响显著;对"站秆"和"残茬"切碎的各因素取值为:喂入压辊转速399.2、401.64 r/min,动刀转轴转速968.12、977.23 r/min,动定刀间隙0.52、0.49 mm时,稻秸秆切碎合格长度率为95.78%、96.98%,功率损耗为3.09、2.68 k W。经整机田间试验,该装置的秸秆田间覆盖效果达到油菜种植农艺要求。该研究为多功能油菜覆草直播播种机产业化提供了技术参考。     

康集生态农场物流结构及氮素循环效率的研究

本文以氮素循环为例，详细分析了康集生态农场的物流结构和循环效率。结果表明，康集生态农场自开发建设以来，已初步建成以林果农种植、家畜家禽饲养、鱼类养殖为主的物流结构系统。系统的氮素产投比逐年上升，平均达到0.255，种植业有机氮与无机氮投入比为1.19，系统稳定性指数为0.98，第二性生产的氮素转化率达19.94%，有机废物利用总量含氮11934.5公斤。根据整个系统在氮素利用上的潜力和物流状况，本文提出了提高系统氮素利用效率和增强系统稳定性的途径与措施。     

面向21世纪的中国农业工程议程探讨

综述了中国2000～2030年瓶颈时期食物安全和农业水资源安全问题的各种预测;讨论了农业科技的对策;提出了实现中国农业现代化及贯彻国家生态环境建设规划(2000～2050)所需优先发展的农业工程科技领域。建议在这些优先领域,大力开展结合各个地区特定条件的国际合作研究和合资经营。开发、推广与实施先进适用型技术。指出这是获得未来潜在市场最高份额以及快速发展的途径。     

Carbon stocks and sequestration potentials of agricultural soils in the federal state of Baden‐Württemberg,SW Germany

Soil organic carbon (SOC) inventories are important tools for studying the effects of land‐use and climate change and evaluating climate‐change policies. A detailed inventory of SOC in the agricultural soils of the federal state of Baden‐Württemberg was therefore prepared based on the highest‐resolution geo‐referenced soil, land‐use, and climate data (BÜK200 inventory). In order to estimate the quality of different approaches, C inventories of the region were also prepared based on data from the National Inventory Report (UBA, 2003) and by applying the IPCC (1997) method to the two data sets. Finally, the BÜK200 inventory was used to estimate potentials of no‐tillage agriculture (NT) and peatland restoration to contribute to C sequestration and greenhouse‐gas (GHG)‐emission mitigation since both measures are discussed in this context. Scenario assumptions were change to NT on 40% of the cropland and restoration of 50% of cultivated peatlands within 20 years. On average, grasslands contained 9.5 kg C m^–2 to 0.3 m depth as compared to only 6.0 kg C m^–2 under cropland, indicating strong land‐use effects. The SOC content depended strongly on waterlogging and elevation, thus reflecting reduced C mineralization under aquic moisture regimes and low temperatures. Comparison of the BÜK200 inventory with the approach used for UBA (2003) showed high inconsistencies due to map resolution and SOC contents, whereas the IPCC method led to fairly good agreements. Results on the simulated effects of NT and peatland restoration suggested that 5%–14% of total agricultural GHG emissions could be abated with NT whereas peat restoration appeared to have a minor mitigation potential (0.2%–2.7%) because the total area of cultivated organic soils was too small to have larger impact.     

再造一个山川秀美的黄土高原——对黄土高原水土流失治理与生态农业建设的认识

<正>当从《陕西日报》上见到江泽民总书记在姜春云副总理《陕北地区治理水土流失,建设生态农业的调查报告》上的批示后.我所的科技人员心情待别激动.40多年来,我所科技人员坚持以黄土高原为重点开展水土保待科学研究,100余项科研成果获得了省、部级以上的奖励 近10余年来承担黄土高原综合治理国家科技攻关项目科研成果,获国家科技进步一等奖 有些科研成果已在治理工作中得到推广和应用.从科技实践中我们深切地体会到,江泽民总书记的批示完全符合实际、完全正确.我们通过科技攻关建立的安塞纸坊沟等小流域水土保持型生态农业实体示范模型,显示了黄土高原丘陵沟壑区严重退化的生态环境用20年的时间可以恢复,并走上良性循环的轨道.证明了只要依靠科学技术,坚持实施以生态效益为核心,社会和经济效益并举的综合治理方针和可持续发展战略,再造一个山川秀美的黄土高原的愿望一定能实现.     

Soil management problems in multiply cropped paddy fields in China

Summary Multiple cropping of paddy fields has now been widely adopted in East China, in order to increase annual grain yields. The management practices recommended for these multiple cropped fields include the use of mineral fertilizers in combination with organic manure, to sustain a better soil nutrient balance, the adoption of rice-straw manuring, and use of zero or minimum tillage. This paper presents the results of a series of longterm experiments in multiple cropping and discusses the problems associated with these techniques.