施用木质素对春玉米生长发育及产量的影响研究

试验研究施用木质素对春玉米生长发育及产量的影响结果表明 ,施用木质素可促进春玉米对N、P的吸收 ,提高肥料利用率 ,减少肥料污染和提高作物品质 ,有显著增产作用 ,且不同处理春玉米增产率均≥ 2 0 %。     

不同施氮方式对玉米产量及N 2O排放的影响

通过3年定位试验,采用静态箱/气相色谱法对壤质草甸土区玉米生产进行了全生长季N2O排放通量的观测,分析了不同施氮方式对N2O排放总量、排放系数和玉米产量的影响。结果表明：减少氮肥用量20%的缓控释肥处理与秸秆还田配化肥处理产量居高,而且二者间差异不显著;秸秆还田促进了农田土壤N2O排放,使得秸秆还田配化肥处理的年均N2O季节排放总量最高,达到1.50 kg N·hm-2;年均N2O季节排放总量与施肥量之间相关系数达到了0.97;随着试验年限的增加,N2O-N季节排放系数受施肥量的影响逐年增加,相关系数从2009年的-0.015增加到2011年的0.624。因此不同施氮方式对N2O季节排放的影响需要通过多年定位来准确把握,同时在研究农田N2O-N季节排放时要适当考虑植株生长过程中N2O的排放。兼顾产量和减排2个因素,建议推广缓控释肥的减量施用。     

水肥条件对小麦、玉米N、P、K吸收的影响

水、N是影响作物N、P、K吸收的重要因素。通过对 6个水分等级和 5个N肥等级相互搭配的研究结果表明 ,高水、高N处理不利于小麦N吸收 ,而玉米是耐肥作物 ,相同灌水条件下 ,玉米的吸N量随施N量的增加而增加。在低灌水条件下 (W 0、W 1处理 ) ,玉米子粒吸N量很低 ,变幅为 0～17.3kg/hm2,并且不受施N量的影响 ;而小麦子粒吸N量仍达 36.6～154.2kg/hm2。小麦与玉米吸P量的变化趋势与吸N量的变化趋势非常接近。但是 ,作物的吸K量随灌水量增加有明显增加的趋势 ,在玉米上表现尤其明显 ,并且作物的吸K量主要存在于茎秆中 ,因此 ,在当地推广和宣传秸秆还田很有必要     

施氮方式对玉米氮吸收及土壤养分、N2O排放的影响

通过3年定位试验,研究不施氮肥、农民传统施氮、比传统施氮减量20%、减氮20%配合秸秆还田、减氮20%施用包膜尿素处理对玉米年际产量、植株氮吸收、土壤养分变化及N2O排放的影响。结果表明:包膜尿素处理产量最高,比空白处理增产18.50%,比产量次高的秸秆还田处理仅增产0.51%,二个处理间产量差异不显著;包膜尿素处理和秸秆还田处理可增加植株氮的吸收固定;秸秆还田处理的肥料利用率和植株总氮积累量高于包膜尿素处理,但其氮收获指数最低,为0.606,从注重品质角度,包膜尿素处理的效果略好于秸秆还田处理;各施肥处理都比空白处理提高了土壤主要养分含量,但从有机质、全氮、有效磷和速效钾含量提升综合评价,包膜尿素处理和秸秆还田处理对土壤的培肥作用好于农民习惯施肥处理;秸秆还田处理的N2O-N季节排放总量和排放系数都最高,分别为N 1.50 kg·hm-2·季-1和0.27。因此,从保产稳产、培肥地力、提升品质、减少N2O排放综合考虑,建议推广比农民习惯施肥量减少氮量20%的包膜尿素一次性施入在玉米生产中的应用。     

硫脲及抑制剂组合对土壤尿素氮转化和玉米产量的影响

采用培养试验和田间小区试验相结合,研究了两种浓度硫脲及低用量硫脲和硝化抑制剂双氰胺(DCD)、脲酶抑制剂苯基磷酰二胺(PPD)组合对土壤脲酶活性、土壤尿素氮转化和玉米产量的影响。培养试验表明,硫脲及抑制剂组合对土壤脲酶活性有显著的抑制作用,抑制时间为2周。TU、TU1+DCD和TU1+PPD,对土壤NH4+-N的释放、NH4+-N向NO3--N的进一步转化有显著的抑制作用,进而影响土壤中速效氮的总量变化。田间试验表明,施用抑制剂显著增加了玉米百粒重和产量,增产幅度为9.14%1～1.49%。     

不同氮磷施肥量对玉米生育期土壤微生物量的影响

通过田间小区试验研究了不同N、P施肥量对玉米生育期土壤微生物量C、N、P的影响。结果表明，不同N、P施肥量对微生物量C无明显影响；施N肥量高(225kg/hm²)时降低微生物量N；当施P肥达225kg/hm²时则对微生物量P产生明显的抑制作用。     

不同氮水平下CO2浓度升高对小麦土壤可溶性C、N和P的影响

采用FACE(Freeaircarbondioxideenrichment)技术,研究了不同N施肥水平下,大气CO2浓度升高对稻/麦轮作小麦季土壤可溶性C、N、P的影响。结果表明,高CO2使土壤可溶性C在小麦前期和0~5cm土层降低,成熟期增加,对水稻和小麦不同轮作季土壤可溶性C的影响不同。在低N和常规N处理下,高CO2使小麦分蘖期土壤可溶性N含量分别增加17.2%和18.9%,在其他生长期,土壤可溶性N含量降低9.8%~63.0%,拔节期降低幅度最大分别为63.0%和50.4%,土层0~5cm降低幅度>5~15cm土层;小麦季和水稻季一样需要增加N肥施用量。CO2浓度升高增加了土壤可溶性P的含量,其中低N处理增加幅度高于常规N处理,研究表明小麦生长不会受到P养分的限制。     

华北平原农田生态系统土壤C、N净矿化及尿素转化研究

以华北平原区4个农田生态系统[京郊蔬菜大棚(GH)和河北栾城(LF)、河北南皮(NF)、山东惠民(HF)3个粮田]为研究对象,采用室内好气、恒温、避光条件下培养30.d,对比研究了不同海拔和不同农业扰动强度下的农田生态系统中耕层(020.cm)土壤的净N矿化、净硝化、净C矿化以及尿素的转化,旨在探索人类农业扰动强度和地理海拔对土壤供N潜力和尿素N转化的影响。结果表明,4个地区的土壤供N潜力分别为:14.4、13.2,17.7和16.5.mg/kg,说明高度熟化的华北区农田土壤供N潜力相对稳定。以施用有机肥为主的蔬菜大棚和以施用化肥为主的粮田对土壤供N没有显著影响。农田土壤净矿化后的供N形式主要是NO3--N。以施用有机肥为主的蔬菜大棚积累了较高的土壤有机质和全N,但是土壤净C矿化以及施用尿素后CO2的排放量均低于以施用化肥为主的粮田。尿素在各区域农田土壤中水解转化后均主要以NO3--N形式存在,NO3--N占尿素水解后无机N增量的98%9～9%;华北平原农田生态系统施入尿素态N.30d后,水解成有效态无机N的转化率为63.4%8～3.2%,即每克尿素态N在京郊蔬菜大棚(GH)、栾城高产农田(LF)、南皮农田(NF)和惠民农田(HF)土壤中转化为NO3--N的量分别为0.69、0.82、0.64和0.63.g/kg,同时可使相应区域农田的CO2排放量分别增加CO21.20、1.360、.67和1.58.g/kg。     

包膜肥对设施番茄产量及土壤氮、磷累积的影响

采用小区试验方法研究包膜肥对设施番茄产量及土壤N、P累积的影响,结果表明:施用包膜肥处理与传统处理相比,在中期50d时提高了表层(0-30cm)土壤中氮的含量,而对60-120cm土层的影响不明显,对磷的影响在表层和地下都不明显。在种植结束时(110d),包膜肥处理在0-120cm的土层中都显著降低了氮的含量,在0-30cm中提高了磷的含量,但在30-120cm的土层中没有显著影响。相同施肥量时,在110d时包膜肥处理降低了N、P在30cm以下土层中的累积,同时包膜肥可显著提高番茄产量;在包膜肥追肥量较传统处理减少1/3时,产量依然没有显著降低。包膜肥处理较传统处理也降低了番茄硝酸盐的累积。     

农田土壤N2O排放和减排措施的研究进展

氧化亚氮(N2O)是一种受人类活动影响的重要温室气体。农业土壤是其主要的排放源之一,土壤中硝化和反硝化作用是N2O产生的主要过程。N2O的排放受多种因素的影响,农业活动尤其是施用化学氮肥是农田N2O排放量增加的主要因素。提高氮肥利用率,使用硝化抑制剂等措施将有助于减少N2O的排放量,更有效的减排措施还有待进一步的研究与应用。     

Effect of crop residue C:N ratio on N2O emissions from Gray Lowland soil in Mikasa,Hokkaido, Japan

Abstract

We studied the effect of crop residues with various C:N ratios on N₂O emissions from soil. We set up five experimental plots with four types of crop residues, onion leaf (OL), soybean stem and leaf (SSL), rice straw (RS) and wheat straw (WS), and no residue (NR) on Gray Lowland soil in Mikasa, Hokkaido, Japan. The C:N ratios of these crop residues were 11.6, 14.5, 62.3, and 110, respectively. Based on the results of a questionnaire survey of farmer practices, we determined appropriate application rates: 108, 168, 110, 141 and 0 g C m^?2 and 9.3, 11.6, 1.76, 1.28 and 0 g N m^?2, respectively. We measured N₂O, CO₂ and NO fluxes using a closed chamber method. At the same time, we measured soil temperature at a depth of 5 cm, water-filled pore space (WFPS), and the concentrations of soil NH⁺ ₄-N, NO^? ₃-N and water-soluble organic carbon (WSOC). Significant peaks of N₂O and CO₂ emissions came from OL and SSL just after application, but there were no emissions from RS, WS or NR. There was a significant relationship between N₂O and CO₂ emissions in each treatment except WS, and correlations between CO₂ flux and temperature in RS, soil NH⁺ ₄-N and N₂O flux in SSL and NR, soil NH⁺ ₄-N and CO₂ flux in SSL, and WSOC and CO₂ flux in WS. The ratio of N₂O-N/NO-N increased to approximately 100 in OL and SSL as N₂O emissions increased. Cumulative N₂O and CO₂ emissions increased as the C:N ratio decreased, but not significantly. The ratio of N₂O emission to applied N ranged from ?0.43% to 0.86%, and was significantly correlated with C:N ratio (y = ?0.59 ln [x] + 2.30, r ² = 0.99, P < 0.01). The ratio of CO₂ emissions to applied C ranged from ?5.8% to 45% and was also correlated with C:N ratio, but not significantly (r ² = 0.78, P = 0.11).     

Effect of urease and nitrification inhibitors on N transformation, gaseous emissions of ammonia and nitrous oxide, pasture yield and N uptake in grazed pasture system

Nitrogen (N) losses via nitrate (NO₃⁻) leaching, ammonia (NH₃) volatilization and nitrous oxide (N₂O) emissions from grazed pastures in New Zealand are one of the major contributors to environmental degradation. The use of N inhibitors (urease and nitrification inhibitors) may have a role in mitigating these N losses. A one-year field experiment was conducted on a permanent dairy-grazed pasture site at Massey University, Palmerston North, New Zealand to quantify these N losses and to assess the effect of N inhibitors in reducing such losses during May 2005-2006. Cow urine at 600 kg N ha⁻¹ rate with or without urease inhibitor N-(n-butyl) thiophosphoric triamide (nBTPT) or (trade name “Agrotain”) (3 L ha⁻¹), nitrification inhibitor dicyandiamide (DCD) (7 kg ha⁻¹) and the use of double inhibitor (DI) containing a combination of both Agrotain and DCD (3:7) were applied to field plots in autumn, spring and summer. Pasture production, NH₃ and N₂O fluxes, soil mineral N concentrations, microbial biomass C and N, and soil pH were measured following the application of treatments during each season. All measured parameters, except soil microbial biomass C and N, were influenced by the added inhibitors during the three seasons. Agrotain reduced NH₃ emissions over urine alone by 29%, 93% and 31% in autumn, spring and summer respectively but had little effect on N₂O emission. DCD reduced N₂O emission over urine alone by 52%, 39% and 16% in autumn, spring and summer respectively but increased NH₃ emission by 56%, 9% and 17% over urine alone during those three seasons. The double inhibitor reduced NH₃ by 14%, 78% and 9% and N₂O emissions by 37%, 67% and 28% over urine alone in autumn, spring and summer respectively. The double inhibitor also increased pasture dry matter by 10%, 11% and 8% and N uptake by the 17%, 28% and 10% over urine alone during autumn, spring and summer respectively. Changes in soil mineral N and pH suggested a delay in urine-N hydrolysis with Agrotain, and reduced nitrification with DCD. The combination of Agrotain and DCD was more effective in reducing both NH₃ and N₂O emissions, improving pasture production, controlling urea hydrolysis and retaining N in NH₄⁺ form. These results suggest that the combination of both urease and nitrification inhibitors may have the most potential to reduce N losses if losses are associated with urine and improve pasture production in intensively grazed systems.     

液面上部气体的置换对土壤厌氧培养下的N2O和CO2排放的影响

To study effect of C2H2 and change of headspace gas on N2O emission,denitrification,as well as CO2 emission,slurries of an agricultural soil were anaerobically incubated for 7 days at 25℃.Both N2O reduction and CO2 emissions were inhibited by the addition of 100 mL L^-1 of C2H2.However,the inhibition to CO2 emission was alleviated by the replacement of headspace gas,and the N2O emission was enhanced by the replacement.Acetylene disappeared evidently from the soil slurries during the incubation.Consequently results obtained from the traditional C2H2 blocking technique for determination of denitrifcation rate,especially in a long-time incubation,should be explained with care because of its side effect exsting in the incubation environments without change of headspace gas.To reduce the possible side effect on the processes other than denitrification ,it is suggested that headspace gas should be replaced several times during a long-time incubation.     

综合产量和土壤N2O排放的马铃薯施氮量分析

施氮可提高作物产量,但同时也增加温室气体N_2O的土壤排放量。研究施氮量与产量和土壤N_2O排放的关系,对保障作物产量并兼顾环境效应的农业生产实践具有重要指导意义。该研究设置N0(0)、N1(67.5 kg/hm~2)、N2(125 kg/hm~2)、N3(187.5 kg/hm~2)4个施氮水平,采用静态箱-气相色谱法对土壤N_2O排放进行田间原位测定,研究施氮量对马铃薯产量、土壤N_2O排放的影响,分析综合产量与土壤N_2O排放的合理施氮量。结果表明:施氮显著增加马铃薯产量和土壤N_2O累积排放量,较不施氮(N0)处理,N1、N2和N3处理马铃薯产量增加78.5%、93.1%和95.6%;生育期N1、N2和N3处理马铃薯土壤N_2O累积排放量分别是N0处理的2.3、4.4和6.7倍。同时,随施氮量增加,N_2O排放系数、硝态氮强度和单产N_2O排放量均显著增加。在低氮处理(N0、N1)时,土壤N_2O排放通量与土壤温度、湿度显著正相关,而在高氮水平时,土壤N_2O排放通量与土壤硝态氮含量显著正相关。施氮67.5 kg/hm~2可确保研究区马铃薯产量并有效降低土壤N_2O排放。     

Nitrate removal from drained and reflooded fen soils affected by soil N transformation processes and plant uptake

Knowledge about nitrate transformation processes and how they are affected by different plants is essential in order to reduce the loss of valuable N fertiliser as well as to prevent environmental pollution due to nitrate leaching or N₂O emission after fertilisation or the reflooding of degraded fens with nitrate-containing municipal sewage. Therefore four microcosm ¹⁵N tracer experiments were performed to evaluate the effect of common wetland plants (Phalaris arundinacea, Phragmites australis) combined with different soil moisture conditions (from dry to reflooded) on nitrate turnover processes. At the end of experiment, the total formation of gaseous N compounds was calculated using the ¹⁵N balance method. In two experiments (wet and reflooded soil conditions) the N₂O and N₂ emissions were also directly determined.Our results show that in degraded fen soils, which process mainly takes place—denitrification or transformation into organic N compounds—is determined by the soil moisture conditions. Under dry soil moisture conditions (water filled pore space: 31%) up to 80% of the ¹⁵N nitrate added was transformed into organic N compounds. This transformation process is not affected by plant growth. Under reflooded conditions (water filled pore space: 100%), the total gaseous N losses were highest (77-95% of the ¹⁵N-nitrate added) and the transformation into organic N compounds was very low (1.8% of ¹⁵N nitrate added). Under almost all soil conditions plant growth reduced the N losses by 20-25% of the ¹⁵N nitrate added due to plant uptake. The N₂ emissions exceeded the N₂O emissions by a factor of 10-20 in planted soil, and as much as 30 in unplanted soil. In the treatments planted with Phragmites australis, N₂O emission was about two times higher than in the corresponding unplanted treatment. 15% of the N₂O and N₂ formed was transported via the Phragmites shoots from the soil into the atmosphere. By contrast, Phalaris arundinacea did not affect N₂O emissions and no emission via the shoots was observed.     

Mitigation options for N2O emission from a corn field in Kalimantan,Indonesia

Abstract

Field experiments were designed to quantify N₂O emissions from corn fields after the application of different types of nitrogen fertilizers. Plots were established in South Kalimantan, Indonesia, and given either urea (200 kg ha^?1), urea (170 kg ha^?1) + dicyandiamide ([DCD] 20 kg ha^?1) or controlled-release fertilizer LP-30 (214 kg ha^?1) prior to the plantation of corn seeds (variety BISI 2). Each fertilizer treatment was equivalent to 90 kg N ha^?1. Plots without chemical N fertilizer were also prepared as a control. The field was designed to have three replicates for each treatment with a randomized block design. Nitrous oxide fluxes were measured at 4, 8, 12, 21, 31, 41, 51, 72 and 92 days after fertilizer application (DAFA). Total N₂O emission was the highest from the urea plots, followed by the LP-30 plots. The emissions from the urea + DCD plots did not differ from those from the control plots. The N₂O emission from the urea + DCD plots was approximately one thirtieth of that from the urea treatment. However, fertilizer type had no effect on grain yield. Thus, the use of urea + DCD is considered to be the best mitigation option among the tested fertilizer applications for N₂O emission from corn fields in Kalimantan, Indonesia.     

氮、磷、钾、锌配施对小白菜产量和品质的效应

应用“416-B”最优混合设计，研究了氮、磷、钾、锌肥对小白菜产量和品质的效应。结果表明，施用氮、磷、钾、锌的增产效果为氮〉锌〉钾〉磷。氮与磷、钾、锌配施有利于小白菜增产和品质的改善。在本试验条件下，小白菜高产、优质施肥方案为每千克土施N0．26g、P2O5 0．11g、K2O 0．42g、Zn0．017g，目标产量790．7g/盆FW，鲜小白菜中含锌81．9mg／kg，可溶性糖1．63％，Vc117．9mg／kg，硝酸盐809.5mg／kg。     

Fungal N2O production in an arable peat soil in Central Kalimantan,Indonesia

Abstract

To clarify the microbiological factors that explain high N₂O emission in an arable peat soil in Central Kalimantan, Indonesia, a substrate-induced respiration-inhibition experiment was conducted for N₂O production. The N₂O emission rate decreased by 31% with the addition of streptomycin, whereas it decreased by 81% with the addition of cycloheximide, compared with a non-antibiotic-added control. This result revealed a greater contribution of the fungal community than bacterial community to the production of N₂O in the soil. The population density of fungi in the soil, determined using the dilution plate method, was 5.5 log c.f.u. g^?1 soil and 4.9 log c.f.u. g^?1 soil in the non-selective medium (rose bengal) and the selective medium for Fusarium, respectively. The N₂O-producing potential was randomly examined in each of these isolates by inoculation onto Czapek agar medium (pH 4.3) and incubation at 28°C for 14 days. Significant N₂O-producing potential was found in six out of 19 strains and in five out of seven strains isolated from the non-selective and selective media, respectively. Twenty-three out of 26 strains produced more than 20% CO₂ during the 14-day incubation period, suggesting the presence of facultative fungi in the soil. These strains were identified to be Fusarium oxysporum and Neocosmospora vasinfecta based on the sequence of 18S rDNA, irrespective of the N₂O-producing potential and the growth potential in conditions of low O₂ concentration.