生物炭施用下潮土团聚体微生物量碳氮和酶活性的分布特征

  【目的】  探究生物炭配施化肥对不同粒级团聚体中微生物量碳、氮 (MBC、MBN) 含量和胞外酶活性的影响,分析影响团聚体胞外酶活性变化的主控因素,为提升土壤质量提供科学依据。  【方法】  田间微区试验在河南现代农业研究基地进行,供试土壤为石灰性潮土。设置4个处理:不施肥 (CK)、单施化肥 (NPK)、单施生物炭 (BC) 和生物炭配施化肥 (BC+NPK),生物炭是以花生壳为原料高温裂解制备而成,仅在试验开始前施用一次,化肥每季均施用。试验开始于2017年小麦季,于2019年9月玉米收获后采集耕层土壤样品,测定土壤养分含量,分析各粒径团聚体MBC、MBN含量和酶活性。  【结果】  与CK相比,NPK处理可显著提高耕层土壤有效磷、速效钾和硝态氮含量,BC处理可显著提高有机碳和全氮含量,BC+NPK处理则显著提高了以上各指标含量。与CK相比,BC处理显著降低了粒径2～0.25 mm团聚体MBN含量,并明显增加了该粒径的MBC/MBN值;BC+NPK处理显著增加了粒径 > 2 mm和0.25～0.053 mm团聚体中MBC含量 (增幅分别为59.57%和34.68%),也增加了耕层土壤、粒径 > 2 mm和2～0.25 mm团聚体中MBN含量 (增幅分别为17.33%、42.24%和19.28%)。与CK相比,NPK、BC和BC+NPK处理均显著增加粒径 > 2 mm团聚体微生物熵,而BC和BC+NPK处理则显著降低了耕层土壤、粒径2～0.25 mm和0.25～0.053 mm团聚体微生物熵。与CK相比,NPK和BC+NPK处理均显著提高了粒径2～0.25 mm和0.25～0.053 mm团聚体中β-葡糖苷酶、β-纤维二糖苷酶、α-葡糖苷酶和β-木糖苷酶活性;在粒径 > 2 mm团聚体中,仅BC+NPK处理明显提高了该四种酶的活性。与CK相比,NPK和BC+NPK处理均明显提高了粒径 > 2 mm团聚体中脲酶活性及粒径0.25～0.053 mm团聚体中乙酰氨基葡糖苷酶活性,仅BC+NPK处理可显著提高粒径 > 2 mm和0.25～0.053 mm团聚体中亮氨酸氨基肽酶活性。团聚体酶活性变化与MBC、MBN含量以及MBC/MBN值显著相关。粒径 > 2 mm团聚体中酶活性变化与微生物熵、全氮和MBC含量均显著相关,粒径2～0.25 mm团聚体中酶活性变化与MBC/MBN值显著相关,而粒径0.25～0.053 mm团聚体中酶活性变化与MBC含量显著相关。  【结论】  生物炭与化肥配施有利于土壤碳的固存,改善土壤微环境,提升土壤质量,且生物炭添加到土壤中有较长的后效。     

保水剂对粘质潮土团聚体分布、稳定性及玉米养分积累的影响

通过玉米盆栽试验,研究了4种不同类型保水剂对粘质潮土团聚体分布、稳定性和玉米养分积累及吸收利用的影响。结果表明:保水剂保水效果在玉米生长中后期显现,收获期各处理土壤含水量比对照提高21.45%~65.09%;通过计算5种土壤团聚体特征参数并分析其与土壤粒径组成的相关性发现,聚丙烯酸钠(WT_1)与自制有机肥型保水剂(OSC)的土壤水稳性大团聚体数量(R_(0.25))比施肥处理(T_1)显著提高72.40%和58.00%,平均重量直径(MWD)和几何平均直径(GMD)较T_1分别显著提高45.91%,67.89%和57.34%,64.11%,土壤不稳定团粒指数(E_(LT))显著降低18.51%和14.83%;各保水剂处理使分形维数(D)降低0.10%~2.64%;GMD与土壤各级颗粒含量均呈极显著相关(p0.01),较其他参数可更准确的反应土壤团聚体分布及稳定性;聚丙酰胺型保水剂(AS)和OSC对于土壤氮素的保持和促进氮素转化效果更好,籽粒含氮量比T_1分别显著上升10.37%和15.67%。OSC对提高土壤团聚体和促进养分吸收利用均具有显著效果,这对进一步研制复合功能保水剂提供了参考。     

土地利用类型对土壤微生物量和有机质的影响

对陕北黄土丘陵区农地、园地、人工草地、荒地、灌木林地、经济林地和乔木林地等7种不同土地利用类型土壤剖面4个土壤层次的土壤微生物量碳(MBC)、微生物量氮(MBN)、土壤呼吸(RS)和土壤有机质含量(SOM)进行了测定.分析了MBC,MBN,RS,SOM和全氮(TN)之间的相关性;并对土壤微生物对土壤健康的生物指示功能和土地利用类型对土壤有机质的影响进行了研究.结果表明,各土地利用类型表层土壤MBC和MBN分别在84.14～512.78和4.29～41.83 mg/kg之间,RS在108.69～235.71 mg/kg之间.荒地和乔木林地的土壤微生物量含量和RS值较高,农地较低;SOM在0.510%～1.547%之间,在乔木林地和经济林地较高,在农地,园地和人工草地较低,且在不同土地利用类型之间的差异显著.土壤微生物量和RS与SOC,TN显著相关,说明土壤微生物学特征可以用来表示土壤健康水平.农地转变为其它土地利用类型后会明显提高土壤微生物量和有机质含量,尤以表层土壤增幅最为明显.     

三峡库区不同植被土壤微生物量碳氮磷生态化学计量特征

土壤微生物通过矿化和固持营养而显著影响土壤肥力。以湖北宜昌点军区三种植被类型(柏树、橘树、菜地)的土壤作为研究对象,对土壤微生物量碳氮磷及其生态化学计量进行了研究,探讨了不同植被覆盖土壤微生物量碳氮磷特征及它们之间的联系。结果表明:不同植被覆盖显著改变土壤微生物量碳氮磷含量,土壤微生物量碳(MBC)、氮(MBN)都是柏树地显著大于柑橘地和菜地,而菜地和柑橘地之间无显著性差异。土壤微生物量磷(MBP)的大小顺序为菜地柏树地橘树地。相关性分析的结果表明土壤有机碳、全氮和微生物量碳氮互相之间具有显著的正相关性(p0.01),土壤全磷与土壤微生物量磷之间也具有显著的正相关性(p0.01),这意味着土壤微生物量可以作为土壤肥力变化的指标。三种植被类型的土壤MBC/MBN之间都无显著性差异,而土壤MBC/MBP和MBN/MBP的变化顺序是橘树地柏树地菜地。MBC/MBP和MBN/MBP与MBP之间具有显著的负相关性(p0.01),而微生物碳氮与MBC/MBN,MBN/MBP和MBC/MBP之间都无显著的相关性。这意味着土壤MBC/MBP和MBN/MBP的变化主要与微生物量磷具有显著的关系。     

山核桃集约经营过程中土壤微生物量碳氮的变化

[目的]研究不同集约经营历史山核桃林的土壤微生物量碳氮的演变规律,为山核桃林地土壤管理提供科学依据。[方法]在浙江省临安市分别采集并分析了经营历史为5,10,15,20a的山核桃林土壤样品,并与天然混交林(0a)进行比较。[结果]天然混交林改造为山核桃纯林并经集约经营后,林地土壤微生物量碳(MBC)、微生物量氮(MBN)、MBC/MBN,MBC/SOC均表现出先下降而后上升的趋势,经过10a经营后降到最低水平,与0a相比,0—10cm土层MBC,MBN和MBC/SOC分别降低了52.1%,32.0%和31.0%。经营10a的林地土壤MBC/MBN显著低于前期经营林地,而MBN/TN在经营过程中的差异并不显著。[结论]山核桃集约经营后,林地土壤微生物量碳氮含量显著下降。     

菌渣还田对设施土壤微生物量碳、氮的影响

[目的]探究设施土壤微生物量碳、氮对菌渣还田的响应,为实现设施瓜菜生产的可持续发展提供理论依据和技术支持。[方法]以草菇菌渣为材料,在山东省莘县进行了田间试验,以常规鸡粪还田为对照(CON),设置5个菌渣(FR)还田量,研究菌渣还田对设施土壤有机碳(SOC)、全氮(TN)和微生量碳(MBC)、氮(MBN)的影响。[结果] 5个菌渣还田处理的菌渣使用量分别为15,30,45,60和75 t/hm~2)相比CON增加了SOC和TN。SOC分别增加了12.0%,11.2%,21.6%,33.1%和31.7%,TN分别增加了3.1%,6.3%,19.9%,29.4%和26.4%。除FR_1以外,其他4个菌渣还田处理相比增加了MBC和MBN,MBC分别增加了16.1%,19.9%,36.8%和50.7%,MBN分别增加了3.3%,37.7%,40.4%和60.9%。相比CON,高量菌渣还田处理增加了MBC/SOC和MBN/TN。相关分析表明,MBC,MBN与SOC和TN均呈极显著正相关。[结论]菌渣还田可以提高土壤有机碳、土壤全氮和土壤微生物碳、氮。土壤微生物碳、氮含量随着菌渣还田量的增加而增加,因此菌渣还田是提高设施土壤微生物活性及土壤肥力的有效措施。     

喀斯特峰丛洼地不同植被类型土壤微生物量碳氮磷和养分特征

  目的  探讨桂西北喀斯特峰丛洼地不同植被类型的土壤理化性质和微生物碳(MBC)、微生物氮（MBN）、微生物磷（MBP）含量的变化特征及它们之间的关系。  方法  利用生态化学计量方法和Pearson相关性分析方法研究不同植被类型和土层深度对土壤MBC、MBN、MBP含量和土壤养分含量分布特征的影响。  结果  （1）不同植被类型土壤养分含量和MBC、MBN、MBP含量依次为次生林 > 灌木 > 灌草 > 草地 > 耕地;土壤养分垂直分布表现为随着土层深度加深而下降,不同土层间土壤有机碳（SOC）、全氮（TN）、全磷（TP）含量差异显著,土壤MBC、MBN和MBP含量在不同植被类型和不同土层间差异显著,均表现为MBC > MBN > MBP。（2）不同植被类型土壤MBC/SOC和MBP/TP的值较小,MBN/TN的差异较大。不同植被类型的土壤MBC/MBN差异显著,MBC/MBP变化范围较大,MBN/MBP表现为次生林 > 灌草 > 灌木 > 草地 > 耕地。（3）土壤MBC和MBN与SOC、TN、速效氮和速效钾呈显著或极显著正相关,与土壤容重、pH值表现出不同程度的负相关,表明植被恢复过程中土壤MBC和MBN可作为衡量土壤养分的敏感性指标。  结论  不同植被类型的土壤微生物生物量碳氮磷、养分含量和化学计量特征有明显的表聚效应,随着植被的正向演替,土壤结构、养分和微生物群落功能得到显著提高。     

有机物料输入稻田提高土壤微生物碳氮及可溶性有机碳氮

土壤微生物量碳、氮和可溶性有机碳、氮是土壤碳、氮库中最活跃的组分,是反应土壤被干扰程度的重要灵敏性指标,通过设置相同有机碳施用量下不同有机物料处理的田间试验,研究了有机物料添加下土壤微生物量碳（soil microbial biomass carbon,MBC）、氮（soil microbial biomass nitrogen,MBN）和可溶性有机碳（dissolved organic carbon,DOC）、氮（dissolved organic nitrogen,DON）的变化特征及相互关系。结果表明化肥和生物碳、玉米秸秆、鲜牛粪或松针配施下土壤微生物量碳、氮和可溶性有机碳、氮显著大于不施肥处理（no fertilization,CK）和单施化肥处理,分别比不施肥处理和单施化肥平均高23.52%和12.66%（MBC）、42.68%和24.02%（MBN）、14.70%和9.99%（DOC）、22.32%和21.79%（DON）。化肥和有机物料配施处理中,化肥+鲜牛粪处理的微生物量碳、氮和可溶性有机碳、氮最高,比CK高26.20%（MBC）、49.54%（MBN）、19.29%（DOC）和32.81%（DON）,其次是化肥+生物碳或化肥+玉米秸秆处理,而化肥+松针处理最低。土壤可溶性有机碳质量分数（308.87 mg/kg）小于微生物量碳（474.71 mg/kg）,而可溶性有机氮质量分数（53.07 mg/kg）要大于微生物量氮（34.79 mg/kg）。与不施肥处理相比,化肥和有机物料配施显著降低MBC/MBN和DOC/DON,降低率分别为24.57%和7.71%。MBC和DOC、MBN和DON随着土壤有机碳（soil organic carbon,SOC）、全氮（total nitrogen,TN）的增加呈显著线性增加。MBC、MBN、DOC、DON、DOC+MBC和DON+MBN之间呈极显著正相关（P<0.01）。从相关程度看,DOC+MBC和DON+MBN较MBC、DOC、MBN、DON更能反映土壤中活性有机碳和氮库的变化,成为评价土壤肥力及质量的更有效指标。结果可为提高洱海流域农田土壤肥力,增强土壤固氮效果,减少土壤中氮素流失,保护洱海水质安全提供科学依据。     

有机无机复混肥优化运筹对稻田肥力的影响

通过田间试验探讨了不施分蘖肥的有机无机复混肥运筹模式对机插水稻土壤总碳(TC)、总氮(TN)、微生物碳(MBC)、微生物氮(MBN)、土壤呼吸强度以及线虫特征等土壤肥力关键指标的影响。结果表明,有机无机复混肥作基肥施用,不施分蘖肥,穗肥施用一次(处理FMT)或二次(处理FMO)时水稻产量能够达到或超过单施化肥处理水平。与单施化肥相比,有机无机复混肥处理显著提高了土壤微生物量碳(MBC)和氮(MBN),MBC平均提高14.5%,MBN提高21.4%;土壤呼吸强度也得到明显提高,平均增幅31.8%,然而有机无机复混肥对土壤总碳(TC)和全氮(TN)无显著影响。有机无机复混肥处理降低了耕层(0~10 cm)土壤线虫密度,并导致食细菌线虫优势属头叶属和真头叶属相对丰度下降,食细菌线虫次优属绕线属、连胃属及植食性线虫潜根属相对丰度有所提高。应用土壤养分指标(TC、TN)、生物指标(MBC、MBN、线虫数量、土壤呼吸强度)进行主成分分析和聚类分析,结合水稻产量、肥料利用率,表明有机无机复混肥运筹是一项集培肥、增产、操作性强的施肥方式。     

城市不同功能区绿地土壤微生物量碳氮及溶解性碳氮分布特征及影响因素

为研究城市功能分区对绿地土壤活性碳氮的影响,选择合肥市不同功能区(老商业区、老工业区、居民服务区、近郊森林公园)绿地土壤为研究对象,分析了土壤微生物量碳氮(MBC、MBN)、溶解性碳氮(DOC、DON)、有机碳(SOC)、全氮(TN)以及土壤基本理化性质的差异及其相互关系。结果表明,功能区类型对土壤微生物量碳氮及溶解性碳氮影响显著(P0.05),且0~30 cm土层含量均为近郊森林公园高于城区内各功能区。土层厚度对MBC、DOC、DON含量影响显著,MBC、DON在各功能区中均随土层深度增加而递减,森林公园MBN、DOC均为10~20 cm含量最高。不同功能区MBC/MBN在6~14间波动,以此预测本研究范围内土壤微生物可能以真菌和放线菌为主,细菌较少。本研究未证实DOC与MBC、MBC与DON、DON与MBN间的相关性,MBC+DOC、MBN+DON比MBC、DOC、DON、MBN更能反应土壤活性碳氮库与土壤微生物量。总体来说,相比城区内各功能区,近郊森林公园更利于土壤生物量碳氮及溶解性有机碳氮的积累。     

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.     

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.     

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。     

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.     

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。     

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.     

Assessment the effect of homogenized soil on soil hydraulic properties and soil water transport

Soil hydraulic properties play a crucial role in simulating water flow and contaminant transport. Soil hydraulic properties are commonly measured using homogenized soil samples. However, soil structure has a significant effect on the soil ability to retain and to conduct water, particularly in aggregated soils. In order to determine the effect of soil homogenization on soil hydraulic properties and soil water transport, undisturbed soil samples were carefully collected. Five different soil structures were identified: Angular-blocky, Crumble, Angular-blocky (different soil texture), Granular, and subangular-blocky. The soil hydraulic properties were determined for undisturbed and homogenized soil samples for each soil structure. The soil hydraulic properties were used to model soil water transport using HYDRUS-1D.The homogenized soil samples showed a significant increase in wide pores (wCP) and a decrease in narrow pores (nCP). The wCP increased by 95.6, 141.2, 391.6, 3.9, 261.3%, and nCP decreased by 69.5, 10.5, 33.8, 72.7, and 39.3% for homogenized soil samples compared to undisturbed soil samples. The soil water retention curves exhibited a significant decrease in water holding capacity for homogenized soil samples compared with the undisturbed soil samples. The homogenized soil samples showed also a decrease in soil hydraulic conductivity. The simulated results showed that water movement and distribution were affected by soil homogenizing. Moreover, soil homogenizing affected soil hydraulic properties and soil water transport. However, field studies are being needed to find the effect of these differences on water, chemical, and pollutant transport under several scenarios.     

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.