苜蓿秸秆配施玉米秸秆还田对氮矿化、微生物生物量和酶活性的影响

秸秆的质量是影响秸秆还田后氮素矿化的重要因子.玉米秸秆C/N比较高,还田后往往造成对土壤氮素的固持,因此秸秆直接还田要补施氮肥,而在如今的农业生产中为满足对粮食产量的需求,氮肥的施用越来越多,不仅增加了生产成本还危害了土壤质量.在秸秆还田条件下,如何能够更加科学合理地施用氮肥是一个关键问题.该试验在可控条件下,研究苜蓿秸秆和玉米秸秆共同还田对氮矿化、土壤微生物生物量碳氮和酶活性的影响,比较豆科作物秸秆或者氮肥配施玉米秸秆在相同C/N下(25:1)还田对土壤供氮、土壤微生物生物量和酶活性的影响.室内实验共设置4个处理:(1)对照(CK);(2)玉米秸秆单施(M);(3)苜蓿秸秆配施玉米秸秆调节C/N为25:1 (MM);(4)无机氮肥配施玉米秸秆调节C/N为25:1(MF),在25℃下共培养270 d.玉米秸秆单施在整个培养过程中均表现为对土壤氮素的固持作用,苜蓿秸秆与氮肥配施米秸秆均缓解了土壤微生物对土壤氮素固持作用,提高了土壤无机氮含量,苜蓿秸秆配施相比于氮肥配施延长了氮素的可利用性.苜蓿秸秆与氮肥配施提高了土壤微生物生物量碳氮含量以及转化酶和β-葡萄糖苷酶活性,并且以苜蓿配施处理最高.与玉米秸秆单施相比,苜蓿秸秆配施对脲酶活性影响没有差异,氮肥配施显著降低了脲酶活性.相关性分析表明,氮输入量显著影响了土壤无机氮含量、土壤微生物生物量和酶活性.相比于氮肥配施玉米秸秆还田,苜蓿秸秆配施玉米秸秆还田具有较高的土壤无机氮含量、土壤微生物量和酶活性.因此,我们认为相比于氮肥配施玉米秸秆还田,苜蓿秸秆配施玉米秸秆还田是一个比较好的农业生产实践模式.     

西安蔬菜主产区土壤硝态氮累积现状与蔬菜产品、浅层地下水氮素污染调查研究

以西安郊区主要周边蔬菜产区为研究地点,通过分析蔬菜鲜样、菜田土壤2 m垂直分层土样、浅层地下水的水样,研究蔬菜及菜田生态系统氮肥污染现状.结果表明,按我国的地下水硝酸盐含量标准,在选点采样中1.5～3 m深的地下水硝酸盐含量超标,菜田土层土质疏松与浇水次数较多的菜田硝酸盐向下淋洗现象明显,温室较露地2 m深土层硝态氮与铵态氮分布浓度高,菜田2 m深土层中常有硝态氮与铵态氮的聚集峰,不同深度地下水的菜田韭菜硝酸盐含量差异明显.     

鸡传染性支气管炎病毒地方分离株S1、N和M基因的克隆与表达

摘要：将IBVSX16株的S1、N和M基因克隆入真核表达载体pVAX1,构建IBV真核表达载体pVAX1-16S1、pVAX1-16N和pVAX1-16M。体外转染BHK-21细胞,用间接ELISA检测到目的蛋白表达,用构建的3个表达载体免疫小鼠,从小鼠血清中检测到了抗IBV抗体,初步证实用IBVS1、N和M基因作为核酸疫苗免疫动物,可以激活机体免疫应答。     

Effects of land-use type and nitrogen addition on nitrous oxide and carbon dioxide production potentials in Japanese Andosols

Land-use type and nitrogen (N) addition strongly affect nitrous oxide (N₂O) and carbon dioxide (CO₂) production, but the impacts of their interaction and the controlling factors remain unclear. The aim of this study was to evaluate the effect of both factors simultaneously on N₂O and CO₂ production and associated soil chemical and biological properties. Surface soils (0–10 cm) from three adjacent lands (apple orchard, grassland and deciduous forest) in central Japan were selected and incubated aerobically for 12 weeks with addition of 0, 30 or 150 kg N ha^–1 yr^–1. Land-use type had a significant (p < 0.001) impact on the cumulative N₂O and CO₂ production. Soils from the apple orchard had higher N₂O and CO₂ production potentials than those from the grassland and forest soils. Soil net N mineralization rate had a positive correlation with both soil N₂O and CO₂ production rates. Furthermore, the N₂O production rate was positively correlated with the CO₂ production rate. In the soils with no N addition, the dominant soil properties influencing N₂O production were found to be the ammonium-N content and the ratio of soil microbial biomass carbon to nitrogen (MBC/MBN), while those for CO₂ production were the content of nitrate-N and soluble organic carbon. N₂O production increased with the increase in added N doses for the three land-use types and depended on the status of the initial soil available N. The effect of N addition on CO₂ production varied with land use type; with the increase of N addition doses, it decreased for the apple orchard and forest soils but increased for the grassland soils. This difference might be due to the differences in microbial flora as indicated by the MBC/MBN ratio. Soil N mineralization was the major process controlling N₂O and CO₂ production in the examined soils under aerobic incubation conditions.     

A 15N tracing technique-based analysis of the fate of fertilizer N: a 4-year case study in eastern China

The fate of fertilizer N applied with different irrigation amounts in tobacco fields was quantitatively studied by applying ¹⁵N double-labelled NH₄NO₃ in lysimeters. The ¹⁵N (fertilizer N originating from the fertilizer applied in 2011) in tobacco plants, ¹⁵N in soils and ¹⁵N loss were observed continuously from 2011 to 2014. The results showed that 21.6% of ¹⁵N was utilized by tobacco plants, 72.1% remained in the 0–60 cm soil layer and 6.3% was lost from the soil–plant system after the first season’s harvest (2011) of flue-cured tobacco. During the four seasons from 2011 to 2014, cumulative utilization of ¹⁵N by tobacco plants was 34.3%, while 54.2% remained in the 0–60 cm soil layer, and 11.5% was lost via mechanisms such as leaching and volatilization. The fate of ¹⁵N in terms of accumulation in plants and soils or losses from the soil–plant system from 2012 to 2014 was greatly affected by the fertilizer and irrigation management strategies in 2011. The results of this investigation suggest that the major amount of fertilizer N applied during the first season remains available in the soil for utilization by tobacco plants after 4 years.     

不同种植间距对香根草植物边坡优先流发育特征的影响

[目的]分析优先流在香根草边坡中的发育特征,研究植物根系与优先流之间的关系,为进一步研究降雨条件下植物根系对边坡土体稳定性的影响提供理论依据。[方法]以种植间距为50 cm和10 cm的香根草为研究对象,模拟30 mm和50 mm两种不同的降雨量,采用示踪剂试验研究了香根草边坡土壤的优先流发育特征。[结果]香根草种植间距从50 cm减少到10 cm会增大边坡的水力响应。在50 mm的降雨量作用下,10 cm种植间距的香根草边坡土壤的染色面积比率和优先流比分别是50 cm的1.55,1.76倍。表层土0—10 cm土层深度范围内染色路径数量变化不明显,在10—35 cm深度土层范围,10 cm种植间距的染色路径数量多于50 cm种植间距的香根草边坡土壤。当降雨量由30 mm增加至50 mm时,水流会通过优势通道更迅速迁移到边坡土壤中。降雨量为30 mm土壤的染色面积比率(36.11%)和优先流比(67.25%)小于50 mm土壤的染色面积比率(49.68%)和优先流比(79.96%),并且染色路径数量随着降雨量的增加而增多。[结论]香根草根系特征与优先流关系密切。选择植物护坡时,应合理选...     

荠菜CBF冷诱导途径多价载体的构建和烟草转化

为了研究荠菜CBF抗冷途径多基因共表达对转基因植株耐寒性的影响,通过同尾酶法将CbCBF、CbICE53、CbRCI35以及CbCOR15bP进行结合,构建了CbCOR15bP::CbICE53+pCaMV35S::CbCBF+pCaMV35S::CbRCI35多价植物表达载体并进行了烟草的转化,通过形态观察以及电解质渗透率和相对水含量这两个生理指标的测定显示,转基因植株在4℃和-4℃低温处理情况下,多基因共转化的转基因植株在电解质渗透率和相对水含量与野生型和空载对照之间的差异非常明显,转基因植株在低温下的抗寒冻能力也明显增强,说明CBF途径多基因共转化可以明显提高烟草的抗寒冻能力,此项研究具有一定的实际应用意义。     

氮肥基追施比例对芝麻产量和氮素吸收、分配的影响

【目的】研究实现芝麻高产、提高氮肥利用效率、减少氮肥残留的氮肥最佳基追比例。【方法】采用盆栽试验,供试芝麻品种为‘郑太芝1号’,设置4个氮肥基追比例处理,氮肥底施与初花期追施比例分别为1∶0(N1∶0)、2∶1(N2∶1)、1∶2(N1∶2)、0∶1(N0∶1)。利用15N示踪技术,每盆施含有15N标记的总氮0.9g,分析各处理芝麻产量及氮素的吸收、分配特征。【结果】不同处理相比,N2∶1处理单株产量最高,N1∶2处理次之,N2∶1与N1∶0、N0∶1处理差异达显著水平。在初花期,N2∶1处理,芝麻单株生物量和植株总吸氮量均最高,不施基肥的N0∶1处理最低;各处理植株对肥料氮的吸收表现为N1∶0>N2∶1>N1∶2,对土壤氮的吸收以N2∶1最高;肥料氮和土壤氮在各器官中的分配均为叶>茎>根。在成熟期,N2∶1处理的单株总生物量最大,单株籽粒吸氮量和总吸氮量也最高,N1∶0处理最低,两者差异达显著水平;植株对肥料氮和土壤氮的吸收比例为23.7%~29.1%和70.9%~76.3%;对肥料氮和土壤氮的吸收均为籽粒>叶片>茎>蒴皮>根,籽粒吸氮量明显高于其它器官,籽粒占总吸氮量的33.0%~44.3%。N2∶1处理氮肥利用率最高,为32.5%,N2∶1、N1∶2、N0∶1处理间差异不显著,但均与N1∶0(17.8%)差异达显著水平。不同处理芝麻收获后土壤15N回收率以N2∶1处理的最低(16.2%),N0∶1处理的最高(31.3%)。【结论】在本试验条件下,氮肥底施与初花期追施比例为2∶1时,芝麻产量和生物量以及氮肥利用率最高,氮肥土壤残留量最少,是最佳氮肥基追施比例。     

淹水稻田氮的损失

A field microplot experiment was conducted during the tillering stage of paddy rice to investigate nitrogen(N) Iosses from flooded rice fields following fertilizer application. After application of ammonium bicarbonate, most of nitrogen in the flood water was present as NH₄-N and its concentration varied widely with time. Concentrations of both NO₃-N and NO₂-N in the floodwater were low due to the weakened nitrification. Under flooded anaerobic reducing conditions, soil solution concentrations of NO₃-N and NH₄-N were nothigh, ranging from 0.6 mg L^-1 to 4.8 mg L^-1, and decreased with soil depth. However, the ground water wasstill contaminated with NO₃-N and NH₄-N. Rainfall simulation tests showed that the N losses via runoff inrice fields were closely related to the time intervals between fertilizer applications and rainfall events. Whena large rain fell for a short period after fertilizer application, the N losses via runoff could be large, which could have a considerable effect on surface water quality. Both irrigation and N fertilizer application must be controlled and managed with great care to minimize N losses via runoff from agricultural land.     

水氮管理模式对不同氮效率水稻氮素利用特性及产量的影响

以高产氮高效品种(德香4103)和中产氮低效品种(宜香3724)为材料,通过“淹水灌溉+氮肥优化运筹(W1N1)”、“控制性交替灌溉+氮肥优化运筹(W2N1)”、“旱种+氮肥优化运筹(W3N2)” 3种水氮管理模式处理,研究其对氮素利用及产量的影响及其生理特性,并探讨氮素利用及产量与生理响应间的关系。结果表明,氮效率品种间的差异与水氮管理模式对水稻氮素利用特征、灌溉水生产效率、生理特性及产量均存在显著影响;不同氮效率品种间在氮肥利用效率方面的差异明显高于水氮管理模式的调控效应;而水氮管理模式对灌溉水生产效率、总吸氮量、氮素干物质生产效率及稻谷生产效率的调控作用显著。W2N1相对于W1N1及W3N2水氮管理模式能促进不同氮效率水稻拔节至抽穗期、抽穗至成熟期氮素的累积,提高功能叶谷氨酰胺合成酶(GS)活性、光合速率(P_n)及根系活力,进而提高稻谷产量及氮肥利用率,且对中产氮低效品种的调控效应显著高于对高产氮高效品种,为本试验最佳的水氮管理模式。高产氮高效品种的平均总颖花数、拔节至抽穗期稻株氮累积量、功能叶GS活性、P_n及根系活力均显著高于氮低效品种,尤其结实期高产氮高效品种更有利于维持叶片及根系的代谢同化能力,利于氮素转运、再分配到籽粒中提高稻谷生产效率及氮肥利用效率,是氮高效品种相对于氮低效品种高产、氮高效利用的重要原因。相关分析表明,水氮管理模式下不同氮效率水稻主要生育时期功能叶GS活性、P_n及根系活力与氮素利用及稻谷产量均存在显著或极显著的正相关;尤其以水稻抽穗期剑叶GS活性及根系活力与氮素利用及稻谷产量的正相关性最高。