密集化学农业下热带变性土中的微生物种群、活性及基因丰度

There are increasing concerns on the environmental impacts of intensive chemical agriculture.The effect of high agrochemical inputs used in intensive chemical farming was assessed on soil microbiological,molecular and biochemical properties in tropical Vertisols in India.Farm field sites under normal cultivation of arable crops using high inputs of fertilizers and pesticides in chili(Capsicum annum L.,5.0× dose for fertilizers and 1.5× dose for pesticides over normal inputs) and black gram(Vigna mungo L.Hepper,2.2x dose for fertilizers and 2.3× dose for pesticides over normal inputs) were compared with adjacent sites using normal recommended doses.Organic carbon and basal respiration showed no response to high inputs of fertilizers and pesticides in soils of both crops.Labile carbon decreased by 10% in chili soils and increased by 24% in black gram soils under high input farming system.The proportion of soil labile carbon as a fraction of soil organic carbon was unaffected by high inputs.The labile carbon mineralization coefficient(qM_(LC)) increased by 50.0% in chili soils,indicating that the soil microorganisms were under stress due to high agochemical inputs,whereas qM_(LC) decreased by 36.4% in black gram soils.Copiotrophs increased due to high inputs in soils of both chili(63.1%) and black gram(47.1%).Oligotrophs increased by 10.8% in black gram soils but not in chili soils.The abundance of amoA gene reduced by 39.3% in chili soils due to high inputs and increased significantly by 110.8% in black gram soils.β-Glucosidase also increased by 27.2% and 325.0%,respectively.Acid phosphatase activity reduced by 29.2% due to high inputs in chili soils and increased by 105.0% in black gram soils.The use of high agrochemical inputs thus had adverse consequences on biological health in chili but not in black gram soils.In soils cultivated with black gram,the moderating effect of cultivating legumes and their beneficial effect on soil health were evident from the increase in soil labile carbon,lower qM_(LC),higher amoA gene and enzyme activities.Overall results showed that cultivation of legumes permits intensive chemical farming without deteriorating soil biological health.     

沈阳市农业资源利用效率的研究

现依据比值分析理论计算了2001~2006年沈阳市耕地、化肥、水资源以及其它主要农业资源的消耗系数,以此评价该地区资源的利用效率。结果表明:2001~2006年沈阳市耕地资源、电力资源的消耗系数整体呈波动性下降趋势,农业生产效率显著提高;化肥、农药、农膜、农用机械、柴油资源消耗系数有不同程度的增长,资源的利用效率有所降低,因此沈阳市在提高农产品产量和农业主要资源利用效率的同时,应对化肥等化学产品的投入加以控制,减少资源的浪费,以实现农业的可持续发展。     

Near‐surface paleosols in coastal sands at the outlet of Hadera stream (Israel) in the light of archeology and luminescence chronology

Catenary changes, archeology, micromorphology, and magnetic mineralogy of paleosols in coastal sands, Israel, were investigated under chronostratigraphic control by available luminescence datings from adjacent sites. At the outlet of Hadera stream, eolianites (Hebrew: “kurkar”) underlie paleosols with Epipaleolithic (approx. 17–20 ky) artifacts at the top and occasional Mousterian (>40 ky) artifacts in the subsoil. The optically stimulated–luminescence/infrared stimulated–luminescence (OSL/IRSL) dates (>50–12 ky) from adjacent sites roughly agree with the archeological findings. The paleosols show a magnetically depleted Vertisol superimposed on a magnetically enhanced cumulative Chromic Luvisol (WRB) (USDA: Rhodoxeralf, Israeli class.: Hamra). The latter contain approx. 0.25 mm thick, isotropic clay infillings distinctly separated from the soil matrix. These infillings are tentatively interpreted as the result of strong environmental disturbances, such as surface desiccation, subsequent waterlogging, and enhanced dust deposition, presumably at the time of the Last Glacial Maximum. In addition to the massive accumulation of eolian dust, diverse pedogeomorphic changes lagging in time from the onset of climatic deterioration may have taken place in coastal settings. Recurrent desiccation cracks may have exposed subsurface materials repeatedly to sunlight, consequently resetting the luminescence signal. The eolianite sequences are thus distinct from loess/paleosol sequences from temperate climates and have to be treated more rigorously at a site‐specific level.     

“豆—稻—菜”循环耕作模式及应用效果

阐述了“豆-稻-菜”循环耕作模式的应用效果与应用前景,该模式实行粮经作物多茬轮作和水旱轮作的办法．不仅能有效提高经济效益和社会效益,还能改善生态环境．具有良好的生态效益,适于我国东南沿海周年三熟地区推广。     

南方丘区两熟制稻田保护性耕作的稻田生态效应

本文针对四川省两熟制稻-麦（油）秸秆资源丰富,但处理难的现状,研究了在稻田保护性耕作技术体系下,秸秆还田种类（麦秸、油莱秸）和还田数量（全量、半量）的稻田生态效应。结果表明,麦秸、油莱秸全量还田增产效果明显,分别比对照增产4．84％、6．20％;秸秆还田节水效益不明显,麦秸水分生产效率未得到改善,油莱秸还田水稻水分生产效率增加,油全、油半处理灌溉水分生产效率、水分生产效率分别比对照高0．048、0．045、0．039、0．032;秸秆还田能有效培肥土壤,土壤全N、P、速效养分及微量元素含量显著提高,其中土壤速效氮麦全、麦半处理分别增加14．5、18．1mg／kg;此外,秸秆全量还田投入／产出值高,具有显著的经济效益。因此,稻田保护性耕作技术为秸秆的高效循环利用提供了有效途径。     

培育农机融资租赁市场对农业机械化发展的作用

分析了农机融资租赁的市场潜力、发展环境及实施的合理性,指出开展农机融资租赁业务,对于解决农机投入不足,降低农机使用成本,拉动农机需求,推进农业机械化进程具有积极的作用。提出了培育和扶持农机融资租赁市场的措施。     

劳动力价格上升、要素替代与要素投入结构变化 ——来自中国大豆生产的证据

为了探析劳动力价格上升背景下非三大主粮粮食作物要素投入结构的变化情况,文章采用1991—2018年中国大豆生产要素价格和要素投入的相关数据,基于超越对数成本函数,运用似不相关回归估计我国大豆生产成本份额方程,并测算要素需求弹性和替代关系。研究结果表明:在我国大豆生产中,劳动力和化肥需求缺乏弹性,机械需求富有弹性但有减弱趋势;机械、化肥和劳动力之间存在两两替代关系,其中机械与劳动替代关系最强,化肥与劳动替代关系最弱;机械对劳动的替代关系有下降趋势,化肥对劳动的替代关系有上升趋势。因此,建议通过以下方式优化我国大豆生产要素投入结构:1)通过农机具购置补贴等政策进一步促进大豆生产机械技术推广,降低生产成本;2)用地与养地相结合,统筹作物轮作和种植业结构调整,加强技术攻关,加大大豆生产机械技术研发和推广;3)兼顾化肥利用效率和生态收益,优化肥料施用种类,采用生物和物理方式来代替部分化学肥料,借助机械和“外包”服务优化施肥方式。     

能量高效的事件驱动型大规模农业监测WSNs协作式传输策略

针对农作物分布广泛、农业环境恶劣的特点,利用协作式多输入多输出技术具有的低能耗、高可靠特性,结合事件驱动型农业监测的无线传感器网络,提出了能量高效的基于空时分组码的多跳协作式多输入多输出传输策略。该策略建立了包括节点剩余能量、最优跳距等因素的综合多跳路由;此外,还建立了精确的能耗模型,确定了满足网络最小能耗时的协作节点个数和最优跳距。仿真结果表明,通过能耗模型求出的最优跳距和协作节点个数减少了能量消耗;同现有的无线传感器网络中具有能量效率和事件聚类的自适应路由协议相比,提出的传输策略能显著地提高能量有效性和延长网络寿命。     

农业保险会影响农户农药施用吗？——来自4省粮农的生产证据

为探究农业保险对农户农药施用行为的影响,采用2015年黑龙江、河南、浙江、四川4省1 039户粮农调研数据,以地块为研究对象,实证分析农户参保行为对农药施用的影响。结果显示:参保地块的农药施用次数显著低于未参保地块。利用工具变量(IV)及倾向得分匹配(PSM)控制内生性后结果不变。表明,参保行为抑制了农户施用农药。但就估计系数来看,参保地块农药施用次数减少约0.25～0.75次。说明我国现行的"低保障、广覆盖"粮食作物保险制度能在一定程度上抑制农药的施用,但抑制作用有限。长远看,伴随粮食保险保障水平提高,这种抑制作用可能会进一步彰显。这意味着农业保险除能实现分散农业风险的政策目标外,还对减少农药施用产生积极影响。     

中国农田氮肥投入和生产效率

过去40年,中国氮肥用量增加、氮肥效率下降引起了国内外普遍关注,但中国不同作物氮肥用量及其利用效率缺乏大样本数据研究。本文通过农户调查及文献资料,对1970~2009年,尤其是从2000到2009年,中国主要农作物施氮量(化肥氮)、产量、氮效率(氮肥偏生产力)进行了研究。与2000~2003年相比,2008~2009年粮食、蔬菜、果树平均氮肥用量增加,单产增加,氮效率提高。粮食、蔬菜、果树氮肥用量分别增加26、36、107 kg/hm~2,产量分别增加1 280、5 722、18 802 kg/hm~2,氮效率分别增加2.2、6.6、25.2 kg/hm~2。东北、华北和长江中下游三大粮食作物主产区的氮效率都显著提高,而西北、西南和华南等地没有提高。与2000~2003年相比,2008~2009年中国平均氮效率的上升主要是因为单产大幅提高,而非氮肥用量下降。中国粮食作物单产较低,而氮肥用量高,未来在稳定氮肥投入的情况下继续提高单产是增效的主要途径。中国蔬菜和果树氮投入量太高,应该加强管理降低氮肥用量。