减氮对麦玉轮作农田土壤反硝化细菌群落结构和多样性的影响

探究减氮对华北地区麦玉轮作农田土壤反硝化细菌群落结构和多样性影响,为华北地区麦玉轮作农田氮肥管理提供技术支持,本研究以不施氮为对照（CK）,设置 2个施氮量,分别为常规施氮量（纯氮 300 kg·hm^-2,N2）、减氮 20%（纯氮 240 kg·hm^-2,N1）,提取土壤DNA,用nirS（细胞色素cd1-亚硝酸还原酶）、nirK（Cu-亚硝酸还原酶）引物扩增后采用MiSeq PE300测序技术,研究施氮量对麦玉轮作农田土壤性状及nirS、nirK反硝化细菌群落结构及多样性的影响。结果表明,3个处理nirS、nirK反硝化细菌α-多样性指数无显著差异,nirS反硝化细菌α-多样性高于nirK。减氮显著影响nirS、nirK反硝化细菌物种组成。减氮对nirS、nirK反硝化细菌门水平及nirK纲水平物种组成无显著影响,但显著降低了nirS反硝化细菌Deltaproteobacteria（δ-变形菌纲）相对丰度;减氮显著影响nirS、nirK属水平物种组成。硝态氮、速效磷、pH值是影响土壤nirS反硝化细菌属水平群落结构主要环境因子;pH值是影响土壤nirK反硝化细菌属水平群落结构的主要环境因子。研究表明,适量减氮不影响反硝化细菌α-多样性,但显著影响反硝化细菌属水平群落组成和群落结构,减氮主要是通过影响土壤性状及微生物群落结构进而影响农田土壤N₂O排放。     

陕西蔬果电动作业农机发展思考

陕西省果蔬种植面积较大,果蔬作物多样,但大多数是家庭或小农场种植模式,但南北地形地貌差异较大,传统大型机械作业不便且费用较高,通过适度规模的宜机化改造后,中小型马力的动农机可完全适用小区域化果蔬园,在山丘区果园及设施种植环境下中小型电动农机就有很大的发展前景,并且中小型电动农机具在提质增效、智能化提升及节能减排方面也有较为广阔的发展空间。     

From alley cropping to rotational fallow: Farmers' involvement in the development of fallow management techniques in the humid forest zone of Cameroon

Alley cropping was introduced in the humid forest zone of Cameroon to increase soil fertility in 1987, but until 1992 the adoption rate had remained low. To better understand the reasons behind this, three types of on farm trials were established from fully researcher controlled to fully farmer controlled. During the evaluation of the technology with farmers a number of modifications were registered (1) Pruning height and frequency: Because of the difficulties to consistently cut back at 30 cm, farmers decided to slash at ground level as they normally do while slashing the natural fallow vegetation. This equally allowed for more flexibility in time of pruning. (2) Cropping intensity and pattern: Initially, alleys were cropped each year. This however had several shortcomings. Having observed the positive impact of incidental fallow period in a farmer's field, it was decided to introduce a fallow phase of at least one year. During the fallow period the plot can be used for fodder production, bee farming and production of stakes. (3) Residue management: Fire went incidentally in a farmer's tree plot after slashing, and the trees were not affected. This gave farmers an alternative way to manage the residue, by controlling the fire, before bringing in other crops such as groundnut and cassava. (4) Agroforestry species: Because Leucaena leucocephala, in spite of it soil fertility restoration potential, rapidly became a noxious weed, farmers have asked for a less invasive species. Calliandra calothyrsus was introduced for this purpose and became a good bee forage. With these modifications, the original alley cropping system has evolved into a rotational tree fallow with higher adoption potential. From about 15 farmers who were testing the technology in 1992, the number increased to 52 in 1996, 120 in 1997 and 236 in 1998. This revised version was published online in June 2006 with corrections to the Cover Date.     

景电灌区绿洲综合生态系统管理耦合技术评价分析

以甘肃省景电灌区的3种典型村落(紧邻沙漠的大咀子村、以砂田为传统耕作方式的寺滩村和以盐碱地种植枸杞为主的红跃村)为研究对象,采用参与式方法调查了村民对沙地封育、保护性耕作、盐碱地种植枸杞(Lyciumchinense)、生态家园建设、防护林体系建设5项措施构成的绿洲综合生态系统管理体系的接受程度,利用层次分析法量化分析农民对管理措施的认可度和满意度。结果表明:目标层满意度加权平均值为8.569,说明综合生态系统管理的各项措施得到了农民的普遍认可;各准则层满意度权重排序为:沙地封育(0.417)保护性耕作(0.263)盐碱地种植枸杞(0.160)生态家园建设(0.097)防护林体系建设(0.062),各指标贡献值差异明显,说明农民对5项措施的认可度和满意度不同;不同村落对综合生态系统管理体系的认可度不同,同村落对不同管理措施的满意度及认可度权重差异较大;针对灌区发展现状,结合评价结果,提出了绿洲综合生态系统管理耦合技术及建设对策。     

杂交苜蓿(Medicago varia Martyn)根系特性的研究

杂交苜蓿是野苜蓿 (M .falcata)和紫苜蓿 (M .sativaL .)的杂交后代 ,兼具亲本的许多优良性状 ,适于广泛栽培。对其在根系特性上所表现出的优势进行研究发现 :根颈处的劈裂将植株分为母株与子株 ,实现营养繁殖 ;位于茎基部的当年芽数量明显大于亲本 ,是地上生物量增长的基础 ;明显的缩根现象有利于茎基部和根颈顶部芽的产生和越冬 ;明显优于亲本的侧根与不定根 ,为根劈裂分株繁殖的植株提高地上生物量奠定了基础     

公共危机中企业社会责任实践创新——基于新冠疫情下蒙牛供应链扶贫的案例研究

新冠疫情使我国各行业皆受到不同程度的影响。在疫情背景下,内蒙古蒙牛乳业（集团）股份有限公司（简称“蒙牛”）作为乳业龙头企业,在履行社会责任过程中不仅维持行业稳定,更实现企业自身发展。本文基于品牌效应与交易成本理论,对疫情下蒙牛供应链扶贫案例进行研究。研究发现,公共危机下,龙头企业社会责任实践创新,对社会及行业稳定意义重大;供应链扶贫依托合理的内部作用机制可以实现企业、相关参与方、被帮扶方与消费者的共赢。     

畜牧业温室气体排放机制及其减排研究进展

全球气候变暖已经成为人类共同关注的话题,畜牧业温室气体排放量占全球总量的18%,成为导致全球气候变暖的主要原因。因此,研究各种畜禽温室气体排放机制,找出畜禽温室气体的影响因子,对减少温室气体排放有着非常重要的意义。文章综述了畜禽温室气体排放的机理,提出减少畜禽温室气体排放的措施与对策,为探索节能、低温室气体排放的环保养殖提供参考。     

Successful reduction of a monozygotic equine twin pregnancy via transabdominal ultrasound‐guided cardiac puncture

In horses, twin pregnancy is pathological and represents a potentially life‐threatening condition to the mare and foal. Twinning occurs in approximately 2% of pregnancies. Of these, the majority of cases are dizygotic twins, resulting from 2 ovulations and monozygotic twins are rare. A 12‐year‐old Quarter Horse mare was presented for breeding management with shipped cooled semen and embryo transfer. Seven days post ovulation, a single late morula/early blastocyst was recovered and transferred immediately to a recipient mare. Thirty‐six days after transfer, transrectal ultrasound examination revealed the presence of 2 embryos. A transcutaneous reduction of one of the fetuses was performed successfully at 128 days of gestation. This report is the first to describe a successful reduction of monozygotic twins by transcutaneous ultrasound‐guided cardiac puncture.     

西部少数民族贫困山区扶贫模式研究——以四川省昭觉县为例

西部民族贫困山区是我国扶贫攻坚的重点和难点地区,其扶贫工作的好坏直接关系：我国民族团结、全面建设小康社会目标的实现。在分析西部民族贫困山区县——四川省昭觉县农村贫困与扶贫工作现状的基础上,总结了适合民族贫困山区县的扶贫模式——“三集中”扶贫模式,提出通过发展县域循环经济和建立健全生态环境补偿机制来推广发展“三集中”扶贫模式的对策建议。