长期施肥对黑土酶活性和微生物呼吸的影响

以农业部哈尔滨黑土生态环境重点野外科学观测试验站28年长期定位试验为平台,研究了长期施用不同肥料对黑土酶活性及微生物呼吸强度的影响。结果表明,长期不同施肥处理后黑土过氧化氢酶、转化酶和脲酶的活性均产生较大的差异,有机无机肥料配合施用处理的土壤中脲酶和转化酶活性显著地高于单施化肥、有机肥和不施肥处理,施肥对土壤过氧化氢酶具有一定的抑制作用。相同施肥条件下0~20 cm土层土壤过氧化氢酶、转化酶和脲酶的活性均高于20~40 cm土层酶活性。此外,施肥对土壤真菌、细菌的呼吸都有一定的抑制作用。     

长期定位施肥下黑土呼吸的变化特征及其影响因素

阐明长期不同施肥下的土壤呼吸特征及其影响机制对黑土区固碳减排研究至关重要。该研究基于1990年开始的国家土壤肥力与肥料效益监测网站-吉林省公主岭市黑土监测基地,选取不施肥(CK)、单施氮磷钾肥(NPK)、无机肥配施低量有机肥(NPKM1)、1.5倍的无机肥配施低量有机肥(1.5(NPKM1))、无机肥配施高量有机肥(NPKM2)和无机肥配施秸秆(NPKS)6个处理,明确了长期不同施肥下土壤总呼吸和异养呼吸的季节变化特征,并分析了土壤温度、水分、微生物量碳氮、铵态氮、硝态氮与土壤呼吸和异养呼吸的关系。结果表明:长期有机无机肥配施可以显著提高土壤有机碳、全氮、土壤速效磷、有效钾的含量和土壤活性有机碳库组分含量(P0.05);与不施肥相比,长期有机无机肥配施和无机配施秸秆处理分别显著增加土壤呼吸及异养呼吸碳累积排放量56.32%~86.54%和70.01%~100.93%;根系呼吸对土壤呼吸的整体贡献为23.68%~34.30%;相关分析表明,土壤呼吸速率和异养呼吸速率与土壤温度极显著正相关(P0.01),与土壤含水率呈显著负相关(P0.01),土壤温度可以分别解释土壤呼吸和异养呼吸变化的42.79%和39.61%;土壤微生物量碳氮、土壤硝态氮均与土壤呼吸速率和异养呼吸速率极显著相关(P0.01),土壤微生物量碳氮、土壤硝态氮可以分别解释土壤呼吸和异养呼吸变化的78.42%和77.18%,58.33%和56.79%,59.29%和59.14%;土壤铵态氮虽然显著影响土壤呼吸速率(P0.05),可以解释土壤呼吸变化的5.56%,但其对异养呼吸速率的影响不显著。综合来看,微生物量碳对土壤呼吸及异养呼吸的影响最大,而土壤含水率(15%)越高则土壤呼吸越弱;无机配施秸秆处理可以提高土壤碳库组分含量,且作物生育期内土壤呼吸及异养呼吸碳累积释放量均低于等氮量下施用有机肥(NPKM1)的处理,为最佳的农田管理措施。     

稻麦轮作系统中大气CO2浓度升高对冬小麦生长季土壤呼吸的影响

Studies on the effect of elevated CO2 on C dynamics in cultivated croplands are critical to a better understanding of the C cycling in response to climate change in agroecosystems. To evaluate the effects of elevated CO2 and different N fertilizer application levels on soil respiration, winter wheat （Triticum aestivum L. cv. Yangmai 14） plants were exposed to either ambient CO2 or elevated CO2 （ambient [CO2] ＋ 200 μmol mol-1）, under N fertilizer application levels of 112.5 and 225 kg N ha-1 （as low N and normal N subtreatments, respectively）, for two growing seasons （2006-2007 and 2007-2008） in a rice-winter wheat rotation system typical in China. A split-plot design was adopted. A root exclusion method was used to partition soil respiration （RS） into heterotrophic respiration （RH） and autotrophic respiration （RA）. Atmospheric CO2 enrichment increased seasonal cumulative RS by 11.8% at low N and 5.6% at normal N when averaged over two growing seasons. Elevated CO2 significantly enhanced （P 〈 0.05） RS （12.7%）, mainly due to the increase in RH （caused by decomposition of larger amounts of rice residue under elevated CO2） during a relative dry season in 2007-2008. Higher N supply also enhanced RS under ambient and elevated CO2. In the 2007-2008 season, normal N treatment had a significant positive effect （P 〈 0.01） on seasonal cumulative RS relative to low N treatment when averaged across CO2 levels （16.3%）. A significant increase in RA was mainly responsible for the enhanced RS under higher N supply. The correlation （r2） between RH and soil temperature was stronger （P 〈 0.001） than that between RS and soil temperature when averaged across all treatments in both seasons. Seasonal patterns of RA may be more closely related to the plant phenology than soil temperature. The Q10 （the multiplier to the respiration rate for a 10 ℃ increase in soil temperature） values of RS and RH were not affected by elevated CO2 or higher N supply. These results mainly suggested that the increase in RS at elevated CO2 depended on the input of rice residue, and the increase in RS at higher N supply was due to stimulated root growth and concomitant increase in RA during the wheat growing portion of a rice-winter wheat rotation system.     

博德特氏菌HN36对土壤酶活性和呼吸强度的影响

研究了博德特氏菌HN36(Bordetella sp.)对受二氯喹啉酸污染土壤中的土壤酶活性和呼吸强度的影响。结果表明,与对照相比,加入HN36后均能提高土壤过氧化氢酶、蔗糖酶、多酚氧化酶、脲酶及碱性磷酸酶酶活性和呼吸强度,且随着接种量的增加而增强。当接种量为3×1010个.g-1干土时,效果最好。     

不同生物有机肥用量对土壤活性有机质和酶活性的影响

通过盆栽试验研究了不同有机质含量的土壤中,不同用量生物有机肥对棉花苗期土壤活性有机质和5种酶活性的影响。结果表明,不同土壤随着生物有机肥施用量的增加,其活性有机质及碳库管理指数(CMI)均显著增加。其中高有机质含量土壤施用生物有机肥20 g/kg效果显著,中等有机质含量土壤和低有机质含量土壤施用生物有机肥30、40 g/kg效果显著。5种土壤酶活性施肥处理均高于对照(CK),并且土壤酶活性与施用量成正比。脲酶、蔗糖酶、多酚氧化酶在施用生物有机肥10、20 g/kg与其它处理相比变化显著,过氧化氢酶、蛋白酶变化不显著。相关分析表明,有机质与活性有机质和CMI在棉花出苗0 d相关系数分别为0.831**、0.542*;在出苗后60 d相关系数分别为0.928**、0.635**,其中有机质与活性有机质相关性最高。而CMI与有机质和活性有机质在棉花出苗0 d相关系数分别为0.542*、0.896**,在出苗后60 d分别为0.635**、0.842**,说明活性有机质相对于有机质与CMI关系更为密切。蔗糖酶、过氧化氢酶、多酚氧化酶与土壤有机质和活性有机质在棉花出苗0 d和出苗后60 d存在显著相关,表明活性有机质与土壤酶活性能够较好的反映肥力水平。     

玉米立茬与粉碎秸秆覆盖对生长季土壤呼吸的影响

农田土壤呼吸(Rs)是全球CO_2循环的重要组成部分,生长季土壤呼吸对于作物的产量有巨大的影响,同时,作物残茬的覆盖模式会影响土壤呼吸。该文应用了粉碎秸秆覆盖地表(SH)和立茬覆盖地表(ST)是两种主流的作物残茬覆盖地表模式,自2000年起,玉米收获之后,在试验地块施用这2种作物残茬覆盖地表的模式。自2013年开始,在试验地块测量每年冬季的土壤结冻深度,积雪的厚度与CO_2通量,土壤温度与湿度。总土壤呼吸分为异养呼吸(HR)和根际呼吸(RR),该文使用放射性碳标记技术和数学方程计算异养呼吸和根际呼吸的CO_2通量。试验结果显示,与SH处理相比,ST处理地表平均积雪厚度可以增加44%,最大土壤冻深降低18%,并且冻土完全融化的时间将提前10到27 d。ST与SH的平均CO_2通量分别为16.55和14.02 mmol/m~2h。对于整个生长季,SH与ST的土壤呼吸差别在生长季开始和结束时期较小,在生长季的中期较大。ST的平均Rs比SH多3.3 mmol/m~2h,在ST中,HR是Rs的主要构成部分,而RR只约占总土壤呼吸10%。冗余分析结果显示,Rs和HR与土壤温度和积雪厚度呈正相关,与冻土深度呈负相关。该文的研究结果显示相比较于粉碎秸秆残茬覆盖,立茬覆盖地表有利于提高生长季的土壤呼吸,可为玉米的光合作用提供较多CO_2,这将有利于作物增产。     

连年翻压绿肥对植烟土壤微生物量及酶活性的影响

通过3年田间定位试验,研究连年翻压绿肥对植烟土壤微生物量碳、氮及酶活性的影响。结果表明,连年翻压绿肥能提高土壤微生物量碳、氮及土壤脲酶、酸性磷酸酶、蔗糖酶、过氧化氢酶的活性,且随翻压年限的增加而增加。整个生育期,翻压3年绿肥的处理与对照相比微生物量碳、氮分别提高31.0%~67.1%、23.0%~145.1%;土壤脲酶、酸性磷酸酶、蔗糖酶、过氧化氢酶活性分别提高34.4%~51.9%、11.0%~18.6%、58.0%~172.7%、24.0%~50.0%,表明翻压绿肥后土壤生物过程活跃,利于有机物质的转化和烤烟正常生长所需的营养供应。动态变化特征表明,翻压绿肥1、2、3年的各处理微生物量碳、氮均在团棵期出现峰值,土壤脲酶、酸性磷酸酶、过氧化氢酶均在旺长期出现峰值。在出现峰值时翻压3年的处理与对照相比微生物量碳、氮分别提高67.1%、60.7%;土壤脲酶、酸性磷酸酶、过氧化氢酶活性分别提高51.9%、14.2%、30.6%。此时正值生育旺期,利于烟株生长发育,说明连年翻压绿肥后培肥土壤效果显著。土壤微生物量C、N和酶活性能灵敏反映土壤肥力的变化,可作为评价土壤质量的生物学指标。     

基于组分区分的南方红壤丘陵土壤呼吸对植被类型转换的响应

土壤呼吸是陆地生态系统碳循环的重要环节之一。长时期的水土保持生态建设导致南方红壤丘陵区植被类型转换非常普遍。探讨植被转换对土壤呼吸及其关键组分的影响,不仅对深入了解土壤呼吸与碳循环的内在机制有着重要的理论价值,还可以为科学评价水土保持生态建设在应对气候变化方面的作用提供科学依据。依托江西水土保持生态科技园对侵蚀退化裸地及其恢复承建后的百喜草地、柑橘果园和湿地松人工林进行了一年尺度的土壤呼吸速率监测。结果表明,土壤呼吸速率月变化呈夏高冬低的曲线模式,最大值出现在8月份或9月份,最小值出现在1月份,植被转换没有改变土壤呼吸的季节变化模式。土壤呼吸速率的季节变化主要受浅层土壤温度的控制,与土壤含水率没有显著关系,5 cm深度土壤温度能解释总呼吸速率和异养呼吸速率季节变异的83.3%和86.0%。随着植被类型由裸地向草地、果园和林地转换,土壤呼吸的温度敏感性系数Q10值由1.86增大到2.20、2.72和2.75,即土壤呼吸对土壤温度的变化越来越敏感。异养呼吸占土壤总呼吸的比例呈现出单峰曲线模式,平均达到72.3%,且随土壤呼吸速率的增大而增大。南方红壤丘陵区侵蚀裸地向人工草地、果园和湿地松人工林转换的过程中土壤呼吸速率有所增强,草地与裸地之间土壤总呼吸速率存在显著性差异,草地与裸地、草地与林地之间土壤异养呼吸速率差异显著。在区域或生态系统尺度上,植被类型是土壤呼吸的重要影响因子。     

黄土高原半干旱地区撂荒地次生植被演替过程中土壤微生物活性研究

To show the vegetation succession interaction with soil properties, microbial biomass, basal respiration, and enzyme activities in different soil layers (0--60 cm) were determined in six lands, i.e., 2-, 7-, 11-, 20-, 43-year-old abandoned lands and one native grassland, in a semiarid hilly area of the Loess Plateau. The results indicated that the successional time and soil depths affected soil microbiological parameters significantly. In 20-cm soil layer, microbial biomass carbon (MBC), microbial biomass nitrogen (MBN), MBC/MBN, MBC to soil organic carbon ratio (MBC/SOC), and soil basal respiration tended to increase with successional stages but decrease with soil depths. In contrast, metabolic quotient (qCO2) tended to decrease with successional stages but increase with soil depths. In addition, the activities of urease, catalase, neutral phosphatase, β-fructofuranosidase, and carboxymethyl cellulose (CMC) enzyme increased with successional stages and soil depths. They were significantly positively correlated with microbial biomass and SOC (P < 0.05), whereas no obvious trend was observed for the polyphenoloxidase activity. The results indicated that natural vegetation succession could improve soil quality and promote ecosystem restoration, but it needed a long time under local climate conditions.     

Biotic community shifts explain the contrasting responses of microbial and root respiration to experimental soil acidification

Soil respiration is comprised primarily of root and microbial respiration, and accounts for nearly half of the total CO₂ efflux from terrestrial ecosystems. Soil acidification resulting from acid deposition significantly affects soil respiration. Yet, the mechanisms that underlie the effects of acidification on soil respiration and its two components remain unclear. We collected data on sources of soil CO₂ efflux (microbial and root respiration), above- and belowground biotic communities, and soil properties in a 4-year field experiment with seven levels of acid in a semi-arid Inner Mongolian grassland. Here, we show that soil acidification has contrasting effects on root and microbial respiration in a typical steppe grassland. Soil acidification increases root respiration mainly by an increase in root biomass and a shift to plant species with greater specific root respiration rates. The shift of plant community from perennial bunchgrasses to perennial rhizome grasses was in turn regulated by the decreases in soil base cations and N status. In contrast, soil acidification suppresses microbial respiration by reducing total microbial biomass and enzymatic activities, which appear to result from increases in soil H⁺ ions and decreases in soil base cations. Our results suggest that shifts in both plant and microbial communities dominate the responses of soil respiration and its components to soil acidification. These results also indicate that carbon cycling models concerned with future climate change should consider soil acidification as well as shifts in biotic communities.     

Impact of deforestation on soil physicochemical characteristics,microbial biomass and microbial activity of tropical soil

The study dealt with the assessment of the impact of deforestation on tropical soil through a comparative analysis of physicochemical and microbiological parameters of natural forest and a deforested barren site. With significant decline in clay, texturally the soil of the deforested barren site was observed to be different from that of natural forest. Bulk density and porosity data revealed structural deterioration of deforested barren soil. The soil hydrological regime was also adversely affected by the deforestation. Levels of soil organic carbon, total nitrogen, microbial biomass C, N and microfungal biomass also exhibited significant decline in deforested site. Analysis of microbial respiratory quotient (q CO₂) was also observed to be impaired in the deforested site. Copyright © 2001 John Wiley & Sons, Ltd.     

长期施有机肥与缺素施肥对潮土微生物活性的影响

利用中国科学院封丘农业生态国家实验站潮士农田生态系统养分平衡长期定位试验地,研究长期施有机肥或缺索施肥对农田土壤呼吸强度及酶活性的影响.结果发现,与不施肥对照(CK)相比.施肥处理均不同程度地提高了土壤的呼吸强度及转化酶、脲酶与磷酸酶活性;从N、P、K平衡施肥角度比较,施有机肥[OM)与有机无机配施(1/20M+1/2NPK)的效果均显著高于施无机肥(p<0.05);从缺素施肥角度分析,缺P显著低于NPK处理(p<0.05),缺N次之,缺K影响较小.结果表明,长期配施有机肥更有利于提高潮土的微生物活性,长期缺施P肥最不利于保育潮土的微生物学质量.     

寿光大棚菜地土壤呼吸强度、酶活性、pH与EC的变化研究

为防治土壤退化、促进农业可持续发展提供科学依据,以寿光地区露地土壤作对照,研究了连作1、5、8和12年大棚蔬菜(番茄)土壤有关生物学指标的变化。结果表明,土壤呼吸强度和脱氢酶活性棚内高于棚外,并随连作年限延长开始增强而后减弱,由于管理差异,12年棚龄土壤又回升。随着连作年限延长,土壤脲酶活性逐渐减弱,而过氧化氢酶活性逐渐增强;土壤呼吸强度和酶活性都由表层向底层逐渐减弱。土壤pH随连作年限增加逐渐下降,而EC逐渐增加,至12年棚龄时,与对照比0—20 cm土层pH下降了1.06单位,其他层次变化不显著。试验还表明,该地区表层土壤pH变化于6.45~7.51,EC 0.5 mS/cm,能较好地满足作物生长需要,同时,EC是影响土壤pH及酶活性变化的重要因素。土壤EC及过氧化氢酶活性可作为反映大棚菜地土壤质量变化的参考指标。     

Effects of warming, wetting and nitrogen addition on substrate-induced respiration and temperature sensitivity of heterotrophic respiration in a temperate forest soil

Soil heterotrophic respiration and its temperature sensitivity are affected by various climatic and environmental factors.However,little is known about the combined effects of concurrent climatic and environmental changes,such as climatic warming,changing precipitation regimes,and increasing nitrogen(N)deposition.Therefore,in this study,we investigated the individual and combined effects of warming,wetting,and N addition on soil heterotrophic respiration and temperature sensitivity.We incubated soils collected from a temperate forest in South Korea for 60 d at two temperature levels(15 and 20℃,representing the annual mean temperature of the study site and 5℃warming,respectively),three moisture levels(10%,28%,and 50%water-filled pore space(WFPS),representing dry,moist,and wet conditions,respectively),and two N levels(without N and with N addition equivalent to 50 kg N ha^-1year^-1).On day 30,soils were distributed across five different temperatures(10,15,20,25,and 30℃)for 24 h to determine short-term changes in temperature sensitivity(Q₁₀,change in respiration with 10℃increase in temperature)of soil heterotrophic respiration.After completing the incubation on day 60,we measured substrate-induced respiration(SIR)by adding six labile substrates to the three types of treatments.Wetting treatment(increase from 28%to 50%WFPS)reduced SIR by 40.8%(3.77 to 2.23μg CO₂-C g^-1h^-1),but warming(increase from 15 to 20℃)and N addition increased SIR by 47.7%(3.77 to 5.57μg CO₂-C g^-1h^-1)and 42.0%(3.77 to 5.35μg CO₂-C g^-1h^-1),respectively.A combination of any two treatments did not affect SIR,but the combination of three treatments reduced SIR by 42.4%(3.70 to 2.20μg CO₂-C g^-1h^-1).Wetting treatment increased Q₁₀by 25.0%(2.4 to 3.0).However,warming and N addition reduced Q₁₀by 37.5%(2.4 to 1.5)and 16.7%(2.4 to 2.0),respectively.Warming coupled with wetting did not significantly change Q₁₀,while warming coupled with N addition reduced Q₁₀by 33.3%(2.4 to 1.6).The combination of three treatments increased Q₁₀by 12.5%(2.4 to 2.7).Our results demonstrated that among the three factors,soil moisture is the most important one controlling SIR and Q₁₀.The results suggest that the effect of warming on SIR and Q₁₀can be modified significantly by rainfall variability and elevated N availability.Therefore,this study emphasizes that concurrent climatic and environmental changes,such as increasing rainfall variability and N deposition,should be considered when predicting changes induced by warming in soil respiration and its temperature sensitivity.     

Influence of microbial activity and soil moisture on herbicide immobilization in soils

Mobility, extractability, and disappearance of the herbicides diuron, terbuthylazine, metolachlor, and pendimethalin were examined in incubation experiments with two topsoil samples of different natural microbial activity and after sterilization. Soil moisture was held constant at 10, 40, and 60 % WHC. In other variants, the soil water content was changed during the incubation. The four herbicides reveal a fairly different extent of microbial and chemical degradation and immobilization. The herbicide mobility – expressed by coefficients of partition between adsorbed and dissolved herbicide amounts – decreases at a lower rate and extent, when the microbial activity is low or the soil is sterile. With increasing initial soil moisture, also herbicide mobility and extractability increase; but in the course of time, abiotic immobilization occurs to a higher extent. When soil moisture changes during the incubation, formerly non‐extractable herbicide fractions (up to 40 % of the applied amounts) become extractable. Kinetics of herbicide immobilization follow an empirical sigmoidal function, which describes three periods of immobilization. The three‐period shape of the curve and its possible reasons are discussed for the data of the incubation experiments as well as for the results of a long‐term field trial with diuron.     

生物炭还田对植烟土壤活性有机碳及酶活性的影响

为探索不同来源的生物炭及其还田方式对连作植烟土壤的改良效果,以四川盐源红壤为研究对象,通过田间试验研究了不同生物炭类型(玉米秸秆生物炭YM、油菜秸秆生物炭YC)配合不同还田方式(条施、穴施、条施+穴施)下,土壤有机碳组分和土壤酶活性在烤烟不同生育期的变化特征.结果 表明,生物炭类型和还田方式显著改变了土壤总有机碳(TO...     

Seasonal variations of soil microbial biomass and activity in warm- and cool-season turfgrass systems

Plant growth can be an important factor regulating seasonal variations of soil microbial biomass and activity. We investigated soil microbial biomass, microbial respiration, net N mineralization, and soil enzyme activity in turfgrass systems of three cool-season species (tall fescue, Festuca arundinacea Schreb., Kentucky bluegrass, Poa pratensis L., and creeping bentgrass, Agrostis palustris L.) and three warm-season species (centipedegrass, Eremochloa ophiuroides (Munro.) Hack, zoysiagrass, Zoysia japonica Steud, and bermudagrass, Cynodon dactylon (L.) Pers.). Microbial biomass and respiration were higher in warm- than the cool-season turfgrass systems, but net N mineralization was generally lower in warm-season turfgrass systems. Soil microbial biomass C and N varied seasonally, being lower in September and higher in May and December, independent of turfgrass physiological types. Seasonal variations in microbial respiration, net N mineralization, and cellulase activity were also similar between warm- and cool-season turfgrass systems. The lower microbial biomass and activity in September were associated with lower soil available N, possibly caused by turfgrass competition for this resource. Microbial biomass and activity (i.e., microbial respiration and net N mineralization determined in a laboratory incubation experiment) increased in soil samples collected during late fall and winter when turfgrasses grew slowly and their competition for soil N was weak. These results suggest that N availability rather than climate is the primary determinant of seasonal dynamics of soil microbial biomass and activity in turfgrass systems, located in the humid and warm region.