摘要
土壤盐碱化严重制约农业的可持续发展,但施用改性生物炭对盐碱地改良效果显著。为探究改性生物炭改良盐碱土壤的作用机制,本文归纳总结了不同改性方式对原生物炭理化性质的影响,以及改性生物炭对盐碱地的改良效果和影响因素。结果表明,改性生物炭具有比表面积大、含氧官能团类型和数量多、碱性物质比例下降等特点;可以促进盐碱化土壤团粒结构的形成,增加对盐分离子的吸附和养分保持,改变土壤微生物的功能结构,增强作物应对外界胁迫的能力。然而改性生物炭长期效应及在不同类型盐碱地上应用差异的研究较少。未来应进行不同类型盐碱地应用的大田试验,深入研究改性生物炭对不同盐分离子的吸附能力及长效作用,优化在不同盐碱类型下的改良途径。
由于气候干旱、成土母质富含盐基离子以及灌溉不合理、开发过度等多重因素导致了盐碱地的形成与发
生物炭是生物质在限氧条件煅烧而成的富碳材料,作为一种温和的土壤改良剂,在改善酸性土壤pH、提高营养元素有效性以及缓解铝毒等方面已经取得显著成
改性生物炭虽然在盐碱化土壤的改良中表现出突出潜力,但目前在盐碱地上应用的改性生物炭类型有限,且不同改性方式会对生物炭理化性质的改变有显著差异,在盐碱地上施用效果也会有不同的侧重。
因此,本文综述了生物炭的改性方法和改性特征,改性生物炭在盐碱地上的应用情况及不同类型改性生物炭对于盐碱地改良产生显著影响的可能机制,并提出未来研究重点和发展方向,以期为改性生物炭在盐碱地上的合理应用和生产实践提供理论依据。
生物炭在土壤改良中应用广泛,但在复杂的土壤环境中,其比表面积、孔隙度和官能团具有局限性,无法满足理想的改良效果要求。为优化生物炭的表面结构和理化性质、提高其应用性能,越来越多的学者集中于生物炭的改性研究,其制备流程通常分为前处理和后处理2种类型(

图1 改性生物炭的制备流程
Fig.1 Preparation process of modified biochar
物理改性包括球磨、气体活化、紫外线照射等,是一种在改性过程中不需要使用化学试剂的绿色、环境友好型改性方式。球磨研磨将生物炭内部孔隙网络暴露、含氧官能团引入生物炭表面,比表面积扩
化学改性是提升生物炭表面性能最常用的方式,通过加入酸(H3PO4、HNO3、HCl、H2SO4)、碱(NaOH、KOH)或氧化剂(H2O2、KMnO4)来实现对生物炭理化性质的改善。酸碱改性对于生物炭表面酸碱基团的影响十分显著,KOH改性后碱性基团的比例进一步增加,而H3PO4改性后酸性基团显著升高,约是碱性基团的3.3
金属改性可使生物炭获得更大的比表面积和更多的吸附位点,改变生物炭金属元素含量和表面电荷,具有良好的静电吸引和沉淀能力。外源金属氧化物的负载能够显著提升生物炭对阴离子的吸附能
研究发现,生物炭通过C
改性生物炭能够通过增加土壤中胶结物质含量,增强对植物、微生物的间接调控以及对水分的有效固持起到改善盐碱土壤物理性质的作用。降低盐碱土壤容重和增加孔隙度的直接机制是生物炭的高孔隙度、低容重和盐碱土的低孔隙度、高容重进行“中和作用”,土壤团聚结构的改善也有利于形成土壤多级孔隙,降低土壤容
生物炭灰分中的碱金属、碱土金属化合物含量高,碱性官能团比例显著高于酸性官能团的特性使其pH值呈碱
有研究显示,生物炭改性后对降低盐碱土壤pH值无显著效果,甚至略有升高,这与改性后暴露出更多的碱性官能团和矿物质有
改性生物炭具有优良的吸附性能,可以减少养分流失。FeCl3改性生物炭通过静电吸引和配位体交换作用促进磷酸盐的吸附,减少了养分的浸
土壤微生物对土壤理化性质和作物生长具有重要作用,可以通过改变根际环境影响植物获取养分的能力。生物炭通过为微生物提供碳(C)、氮(N)、磷(P)等营养底物和定殖空间,调节土壤微域环境,影响微生物群落的结构和功
目前改性生物炭对于盐碱土壤真菌的研究较少,已有研究发现相较其他处理,酸化改性生物炭分别导致布氏白粉菌属和镰刀菌属相对丰度降低31.34%~73.92%、37.89%~67.48%,通过功能基因预测也发现酸化改性生物炭处理下病原真菌的功能预测值比其他处理低48.37%~58.13%,进一步验证了施用酸化改性生物炭可以降低致病真菌的相对丰
改性生物炭通过改善盐碱土壤理化性质可以缓解植物盐碱胁迫,促进植物生长。主要机制有两方面:(1)降低土壤盐分离子浓度。改性生物炭含氧官能团数量增加,比表面积增大,对N
植物耐盐性的增强也是改性生物炭缓解植物盐碱胁迫的重要途径。通过对植物叶片代谢组学研究发现改性生物炭处理可以调控多种代谢产物(L-瓜氨酸、3-甲基-1-戊醇、异烟酸等)和代谢途径,植物抗氧化水平和抗盐碱胁迫能力增
近年来,随着改性生物炭改良盐碱土所受关注度的增加,改性生物炭在盐碱土改良上取得了一定的进展。本文重点阐述了不同改性生物炭特征及其对盐碱地的改良效果。生物炭适当改性进一步优化了原生物炭比表面积大、孔隙丰富的特性,增加了生物炭表面含氧官能团类型和数量,降低了生物炭碱性特征,解决了原生物炭对阴离子吸附能力弱以及在盐碱地中应用效果差等问题。改性生物炭在盐碱地改良中可以实现降低土壤盐碱度、提高土壤养分有效性和调节植物根际微域环境、缓解植物盐碱胁迫的目标,因此改性生物炭具有广阔的应用前景。但关于改性生物炭在盐碱地改良中仍有以下问题亟待解决:
1) 优化改性生物炭在不同盐碱地类型下的改良途径。不同盐碱地类型土壤理化性质和主要盐分阴离子有较大差异,需结合X射线衍射、傅立叶红外光谱及X射线光电子能谱等技术手段,探究施入土壤前后的改性生物炭理化性质、结构形貌等变化,进一步检验在改良不同类型盐碱地中的主导吸附机制,如物理吸附、官能团吸附、离子交换机制,探究不同盐分离子对改性生物炭的响应,以此来优化改性生物炭在不同盐碱类型下的改良途径。
2) 验证改性生物炭的长期效应。目前盐碱土壤上改性生物炭的施用研究以盆栽或小规模试验为主,所获得的结果缺乏长期定位大田试验的验证。已有研究初步证明改性生物炭对促进土壤氮磷养分有效性具有长期效应,但对于生物炭吸附的盐离子是否会出现大量解吸造成土壤盐分含量再次增加,对植物根际微域环境的影响及对土壤养分供给的长效能力仍需进行研究验证。
3) 明晰改性生物炭添加下微生物的响应机制,建立生物学修复技术。土壤盐分改变如何影响土壤微生物演替过程,微生物功能基因表达与环境改变的内在机制,以及定殖于生物炭表面的微生物群落组成、结构和功能仍需深入探究。应利用高通量测序、非靶向代谢组学、宏基因组学等技术深入揭示改性生物炭施加下盐碱化土壤微生物群落生态学机制,为盐碱化土壤生物修复技术的建立提供理论依据。
4) 优化改性炭的性能并控制成本。原料类型、热解温度以及改性条件能够显著影响生物炭与改性生物炭的性质,因此,未来研究应更加具体地对生物炭制备和改性方式进行分类和整合,建立不同原料生物炭改性的系统化构架,在盐碱地改良的研究中选取更加高效的改性方式,但目前改性生物炭的研究大多处于试验阶段,因效能或成本问题未能广泛应用于实际,未来的研究应集中于选取低成本、操作简单、实用性强的生物炭改性方式。
参考文献References
路晓筠,项卫东,郑光耀,等.盐碱地改良措施研究进展[J].江苏农业科学,2015,43(12):5-8.LU XY, XIANG W D, ZHENG G Y, et al.Research progress on improvement measures of saline - alkaline land[J].Jiangsu agricultural sciences, 2015, 43(12): 5-8(in Chinese with English abstract). [百度学术]
杨劲松.中国盐渍土研究的发展历程与展望[J].土壤学报,2008,45(5):837-845.YANG J S.Development and prospect of the research on salt-affected soils in China[J].Acta pedologica sinica, 2008, 45(5):837-845(in Chinese with English abstract). [百度学术]
杨劲松,姚荣江,王相平,等.中国盐渍土研究:历程、现状与展望[J].土壤学报,2022,59(1):10-27.YANG J S, YAO R J, WANG X P, et al.Research on salt-affected soils in China: history, status quo and prospect[J].Acta pedologica sinica, 2022, 59(1): 10-27(in Chinese with English abstract). [百度学术]
郭家鑫,鲁晓宇,陶一凡,等.盐碱胁迫对棉花生长和养分吸收的影响[J].干旱地区农业研究,2022,40(4):23-32,59.GUO J X, LU X Y,TAO Y F,et al.Effects of saline and alkaline stresses on growth and nutrient uptake of cotton[J].Agricultural research in the arid areas,2022,40(4): 23-32,59(in Chinese with English abstract). [百度学术]
ABDUL W.Potassium-sodium interactions in soil and plant under saline‐sodic conditions[J].Journal of plant nutrition and soil science,2013,176(3):344-354. [百度学术]
HU L X,ZHANG P P,JIANG Y,et al.Metabolomic analysis revealed differential adaptation to salinity and alkalinity stress in Kentucky bluegrass (Poa pratensis)[J].Plant molecular biology reporter,2015,33(1):56-68. [百度学术]
丛铭,张梦阳,夏浩,等.施用生物炭对红壤中不同形态钾含量及小白菜生长的影响[J].华中农业大学学报,2020,39(4):22-28.CONG M,ZHANG M Y,XIA H,et al.Effect of biochar application on potassium content of different forms in red soil and the growth of pakchoi[J].Journal of Huazhong Agricultural University,2020,39(4):22-28(in Chinese with English abstract). [百度学术]
刘强,袁延飞,刘一帆,等.生物炭对盐渍化土壤改良的研究进展[J].地球科学进展,2022,37(10):1005-1024.LIU Q,YUAN Y F,LIU Y F,et al.Research progress:the application of biochar in the remediation of salt-affected soils[J].Advances in earth science,2022,37(10):1005-1024(in Chinese with English abstract). [百度学术]
张进红,吴波,王国良,等.生物炭对盐渍土理化性质和紫花苜蓿生长的影响[J].农业机械学报,2020,51(8):285-294.ZHANG J H,WU B,WANG G L,et al.Effects and evaluation of biochar on physical-chemical properties of coastal saline soil and alfalfa growth[J].Transactions of the CSAM,2020,51(8):285-294(in Chinese with English abstract). [百度学术]
申书伟,张丹丹,王敏鸽,等.木醋液酸化生物炭与氮素配施对盐渍土壤活性氮及氨挥发的影响[J].环境科学,2022,43(5):2779-2787.SHEN S W,WANG D D,WANG M G,et al.Effects of combined application of wood vinegar-acidified biochar and nitrogen on active nitrogen and ammonia volatilization in saline soil[J].Environmental science,2022,43(5):2779-2787(in Chinese with English abstract). [百度学术]
刘国欢.改性生物炭对盐碱地改良及冬小麦生长特征影响的研究[D].西安:西安理工大学,2021.LIU G H.Effects of modified biochar on saline alkali soil improvement and growth characteristics of winter wheat[D].Xi’an:Xi’an University of Technology,2021(in Chinese with English abstract). [百度学术]
WANG W,MA X L,SUN J,et al.Adsorption of enrofloxacin on acid/alkali-modified corn stalk biochar[J].Spectroscopy letters,2019,52(7):367-375. [百度学术]
PENG H B,GAO P,CHU G,et al.Enhanced adsorption of Cu(II) and Cd(II) by phosphoric acid-modified biochars[J].Environmental pollution,2017,229:846-853. [百度学术]
GHASSEMI-GOLEZANI K,FARHANGI-ABRIZ S.Biochar-based metal oxide nanocomposites of magnesium and manganese improved root development and productivity of safflower (Carthamus tinctorius L.) under salt stress[J/OL].Rhizosphere,2021,19:100416[2023-02-06].http://doi.org/10.1016/j.rhisph.2021.100416. [百度学术]
REN J,LI N,LI L,et al.Granulation and ferric oxides loading enable biochar derived from cotton stalk to remove phosphate from water[J].Bioresource technology,2015,178:119-125. [百度学术]
WU L P,ZHANG S R,WANG J,et al.Phosphorus retention using iron (II/III) modified biochar in saline-alkaline soils:adsorption,column and field tests[J/OL].Environmental pollution,2020,261:114223[2023-02-06].http://doi.org/10.1016/j.envpol.2020.114223. [百度学术]
ZHANG P,XUE B,JIAO L,et al.Preparation of ball-milled red phosphorus-loaded biochar and its highly effective remediation for Cd- and Pb-contaminated alkaline soil[J/OL].The science of the total environment,2022,13:152648[2023-02-06].http://doi.org/10.1016/j.scitotenv.2021.152648. [百度学术]
WANG R Z,HUANG D L,LIU Y G, et al.Synergistic removal of copper and tetracycline from aqueous solution by steam-activated bamboo-derived biochar[J/OL].Journal of hazardous materials,2020,384:121470[2023-02-06].http://doi.org/10.1016/j.jhazmat.2019.121470. [百度学术]
PENG Z Y,ZHAO H,LÜ H H,et al.UV modification of biochar for enhanced hexavalent chromium removal from aqueous solution.[J].Environmental science and pollution research international,2018,25(11):10808-10819. [百度学术]
WU J W,WANG T,ZHANG Y S,et al.The distribution of Pb(II)/Cd(II) adsorption mechanisms on biochars from aqueous solution:considering the increased oxygen functional groups by HCl treatment[J/OL].Bioresource technology,2019,291:121859[2023-02-06].http://doi.org/10.1016/j.biortech.2019.121859. [百度学术]
刘舒蕾,彭慧君,杨佳怡,等.水生植物生物质炭去除水体中氮磷性能[J].环境科学,2019,40(11):4980-4986.LIU S L,PENG H J,YANG J Y,et al.Removal of nitrogen and phosphorus from water by biomass carbon of aquatic plants[J].Environmental science,2019,40(11):4980-4986(in Chinese with English abstract). [百度学术]
SHEN Y F,YUAN R.Pyrolysis of agroforestry bio-wastes with calcium/magnesium oxides or carbonates-focusing on biochar as soil conditioner[J/OL].Biomass and bioenergy,2021,155:106277[2023-02-06].http://doi.org/10.1016/j.biombioe.2021.106277. [百度学术]
LI B Q,GONG J X,FANG J Z,et al.Cysteine chemical modification for surface regulation of biochar and its application for polymetallic adsorption from aqueous solutions.[J].Environmental science and pollution research,2020,28(1):1061-1071. [百度学术]
MA Y,LIU W J,ZHANG N,et al.Polyethylenimine modified biochar adsorbent for hexavalent chromium removal from the aqueous solution[J].Bioresource technology,2014,169:403-408. [百度学术]
ZHANG L X,TANG S Y,HE F X,et al.Highly efficient and selective capture of heavy metals by poly(acrylic acid) grafted chitosan and biochar composite for wastewater treatment[J/OL].Chemical engineering journal,2019,378:122215[2023-02-06].http://doi.org/10.1016/j.cej.2019.122215. [百度学术]
LIU L,ZHANG S,CHEN M,et al.Fe-modified biochar combined with mineral fertilization promotes soil organic phosphorus mineralization by shifting the diversity of phoD-harboring bacteria within soil aggregates in saline-alkaline paddy soil[J].Journal of soils and sediments,2022,23:619-633. [百度学术]
XUE B,HUANG L,HUANG Y N,et al.Roles of soil organic carbon and iron oxides on aggregate formation and stability in two paddy soils[J].Soil & tillage research,2019,187:161-171. [百度学术]
鲁新蕊,陈国双,李秀军.酸化生物炭改良苏打盐碱土的效应[J].沈阳农业大学学报,2017,48(4):462-466.LU X R,CHEN G S,LI X J.Experimental effects of acidified biochar on saline-sodic[J].Journal of Shenyang Agricultural University,2017,48(4):462-466(in Chinese with English abstract). [百度学术]
HAN L F,SUN K,YANG Y, et al.Biochar’s stability and effect on the content,composition and turnover of soil organic carbon[J/OL].Geoderma,2020,364:114184[2023-02-06].http://doi.org/10.1016/j.geoderma.2020.114184. [百度学术]
JOSEPH S,ANAWAR H M,STORER P,et al.Effects of enriched biochars containing magnetic iron nanoparticles on mycorrhizal colonisation,plant growth,nutrient uptake and soil quality improvement[J].Pedosphere,2015,25(5):749-760. [百度学术]
WANG Z J,PAN X,KUANG S P,et al.Amelioration of coastal salt-affected soils with biochar,acid modified biochar and wood vinegar:enhanced nutrient availability and bacterial community modulation[J/OL].International journal of environmental research and public health,2022,19(12):7282 [2023-02-06].http://doi.org/10.3390/ijerph19127282. [百度学术]
EDEH I G,MASEK O,BUSS W.A meta-analysis on biochar's effects on soil water properties - new insights and future research challenges[J/OL].Science of the total environment,2020,714:136857[2023-02-06].http://doi.org/10.1016/j.scitotenv.2020.136857. [百度学术]
DUAN M L,LIU G H,ZHOU B B,et al.Effects of modified biochar on water and salt distribution and water-stable macro-aggregates in saline-alkaline soil[J].Journal of soils and sediments,2021,21(6):2192-2202. [百度学术]
张伟明,修立群,吴迪,等.生物炭的结构及其理化特性研究回顾与展望[J].作物学报,2021,47(1):1-18.ZHANG M W,XIU L Q,WU D,et al.Review of biochar structure and physicochemical properties[J].Acta agronomica sinica,2021,47(1):1-18(in Chinese with English abstract). [百度学术]
林庆毅,姜存仓,张梦阳.生物炭老化后理化性质及微观结构的表征[J].环境化学,2017,36(10):2107-2114.LIN Q Y,JIANG C C,ZHANG M Y.Characterization of the physical and chemical structures of biochar under simulated aging condition[J].Environmental chemistry,2017,36(10):2017-2114(in Chinese with English abstract). [百度学术]
RAHIMZADEH S,GHASSEMI-GOLEZANI K.Biochar-based nutritional nanocomposites altered nutrient uptake and vacuolar
DUAN M L,YAN R P,WANG Q J,et al.Integrated microbiological and metabolomics analyses to understand the mechanism that allows modified biochar to affect the alkalinity of saline soil and winter wheat growth[J/OL].The science of the total environment,2023,866:161330[2023-02-06].http://doi.org/10.1016/j.scitotenv.2022.161330. [百度学术]
FARHANGI-ABRIZ S,GHASSEMI-GOLEZANI K.Changes in soil properties and salt tolerance of safflower in response to biochar-based metal oxide nanocomposites of magnesium and manganese[J/OL].Ecotoxicology and environmental safety,2021,211:111904[2023-02-06].http://doi.org/10.1016/j.ecoenv.2021.111904. [百度学术]
ZHANG P,BING X,JIAO L,et al.Amelioration effects of coastal saline-alkali soil by ball-milled red phosphorus-loaded biochar[J/OL].Chemical engineering journal,2022,431:133904[2023-02-06].http://doi.org/10.1016/j.cej.2021.133904. [百度学术]
郭大勇,商东耀,王旭刚,等.改性生物炭对玉米生长发育、养分吸收和土壤理化性状的影响[J].河南农业科学,2017,46(2):22-27.GUO D Y,SHANG D Y,WANG X G,et al.Effects of modified biochar on growth,nutrients uptake of maize and soil physicochemical properties[J].Journal of Henan agricultural sciences,2017,46(2):22-27(in Chinese with English abstract). [百度学术]
CHANG R H,SOHI S P,JING F Q,et al.A comparative study on biochar properties and Cd adsorption behavior under effects of ageing processes of leaching,acidification and oxidation[J/OL].Environmental pollution,2019,254(2):113123 [2023-02-06].http://doi.org/10.1016/j.envpol.2019.113123. [百度学术]
WU L P,WEI C B,ZHANG S R,et al.MgO-modified biochar increases phosphate retention and rice yields in saline-alkaline soil[J].Journal of cleaner production,2019,235:901-909. [百度学术]
CHEN T T,LIU C,ZHANG F,et al.Acid-modified biochar increases grain yield and reduces reactive gaseous N losses and N-related global warming potential in alternate wetting and drying paddy production system[J/OL].Journal of cleaner production,2022,377:134451[2023-02-06].http://doi.org/10.1016/j.jclepro.2022.134451. [百度学术]
ZHANG M Y,RIAZ M,XIA H,et al.Four-year biochar study:Positive response of acidic soil microenvironment and citrus growth to biochar under potassium deficiency conditions[J/OL].The science of the total environment,2022,813:152515[2023-02-06].http://doi.org/10.1016/j.scitotenv.2021.152515. [百度学术]
XIA H,RIAZ M,MING C,et al.Assessing the difference of biochar and aged biochar to improve soil fertility and cabbage (Brassica oleracea var.capitata) productivity[J].Journal of soils and sediments,2022,23:606-618. [百度学术]
MAO X X,YANG Y,GUAN P B,et al.Remediation of organic amendments on soil salinization:focusing on the relationship between soil salts and microbial communities[J/OL].Ecotoxicology and environmental safety,2022,239:113616 [2023-02-06].http://doi.org/10.1016/j.ecoenv.2022.113616. [百度学术]
ZHANG M Y,XIA H,RIAZ M,et al.Various beneficial microorganisms colonizing on the surface of biochar primarily originated from the storage environment rather than soil environment[J/OL].Applied soil ecology,2023,182:104700 [2023-02-06].http://doi.org/10.1016/j.apsoil.2022.104700. [百度学术]
RAHMAN A,HOSSAIN M S,MAHMUD J A.Manganese-induced salt stress tolerance in rice seedlings:regulation of ion homeostasis,antioxidant defense and glyoxalase systems[J].Physiology and molecular biology of plants,2016,22(3):291-306. [百度学术]
李佳,曹先梅,刘立云,等.镁对槟榔幼苗光合特性和叶绿体超微结构的影响[J].植物营养与肥料学报,2019,25(11):1949-1956.LI J,CAO X M,LI L Y,et al.Effects of different magnesium nutrition levels on photosynthetic characteristics and chloroplast ultrastructure of areca palm seedlings[J].Journal of plant nutrition and fertilizers,2019,25(11):1949-1956 (in Chinese with English abstract). [百度学术]
GHASSEMI-GOLEZANI K,FARHANGI-ABRIZ S,ABDOLI S.How can biochar-based metal oxide nanocomposites counter salt toxicity in plants?[J] Environmental geochemistry and health,2021,43(5):2007-2023. [百度学术]