高肥力土壤条件下不同基因型花生对氮素利用的差异

在桶栽条件下,利用¹⁵N示踪技术,选用20个基因型花生为供试材料,研究了高肥力土壤条件下不同基因型花生对氮素利用的差异.结果表明:高肥力土壤条件下花生氮素营养以土壤氮为主,根瘤固氮次之,肥料氮最低.不同基因型间花生对全氮、肥料氮、土壤氮和根瘤固氮的吸收和积累均存在显著差异,基因型间遗传变异以根瘤固氮最大,肥料氮和土壤氮相当.氮素荚果生产效率和氮肥利用率基因型间差异显著,最高值分别为最低值的3.6和2.1倍.全氮、肥料氮、土壤氮和根瘤固氮的氮素收获指数基因型间均存在显著遗传变异,且以根瘤固氮的氮素收获指数基因型间遗传变异最大.花生荚果产量与不同氮源氮素积累量及氮素收获指数、氮素荚果生产效率和氮肥利用率呈显著或极显著正相关.依据花生对不同氮源氮素吸收积累和荚果产量筛选出全氮高积累高产型、肥料氮高积累高产型、土壤氮高积累高产型和根瘤固氮高积累高产型四大类型花生,其中四大类型特征兼有的有4个花生基因型.     

生态因子及其交互作用对拟南芥(Arabidopsis thaliana)表型可塑性的影响

以拟南芥(Arabidopsis thaliana)两种基因型(ws-0和col-0)材料,采用复因子混合水平正交试验设计开展盆栽实验,研究了土壤盐分、土壤水分、光照强度、去叶处理等生态因子及其交互作用对受试植株18个表型特征的影响.结果表明生态因子对植物表型可塑性的影响是有针对性的:土壤水分主要影响植物体构件数目;土壤盐分主要影响生物量、角果数及种籽总数等直接反映植株适合度的表型特征;光照条件则主要影响植物的物候表型特征.植物体表型可塑性的方向随水分梯度的变化而发生改变.生态因子交互作用对植物表型可塑性的影响效果不是各因子独立作用的简单加和:对某个表型特征都有显著影响的两个生态因子其交互作用对该特征可能没有影响;反之,受两个生态因子交互作用影响显著的表型特征也可能不受它们的独立影响.在对生态因子交互作用作出响应时,col-0的9个特征表现出可塑性,而ws-0仅有4个表型是可塑的;同一基因型内彼此相关的表型特征在可塑性上也具一致性.抽苔时莲座叶数与角果平均籽粒数不受任何生态因子及其交互作用的影响,这两个表型作为数量特征而未表现出可塑性.     

不同施肥处理与地膜覆盖对土壤微生物群落功能多样性的影响

微生物多样性是表征土壤质量变化的敏感指标。应用Biolog技术探讨了不同施肥处理与地膜覆盖对土壤微生物功能多样性的影响,从微生物功能多样性的角度评价施肥与地膜覆盖对土壤质量的影响。试验结果表明：裸地条件下,肥料合理配施可以增强微生物对碳源的利用程度（AWCD）,显著增加微生物功能多样性（Shannon指数）。地膜覆盖和施肥的交互作用降低了微生物对碳源的利用率,降低微生物的丰富度,改变其均匀度。土壤微生物碳源利用的聚类和主成分分析表明,各施肥处理在碳源的利用上存在较大差异,覆膜加剧了各处理之间的分异程度。糖类和氨基酸类碳源是微生物利用的主要碳源。土壤微生物对碳源利用受到土壤pH、速效钾的显著影响。此外,有机碳、速效氮含量和土壤碳氮比与土壤微生物群落功能多样性密切相关。     

不同降水年型下长期施肥旱地小麦产量效应

以黄土高原30年长期肥料定位试验为基础,依据降水将生育年划分为干旱年、平水年和丰水年,研究不同施肥方式对黄土高原冬小麦产量、肥料贡献率和降水利用率的影响.结果表明: 小麦连续种植30年中,氮磷配施和氮磷钾配施下小麦产量、肥料贡献率和降水利用率显著高于不施肥和单施肥处理,氮磷钾配施下小麦产量、肥料贡献率和降水利用率分别达到3480 kg·hm^-2、61.45 kg·kg^-1、6.13 kg·mm^-1·hm^-2;不同降水年型下,丰水年小麦产量、肥料贡献率和降水利用率相对较高;使用逐步回归分析可知,不同降水年型下小麦产量主要受氮磷肥施用量、休闲期降水和越冬期降水影响.黄土旱塬可以通过提高氮磷用量同时适当施用钾肥,以及在休闲期做好蓄水保墒工作来提高小麦产量.     

Cu、Pb和丁草胺污染对土壤呼吸强度的影响

采用室内碱液吸收法研究了重金属Cu 、Pb 和丁草胺及其复合污染对土壤呼吸强度的影响及其随时间的动态变化.重金属Cu 、Pb 和丁草胺单一污染对土壤呼吸强度的影响,随污染物的浓度和培养时间而变化,DMRT 法检验表明,在后期各处理与对照间的呼吸强度都存在显著差异,前期则差异不显著.复合污染中,丁草胺与Cu 复合污染对土壤呼吸强度的影响在培养后期存在明显的交互作用,而丁草胺与Pb 复合污染对土壤呼吸强度的影响在培养前期存在一定的的交互作用,Cu 与丁草胺复合污染及Pb 与丁草胺的复合污染对土壤呼吸强度变化率的影响大于单一污染对土壤呼吸强度变化率的影响,复合污染对土壤呼吸强度变化率的影响表现为:丁草胺与Cu 复合污染>丁草胺与Pb 复合污染.     

小麦-玉米轮作体系多年定位试验中作物氮肥利用率计算方法探讨

近年来,国内学者针对氮肥利用率的概念、内涵和计算方法进行了深入的思考与探讨,在提出质疑的同时也给出了一些改进的计算方法.本文结合5年试验数据,以小麦-玉米轮作体系多年定位试验为研究对象,初步探讨了这些改进方法在农田氮肥利用状况评价中的适用性.结果表明: 利用常规差减法分两季作物分别计算当季氮肥利用率时存在小区土壤肥力不均一的弊端,且计算值逐年增大,已不能很好地反映田间实际情况;将小麦 玉米轮作体系作为整体计算体系累计氮肥利用率,可以确保计算建立在小区土壤肥力均一的基础上,且计算值较低,变异较小;基于比值法计算的体系氮肥利用率较累计计算法数值偏大,年际间变异最小,数值最稳定;土壤氮素平衡法计算体系氮肥利用率时,考虑了土壤养分在作物种植前后的盈亏和环境养分的输入,计算值最大,年际间变异也最大.
     

双氰胺对碳酸氢铵在土壤中氮素转化的影响

采用室内培养试验方法,研究了双氰胺对碳酸氢铵中的铵态氮在土壤中动态变化的影响。结果表明,无论是碳铵与双氰胺的机械混施,还是含双氰胺的长效碳铵,在抑制铵态氮硝化产生硝态氮的同时对氨挥发也有一定的抑制作用,使土壤在更长的时间内保持更高的铵态氮含量,并对碳铵施入后土壤的酸碱化强度起到了缓冲作用。添加双氰胺不但提高了碳铵的氮肥利用率,还减少了肥料氮素损失.     

不同遮荫条件下施肥量对西南干热区小粒咖啡产量和肥料利用的影响

干热区小粒咖啡肥光管理粗放,产量和肥料利用率受到限制。为探明干热区小粒咖啡节肥高产的肥光耦合模式,通过大田试验,设置4个遮荫度(100%NR、75%NR、60%NR、45%NR,NR为自然光照)和4个施肥量(不施肥及666.67、1000、1333.33 kg·hm^-2),研究不同肥光处理对小粒咖啡冠层结构、产量、肥料利用率、土壤养分含量及微生物生物量碳的影响。结果表明: 遮荫和施肥对小粒咖啡冠层结构、产量及肥料利用率、土壤养分含量及微生物生物量碳影响显著。小粒咖啡土壤养分含量及微生物生物量碳随遮荫度的增加而减少。土壤养分含量随施肥量增加而增加,微生物生物量碳则先增后减,施肥量1000 kg·hm^-2时达最大(200.30 mg·kg^-1)。遮荫和施肥对小粒咖啡叶面积指数、开度等冠层结构影响显著。叶面积指数与开度、林隙分数、总定点因子、冠下总辐射呈显著负相关。通过响应面分析及空间分析可得,当肥料偏生产力、产量、肥料农学利用率及肥料增产率达到最大时,对应的遮荫和施肥组合分别为80%NR和666.67 kg·hm^-2、79%NR和1286.81 kg·hm^-2、79%NR和967.74 kg·hm^-2、82%NR和1075.27 kg·hm^-2。产量、肥料农学利用率和肥料增产率同时达到大于等于最大值的80%时,遮荫和施肥区间为68%～77%NR和946.24～1178.79 kg·hm^-2。在本试验条件下,最优遮荫度及施肥量组合为75%NR和1000 kg·hm^-2。     

缓/控释肥料研究进展

缓/控释肥料对作物产量的影响因作物种类、肥料种类和试验条件而异,大多数植物增产比较明显,如大豆使用长效尿素,与普通尿素相比增产幅度最高可达33%。各种类型的缓/控释肥料,均可不同程度的提高肥料利用率。缓/控释肥料在农业上的应用能有效地保护生态环境,如抑制土壤NH4 向NO3-氧化,减少土壤NO3-的积累,从而减少氮肥以NO3-形式淋溶损失,减少了施肥对环境的污染;可以减少土壤N2O的释放等。提出了目前缓/控释肥料在农业应用中存在的问题及今后的发展方向。     

土壤抑真菌作用与细菌群落结构的关系

自然清洁土壤所具有的抑真菌作用,是健康土壤的一种自然属性,也是土壤质量的重要指标之一,对控制农作物土传病原真菌的爆发具有积极的生态学意义.本试验以中国科学院沈阳生态实验站近10年未受农药和肥料影响的撂荒地土壤作为自然清洁土壤样品,通过高温（对照、100 ℃、110 ℃、121 ℃）处理得到具有不同抑真菌作用的土壤模型,采用PCR DGGE(变性梯度凝胶电泳)方法对上述土壤样品的细菌群落结构进行分析.结果表明：土壤抑真菌作用与土壤细菌群落结构紧密相关;对照清洁土壤抑真菌作用最强,处理后土壤细菌群落结构偏离自然清洁土壤愈远,土壤抑真菌能力愈差;DGGE特异性条带切胶测序结果表明,Sphingomonas asaccharolytica、Nitrospira sp.、Hyphomicrobiaceae sp.、Bacillus megaterium和Micrococcus sp.可能与土壤抑真菌作用密切相关.     

氮肥对受践踏胁迫结缕草草坪恢复生长的影响

以日本结缕草草坪为试材,采用田间试验,研究在不同践踏胁迫下,施用氮肥对草坪生长的影响。结果表明,施氮肥有利于受践踏草坪的恢复生长,在不同程度践踏胁迫下,施氮素8 g/m2,可不同程度地增加草坪的密度、株高生长量和地上生物量;总叶绿素含量比对照明显增加。     

Cyanobacterial inoculation and nitrogen fertilization in rice

During three rice-growing seasons in Uruguay, field experiments were conducted to study the contribution of cyanobacterial inoculation and chemical N fertilization to rice production. Neither grain yield nor fertilizer recovery by the plant were affected by inoculation with native cyanobacterial isolates. A low fertilizer use efficiency (around 20%) was observed when labelled (NH₄)₂SO₄ was applied at sowing. Recovery of applied ¹⁵N by the soil–plant system was 50%. Inoculation did not modify ¹⁵N uptake by the plant when the fertilizer was three-split applied either. The total N-fertilizer recovery was higher when the fertilizer was split than when applied in a single dose. Plant N-fertilizer uptake was higher when the fertilizer was applied at tillering. Uptake of ¹⁵N from cyanobacteria by rice was studied in a greenhouse pots experiment without chemical nitrogen addition. Recovery of ¹⁵N from labelled cyanobacteria by rice in greenhouse growth conditions was similar to that of partial recovery of (NH₄)₂SO₄ applied at sowing in the field. Cyanobacterial N mineralization under controlled conditions was fast as cyanobacterial N was detected in plants after 25 days. Moreover 40 days after inoculation non-planted and inoculated soil had more inorganic N than the non-inoculated one.     

氮肥运筹对砂田西瓜产量、品质及氮素积累与转运的影响

通过田间试验研究了不同氮肥运筹方式对砂田西瓜产量、品质及氮素和干物质积累与转运的影响.结果表明： 基肥氮过低或过高均不利于砂田西瓜苗期生长,伸蔓期或膨果期不施氮肥则限制了西瓜“源”或“库”的形成,在相同的施氮量水平下,T₄(30%基肥+30%伸蔓肥+40%膨瓜肥)和T₆\[100%基肥+长效复合肥添加剂(NAM)\]处理较传统施肥模式T1(30%基肥+70%伸蔓肥)西瓜坐果后茎叶干物质和氮素积累量显著降低,而果实干物质和氮素积累量显著增加.其中,T₄处理的氮素运转率和氮素贡献率分别达到33.6%和12.0%,T₄和T₆处理的氮素收获指数、氮肥偏生产力和氮肥利用率较传统施肥模式T₁分别显著提高14.1%和12.7%、11.6%和12.5%、5.3%和8.7%.T₄和T₆处理较T₁西瓜分别增产11.6%和12.5%,可溶性糖含量分别显著提高16.5%和11.7%,有效酸度分别提高4.5%和2.8%,糖酸比分别提高19.4%和13.4%,Vc含量分别提高35.6%和19.0%.因此,T₄和T₆处理为砂田西瓜高产优质的较优氮肥运筹模式,若减轻砂田施肥难度,延长砂田使用年限,可采用100%基肥+NAM(T₆)的施肥方式.     

Effect of Amendments on the Microbial Utilization of Oil Applied to Soil

Replicate field plots comprising a control, plus oil, plus oil and bacteria, plus oil and fertilizer (urea-phosphate; 27:27:0), and plus oil, bacteria, and fertilizer were monitored over a 308-day period for changes in bacterial and mold numbers. Changes in the chemical composition of the oil applied to the plots was followed by using chromatographic techniques. Application of fertilizer resulted in a stimulation of bacterial numbers and in the rate of utilization of n-alkane components of the saturate fraction. The application of oil-utilizing bacteria, however, resulted in only a slightly accelerated rate of utilization of n-alkane components of chain lengths C20 to C25. The isoprenoids, phytane and pristane, were still present in gas-liquid chromatography profiles after digestion of the n-alkane components of the saturate fraction. Those plots which received fertilizer showed an accelerated rate of recovery of native vegetation.     

稻茬冬小麦氮肥吸收、残留和损失特性

为推进稻茬小麦氮肥合理施用,采取田间¹⁵N示踪技术研究了施氮量(0、150、225、300 kg·hm^-2,分别表示为N₀、N₁₅₀、N₂₂₅、N₃₀₀)对氮肥回收、残留、损失和籽粒产量的影响。结果表明: 随施氮量增加,小麦植株不同来源氮素积累量显著增加,氮肥回收率则显著下降。基肥氮以越冬至拔节期在植株中的积累量最高,追肥氮以拔节至开花期积累量最高;成熟期各处理追肥氮在植株中的积累量均高于基肥氮,N₁₅₀处理植株中土壤氮的积累量高于肥料氮,N₂₂₅、N₃₀₀处理呈相反趋势。随施氮量增加,成熟期0～100 cm土层氮肥残留量显著增加,肥料氮在60～100 cm土层残留比例逐渐升高。小麦全生育期氮肥损失量和损失率均随施氮量增加而增加,基肥氮损失量以播种至越冬期最高,追肥氮损失量以拔节至开花期最高。综合考虑籽粒产量,N₂₂₅处理可作为稻茬小麦氮肥推荐用量,相应的籽粒产量为6735 kg·hm^-2,氮肥回收率、土壤残留率和损失率分别为42.6%、34.0%和23.3%。     

Nitrogen recoveries from organic amendments in crop and soil assessed by isotope techniques under tropical field conditions

The integration of multipurpose legumes into low-input tropical agricultural systems is needed because they are a nitrogen (N) input through symbiotic fixation. The drought-tolerant cover legume canavalia (Canavalia brasiliensis) has been introduced for use either as forage or as a green manure into the crop-livestock system of the Nicaraguan hillsides. To evaluate its impact on the subsequent maize crop, an in-depth study on N dynamics in the soil-plant system was conducted. Microplots were installed in a 6-year old field experiment with maize-canavalia rotation. Direct and indirect ¹⁵N-labelling techniques were used to determine N uptake by maize from canavalia residues and canavalia-fed cows?? manure compared to mineral fertilizer. Litter bags were used to determine the N release from canavalia residues. The incorporation of N from the amendment into different soil N pools (total N, mineral N, microbial biomass) was followed during the maize cropping season. Maize took up an average of 13.3 g?N?m^?2, within which 1.0 g?N?m^?2 was from canavalia residues and 2.6 g?N?m^?2 was from mineral fertilizer, corresponding to an amendment N recovery of 12% and 32%, respectively. Recoveries in maize would probably be higher at a site with lower soil available N content. Most of the amendment N remained in the soil. Mineral N and microbial N were composed mainly of N derived from the soil. Combined total ¹⁵N recovery in maize and soil at harvest was highest for the canavalia residue treatment with 98% recovery, followed by the mineral fertilizer treatment with 83% recovery. Despite similar initial enrichment of soil microbial and mineral N pools, the indirect labelling technique failed to assess the N fertilizer value of mineral and organic amendments due to a high N mineralization from the soil organic matter.     

Field study of the fate of labelled fertilizer ammonium-N applied to sesame and sunflower in a sandy soil

The recovery in crop and soil of labelled fertilizer ammonium-N applied to sesame and sunflower growing on sandy soil was measured. The sesame and sunflower received respectively 238 and 143 kg Nha⁻¹ as (NH₄)₂SO₄ enriched with 4.63 At. %¹⁵N excess. In the plants, the Ndff was 31.19% and 31.96% in sesame and sunflower, respectively. The fertilizer recovery by sunflower was 22.3%, by sesame only 12.3%. The amount of fertilizer N remaining in the soil at harvest was 13.04% for the sesame and 5.95% for the sunflower plot. The loss of fertilizer N under sesame was 74.66% and 71.75% under sunflower. The average of seed yield of the plants inside the¹⁵N plot was compared with the seed yield of the same amount of plants from outside the¹⁵N plot. They did not differ significantly, indicating that the results obtained from the¹⁵N plot can be extrapolated to the rest of the field.     

Prediction of long-term fertilizer nitrogen requirements of maize in the tropics using a nitrogen balance model

A simple N balance model was used to calculate fertilizer requirement for a target N uptake by maize. Nitrogen uptake from soil sources and target uptake of N with fertilizer N additions were obtained from fertilizer trials in Africa and Latin America. Most experiments had data for only one cropping period, although some from Latin America had data for four to six crops. The transfer coefficient of fertilizer N to the crop was adjusted to realize maximum recovery of fertilizer N under best methods of fertilizer application. The time constants of transfer of soil N to the crop were allowed to vary and were affected mainly by soil texture. Where 4 to 6 cropping periods were available good agreement between actual and predicted fertilizer N requirements was obtained. With this approach long-term fertilizer N requirements for 14 sites were predicted using first cropping period N uptake. This study showed that pools of organic N in more coarse-textured soils were usually smaller and declined more rapidly than in fine-textured soils. Labile organic N pools declined with time under all simulations, but approached equilibrium within 10 croppings seasons. Equilibrium N uptake from the soil organic N pool was predicted to be 31 kg ha^–1 for the more coarse-textured soils and 36 kg ha^–1 for the fine-textured soils. Long-term projections of fertilizer requirements using input data of the field experiments were reasonable, and effects of legume green manures and other amendments could be clearly evaluated.     

有机肥防治生姜青枯病及其RAPD分析

利用随机扩增多态性技术研究生姜连作地、施加有机肥后的生姜连作地及新开地中土壤微生物多样性与生姜青枯病的关系,结果发现,连作地的青枯病发病率为100％、新开地没有发病,而施加有机肥的连作地生姜青枯病发病率降至37．64％。发现施加有机肥连作地的真菌、放线菌数量增加。多样性指数分析发现Shannon指数、Simpson指数等均显著增加。随机扩增条带出现连作地的条带丰富度较少、新开地的条带最多、施加有机肥连作地的RAPD条带明显多于连作地,接近新开地,并出现了一些连作地没有的特异条带。这些结果表明,施加有机肥可以改善土壤微生物群落结构,提高微生物多样性,从而抑制病害发生。     

Comparison of the efficiency of urea,aqueous ammonia and ammonium sulphate as nitrogen fertilizers

Summary Nitrogen-15 labelled urea, aqueous NH₃ and (NH₄)₂SO₄ were applied to soils contained in pots. The fertilizers were injected in 5 cm³ of solution, 3.5 cm below the soil surface, to simulate a fertilizer band in the field. Ryegrass (Lolium perenne) was planted, and several cuttings and roots were harvested. Efficiency was determined as the recovery of fertilizer-N in the plant tissues and soil.Total recovery varied from 94 to 100%. There was no significant difference between the total recovery of the 3 fertilizer forms, although recovery in the soil component was lower for (NH₄)₂SO₄ than for urea or NH₃. There was a significant difference in total recovery between soils due to the soil component. Only small amounts of¹⁵N were not recovered, whereas laboratory experiments reported elsewhere had demonstrated that substantial gaseous losses of N as N₂, N₂O and NO +NO₂ occurred in these soils during nitrification of added NH₃ fertilizer.