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.     

Discriminating factors of the spatial variability of soil quality parameters at landscape‐scale

The aim of the study was to evaluate the spatial variability pattern of some soil quality parameters at landscape‐scale, particularly soil microbial biomass‐C (C_mic) and ‐N (N_mic), and soil microbial activity (respiration) as well as soil organic carbon (C_org), and hot water extractable carbon (C_hwe) by multivariate analyses of variance and canonical discriminant analyses (CDA). The study area was the Trier region, Rhineland‐Palatinate, which is characterized by a wide range of soil types developed from various parent materials. Additionally, the investigated fields differed in soil management intensity (conventional, integrated, organic farming) and crops grown. Within the whole study area CDA revealed a separation into three sub‐areas. Within the sub‐areas the soil quality parameters were significantly influenced by the soil management systems and the crops grown. Despite the spatial variability and the relationship to soil management, the contents of C_mic could be predicted by stepwise multiple linear regression models, both for arable and grassland soils. The explained variance for the regression models were 72 % for arable soils and 63 % for grassland soils, respectively. Regression models for predicting N_mic and microbial activity revealed an explained variance between 30 and 58 %.     

废弃农耕地自然演替过程中微生物群落与土壤特性间的关系

The changes of microbial biomass carbon (MBC) and nitrogen (MBN) and microbial community in the topsoil of the abandoned agricultural land on the semi-arid Loess Plateau in China during the natural succession were evaluated to understand the relationship between microbial community and soil properties. MBC and MBN were measured using fumigation extraction, and microbial community was analyzed by the method of fatty acid methyl ester (FAME). The contents of organic C, total N, MBC, MBN, total FAME, fungal FAME, bacterial FAME and Gram-negative bacterial FAME at the natural succession sites were higher than those of the agricultural land, but lower than those of the natural vegetation sites. The MBC, MBN and total FAME were closely correlated with organic C and total N. Furthermore, organic C and total N were found to be positively correlated with fungal FAME, bacterial FAME, fungal/bacterial and Gram-negative bacterial FAME. Natural succession would be useful for improving soil microbial properties and might be an important alternative for sustaining soil quality on the semi-arid Loess Plateau in China.     

土壤微生物对不同粒径、不同表面和孔隙性质生物炭的响应

Biochars are known for their heterogeneity, especially in pore and surface structure associated with pyrolysis processes and sources of feedstocks. The surface area of biochar is likely to be an important determinant of the extent of soil microbial attachment, whereas the porous structure of biochar is expected to provide protection for soil microorganisms. Potential interactions between biochars from different sources and with different particle sizes were investigated in relation to soil microbial properties in a short-term incubation study. Three particle size(sieved) fractions(0.5–1.0, 1.0–2.0 and 2.0–4.0 mm) from three woody biochars produced from jarrah wood,jarrah and wandoo wood and Australian wattle branches, respectively, were incubated in soil at 25?C for 56 d. Observation by scanning electron microscopy(SEM) and characterisation of pore and surface area showed that all three woody biochars provided potential habitats for soil microorganisms due to their high porosity and surface areas. The biochars were structurally heterogeneous,varying in porosity and surface structure both within and between the biochar sources. After the 56-d incubation, hyphal colonisation was observed on biochar surfaces and in larger biochar pores. Soil clumping occurred on biochar particles, cementing and covering exposed biochar pores. This may have altered surface area and pore availability for microbial colonisation. Transient changes in soil microbial biomass, without a consistent trend, were observed among biochars during the 56-d incubation.     

Soil microbial biomass response to woody plant invasion of grassland

Woody plant proliferation in grasslands and savannas has been documented worldwide in recent history. To better understand the consequences of this vegetation change for the C-cycle, we measured soil microbial biomass carbon (C_mic) in remnant grasslands (time 0) and woody plant stands ranging in age from 10 to 130 years in a subtropical ecosystem undergoing succession from grassland to woodlands dominated by N-fixing trees. We also determined the ratio of SMB-C to soil organic carbon (C_mic/C_org) as an indicator of soil organic matter quality or availability, and the metabolic quotient (qCO₂) as a measure of microbial efficiency. Soil organic carbon (C_org) and soil total nitrogen (STN) increased up to 200% in the 0–15 cm depth increment following woody plant invasion of grassland, but changed little at 15–30 cm. C_mic at 0–15 cm increased linearly with time following woody plant encroachment and ranged from 400 mg C kg⁻¹ soil in remnant grasslands up to 600–1000 mg C kg⁻¹ soil in older (>60 years) woody plant stands. C_mic at 15–30 cm also increased linearly with time, ranging from 100 mg C kg⁻¹ soil in remnant grasslands to 400–700 mg C kg⁻¹ soil in older wooded areas. These changes in C_mic in wooded areas were correlated with concurrent changes in stores of C and N in soils, roots, and litter. The C_mic/C_org ratio at 0–15 cm decreased with increasing woody plant stand age from 6% in grasslands to <4% in older woodlands suggesting that woody litter may be less suitable as a microbial substrate compared with grassland litter. In addition, higher qCO₂ values in woodlands (0.8 mg CO₂-C g⁻¹ C_mic h⁻¹) relative to remnant grasslands (0.4 mg CO₂-C g⁻¹ C_mic h⁻¹) indicated that more respiration was required per unit of C_mic in wooded areas than in grasslands. Observed increases in C_org and STN following woody plant encroachment in this ecosystem may be a function of both greater inputs of poor quality C that is relatively resistant to decay, and the decreased ability of soil microbes to decompose this organic matter. We suggest that increases in the size and activity of C_mic following woody plant encroachment may result in: (a) alterations in competitive interactions and successional processes due to changes in nutrient dynamics, (b) enhanced formation and maintenance of soil physical structures that promote C_org sequestration, and/or (c) increased trace gas fluxes that have the potential to influence atmospheric chemistry and the climate system at regional to global scales.     

有机物料对红壤团聚体稳定性的影响

试验设置了对照(CK)、秸秆混匀(M-Str)、秸秆覆盖(Str)、生物质炭混匀(BC)和猪粪混匀(SM)5个处理,采用室内培养法研究有机物料种类与施用方式对红壤团聚体稳定性的影响。结果表明,秸秆混匀与猪粪处理下土壤有机碳(SOC)、热水溶性有机碳(HWC)、土壤抗破碎性和团聚体水稳定性(MWD)显著提高(p0.05),而秸秆覆盖对土壤有机碳和土壤团聚体形成的提升作用不明显(p0.05)。相对于对照处理,生物质炭提高了土壤有机碳含量,但对团聚体稳定性的影响不显著(p0.05)。秸秆混匀和猪粪处理下团聚体稳定性的变化与土壤累积呼吸之间存在线性关系(p0.05)。可见,有机物的性质(秸秆、猪粪和生物质炭)与还田方式(混匀和覆盖)对红壤团聚体的稳定性存在显著差异。     

The response of soil microbial biomass and activity of a Norway spruce forest to liming and drought

Long-term effects of liming and short-term effects of an experimentally induced drought on microbial biomass and activity were investigated in samples from the O-layer (Of/Oh) and uppermost mineral soil (0—10 cm) in a spruce forest near Schluchsee (Black Forest, South-West Germany). Seven years after lime application a marked increase of pH values was restricted to the O-layer. The contents of C and N in the O-layer of the limed plot appeared to be lower, whereas in the A-horizon from the limed plot the contents of C and N appeared to be higher than on the control. However, these differences were statistically not significant due to a distinct spatial variability of topsoil conditions. On the limed plots C_mic, N_mic, and P_mic in the O-layer were lower in comparison to the control whereas differences in the A-horizon were negligible. In both sampling depths of the limed plot protease activity was higher while N-mineralization was lower. The other microbial activities studied (basal respiration, catalase activity) followed no consistent pattern after liming. Drought and drought in combination with liming, respectively, had no clear effects on microbial biomass and activity. Only in the A-horizon of the control, there is some evidence for drought stress for microorganisms. The high variability of results from the drought experiment (roof installation) is likely due to the marked spatial variability of top soil properties as well as imperfect and uneven achievement of experimental drought. Nevertheless, our study indicates that long-term effects of liming on microorganisms highly depend on site conditions. Thus, liming operations which currently affect vast areas of forest land should be accompanied by monitoring of soil organisms and their activities to reduce the possibility of a loss in functional diversity of soil organisms.     

机械压实对新疆绿洲农田土壤微生物活性及碳排放的影响

为探究机械压实对绿洲农田土壤微生物活性和碳排放的影响,在参考新疆农田耕作层土壤容重分布特征的基础上,选取1.15（T1.15）、1.30（T1.30）、1.45（T1.45）和1.60 g/cm3（T1.60）4个容重梯度模拟机械压实土壤程度,测定不同处理0～120 d内土壤有机碳、微生物生物量碳、氮、酶活性以及碳排放速率变化特征。结果表明：1）试验周期内（0～120 d）,土壤微生物生物量碳、氮、脲酶和过氧化氢酶活性随试验周期的延长而降低,随土壤容重增加呈先升高后降低趋势,容重为1.45 g/cm3时最高。2）T1.15、T1.30、T1.45和T1.60处理土壤碳累积排放量分别为557.26、653.48、665.00和522.01 g/m2,也表现出随容重增加先升高后降低的趋势,T1.45处理最高。3）土壤碳排放与土壤有机碳、可溶性有机碳、微生物生物量碳、氮、脲酶和过氧化氢酶活性显著正相关（P<0.05）。综上,土壤压实通过改变土壤微生物生物量和酶活性影响土壤碳排放速率;当绿洲农田土壤容重大于1.45 g/cm3时,应进行适当的翻松,使土壤微生物活性达到最佳水平。     

Soil properties and habitats determine the response of bacterial communities to agricultural wastewater irrigation

Increasing temperatures and variability of precipitation events due to climate change will lead in the future to higher irrigation demands in agroecosystems.However,the use of secondary treated wasterwater(TWW)could have consequences for the receiving soil environment and its resident microbial communities.The objective of this study was to characterize the importance of soil properties and habitats to the response of soil bacteria and archaea to irrigation with TWW.Two agricultural soils with contrasting textures(loamy sand or silt loam)and,for each,three variants differing in soil organic carbon and nitrogen,as generated by long-term fertilization,were analyzed.For each of these six soils,prokaryotic communities from two habitats,i.e.,root-free bulk soil and the rhizosphere of developing cucumber plants in the greenhouse,were characterized.Communities were analyzed by the quantity and diversity of their polymerase chain reaction(PCR)-amplified 16S rRNA genes.To account for TWW-associated nutrient effects,potable water(PW)served as a control.Amplicon sequence analysis showed that prokaryotic communities mainly consisted of bacteria(99.8%).Upon irrigation,regardless of the water quality,prokaryotic diversity declined,p H increased,and no bacterial growth was detected in bulk soil.In contrast,the growth of cucumbers was stimulated by TWW,indicating that plants were the main beneficiaries.Moreover,strong responses were seen in the rhizosphere,suggesting an indirect effect of TWW by altered rhizodepositions.The main bacterial responders to TWW were Proteobacteria,Bacteroidetes,Actinobacteria,and Planctomycetes.Changes in bacterial communities due to TWW were less pronounced in all variants of the silt loam,indicating the importance of clay and soil organic carbon for buffering effects of TWW on soil bacterial communities.Hence,soil organic carbon and soil texture are important parameters that need to be considered when applying TWW in agriculture.     

PH对红壤微生物生物量碳和生物量磷的影响

The impact of pH changes on microbial biomass carbon (Cmic) and microbial biomass phosphorus (Pmic) were examined for 3 red soils under citrus production with different lengths of cultivation. Soil pH significantly affected Cmic and Pmic. The Cmie and Pmic changes, as a function of soil pH, appeared to follow a normal distribution with the original soil pH value at the apex and as pH increased or decreased compared to the original soil pH, Cmic and Pmic declined. Moreover, there were critical pH values at both extremes (3.0 on the acidic side and 8.0 to 8.5 on the alkaline side), beyond which most of microorganisms could never survive. The effect of pH on Cmic and Pmic was also related to the original soil pH. The higher the original soil pH was, the less Cmic or Pmic were affected by pH change. It is suggested that soil microorganisms that grow in a soil environment with a more neutral soil pH range (i.e. pH 5.5-7.5) may have a greater tolerance to pH changes than those growing in more acidic or more alkaline soil pH conditions.     

长期冬种绿肥改变红壤稻田土壤微生物生物量特性

以进行了31年的双季稻-冬绿肥长期定位试验的红壤性水稻土为对象,研究了长期冬种绿肥条件下土壤微生物生物量特性的季节变化,为阐释冬绿肥措施在稻田生态系统土壤碳氮转化中的作用机制提供理论基础。试验包括双季稻-紫云英(RRV)、双季稻-冬油菜(RRP)、双季稻-黑麦草(RRG)及双季稻-冬闲(RRF)4个处理,在典型时期(绿肥盛花期、绿肥翻压后、早稻成熟期、晚稻收获后)采集土壤样品,分析土壤微生物生物量碳氮及微生物商等方面的变化。结果表明,3种冬绿肥均提高了土壤微生物生物量碳(SMBC)、微生物生物量氮(SMBN)和微生物商,在土壤性质相对稳定的晚稻收获后均显著高于对照处理,全年平均值也多显著高于对照处理。豆科绿肥紫云英对SMBC和SMBN的提高作用最显著,晚稻收获后相对冬闲分别提高了21.12%和98.45%,全年平均值分别提高了15.92%和36.49%。取样时期对SMBC、SMBN和微生物商有较大的影响,但变化趋势基本一致,即绿肥翻压前后无明显变化,早稻成熟期降至最低,至晚稻收获后再次上升。SMBC/SMBN比值在不同绿肥处理间差异不大,但有明显的季节变化,早稻成熟期较高而晚稻收获后降低。因此,南方稻田冬种绿肥后土壤微生物特性明显改善,冬种绿肥是提升稻田土壤肥力的高效措施。     

Impact of agricultural land use on distribution of microbial biomass and activity within soil aggregates

The presence of aggregates of various sizes in the soil is an important condition for soil carbon sequestration. In this system, microbial biomass is a key link. This work was devoted to the study of the influence of land use systems on the distribution of SOС, MB-SIR, microbial activity and eco-physiological indices (qCO₂, QR, MB-SIR/SOС and qCO₂/SOС) in relation to the size of soil aggregates. The distribution of SOС, MB-SIR and mineralization activity among the aggregates was heterogeneous. In the soil of crop rotation, high mineralization activity and MB-SIR were found in the aggregates 0.5–0.1 mm, in the monoculture soil in aggregates <0.1 mm and in the control soil in the aggregates 1–0.25 mm. There was a general trend towards a decrease in microbial activity, MB-SIR and SOС availability with an increase in aggregate size. In agricultural soils, microbial activity was determined by large aggregates (>5 mm), while in the control soil, by the aggregates 5–1 mm. Depending on the type of site and the size of aggregates, the differences in microbial metabolism were revealed. The qCO₂ and QR values decreased, and the MB-SIR/SOС and qCO₂/SOС increased in the series: control soil > crop rotation > monoculture. In the control soil, the values of the eco-physiological indices decreased with decreasing aggregate size. And vice versa, in agricultural soils, these parameters were the highest in the microaggregates (<0.25 mm). The monoculture soil, in contrast to the control soil and crop rotation soil, turned out to be more energy efficient.     

高寒草原土壤有机碳矿化对水氮添加的响应

[目的]研究不同水氮添加下的高寒草原土壤有机碳矿化过程,探讨土壤性质与土壤碳矿化的关系,为揭示全球变化背景下高寒草原土壤碳转化规律提供科学依据。[方法]设置45%,60%,75%,90%的田间持水量(WHC)4个水分梯度和4个氮添加梯度(0,0.2,0.4,0.8 mg/g)进行室内培养,分析CO_2浓度,测定土壤溶解性有机碳(DOC)、土壤微生物生物量碳(MBC)含量以及土壤酶活性。[结果]①在水或氮添加范围内,土壤有机碳矿化量呈抛物线变化趋势,土壤碳矿化受水分调控更加敏感,氮添加对土壤碳矿化的影响依赖于水分添加量。②土壤水分从45%增加到60%WHC,加速了土壤中可溶性物质溶出,增加了有机碳矿化;施氮量从0 mg/g增加到0.4 mg/g,土壤有机碳含量、土壤微生物量碳含量呈上升趋势,刺激了土壤有机碳的矿化。③90%田间持水量WHC的高水分添加与45%田间持水量土壤水分下的高氮添加(0.8 mg/g)抑制高寒草原土壤碳矿化,高水分添加通过降低土壤通透性抑制有机碳矿化过程,高氮添加通过降低土壤DOC生物有效性、土壤MBC含量、土壤酶活来抑制土壤有机碳矿化过程,高氮添加对碳矿化的抑制作用在90%WHC条件下得到缓解。[结论]随着未来氮沉降量与降雨量的持续增加,青藏高原高寒草原土壤有机碳的矿化作用可能会受到抑制,有利于高寒草原土壤有机碳积累。     

Soil microbial biomass C and N changes in relation to forest conversion in the Northwestern Turkey

Tree species differ in their effect on soil development and nutrient cycling. Conversion of beech coppice to pine plantations can alter soil physical and chemical properties, which in turn may have significant impacts on soil microbial biomass C and N (C_mic, N_mic). The major objective of this study was to evaluate soil quality changes associated with the forest conversion in humid NW Turkey. Results from this study showed that levels of soil organic carbon (C_org), total nitrogen (N_t), moisture, C_mic and N_mic under beech coppice were consistently higher but levels of pH, CaCO₃ and EC were lower compared to pine plantation. Differences between the forest stands in C_mic and N_mic were mainly related to the size of the C_org stores in soil and to tree species. In addition, high level of CaCO₃ is likely to reduce pools of soil organic C and possibly even microbial biomass C and N in pine forests. The average C_mic:N_mic ratios were higher in soils under beech coppice than pine plantation, while C_mic:C_org and N_mic:N_t percentages were similar in both forest types. These results revealed the differences in microbial community structure associated with different tree species and the complex interrelationships between microbial biomass, soil characteristics, litter quantity and quality. Copyright © 2008 John Wiley & Sons, Ltd.     

间作白三叶对苹果/白三叶复合系统土壤微生物量碳、氮及酶活性的影响

以渭北黄土高原苹果园土壤为研究对象,设置传统苹果（Malus domestica Borkh.）园清耕及间作白三叶（Trifolium repens L.）两个处理,测定和分析了不同土层（0—5 cm,5—10 cm,10—20 cm及20—40 cm）的土壤微生物量碳（SMBC）、氮（SMBN）、4种土壤酶活性、有机碳（SOC）和全氮（TN）等指标,从土壤微生物碳、氮及酶活性的角度探讨间作白三叶对苹果/白三叶复合系统土壤的影响。结果表明:间作白三叶能够显著提高土壤微生物量碳、氮的含量和土壤酶活性,提高土壤微生物对有机碳和全氮的利用效率,其作用随着土层深度的增加而降低,在表层土壤效果更为显著。土壤微生物量碳、氮及土壤酶活性与土壤有机碳、全氮呈极显著相关或显著性相关。苹果园土壤微生物量碳、氮及土壤酶活性能敏感响应生草间作,可以作为评价果园生草对果园土壤影响的良好指标。     

Soil Quality Indicators as Affected by Shallow Tillage in a Vineyard Grown in a Semiarid Mediterranean Environment

Within the Mediterranean basin, soil tillage enhances the mineralisation of soil organic matter. We assessed the short‐term impact of shallow tillage [field cultivator (FC), rotary tiller (RT) and spading machine (SM)] on some soil quality indicators [bulk density, water‐stable aggregates, total and labile organic C pools (microbial biomass and extractable organic C), soil respiration and related eco‐physiological indexes] in a Sicilian vineyard. Also no tillage was included. We hypothesized that (i) RT and FC worsened soil quality indicators more than SM, and (ii) within the same tillage system, labile C pools, soil respiration and eco‐physiological indexes will respond more efficiently than chemical and physical soil properties since the tillage starts. The experiment started at March 2009, and each tillage type was applied three times per year (March or April, May and June), with soil tilled up to 15‐cm depth. Soil was sampled (0–15 and 15–30‐cm depth) in March 2009, April 2010, May 2012 and June 2014. SM was very effective in preserving soil organic matter pool and in improving any monitored soil quality indicator, similarly to no tillage. By contrast, RT was the most deleterious machine as it worsened most investigated indicators. Such deleterious effects were due to drastic disruption of soil aggregates and consequent exposition of protected soil organic matter to further microbial mineralization. Labile organic C pools and microbial quotients were the most responsive soil parameters for assessing the impact of shallow tillage on soil quality, even in the short term (<5 years). Copyright © 2016 John Wiley & Sons, Ltd.     

Effects of Land Management on Different Forms of Soil Carbon in Olive Groves in Mediterranean Areas

This study analyses soil organic carbon (SOC) and hot‐water extractable carbon, both measures of soil quality, under different land management—(i) conventional tillage (CT); (ii) CT plus the addition of oil mill waste alperujo (A); (iii) CT plus the addition of oil mill waste olive leaves (L); (iv) no tillage with chipped pruned branches (NT₁); and (v) no tillage with chipped pruned branches and weeds (NT₂)—in a typical Mediterranean agricultural area: the olive groves of Andalusia, southern Spain. SOC values in CT, A, NT₁ and NT₂ decreased with depth, but in NT₂, the surface horizon (0–5 cm) had higher values than the other treatments, 47% more than the average values in the other three soils. In L, SOC also decreased with depth, although there was an increase of 88·5% from the first (0–10 cm) to the second horizon (10–16 cm). Total SOC stock values were very similar under A (101·9 Mg ha⁻¹), CT (101·7 Mg ha⁻¹), NT₁ (105·8 Mg ha⁻¹) and NT₂ (111·3 Mg ha⁻¹, if we consider the same depth of the others). However, SOC under L was significantly higher (p < 0·05) at 250·2 Mg ha⁻¹. Hot‐water extractable carbon decreased with depth in A, CT and NT₁. NT₂ and L followed the same pattern as the other management types but with a higher value in the surface horizon (2·3 and 4·9 mg g⁻¹, respectively). Overall, our results indicate that application of oil mill waste olive leaves under CT (L) is a good management practice to improve SOC and reduce waste. Copyright © 2014 John Wiley & Sons, Ltd.     

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。     

免耕和秸秆还田对潮土酶活性及微生物量碳氮的影响

利用中国科学院封丘农业生态实验站玉米-小麦轮作保护性耕作定位试验平台,研究了全翻耕（(T)、免耕（(NT)、全翻耕+秸秆还田（(TS)以及免耕+秸秆还田（(NTS)处理分别对田间0 ~ 10、10 ~ 20和20 ~ 30 cm土层酶活性及土壤微生物量碳、氮的影响。结果表明：①在0 ~ 10和10 ~ 20 cm土层内,土壤碱性磷酸酶、转化酶、脲酶、脱氢酶活性为免耕处理大于全翻耕处理,有秸秆还田处理大于无秸秆还田处理,以NTS处理最高,T处理最低;在20 ~ 30 cm土层中,土壤碱性磷酸酶、转化酶、脱氢酶活性免耕处理大于全翻耕处理,土壤碱性磷酸酶、转化酶、脲酶活性有秸秆还田处理大于无秸秆还田处理。②在0 ~10和10 ~ 20 cm土层内,土壤微生物量碳、氮均为免耕处理大于全翻耕处理,有秸秆还田处理大于无秸秆还田处理;在20 ~ 30 cm土层中,微生物量碳以NTS处理最高,微生物量氮以TS处理最高;③4种处理下的土壤酶活性和微生物量碳、氮均随着土层的加深而减少,且在各土层中差异达显著水平。