2012年三江平原大豆苗期主要病虫害的防治

由于2012年4月末三江平原地区降水多,导致土壤水分含量高,大豆幼苗发育缓慢,潮湿低温的天气易于大豆病害的发生,对大豆种子萌发、出苗及保全苗十分不利。为此,分析气候条件对大豆苗前苗后的影响,预测主要病虫害发生情况,并提出相应的防治措施,对指导今年的大豆生产具有非常重要的现实意义。     

不同管理模式下农田水氮利用效率及其环境效应

 【目的】定量化不同水氮管理模式下的农田水氮利用效率和环境效应,为制定优化的水肥管理措施提供理论指导。【方法】在华北平原北部的冬小麦-夏玉米轮作区,设置了农民习惯和基于土壤水分养分实时监测的优化管理两种水氮管理模式。首先,应用田间系统的观测数据（2004年10月至2006年9月）对水氮管理模型进行了校验,然后应用校验后的模型计算得到了两种水氮管理模式下的作物产量、农田水分渗漏、氮素淋失、气体损失和水氮利用效率等。【结果】2年内农民习惯和优化管理下的灌水量差别不大,而优化管理的施肥量（540 kg N·hm-2）仅为农民习惯施肥量（1 100 kg N·hm-2）的一半。农民习惯和优化管理模式下的作物年平均产量分别为11 579和11 748 kg·hm-2;两者的水分利用效率分别为1.65和1.72 kg·m-3;氮素利用效率分别为15和24 kg·kg-1 N。氮素淋失和氨挥发是氮素损失的主要途径,农民习惯和优化管理下的氮素淋失分别为407和68 kg N·hm-2;氨挥发分别达到了282和104 kg N·hm-2。【结论】优化管理下的作物产量和水氮利用效率都高于农民习惯管理的,并且氮素损失明显低于农民习惯管理。因此,为了保证该地区的农业可持续发展,必须改进当前农民习惯的水氮管理措施。     

华北平原免耕冬小麦生长发育特征研究

2004—2006年在河北栾城中国科学院农业生态试验站开展了不同耕作方式下冬小麦生长发育特征及其影响因素的比较研究。冬小麦基本苗数和分蘖率在不同耕作方式间差异显著, 表现为免耕<旋耕<翻耕。免耕处理冬小麦分蘖成穗率高于翻耕和免耕处理, 但基本苗数低, 2004—2005生长季比翻耕和旋耕处理分别低28.9%和29.7%, 2005—2006生长季分别低11.7%和10.0%; 免耕处理冬小麦株高、叶面积指数、地上部干物质积累和产量均低于翻耕和旋耕处理, 其中叶面积指数在2004—2005和2005—2006生长季的最高值分别为2.9和6.0, 产量比翻耕降低30.1%和27.19%、比旋耕降低15.3%和25.20%。免耕可保持耕层较高的土壤水分含量, 总体上高于翻耕和旋耕处理; 免耕处理在冬小麦苗期和返青期表现出明显的“降温效应”, 耕层土壤日均温度低于翻耕和旋耕, 冬小麦出苗和返青较翻耕和旋耕分别晚1~3 d和4~5 d。     

Estimation of water consumption and crop water productivity of winter wheat in North China Plain using remote sensing technology

The North China Plain (NCP) is one of the most water stressed areas in the world. The water consumption of winter wheat accounts for more than 50% of the total water consumption in this region. An accurate estimate of the evapotranspiration (ET) and crop water productivity (CWP) at regional scale is therefore key to the practice of water-saving agriculture in NCP. In this research, the ET and CWP of winter wheat in 83 counties during October 2003 to June 2004 in NCP were estimated using the remote sensing data. The daily ET was calculated using SEBAL model with NOAA remote sensing data in 17 non-cloud days whereas the reference daily crop ET was estimated using meteorological data based on Hargreaves approach. The daily ET and the total ET over the entire growing season of winter wheat were obtained using crop coefficient interpolation approach. The calculated average and maximum water consumption of winter wheat in these 83 counties were 424 and 475 mm, respectively. The calculated daily ET from SEBAL model showed good match with the observed data collected in a Lysimeter. The error of ET estimation over the entire growing stage of winter wheat was approximately 4.3%. The highest CWP across this region was 1.67 kg m⁻³, and the lowest was less than 0.5 kg m⁻³. We observed a close linear relationship between CWP and yield. We also observed that the continuing increase of ET leads to a peaking and subsequent decline of CWP, which suggests that the higher water consumption does not necessarily lead to a higher yield.     

三江平原小叶章湿地土壤有机硫矿化特征研究

利用开放系统培养法,分别在不同温度和水分条件下,研究了三江平原小叶章典型草甸和小叶章沼泽化草甸两种湿地类型的不同层土壤有机硫的矿化特征。结果表明,在不同培养条件下,两种小叶章湿地土壤有机硫的矿化具有一致性:每层土壤有机硫累积矿化量随培养时间的延长而增加,二者之间符合一级动力学方程。上层土壤有机硫的矿化量高于下层土壤,好气培养条件下每层土壤有机硫的累积矿化量均高于淹水条件下矿化量;30℃培养条件下每层土壤有机硫的累积矿化量均高于20℃培养条件下矿化量。温度、水分条件和土壤类型对土壤有机硫的矿化影响显著,但它们之间的交互作用影响不明显。对比两种湿地类型不同层土壤有机硫的矿化,发现在不同培养条件下,小叶章沼泽化草甸土壤有机硫的矿化速率和潜力均高于小叶章典型草甸。     

银川地区日光温室非洲菊高产栽培技术要点

作者根据银川地区的生产条件和实践经验,从非洲菊切花生产要求的温室性能、土壤类型、品种和种苗选择方面;定植前的整地施肥、土壤消毒、起垄开沟、定植方面;田间的灌水施肥、温度光照、摘叶疏蕾管理方面;病虫害的发生特点和防治方法方面;切花的采收、分级和包装方面,总结出了几条适合本地日光温室非洲菊切花高产栽培的技术要点.     

Incorporating hydrologic dynamics into buffer strip design on the sub-humid Boreal Plain of Alberta

The status quo in forestry practice is to leave standard width buffers around water bodies in order to prevent the excess transport of sediments and nutrients from terrestrial to aquatic systems. This practice does not seem to be effective in the sub-humid boreal forest where climatic and physiographic variability produces complex hydrologic pathways not well protected by standard width buffers. We developed a remote sensing technique that forms a hydrologic basis for buffer strip design. Synthetic aperture radar (SAR) imagery was used to map, both inundated and saturated areas (herein called wet areas) amenable for surface transport of nutrients and sediments on a low relief landscape in northern Alberta, Canada. Wet areas coverage of the Moose Lake drainage basin showed a semi-logarithmic relationship with daily discharge (r² = 0.72, p < 0.001, n = 18). This relationship was used to define a flow–duration curve for wet areas that could be used as an aspatial assessment of what proportion of a drainage basin should be protected. A probability map of wet areas formation was calculated from the database of 18 images. We demonstrated how the probability map may be used to design adaptive buffer strips for the mitigation of increased nutrient loading to boreal lakes following timber harvesting.     

绿洲防护林体系缓解霜冻作用的调查研究

通过对2004年5月3日晨发生在内蒙古河套平原的大面积霜冻调查显示,绿洲防护林在减轻霜冻方面具有明显作用。由于树体降温放热、林网对气流的阻挡作用以及林冠层对热辐射的影响等,防护林结构较完整的区域冻害明显轻于防护林不够完整的区域;寒流进入林网区后,产生霜冻的能力随纵深距离增大而逐步衰减。加强绿洲防护林体系建设、完善林网结构、重视农田周围闲散荒地的造林绿化对缓减霜冻具有重要意义。     

江汉平原稻田田面水氮磷变化特征研究

在江汉平原地区,因水肥管理粗放,特别是人为排放刚施肥泡田水,水稻种植引发的氮磷面源污染问题比较严重,迫切需要掌握稻田氮、磷动态特征,并据此进行科学的肥水管理。采用大田试验的方法,设置不同氮磷梯度,研究了江汉平原稻田田面水氮磷形态与浓度动态变化特征及施肥的影响。结果表明:施尿素后,田面水可溶性总氮(DTN)、可溶性有机氮(DON)和铵态氮(NH_4~+-N)占总氮(TN)的比例分别在88.0%、44.7%和31.6%以上,且随施氮量增加而增大;施磷肥后,田面水中颗粒态磷(PP)占总磷(TP)的比例为76%～93%,且随施磷量的增加而降低。田面水中氮素浓度与施氮量之间呈分段线性相关关系,当施氮量分别超过287.8、289.9、231.5和336.7kg·hm-2后,TN、DTN、NH_4~+-N和DON的浓度会跃增;田面水中各形态磷素浓度均随施磷量的增加而线性增加。施氮肥后,田面水中TN和DTN浓度均在施肥后1 d达到峰值,在基肥和分蘖肥后5 d、穗肥后2 d降低至与不施氮肥基本接近;NH_4~+-N浓度在基肥和分蘖肥后2d、穗肥后1d达到峰值,基肥和分蘖肥后5 d、穗肥后2 d后降低至与不施氮肥趋同。施磷肥后TP、PP和可溶性总磷(DTP)的浓度均在施肥后1 d达到峰值,3 d后急剧降低,降幅均在79.0%以上。可见,在江汉平原地区,施尿素后田面水中氮素以DTN为主,尤其是DON和NH_4~+-N,施磷肥后以PP为主。减少氮、磷肥用量可降低稻田氮、磷损失,且氮肥施用量应尽可能控制在231.5 kg·hm-2以内。施基肥和分蘖肥后5 d内、施穗肥后2 d内是江汉平原稻田氮素损失的关键控制期,施磷肥后3 d内是磷素流失的关键控制期。