耕作措施对陇中旱农区土壤细菌群落的影响

为探究耕作措施对陇中旱农区麦豆轮作系统土壤细菌多样性的影响,借助2001年在陇中旱农区建立的不同耕作措施长期定位试验,应用高通量测序技术比较传统耕作(T)与3种保护性耕作(免耕(NT)、传统耕作+秸秆还田(TS)和免耕+秸秆覆盖(NTS))对麦豆轮作体系土壤有机碳、全氮、微生物生物量碳、微生物生物量氮及细菌群落结构影响。结果表明:1)相对于传统耕作,秸秆还田显著增加0～10 cm、10～30 cm土壤有机碳、全氮、微生物量碳和微生物量氮含量,其中NTS处理0～10 cm、10～30 cm土层有机碳、全氮、微生物量碳和微生物量氮含量较传统耕作分别提高28.27%、114.16%、13.51%、49.14%和39.86%、98.05%、10.78%、40.72%。2)酸杆菌门(26.42%)、变形菌门(19.86%)和放线菌门(19.44%)为陇中旱农区麦豆轮作系统土壤细菌的主要优势种群,NTS处理下酸杆菌门、放线菌门和变形菌门丰度较传统耕作显著提高35.11%、33.77%和30.17%。3)与传统耕作相比,保护性耕作提高了0～30cm土层土壤细菌的Observedspecies指数、Chao指数、香农指数、辛普森指数,以NTS处理提高最为显著。因此,在陇中旱农区推广以免耕秸秆覆盖为主的保护性耕作措施有利于增加土壤碳氮固存、提高土壤细菌群落丰度和多样性和土壤的生物活性,促进农业的可持续发展。     

耕作措施对陇中麦豆轮作系统土壤真菌群落的影响

为探究耕作措施对陇中旱农区麦豆轮作系统土壤真菌多样性的影响,依托2001年布设在陇中旱农区的田间定位试验,应用高通量测序技术比较传统耕作(T)与3种保护性耕作[免耕(NT)、传统耕作+秸秆还田(TS)和免耕+秸秆覆盖(NTS)]对麦豆轮作体系真菌群落结构的影响。结果表明:1)子囊菌门(52.74%)、担子菌门(14.10%)为陇中旱农区麦豆轮作系统土壤真菌的主要优势种群,免耕秸秆覆盖处理下担子菌门丰度较传统耕作增加15.01%,免耕处理子囊菌门、担子菌门丰度较传统耕作分别提高3.67%、1.86%。2)保护性耕作措施能不同程度提高0～30 cm土层土壤真菌丰富度与多样性指数,其中以免耕秸秆覆盖效果最明显,但各处理间差异不显著;较传统耕作,0～30 cm土层土壤真菌特有OTU数量NTNTSTST,同时较传统耕作,免耕秸秆覆盖处理土壤真菌OTU数量提高8.07%,免耕处理提高12.41%。因此,在陇中旱农区推广以免耕秸秆覆盖为主的保护性耕作措施有利于提高土壤真菌群落丰富度和多样性。     

耕作方式对农田土壤理化性质、微生物学特性及小麦营养品质的影响

【[目的 ]】耕作措施对土壤健康和作物营养品质提升具有关键作用,明确不同耕作方式对土壤理化性质、微生物学特性及小麦营养品质的影响,为集约化农田可持续管理提供理论依据。【[方法 ]】田间试验自2012年起在山东德州进行,供试土壤为潮土,种植制度为小麦–玉米轮作。设置4种耕作模式处理：传统耕作、旋耕、休耕和免耕。2020年,采集0—20 cm土层土样分析土壤物理、化学性质和细菌群落结构,采集小麦籽粒样品分析其营养品质。【[结果 ]】与传统耕作相比,免耕、休耕和旋耕处理显著提高了土壤含水量、铵态氮、硝态氮、有机质、全氮及有效磷含量,休耕还显著提高了土壤容重,降低了土壤孔隙度。免耕、休耕和旋耕处理显著提高土壤微生物量碳、氮含量以及土壤细菌群落多样性指数,休耕及免耕处理提高土壤厚壁菌门(Firmicutes)、疣微菌门(Verrucomicrobia)的相对丰度,降低放线菌门(Actinobacteria)的相对丰度。从营养品质变化来看,休耕显著提高小麦籽粒蛋白质、淀粉、微量元素的含量,旋耕和免耕显著增加小麦籽粒蛋白质含量,除天冬氨酸外,其他16种氨基酸组分变化趋势与氨基酸总量变化基本一致。Pe...     

免耕对不同麦玉轮作农田土壤碳组分及理化性质的影响

为探讨耕作及轮作方式对农田土壤理化性质和碳组分的影响,设置免耕、传统耕作2种耕作方式,以及小麦-玉米轮作、小麦/玉米间作、小麦-冬油菜-玉米轮作3种种植模式,共形成6个处理,研究结果表明:与传统耕作相比,免耕增加了0~5 cm、5~20 cm土层全氮、全磷、速效磷和含水量,而降低了的土壤pH和土壤容重。免耕小麦/玉米间作(NT.W1/NT.WM.1)处理的土壤容重、含水量、全氮、全磷含量高于NT.WRM3和NT.WM5处理,在不同土层间,土壤全氮、全磷和速效磷含量随着土层深度的增加而降低。土壤碳组分含量总体表现为免耕处理高于传统耕作处理,免耕处理0~5 cm土层土壤有机碳、颗粒有机碳、可溶性有机碳、微生物量碳含量较相应传统耕作分别增加了1.31%~36.57%、2.07%~35.22%、2.38%~4.78%、2.08%~11.68%,在5~20 cm土层,免耕处理土壤有机碳和微生物量碳含量高于传统耕作。在不同免耕处理下,土壤有机碳,颗粒有机碳和微生物量碳含量在0~5 cm、5~20 cm土层总体表现为NT.WM5高于其他免耕处理,相关性分析表明,有机碳、微生物量碳和速效磷呈极显著正相关,容重和有机碳呈极显著负相关。综上所述,免耕小麦/玉米间作利于改善土壤理化性质,小麦-玉米轮作有利于提高土壤有机碳,颗粒有机碳和微生物量碳含量。     

不同耕作方式下玉米农田土壤养分及土壤微生物活性变化

通过连续3年的野外调查与室内分析试验,研究了不同耕作方式（翻耕、旋耕、免耕）对玉米农田土壤养分及土壤微生物活性的影响。结果表明,不同耕作方式下土壤pH值略显酸性,土壤容重与土壤总孔隙度变化趋势相反;土壤容重基本表现为:免耕 > 翻耕 > 旋耕;土壤总孔隙度TSP基本表现为:翻耕 > 旋耕 > 免耕,不同耕作方式差异均显著（p<0.05）。不同耕作方式下土壤养分（有机碳、全氮含量）和有效养分（有效磷、铵态氮和硝态氮）均呈现出一致性规律,大致表现为翻耕 > 旋耕 > 免耕,不同耕作方式下土壤全磷含量差异均不显著（p > 0.05）;与免耕相比,土壤微生物量碳和氮、土壤微生物数量（细菌、真菌、放线菌、固氮菌和纤维素菌）均有明显的增加,大致表现为:翻耕 > 旋耕 > 免耕。土壤微生物活度的变化范围为0.38~0.69,依次表现为翻耕 > 旋耕 > 免耕,不同耕作方式下土壤微生物活度差异均显著（p<0.05）。不同耕作方式下土壤微生物量碳周转率高于氮周转率,说明微生物量碳更新比微生物量氮快,其中翻耕处理下土壤微生物量碳和氮更新较旋耕和免耕快。通径分析发现,不同土壤环境因子对土壤微生物活度产生直接和间接负作用,其中有机碳、全氮、硝态氮、铵态氮、细菌数量对土壤微生物活度产生直接效应;土壤微生物量碳、微生物量氮、真菌数量和固氮菌数量对土壤微生物活度产生间接效应。     

不同类型粪肥还田对土壤酶活性及微生物群落的影响

畜禽粪便作为有机肥还田可以维持和提高土壤有机质、改良土壤,有利于农业可持续发展。不同类型粪肥还田后对土壤生物学性状的影响不同,为探究这一问题,在内蒙古乌兰察布市设置田间试验,包括化肥(F)、羊粪(GM)、猪粪(PM)、牛粪(CM)4个处理,研究其对土壤养分、酶活性及微生物群落的影响。结果表明,施用粪肥较化肥具有增加土壤有机质、全氮、有效磷、铵态氮等养分含量的趋势。不同粪肥较化肥处理的土壤脲酶、蔗糖酶、碱性磷酸酶和过氧化氢酶活性最高增幅分别为32.4%、150.4%、26.8%和30.1%。牛粪处理的土壤微生物生物量碳氮显著提高,分别较化肥增加33.2%和33.4%。不同处理在细菌门水平上的优势种群较一致,放线菌门(Actinobacteria)、变形菌门(Proteobacteria)、酸杆菌门(Acidobacteria)、绿弯菌门(Chloroflexi)、厚壁菌门(Firmicutes)是优势种群。本试验条件下,牛粪处理更能提高土壤微生物生物量碳氮,短期内施用不同粪肥对于提高土壤微生物群落多样性差异不显著,土壤pH、有效磷、铵态氮是影响土壤微生物群落结构的主要环境因子。     

免耕留茬覆盖对旱作燕麦土壤养分及微生物量的影响

以旱作燕麦田为试验对象,设置免耕高留茬高覆盖、免耕低留茬高覆盖、免耕高留茬低覆盖、免耕低留茬低覆盖和常规耕作5个处理,研究了免耕留茬覆盖对土壤养分、微生物量及燕麦产量的影响。结果表明,免耕留茬覆盖各处理均能明显提高土壤0—10cm和10—20cm土层中土壤有机质、全量养分及速效养分含量,0—10cm土层各土壤养分含量均高于10—20cm土层;免耕留茬覆盖对土壤微生物碳、氮具有显著的提高作用,整个生育期抽穗期达到最大值,0—10cm土层土壤微生物量碳、氮均大于10—20cm土层,其中免耕高留茬高覆盖处理效果最佳;免耕留茬覆盖对0—10cm和10—20cm土壤微生物商有显著提高作用,免耕留茬覆盖处理间差异不显著;免耕留茬覆盖对燕麦产量影响显著,其中高留茬高覆盖处理产量最高,为2 111.4kg/hm~2,较常规耕作增产18.6%,产量总体表现为免耕高留茬高覆盖免耕低留茬高覆盖免耕高留茬低覆盖免耕低留茬低覆盖常规耕作。     

秸秆还田和耕作方式对花生土壤微生物量、酶活性和产量的影响

通过两年的田间小区定位试验,研究免耕无秸秆还田(RN)、常规翻耕无秸秆还田(RS)、垄耕无秸秆还田(RD)、免耕秸秆还田(TN)、常规翻耕秸秆还田(TS)、垄耕秸秆还田(TD)6种耕作方式对科尔沁风沙地花生耕层土壤微生物量、土壤酶活性和产量的影响,探究适合辽西风沙半干旱条件下花生高产的耕作方式。结果表明:相同耕作条件下秸秆还田处理组土壤微生物量碳、氮、磷含量和土壤酶活性均高于无秸秆还田处理组,秸秆还田能显著提高土壤微生物量碳、氮、磷含量和酶活性;在相同秸秆还田处理条件下,与常规耕作和垄耕处理相比,免耕处理能显著提高土壤微生物量碳、氮、磷含量和土壤酶活性;免耕秸秆还田处理下,花生产量高出未还田处理4.32%。综上,免耕秸秆还田处理能显著提高土壤微生物量碳、氮、磷含量和土壤酶活性,提高耕层土壤生物学肥力,促进作物增产。     

菜-菌轮作模式下土壤微生物群落结构及多样性的变化

为明确菜-菌轮作模式对土壤微生物的影响,基于高通量测序技术,对4种轮作模式下的土壤微生物群落结构与多样性进行了研究,结果显示：不同轮作模式下土壤样品中真菌和细菌OUT总数分别是2298和15840条,相较于常规轮作模式A,菜-菌轮作模式B、C、D下真菌的OUT总数、ACE指数、Chao1指数、Shannon指数降低显著,Simpson指数增加明显,但细菌的各参数没有显著的差异;其土壤全氮、碱解氮、速效钾、有机质含量显著高于常规轮作模式A;真菌的优势群落是子囊菌门,相对丰度在66%以上,枝孢属、镰刀菌属两类致病菌群的丰度在菜-菌轮作模式B、C、D中降低明显;细菌的优势群落是变形菌门、放线菌门、绿弯菌门以及酸杆菌门,鞘氨醇单胞菌属、伯克霍尔德氏菌属丰度在菜-菌轮作模式B、C、D中显著提高;聚类分析表明菜-菌轮作模式C、D下微生物群落结构相似度最高,常规轮作模式A可划分为区别于菜-菌轮作模式B、C、D的单独类群。综上所述,菜-菌轮作可降低真菌群落丰度,改变土壤微生物群落的结构组成,同时提高土壤中有益菌群的丰度,降低有害菌群的丰度。     

保护性耕作对麦-豆轮作土壤有机碳全氮及微生物量碳氮的影响

通过设置在甘肃省定西市李家堡镇的保护性耕作措施长期定位试验,共设4个处理（T：传统耕作;NT：免耕无覆盖;TS：传统耕作＋秸秆还田;NTS：免耕＋秸秆覆盖）,采用春小麦豌豆双序列轮作（即小麦→豌豆→小麦和豌豆→小麦→豌豆,本文中所指春小麦地、豌豆地分别指2008年种植春小麦、豌豆的轮作次序）,于2008年3月中旬对春小麦、豌豆双序列轮作下的土壤有机碳、全氮、土壤微生物量碳及土壤微生物量氮含量进行了采样测定。结果表明,经过7a的轮作后,两种轮作次序下,0-30cm土层中土壤有机碳、全氮、土壤微生物量碳、土壤微生物量氮含量均有在免耕＋秸秆覆盖、传统耕作＋秸秆还田处理较免耕不覆盖、传统耕作处理高的趋势,且其含量均随着土壤深度的增加而降低。其中,土壤微生物量碳含量在两种轮作次序下的排序均为：免耕＋秸秆覆盖（NTS）〉传统耕作＋秸秆还田（TS）〉免耕不覆盖（NT）〉传统耕作（T）;而土壤微生物量氮含量在春小麦地和豌豆地的排序则分别表现为：免耕＋秸秆覆盖（NTS）〉传统耕作＋秸秆还田（TS）〉传统耕作（T）〉免耕不覆盖（NT）和免耕＋秸秆覆盖（NTS）〉传统耕作＋秸秆还田（TS）〉免耕不覆盖（NT）〉传统耕作（T）。同时,微生物量碳、微生物量氮与有机碳和全氮均呈显著正相关,说明提高土壤有机质、全氮含量的保护性耕作模式有利于土壤微生物量碳与氮的积累。     

Relationship between soil respiration and soil moisture

Microbial activity is affected by changes in the availability of soil moisture. We examined the relationship between microbial activity and water potential in a silt loam soil during four successive drying and rewetting cycles. Microbial activity was inferred from the rate of CO₂ accumulating in a sealed flask containing the soil sample and the CO₂ respired was measured using gas chromatography. Thermocouple hygrometry was used to monitor the water potential by burying a thermocouple in the soil sample in the flask. Initial treatment by drying on pressure plates brought samples of the test soil to six different water potentials in the range -0.005 to -1.5MPa. Water potential and soil respiration were simultaneously measured while these six soil samples slowly dried by evaporation and were remoistened four times. The results were consistent with a log-linear relationship between water potential and microbial activity as long as activity was not limited by substrate availability. This relationship appeared to hold for the range of water potentials from ?0.01 to ?8.5 MPa. Even at ?0.01 MPa (wet soil) a decrease in water potential from ?0.01 to ?0.02 MPa caused a 10% decrease in microbial activity. Rewetting the soil caused a large and rapid increase in the respiration rate. There was up to a 40-fold increase in microbial activity for a short period when the change in water potential following rewetting was greater than 5 MPa. Differences in microbial activity between the wetter and drier soil treatments following rewetting to the original water potentials are discussed in terms of the availability of energy substrate.     

Relationships between soil respiration and soil moisture

The interaction of soil microbes with their physical environment affects their abilities to respire, grow and divide. One of these environmental factors is the amount of moisture in the soil. The work we published almost 25 years ago showed that microbial respiration was linearly related to soil-water content and log-linearly related to water potential. The paper arose out of collaboration between two young researchers from different areas of soil science, physics and microbiology. The project was driven by not only our curiosity but also the freedom to operate without the constraints common to the current system of science management. The citation history shows three peaks, 1989, 1999 and from 2002 to the present day. Interestingly, the annual citation rate is as high as it has ever been. The initial peak is due to the application of the work to studies on microbial processes. The second peak is associated with the rise of simulation modelling and the third with the relevance of the findings to climate change research. In this article, our paper is re-evaluated in the light of subsequent studies that allow the principle of separation of variables to be tested. This re-evaluation lends further credence to the linear relationship proposed between soil respiration and water content. A scaled relationship for respiration and water content is presented. Lastly, further research is suggested and more recent work on the physics of gas transport discussed briefly.     

自然侵蚀量和容许土壤流失量与水土流失治理标准

在总结分析国内有关自然侵蚀量、容许土壤流失量研究成果的基础上,探讨自然侵蚀量与容许土壤流失量的关系,讨论制订水土流失治理标准的思路。认为水土流失治理标准的确定有3个参考值：1）标准值,即一定条件下的容许土壤流失量,是水土流失治理至少要达到的目标,且随着对不同土地利用类型的功能需求与可实施的最佳水土保持措施、以及所在水土流失类型区的侵蚀危害与治理约束条件的不同而不同;2）理想值,即正常自然侵蚀状态下的土壤流失量;3）极端值,即土壤流失量为0,不发生水土流失。水土流失治理应是先控制到现时生态环境与社会经济条件下的容许土壤流失量范围内,逐步达到自然正常侵蚀量或制止水土流失的发生;还应引入环境伦理、环境美学及景观设计等理念,最终实现土地的可持续利用、区域生态系统的健康稳定及人与自然的和谐友好发展。     

Effect of tillage treatments upon soil tests for soil acidity,soil phosphorus and soil potassium at three soil depths

Abstract

Soil samples were obtained at 0–3, 3–6, 6–9 and 0–9 inch depths from experimental plots receiving five tillage treatments. Each of two samplers composited approximately six one‐inch cores from each plot. Soil samples were analyzed for acidity, P and K using routine analysis procedures in the University of Illinois Soil Testing Laboratory.

Few significant differences were attributed to sampler and it was concluded that samplers using similar sampling techniques were obtaining soil samples from the same population.

No significant differences in soil acidity at different depths were observed. The different tillage methods did significantly affect soil P at the 0–3 inch depth, but had no significant effect on soil P at deeper depths. Different tillage methods also significantly affected soil K values at different depths.     

土壤含水率与土壤碱度对土壤抗剪强度的影响

土壤含水率和土壤碱度是表征土壤物理化学性质的两个重要参数。通过室内三轴不固结不排水试验,研究了土壤含水率和土壤碱度对土壤抗剪强度的影响。试验处理采用5种土壤碱度(土壤可交换钠百分比ESP=0、5、10、20、40)和4种土壤质量含水率(0.05、0.10、0.20以及饱和含水率0.34)水平。试验结果显示,土壤黏聚力随着土壤含水率的增加基本上呈先增大后减小之趋势;当土壤含水率在0.10附近时黏聚力达到其最大值。土壤内摩擦角随着土壤含水率的增加而线性减小。土壤碱度对土壤黏聚力的影响机理较为复杂,其影响效果随土壤含水率的增加而减小;但土壤碱度对土壤内摩擦角的影响较小。土壤碱度对土壤抗剪强度的影响程度明显地小于土壤含水率对其的影响程度。     

Nonisothermal nature of soil profiles and soil hydrophysics

The results of studies of thermal water transfer and the functional analysis of nonisothermal soil water exchange (summarizing the current concepts of its physical nature, value, relations to soil properties, contribution to heat conductivity, and use for determining other hydrophysical properties of soils) are presented without going into detail of the mathematical analysis.     

Ecological standardization of soil and soil quality control

Theoretical bases are offered for the ecological soil standardization presuming the scientific substantiating of the allowable ecological state (quality) of the soil and the allowable anthropogenic impact on it. The modern experience of these bases’ application in regulatory-methodological, nature-control, and managerial practices is presented. The criteria are found for determining the levels of the allowable ecological quality of soil and the anthropogenic impact on it. The sources of the anthropogenic impact on the soil are characterized. A unified system of indices of soil quality and anthropogenic impacts and a mechanism for determining the range of the allowable values of these parameters have been developed taking into account the natural conditions and types of land use. Scientific-methodological approaches are proposed that support a certain balance between the allowable ecological status of the soil and the effects on it in connection with the mechanisms of the soil quality control in particular land plots.     

土壤不同形态钾含量与土壤颗粒的关系

土壤含K矿物同其他矿物颗粒一起均分布在不同粒级的土粒中,这些土粒在不同的土壤中构成了不同的配合比例,形成不同的土壤质地的属性。统计表明,<0.05mm与<0.01mm粒级间呈极显著线性相关(r=0.896**,n=92),相关分析表明,不同粒级的土粒与不同形态K间呈显著线性或曲线显著相关,而全K只与<0.05mm粒径的土粒呈极显著相关(r=0.234**,n=73),全K与速效K的数量关系通过全K、<0.05mm、<0.01mm粒级与速效K系统相关组合的算式以数学的方法计算速效K含量。     

Why soil erosion models over-predict small soil losses and under-predict large soil losses

Evaluation of various soil erosion models with large data sets have consistently shown that these models tend to over-predict soil erosion for small measured values, and under-predict soil erosion for larger measured values. This trend appears to be consistent regardless of whether the soil erosion value of interest is for individual storms, annual totals, or average annual soil losses, and regardless of whether the model is empirical or physically based. The hypothesis presented herein is that this phenomenon is not necessarily associated with bias in model predictions as a function of treatment, but rather with limitations in representing the random component of the measured data within treatments (i.e., between replicates) with a deterministic model. A simple example is presented, showing how even a `perfect' deterministic soil erosion model exhibits bias relative to small and large measured erosion rates. The concept is further tested and verified on a set of 3007 measured soil erosion data pairs from storms on natural rainfall and run-off plots using the best possible, unbiased, real-world model, i.e., the physical model represented by replicated plots. The results of this study indicate that the commonly observed bias, in erosion prediction models relative to over-prediction of small and under-prediction of large measured erosion rates on individual data points, is normal and expected if the model is accurately predicting erosion rates as a function of environmental conditions, i.e., treatments.     

黑土区土壤侵蚀厚度对土地生产力的影响及其评价

为了研究黑土区土壤侵蚀厚度对土地生产力的影响,采用盆栽试验,人为剥离黑土表层0、5、10、15、20、25和30 cm土壤以模拟侵蚀厚度不同的耕层土壤,分析土壤侵蚀厚度对土壤理化性质、大豆生物性状和水分利用效率等指标的影响。并对TOPSIS(technique for order preference by similarity to ideal solution)模型进行改进,用于评价侵蚀厚度不同的土壤的土地生产力。结果表明:土壤全N、碱解N、全P、速效P、有机质含量和土壤田间持水率均随侵蚀厚度的增加而递减,土壤容重随侵蚀厚度的增加而递增。土壤侵蚀厚度对大豆生长有显著影响,随着侵蚀厚度的增加,大豆减产率呈"S型"曲线递增,产量、耗水量呈"Z型"曲线递减,水分利用效率呈指数曲线关系递减。改进的TOPSIS模型对不同侵蚀厚度下土地生产力的评价结果较为理想,计算的土地生产力指数随土壤侵蚀厚度的变化呈"Z型"曲线,与大豆产量的变化趋势相同,且二者呈指数函数关系,决定系数达0.996,均方根误差为0.65。研究结果可为黑土区土壤侵蚀防治提供理论依据。