转变耕作方式对长期旋免耕农田土壤有机碳库的影响

土壤深松是解决长期旋免耕农田耕层浅薄化、亚表层（>15～30 cm）容重增加等问题的有效方法之一,而将长期旋免耕农田进行深松必然导致农业生态系统中土壤有机碳（soil organic carbon,SOC）及碳固定速率的变化。因此,为对比将长期旋免耕转变为深松前后农田土壤有机碳库变化,该研究利用连续12a 的旋耕和免耕长期定位试验以及在此基础上连续6 a旋耕-深松和免耕-深松定位试验,对比了转变耕作方式对农田土壤0～30 cm有机碳含量、周年累积速率及其固碳量的影响。研究结果表明,经过连续12 a的旋耕和免耕处理（2002－2014）,2014年免耕处理土壤0～30 cm有机碳储量比试验初期（2002年）提高38%,旋耕处理降低了30%,而对照常规处理无显著差异。免耕处理土壤0～30 cm有机碳储量比旋耕处理高约2.6倍（2014年）。长期免耕显著提高了土壤0～30 cm的有机碳含量,2002~2014年其土壤0～30 cm固碳量为16.69 t/hm2,但长期旋耕导致土壤0～30 cm SOC含量显著降低,表现为土壤有机碳的净损耗,年损耗速率为?0.75 t/hm2。而长期旋耕后进行深松（旋耕-深松处理）6年其土壤0～30 cm的有机碳含量较原旋耕处理提高32%～67%,且显著提高了土壤固碳量及周年累积速率;免耕-深松土壤0～30 cm的有机碳周年累积速率较免耕处理下降了42%。长期旋耕造成有机碳水平下降的条件下,将旋耕处理转变为深松处理在短期内更有利于促进土壤有机碳的积累,而将长期免耕处理转变为深松措施,降低了土壤有机碳的累积速率和固碳量。     

耕作方式对土壤微生物生物量影响的研究

耕作方式对土壤微生物数量及活性有重要的影响 ,虽然前人对不同耕作方式下土壤微生物及土壤化学之间的关系作了大量的研究 ,但关于耕作方式对土壤微生物生物碳Csmb影响的研究很少 ,尤其是关于Csmb与作物氮利用之间的关系研究更少。为确定作物生长季节免耕或常规耕作以及取样部位对Csmb的影响 ,在种植青贮玉米的试验地免耕或常规耕作 3a后 ,选取其第四生长季进行研究。免耕处理下 ,0～ 3 8cm土层和 3 8～ 7 5cm土层的Csmb分别是常规耕作处理下的 87%和 33%。免耕处理下行内取样 0～ 3 8cm土层的Csmb与时间呈线性下降关系 ,在作物生长季节Csmb下降约为 2 9% ,同样对其它取样深度的样品分析 ,其Csmb变化不显著 ,而且季节之间差异也不明显。两种耕作方式下行间取样样品的Csmb明显增加 ,在前人研究中尽管不同的耕作方式使得土层Csmb不同 ,但对于实际生产并没有产生实质性影响 ,因为前人试验结果表明耕作方式不同没有对青贮作物利用肥料中的氮或土壤中的氮发生改变     

长期免耕与施用有机肥对土壤微生物生物量碳、氮、磷的影响

通过设置在江苏省句容农科所的田间定位试验研究长期免耕及施用有机肥料对土壤微生物生物量碳、氮、磷的影响。结果表明 :经过 1 6年 32茬稻—麦水旱轮作后 ,表土层 ( 0～ 5cm)土壤微生物生物量碳、氮、磷含量比亚表层 ( 5～ 1 0cm)分别高 2 7.5 %、43.6%和1 1 %。与常规耕翻相比长期免耕处理表土层土壤微生物生物量碳、氮含量分别增加了2 5 .4%和 45 .4% ,而微生物生物量磷无明显变化规律 ;亚表层的土壤微生物生物量碳、氮、磷免耕与耕翻两种耕作方式间的差异不显著。尽管各施肥处理施用的氮、磷、钾数量完全相等 ,但土壤微生物生物量碳、氮、磷的含量却因肥料种类的不同而异。综合 0～ 5和 5～ 1 0cm土层 ,微生物生物量碳、磷为 :猪粪 化肥 >秸秆 化肥 >绿肥 化肥 >化肥 >不施肥 ,微生物生物量氮则为 :猪粪 化肥 >绿肥 化肥 >秸秆 化肥 >化肥 >不施肥。相关分析结果显示 ,土壤微生物生物量碳、氮与土壤有机碳、土壤全氮和土壤碱解氮之间均呈极显著的正相关 ,表明其与土壤肥力关系密切 ,可作为评价土壤肥力性状的生物学指标     

不同农田生态系统土壤微生物生物量碳的变化研究

试验研究不同农田生态系统土壤微生物生物量碳的变化结果表明,长期单施N、P肥处理对土壤有机碳和微生物生物量碳的影响不明显,施有机肥处理土壤微生物生物量碳及微生物生物量碳/有机碳值均高于其他施肥处理,轮作中引入豆科作物或豆科连作均对土壤微生物生物量碳的积累有显著作用。     

免耕对旱作燕麦田耕层土壤微生物生物量碳、氮、磷的影响

2005～2008年,在内蒙古清水河县研究了免耕留低茬(NL)、免耕留高茬(NH)、免耕留低茬覆盖(NLS)、免耕留高茬覆盖(NHS)和常规耕作(T)5种耕作方式对旱坡地燕麦田耕层土壤微生物生物量碳、氮、磷的影响。结果表明:各处理土壤微生物生物量碳、氮、磷含量在不同年际间的变化趋势一致。土壤微生物生物量碳、氮含量均呈双峰曲线变化,其中,NHS和NLS处理土壤微生物生物量碳的峰值出现在拔节期和灌浆期,NH、NL和T处理的土壤微生物生物量碳的峰值出现在孕穗期和灌浆期,而土壤微生物生物量氮的峰值则出现在苗期和灌浆期。土壤微生物生物量磷呈单峰曲线变化,各处理的峰值均出现在灌浆期。不同年份间、不同生育期间,土壤微生物生物量碳、氮、磷含量的大小顺序为:NHS>NLS>NH>NL>T。其中,免耕各处理的燕麦产量相对常规耕作呈先降低后增加的趋势,以2008年为例,NHS、NLS、NH、NL燕麦产量分别较T增加了22%、17%、11%、5%。综上所述,免耕有利于提高土壤微生物生物量碳、氮、磷含量,而且可有效地增加作物产量,尤其是NHS和NLS处理比较明显。     

施肥和耕作方式对棕壤微生物生物量碳氮的影响

以辽宁省昌图县主要粮食产区为研究对象,分析施肥(化肥、玉米秸秆和有机肥)和耕作方式(旋耕、深松和隔行深松)对棕壤微生物生物量碳、氮(SMB-C、-N)的影响。结果显示,与对照处理相比,施用化肥处理SMB-C、-N分别下降14.3%和13.3%,秸秆回田处理下降12.3%和12.2%,而施用有机肥则显著提高SMB-C、-N,幅度分别为31.7%和38.6%。说明施用化肥明显降低土壤微生物生物量,配施秸秆在短时期内无法缓解化肥施用对微生物生物量的抑制作用,而有机肥却能迅速缓解抑制作用,提高土壤微生物生物量。深松(行行)和隔行深松作为保护性土壤耕作方式,与常规耕作(NPK处理)相比,显著提高了SMB-C、-N,其中深松提高幅度为56.8%和77.0%,隔行深松则为27.7%和36.1%。试验伊始,有机肥处理SMB-C/SOC(土壤有机碳)最高,达到1.57,至实验结束,深松处理最高,为2.15,其次为隔行深松处理。有机肥处理SMB-N/TN(土壤全氮)受年际影响上下波动,深松和隔行深松处理呈现先下降后上升的态势。深松和隔行深松能有效保存土壤养分含量,特别是活性碳、氮库,是土壤肥力贫瘠地区推荐的土壤耕作方式,从人力和机械消耗角度而言,隔行深松更有利于我国农业可持续发展。     

不同碳氮比有机肥对有机农业土壤微生物生物量的影响

有机肥能提高土壤微生物活性, 改善土壤品质。碳氮比是影响有机肥肥效的重要因素。本试验以无肥处理为对照(CK), 设置4个有机肥碳氮比处理(20︰1、15︰1、10︰1、5︰1), 在温室中进行茄子盆栽试验, 定期采集土壤样品, 用熏蒸提取法测定土壤微生物生物量碳(SMBC)、氮(SMBN), 研究等氮条件下不同碳氮比有机肥料对土壤生物活性的影响。试验结果表明, 不同碳氮比的有机肥均能提高土壤的SMBC和SMBN含量, 具体表现为SMBC: 20︰1>10︰1≈15︰1>5︰1>CK, SMBN: 15︰1>10︰1>20︰1>5︰1>CK。SMBC/SMBN的比率反映土壤氮素生物活性, 其值越低, 生物活性越大, 氮素损失越少, 本试验SMBC/SMBN表现为: 15︰1<10︰1<20︰1≈5︰1相似文献   

紫外分光光度法测定农田土壤微生物生物量氮可行性初探

采用氯仿熏蒸浸提-紫外分光光度法和消化法比较测定了田间定位试验不同施肥处理土壤、添加植物残体土壤、添加葡萄糖土壤的微生物生物量碳、氮(SMBC,SMBN)。结果表明,当土壤微生物生物量氮含量较高时(>20 mg kg-1),采用分光光度法与消化法测定的SMBN具有显著正相关关系(P<0.05),但当SMBN量较低时(<20 mg kg-1)时,分光光度法测定与消化法测定的SMBN没有显著相关性。当土壤中添加麦秸和玉米秸时,土壤浸提液颜色较深(黄色),不适合采用分光光度法测定SMBN。因此,熏蒸提取–分光光度法测定SMBN,仅适于土壤浸提液无色透明、且SMBN含量较高的土壤。     

川西平原土壤微生物生物量碳氮磷含量特征及其影响因素分析

本文通过区域调查采样和统计分析,探讨了川西平原土壤微生物生物量碳（MBC）、土壤微生物生物量氮（MBN）和土壤微生物生物量磷（MBP）含量特征及其对气候、海拔、母质和土地利用等因素的响应,揭示了其关键影响因素,以期为川西平原地区土壤质量管理提供参考。结果表明,不同土壤类型的MBC、MBN和MBP含量表现为冲积土显著高于水稻土、潮土和黄壤（P<0.05）,潮土MBC/MBN显著高于水稻土。气候和海拔的影响为：MBC、MBN和MBP含量随着≥ 0℃积温、≥ 10℃积温、年均温和年均降水量的增加呈指数减少,而随干燥度和海拔增加呈线性增加。不同成土母质中,MBC、MBN和MBP含量均为灰色冲积物显著高于老冲积物。不同土地利用方式下,三者含量为草地显著高于水田和旱地,水田、旱地和林地差异不显著。皮尔森相关分析和冗余分析表明,MBC和MBN均与≥ 0℃积温、年均温呈极显著负相关（P<0.01）,与海拔呈极显著正相关关系,MBP与母质呈现极显著负相关关系。逐步回归分析表明,MBC主要受年均温、干燥度、年均降水量和母质的影响;MBN主要受海拔、干燥度和年均降水量的综合影响;MBP主要受母质、年均温、≥ 10℃积温和年均降水量的调控。因此,川西平原土壤MBC、MBN、MBP能灵敏地反映不同采样点气候的变化,可为该区气候变化下土壤碳、氮、磷的响应预测提供参考。     

不同施肥水平及玉米种植对土壤微生物生物量碳氮的影响

以裸地(不种植作物)和玉米种植的田间小区试验为平台,研究不同施肥水平及玉米种植对土壤微生物生物量碳氮的影响。结果表明,当不施肥时,土壤微生物生物量碳氮含量裸地平均值分别为175.98 mg/kg和26.04 mg/kg,种植玉米小区的平均值分别为161.65 mg/kg和22.70 mg/kg,土壤微生物生物量碳氮低于裸地;而施肥时,裸地的土壤微生物生物量碳氮平均值的变化范围分别为182.27~206.27 mg/kg和27.41~31.22 mg/kg,种植玉米小区的变化范围分别为194.70~235.58 mg/kg和35.76~44.66 mg/kg,土壤微生物生物量碳氮高于裸地,可见土壤碳氮的平衡对于土壤微生物生物量碳氮极为重要。裸地和玉米种植小区土壤微生物生物量碳氮均随着施肥量的增加呈现出先增加后降低的趋势,其施氮水平拐点分别为70 kg/hm2和150kg/hm2,表明施肥水平对土壤微生物生物量碳氮具有显著影响。另外,玉米各生育期间土壤微生物生物量碳氮也存在着显著差异,其中,土壤微生物生物量碳氮含量在拔节期处于最低,变动范围分别为154.46~229.09 mg/kg和18.84~31.44 mg/kg;抽雄期处于最高,变动范围分别为171.71~242.48 mg/kg和30.01~50.54 mg/kg。     

长期施用生物有机肥对土壤肥力及微生物生物量碳的影响

为了研究施用生物有机肥(EM堆肥,即有效微生物制剂 堆肥)对土壤肥力及微生物生物量碳的影响,进行了7年的施用15t/hm2.a有机肥、施用7.5t/hm2.a有机肥(包括EM堆肥、EM鸡粪肥和传统有机肥)、施用化肥和对照处理的田间试验。结果表明:长期施用生物有机肥的土壤肥力明显提高。随着生物有机肥用量的提高,碱性土壤的pH值逐渐降低,土壤有机质、全N、碱解氮、有效磷、速效钾、微生物生物量碳含量增加,与有机肥施用量呈显著正相关。施用化肥可一定程度提高土壤有机质、全N和有效养分含量,但作用不明显。施肥对土壤肥力和微生物量碳的影响趋势是:EM堆肥>传统堆肥>化肥>对照。土壤微生物量碳与土壤有机质、全N、碱解氮、有效磷、速效钾含量呈显著正相关,可以作为施肥过程中土壤质量变化的生物学指标。     

不同耕作方式对土壤有机碳、微生物量及酶活性的影响

【目的】依托8年长期(2005~2012)固定道定位试验,研究不同耕作方式对土壤有机碳、土壤微生物量、土壤酶活性在0—90 cm土层的分布特征,为优化中国西北干旱区的耕作方式提供理论依据。【方法】试验包括固定道垄作(PRB)、固定道平作(PFT)与传统耕作(CT)三种耕作模式下的土壤有机碳土壤总有机碳(TOC)、颗粒有机碳(POC)、土壤微生物量碳(MBC)、土壤微生物量氮(MBN)、土壤微生物量磷(MBP)、蔗糖酶、过氧化氢酶、脲酶及小麦产量进行了测定和分析。【结果】在0—90 cm土层,不同耕作方式下的TOC、POC、MBC、MBN、MBP、蔗糖酶活性、脲酶活性均随着土层的增加呈下降趋势,过氧化氢酶活性呈先下降后增大的分布特征;在0—60 cm,固定道保护性耕作能够显著增加心土层作物生长带土壤有机碳储量,有机碳储量大小为PRBPFTCT;PRB、PFT较CT可以显著增加0—10 cm作物生长带TOC、POC、MBC、MBN、MBP含量、蔗糖酶、脲酶活性,其大小为PRBPFTCT;耕作方式对过氧化氢酶活性影响不显著;TOC、POC、MBC、MBN、MBP、蔗糖酶活性、脲酶活性、过氧化氢酶活性之间均达到了显著或极显著相关。【结论】PRB较PFT、CT能够提高耕作层(0—10 cm)土壤有机碳含量、土壤微生物量、土壤酶活性, 增加作物产量, 增大0—60 cm土层有机碳储量,耕作方式(PRB、PFT及CT)对10 cm以下土层土壤环境改善作用不明显。     

Effect of long-term conservation tillage on soil biochemical properties in Mediterranean Spanish areas

In semi-arid Mediterranean areas, studies of the performance of conservation tillage systems have largely demonstrated advantages in crop yield, soil water storage and soil protection against wind and water erosion. However, little attention has been given to interactions between soil biochemical properties under different tillage practices. Biochemical properties are useful tools to assess changes caused by different soil tillage systems in long-term field experiments. This study deals with the effect of long-term tillage practices (reduced tillage and no-tillage vs. traditional tillage) on soil chemical properties and microbial functions in three different sites of Spain (two of them located in the Northeast and one in the Southwest) under semi-arid Mediterranean conditions. Soil biological status, as index of soil quality, was evaluated by measuring microbial biomass carbon (MBC) and dehydrogenase (an oxidoreductase) and protease (a hydrolase) activities at three soil depths (0–5, 5–10 and 10–25 cm). In the three experimental areas, increases in soil organic matter content, MBC and enzymatic activities were found at the superficial layers of soil under conservation tillage (reduced tillage and no-tillage) in comparison with traditional tillage. Values of the stratification ratio of some biochemical properties were significantly correlated with yield production in Northeast sites.Conservation tillage has proven to be an effective strategy to improve soil quality and fertility in Mediterranean areas of Spain.     

Limitations of soil microbial biomass carbon as an indicator of soil pollution in the field

The size of the soil microbial biomass carbon (SMBC) has been proposed as a sensitive indicator for measuring the adverse effects of contaminants on the soil microbial community. In this study of Australian agricultural systems, we demonstrated that field variability of SMBC measured using the fumigation-extraction procedure limited its use as a robust ecotoxicological endpoint. The SMBC varied up to 4-fold across control samples collected from a single field site, due to small-scale spatial heterogeneity in the soil physicochemical environment. Power analysis revealed that large numbers of replicates (3-93) were required to identify 20% or 50% decreases in the size of the SMBC of contaminated soil samples relative to their uncontaminated control samples at the 0.05% level of statistical significance. We question the value of the routine measurement of SMBC as an ecotoxicological endpoint at the field scale, and suggest more robust and predictive microbiological indicators.     

Effects of liming and tillage systems on microbial biomass and glycosidases in soils

This study was undertaken to investigate the long-term influence of lime application and tillage systems (no-till, ridge-till and chisel plow) on soil microbial biomass C (C_mic) and N (N_mic) and the activities of glycosidases (- and -glucosidases, - and -galactosidases and -glucosaminidase) at their optimal pH values in soils at four agroecosystem sites [Southeast Research Center (SERC), Southwest Research Center (SWRC), Northwest Research Center (NWRC), and Northeast Research Center (NERC)] in Iowa, USA. Results showed that, in general, the C_mic and N_mic values were significantly (P <0.001) and positively correlated with soil pH. Each lime application and tillage system significantly (P <0.001) affected activities of the glycosidases. With the exception of -glucosidase activity, there was no lime×tillage interaction effect. Simple correlation coefficients between the enzyme activities and soil pH values ranged from 0.51 (P <0.05) for the activity of -glucosidase at the NWRC site (surface of the no-till) to 0.98 (P <0.001) at the SWRC site. To assess the sensitivity of the enzymes to changes in soil pH, the linear regression lines were expressed in activity/pH values. In general, their order of sensitivity to changes in soil pH was consistent across the study sites as follow: -glucosidase>-glucosaminidase>-galactosidase>-galactosidase>-glucosidase. Lime application did not significantly affect the specific activities (g p -nitrophenol released kg^–1 soil organic C h^–1) of the enzymes. Among the glycosidases studied, -glucosidase and -glucosaminidase were the most sensitive to soil management practices. Therefore, the activities of these enzymes may provide reliable long-term monitoring tools as early indicators of changes in soil properties induced by liming and tillage systems.     

长期施肥与地膜覆盖对土壤微生物量碳氮的影响

通过田间定位试验研究长期施肥与地膜覆盖对土壤微生物量C、N的影响。结果表明，长期施肥与地膜覆盖提高了土壤微生物量C、N含量，长期施有机肥和有机无机肥配施，土壤微生物量C、N显著高于单施化肥和不施肥。相关分析表明，土壤微生物量C、N与土壤有机C、全N均呈极显著的正相关。土壤微生物量C、N可作为指示土壤肥力的重要指标。本试验土壤微生物量C占有机C的比例平均为9．95％，微生物量N占全N的比例平均为10．78％。     

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.     

Evaluating soil microbial biomass carbon as an indicator of long-term environmental change

The aim is to assess whether soil microbial biomass carbon (biomass C) could be used as an indicator of environmental change in natural and semi-natural ecosystems. Biomass C was measured by fumigation-extraction in soils from two sites at Rothamsted. One was a plot from the Broadbalk Wheat Experiment, given inorganic fertiliser and chalk, which has been in continuous cultivation for more than 150 yr. The other was a similar sized area, from Geescroft Wilderness, which has been left to revert to woodland since 1885, after being an arable field. Other soil properties (pH, soil organic C and exchangeable cations) were also measured to compare with biomass C. The coefficients of variation (cvs) of the properties measured were calculated for comparison, little difference was found between the cvs for biomass C from each site: cv=26% for Broadbalk and 23% for Geescroft. The cvs for the other, chemical properties, were mostly <10% for Broadbalk and generally >25% for Geescroft, as expected, given the different cultivation histories. Statistical analysis of the variation in biomass C concentration revealed that such measurements would not be valid indicators of environmental change, without processing impossibly large numbers of samples. To decrease the least significant percentage change to less than 5% after three samplings, 320 samples would have to be taken each time. This would be also be true of the other chemical properties in Geescroft Wilderness, where the measured background variation would mask any subtle environmental change. This indicates that, for some properties at least, statistically significant changes will only be detected in the longer term with regular sampling, e.g. 30-40 yr.     

不同管理措施对西藏河谷农田土壤微生物量碳的影响

土壤微生物量碳(MBC)是反映农田土壤质量的重要指标。本研究以西藏河谷农田生态系统为对象,在中国科学院拉萨农业生态试验站长期施肥样地和农田撂荒地通过随机混合采样获取土壤样品,实验室内以氯仿熏蒸法测定土壤微生物量碳,探讨了不同施肥方式、不同除草方式对西藏河谷农田土壤质量的影响。从3个不同生育期的平均结果来看,施加羊粪样地的土壤微生物量碳比空白样地提高了56.1%,单纯施用化肥样地的微生物量碳比空白样地降低了14.0%,表明有机肥的施用对于提高西藏农田土壤质量具有显著的促进作用,而单纯施用化肥则会导致土壤质量的下降。在农田撂荒地试验中,自然撂荒样地(不除草)的土壤微生物量碳大约为85.2 mg/kg,而经常除草样地的土壤微生物量碳比不除草样地降低约1/4,从而进一步说明有机质输入对于提高高原农田土壤质量具有重要的作用。