中国东部合肥城市土壤氮素矿化特点

Nitrogen cycling has been poorly characterized in urban ecosystems. In this study, the in-situ buried bag incubation technique was used to quantify net rates of N mineralization and nitrification in soils of two urban sites, a street greening belt and a university campus, and a suburban site , a forest park, in Hefei, East China. The average concentration of extractable NO3- in the surface soil (0--10 cm) was significantly higher at the urban sites than the suburban park site, whereas extractable NH4+ concentration was significantly higher at the suburban park site than the urban sites. The forest park soil had greater potential N mineralization (148.1 μg N cm-3) than the soils from the campus (138.3 μg N cm-3) and street (99.8 μg N cm-3). It was estimated that the net mineralization rates varied between 1.63 and 2.69 μg N cm-3 d-1 and net nitrification rates between 0.82 and 1.02 μg N cm-3 d-1 at the suburban forest park site, but the rates varied from 1.27 to 2.41 μg N cm-3 d-1 and from 1.07 to 1.49 μg N cm-3 d-1, respectively, at the urban campus site. Both net mineralization and nitrification rates were lower during dry seasons. Results from regression analysis indicated that net N mineralization was significantly and positively correlated with soil moisture and soil C/N ratio, and was negatively correlated with soil pH. Relative nitrification was, however, significantly and negatively correlated with soil moisture and soil C/N ratio, and was positively correlated with soil pH. Mean relative nitrification was 0.763, indicating the dominance of nitrate cycling relative to ammonium cycling at the urban sites. The urban soils had the great potential for N losses compared to the suburban soils.     

大气CO2浓度升高对温带森林土壤微生物活性的影响

Microorganisms play a key role in the response of soil ecosystems to the rising atmospheric carbon dioxide (CO2) as they mineralize organic matter and drive nutrient cycling. To assess the effects of elevated CO2 on soil microbial C and N immobilization and on soil enzyme activities, in years 8 (2006) and 9 (2007) of an open-top chamber experiment that begun in spring of 1999, soil was sampled in summer, and microbial biomass and enzyme activity related to the carbon (C), nitrogen (N) and phosphorus (P) cycling were measured. Although no effects on microbial biomass C were detected, changes in microbial biomass N and metabolic activity involving C, N and P were observed under elevated CO2. Invertase and dehydrogenase activities were significantly enhanced by different degrees of elevated CO2. Nitrifying enzyme activity was significantly (P < 0.01) increased in the August 2006 samples that received the elevated CO2 treatment, as compared to the samples that received the ambient treatment. Denitrifying enzyme activity was significantly (P < 0.04) decreased by elevated CO2 treatments in the August 2006 and June 2007 (P < 0.09) samples. β-N-acetylglucosaminidase activity was increased under elevated CO2 by 7% and 25% in June and August 2006, respectively, compared to those under ambient CO2. The results of June 2006 samples showed that acid phosphatase activity was significantly enhanced under elevated CO2. Overall, these results suggested that elevated CO2 might cause changes in the belowground C, N and P cycling in temperate forest soils.     

影响静态箱检测开放式气体排放源N2O排放通量的关键因子

为研究影响静态箱检测开放式气体排放源氧化亚氮（N2O）排放通量的关键因子,以提高静态箱检测气体排放通量的准确性,该文在实验室条件下,探究了箱体配置（有无通气孔、有无风扇）和检测条件（不同密闭时间：30、40、50和60 min;不同排放源表面风速：0、0.5、1.0、1.5和2.0 m/s）对300 mm（直径）×300 mm（高度）（D300 mm×H300 mm）的静态箱检测N2O排放通量准确性的影响规律。结果表明,不同配置的静态箱测量结果偏差率随时间的变化趋势均相同,其中有通气孔和风扇的箱体在不同风速下的检测稳定性较好,检测准确性最高。当排放源表面风速为0～2 m/s时,风扇对静态箱检测准确性无显著性影响,排放源表面的风主要通过通气孔影响静态箱的检测准确性。静态箱检测的气体排放通量与实际排放通量的偏差率随排放源表面风速和箱体密闭时间的增加而显著降低。该试验推荐在排放源表面风速小于2 m/s的无粪便堆积的奶牛运动场以及排放源介质相似的开放式气体排放系统中使用有通气孔和风扇的静态箱对N2O排放通量进行检测,密闭50 min。     

内蒙古荒漠化草地土壤碳、氮养分及土壤呼吸的空间异质性研究

There is a limited knowledge of spatial heterogeneity in soil nutrients and soil respiration in the semi-arid and arid grasslands of China. This study investigated the spatial differences in soil nutrients and soil respiration among three desertified grasslands and within two shrub-dominated communities on the Ordos Plateau of Inner Mongolia, China in 2006. Both soil organic carbon (SOC) and total nitrogen (TN) were significantly different (P < 0.01) among the three desertified grasslands along a degradation gradient. Within the two shrub-dominated communities, the SOC and TN contents decreased with increasing distance from the main stems of the shrub, and this “fertile island” effect was most pronounced in the surface soil. The total soil respirations during the growing season were 131.26, 95.95, and 118.66 g C m-2, respectively, for the steppe, shrub, and shrub-perennial grass communities. The coefficient of variability of soil respiration was the highest in the shrub community and lowest in the steppe community. CO2 effluxes from the soil under the canopy of shrub were significantly higher than those from the soil covered with biological crusts and the bare soil in the interplant spaces in the shrub community. However, soil respiration beneath the shrubs was not different from that of the soil in the inter-shrub of the shrub-perennial grass community. This is probably due to the smaller shrub size. In the two shrub-dominated communities, spatial variability in soil respiration was found to depend on soil water content and C:N ratio.     

加气灌溉水氮互作对温室芹菜地N2O排放的影响

为揭示加气条件下不同灌溉和施氮量对设施菜地N2O排放的影响,提出有效的N2O减排措施,该研究以温室芹菜为例,设置充分灌溉(1.0 Ep,I1;Ep为2次灌水间隔内φ20 cm标准蒸发皿的累计蒸发量)和亏缺灌溉(0.75 Ep,I2)2个灌溉水平和0 (N0)、150 (N150)、200 (N200)、250 kg/hm2 (N250)4个施氮水平,采用静态箱-气相色谱法对各处理土壤N2O的排放进行监测,并分析不同灌溉和氮肥水平下土壤温度、湿度、矿质氮(NH4+-N和NO3--N)、硝化细菌和反硝化细菌的变化,以及对土壤N2O排放的影响.结果表明:充分灌水温室芹菜地N2O排放显著(P＜0.05)高于亏缺灌溉;施氮显著(P＜0.05)增加了土壤N2O排放,N150、N200和N250处理的N2O累积排放量分别是N0处理的2.30、4.14和7.15倍.设施芹菜地N2O排放与土壤温度、湿度和硝态氮含量呈指数相关关系(P＜0.01),与硝化细菌和反硝化细菌数量呈线性相关关系(P＜0.01),而与土壤铵态氮没有显著相关关系.灌水和施氮提高芹菜产量的同时,显著增强了土壤N2O排放.综合考虑产量和温室效应,施氮量150 kg/hm2、亏缺灌溉为较佳的管理模式.该研究为设施菜地N2O减排及确定合理的水氮投入量提供参考.     

监测土壤流失的标线法及其测定犁耕运移土壤的尝试

介绍了监测土壤流失和堆积的一种新方法——标线法和在贵州普定喀斯特坡地开展试验研究测定犁耕侵蚀的结果。坡度3°、坡长24.2 m的石灰土旱坡地10次犁耕的试验结果表明:坡顶犁耕侵蚀速率0.67 cm/a,和实际情况相符;顺坡犁耕通量52.6 kg/(m.a),和其他研究者用小石子或137Cs、210Pbex核素示踪法测得的值基本一致。标线法具有简便易行、价值低廉和标线隐蔽性强、不易被发现破坏的特点,所测结果是可靠的。此法解决了侵蚀针或标桩法可能干扰径流和风流场的问题,且不妨碍犁耕,可广泛应用于流水侵蚀、风蚀和犁耕侵蚀的长期监测。标线法测得的是土壤点侵蚀和堆积量值,非常适用于侵蚀随坡长变化的研究。     

静态箱法测定旱地农田温室气体时密闭时间的研究

应用自动观测装置对华北平原冬小麦田典型天气条件下密闭箱内气体排放通量进行了连续测定,分析了不同气体排放通量的变化过程,研究了密闭时间对其产生的影响.结果表明：测定CO2的密闭时间应不超过25min,测定N2O的密闭时间以15～30min为宜,测定CH4的密闭时间应在30min以内.此结果对静态箱法测定农田温室气体具有重要的参考价值.     

长期有机养分循环利用对红壤稻田土壤供氮能力的影响

通过15年的田间定位试验结合盆栽试验,研究了长期有机养分循环利用和不同化肥配施对红壤稻田土壤供氮能力的影响。结果表明,土壤有机碳、全氮、微生物生物量氮(MB-N)和土壤氮的矿化量与生物吸氮量有极显著的正相关关系,是良好的土壤供氮能力指标。长期有机养分循环利用或配合化肥施用能显著提高土壤有机碳、全氮含量和氮的矿化量,提高幅度分别为20.1%4～0.9%、0.460～.60.g/kg和55.0%(6周);明显提高土壤MB-N含量,提高幅度平均为70.3%。长期纯化肥处理对土壤碳、氮库的积累和氮的矿化量的提高作用甚微。盆栽试验表明,长期施用氮肥和氮、磷、钾肥土壤供氮量提高量极小,与长期不施肥相比提高幅度分别为2.1%和6.2%,而有机养分循环利用能显著提高土壤供氮量,提高幅度为33.7%8～9.0%。随着有机养分循环利用和NPK肥配合程度的提高,土壤供氮量提高幅度呈上升的趋势。     

农肥和化肥对黑土农田生态系统氮素循环与平衡影响的研究

在不同施肥处理条件下,分别定量测定了玉米田土壤氮素自生固氮作用、氨化作用、硝化作用、反硝化损失、氨挥发、NO3--N淋溶损失等氮素循环转化途径。研究结果表明,不施肥的土壤生态系统每年土壤全氮将减少-110.5kg/hm2。施肥能够有效地提高土壤氮素转化能力,农肥的氮素转化作用明显高于化肥的氮素转化作用。各处理反硝化损失的氮量为7.26～21.66kg/hm2,淋溶损失量为0.09～0.21kg/hm2,氨挥发损失的氮量为0～15.23kg/hm2。玉米田施肥处理总的氮素平衡处于盈余状态,不施肥处理的氮素平衡处于亏缺状态。单施农肥的盈余量高于单施化肥及农肥化肥配比处理的盈余量,低量施肥模式土壤中氮素的输入和输出基本处于平衡状态,高量施肥模式土壤中氮素处于盈余状态,虽有利于培肥地力,但却造成了肥料的浪费。     

Methane production and oxidation—A review on the pmoA and mcrA gene abundances for understanding the functional potentials of agricultural soils

Global efforts to avert climate change cannot succeed without tackling the emission of methane from soil and other ecosystems. Methane is a greenhouse gas that retains heat in the atmosphere and causes global warming. Its production is the last step of organic matter decomposition, and it is produced by methanogenic archaea bearing the functional gene mcrA (encoding methyl-coenzyme M reductase). Methane production involves the reduction of acetate or carbon dioxide in a microaerophilic or anaerobic environment under the catalytic actions of methyl-coenzyme M to generate methane. On the other hand, methane-oxidizing bacteria, also known as methanotrophs, through the catalytic action of particulate methane monooxygenase (pMMO), oxidize methane and reduce its emission to the atmosphere. In essence, both production and consumption of methane happen within the soil. Methanotrophs and methanogens inhabit the same soil environment. In fact, a shift in the balance between methanogen and methanotroph activities and abundances could influence soil methane emission and global warming. In this review, we highlight recent advances in drivers of methane flux, pmoA (encoding pMMO) and mcrA gene abundances, methane emission and control, relationships between microbial functional gene abundances and soil functions, and methods for studying the pmoA and mcrA gene abundances in soil. We also highlight gaps that need to be filled and the impact of the mcrA/pmoA gene abundance ratio in driving the methane emission rate in soil. We also discuss the various abiotic factors that control pmoA and mcrA gene abundances.     

耕作措施与氮肥对黑土流失及氮损失的影响

为解决东北黑土区坡耕地水土流失严重的问题,探索不同耕作措施和施氮策略对水土流失、氮素养分流失特征的影响,于2015—2016年在黑龙江省哈尔滨市设置径流小区试验,共设9处理。处理1(T1)为裸地;处理2(T2)为荒地;处理3(T3)为优化施氮(180kg N/hm~2),顺垄;处理4(T4)为优化施氮(180kg N/hm~2),横垄;处理5(T5)为增氮施肥(210kg N/hm~2),顺垄;处理6(T6)为减氮施肥(90kg N/hm~2),顺垄;处理7(T7)为替氮施肥((180kg N/hm~2,其中30kg N为有机肥,顺垄);处理8(T8)为优化施氮(180kg N/hm~2),横垄,苜蓿—玉米间作;处理9(T9)为减氮施肥(90kg N/hm~2),顺垄,秸秆覆盖。结果表明,T1的年均产流量为151.0m~3/hm~2,与T1相比,T2、T3、T4、T5、T6、T7、T8、T9分别拦截80.9%,64.4%,83.0%,65.2%,68.0%,60.4%,93.8%,88.1%;T1的年均土壤侵蚀量为9.5t/hm~2,与T1相比,T2、T3、T4、T5、T6、T7、T8、T9分别拦截98.8%,57.3%,88.4%,60.7%,50.6%,56.6%,99.2%,94.4%;T1的年均无机氮地表径流损失为207.6g N/hm~2,与T1相比,T2、T3、T4、T5、T6、T7、T8、T9分别减少无机氮损失43.0%,24.7%,35.5%,20.0%,36.8%,20.2%,75.6%,55.9%。雪水融化径流导致坡耕地的氮素损失不容忽视。坡耕地种植玉米时,单项耕作措施防止水土流失的效果,以生物篱最好,秸秆覆盖少耕较好,横垄次之;多项综合耕作措施中,横垄耕作和生物篱结合,效果均较好。相同耕作模式不同施肥措施中,有机肥替代因地上部作物生长较差有较大的产流量;减氮处理由于较低的无机氮浓度可减少地表径流氮素损失,同时增加产沙量。地表产流量与日降雨量间存在正的线性相关性(R2为0.213 9~0.543 8),T2、T9除外;土壤侵蚀量、无机氮损失量与地表产流量有正的线性相关(R2为0.338 0~0.728 1,0.618 4~0.895 2),T1除外。年均地表产流中,硝态氮浓度与无机氮浓度之比越小,年均地表径流无机氮损失越小。     

北京市大兴区土壤肥力的空间变异

该文旨在揭示北京市大兴区土壤肥力指标及肥力质量空间变化规律,为土壤培肥管理提供指导。通过实测研究区土壤有机质、全氮、速效磷、速效钾和pH值五个肥力指标的含量,运用地统计学方法和Fuzzy综合评判法对其进行计算分析。结果表明：大兴区5种土壤肥力指标中,有机质、全氮、速效钾、pH值的块金值与基台值的比值C0/(C+C0)分别为0.38、0.25、0.29和0.50,说明它们具有中等的空间相关性;速效磷的C0/(C+C0)达到0.88,说明其具有弱的空间相关性;土壤有机质和全氮含量主要由北向南逐渐降低,速效磷主要从西南向东北方向逐渐降低,速效钾主要由东南向西北方向逐渐降低,pH值主要由南向北逐渐降低;大兴区土壤肥力质量呈现出明显的北高南低的趋势,5个等级地块分别占全区总面积的0.21%、6.35%、20.95%、29.45%和43.04%,Ⅲ类、Ⅳ类、Ⅴ类等地占整个区域面积的93.44%。大兴区土壤肥力总体水平偏低,除了与该地区土壤质地偏砂有关,同时也受到人为管理措施的影响。     

缓释肥等氮替代尿素对坡耕地径流氮素流失和青贮玉米生长的影响

为比较单施尿素与尿素和缓释肥配施对云南坡耕地径流氮流失、土壤养分及青贮饲用玉米生长的影响作用。通过自然降雨下的径流槽试验,在等氮条件下按云南常规施肥量设置单施尿素(CK)、添加硝化抑制剂速溶诺泰克^®21等氮替代40%的尿素+60%普通尿素(处理I)和聚谷氨酸增效3代等氮替代40%的尿素+60%普通尿素(处理Ⅱ)3个处理。结果表明:生育期内尿素配施缓释肥的处理I和处理Ⅱ与单施尿素CK处理相比,总氮、铵态氮和硝态氮流失浓度削减量最高分别为2.59,1.60,1.42 mg/L和1.61,1.38,1.25 mg/L;累计流失量与CK相比,处理I、处理Ⅱ的总氮、铵态氮和硝态氮累计流失量分别削减18.56%,16.19%,24.31%和10.75%,8.73%,17.08%。在青贮玉米生育期内,配施缓释肥处理土壤较CK处理铵态氮含量分别显著提高13.94%~45.04%和9.63%~22.39%,硝态氮含量分别显著降低3.70%~29.91%,8.61%~12.55%,土壤微生物生物量氮含量分别显著提高22.13%~31.76%,11.80%~22.81%。尿素配施缓释肥也可以显著提高青贮玉米产量和植株氮吸收量,并通过显著提高植株粗蛋白和粗脂肪含量,降低粗灰分和洗涤纤维含量来提高其品质性状。相关性分析可知,径流氮流失与土壤氮含量、青贮玉米产量和植株吸氮量呈负相关关系,土壤氮素与产量和植株氮吸收均呈正相关关系,产量与植株氮吸收呈极显著正相关关系。综上所述,与单施尿素相比,尿素配施缓释氮肥能够减缓土壤氮素的硝化过程,显著增强土壤的固氮能力,维持土壤高氮素水平,进而提高青贮饲用玉米的产量和品质,为红壤坡耕地青贮玉米种植的施肥提供科学理论依据。     

长期定位试验地耕层土壤氮素空间变异性及其应用

采用地统计学与经典统计学相结合的方法,对中国科学院沈阳生态实验站长期定位试验地耕层土壤全N和碱解N空间变异性特征进行分析的结果表明,在30m×42m的田间尺度下土壤全N和碱解N在0～10cm和10～20cm两个层次的空间变异主要受结构性因子的影响,在135°方向的变异相对较强,说明观测试验地较为均一的田间管理使得随机因子引起的空间变异所占比例大大减弱。根据变异系数和分形维数分析结果,可以认定试验地能够达到长期定位监测的要求。相对误差为5%时采集17个和29个土样可分别达到95%和99%的置信水平,结合克里格插值得出的土壤N素空间分布图,可以确定更为理想的取样方案。     

澳大利亚亚热带地区二代肯宁南洋杉林早期测定土壤C、N所需采集土壤样大小研究

Investigations into forest soils face the problem of the high level of spatial variability that is an inherent property of all forest soils. In order to investigate the effect of changes in residue management practices on soil properties in hoop pine （Araucaria cunninghamii Aiton ex A. Cunn.） plantations of subtropical Australia it was important to understand the intensity of sampling effort required to overcome the spatial variability induced by those changes. Harvest residues were formed into windrows to prevent nitrogen （N） losses through volatilisation and erosion that had previously occurred as a result of pile and burn operations. We selected second rotation （2R） hoop pine sites where the windrows （10-15 m apart） had been formed 1, 2 and 3 years prior to sampling in order to examine the spatial variability in soil carbon （C） and N and in potential mineralisable N （PMN） in the areas beneath and between （inter-） the windrows. We examined the implications of soil variability on the number of samples required to detect differences in means for specific soil properties, at different ages and at specified levels of accuracy. Sample size needed to accurately reflect differences between means was not affected by the position where the samples were taken relative to the windrows but differed according to the parameter to be sampled. The relative soil sampling size required for detecting differences between means of a soil property in the inter-windrow and beneath-windrow positions was highly dependent on the soil property assessed and the acceptable relative sampling error. An alternative strategy for soil sampling should be considered, if the estimated sample size exceeds 50 replications. The possible solution to this problem is collection of composite soil samples allowing a substantial reduction in the number of samples required for chemical analysis without loss in the precision of the mean estimates for a particular soil property.     

滇东北山区坡耕地土壤流失方程研究

滇东北山区是云南省“长江上游水土保持重点防治工程”治理计划的重点区域,该区域水土流失的主体是坡耕地。该项研究通过对３２个试验小区连续３ａ实测数据的统计分析,建立了滇东北山区坡耕地土壤流失方程Ａ＝Ｒ·Ｋ·ＬＳ·Ｃ·Ｐ;并确定了方程中诸因子的求算方法和数值,以及滇东北山区土壤允许流失量,为方程的应用提供了基本的技术数据。并进行了方程的验证,方程计算值与实测值的误差在６％以下,表明该方程在实际应用中具有