【作者】 肖克飚；

【导师】 吴普特；

【作者基本信息】 西北农林科技大学 ， 水土保持与荒漠化防治， 2013， 博士

【摘要】 土壤盐碱化是当前农业生产的重要胁迫因素之一，盐碱土改良利用长期以来也是全球退化土地治理领域的热点问题之一。盐碱地的改良利用是一个长期的、复杂的系统工程，其改良利用的核心是减少土壤有害盐分，改善作物生长发育所需的土壤环境。针对传统技术已经不能满足盐碱地改良和持续提高农业生产力需求的问题，探索新的盐碱地改良技术成为急切解决的科学难题。当前，以耐盐植物利用为核心的技术被普遍认为是未来盐碱地改良修复和高效利用的突破口。本文为探求不同类型耐盐植物对盐碱土改良效果及其机理，在宁夏银北地区以盐碱荒地为对照，选取3种有代表性的不同类型耐盐植物（柽柳、苇状羊茅、油葵），从土壤、植物两方面入手进行试验研究。经过3年（2008-2010）的试验，观测分析了不同类型耐盐植物对盐碱土壤理化性质、土壤盐分含量、土壤微生物特性的变化、耐盐植物对盐分的吸收、运移的及其生物学响应等。得出以下主要结论：（1）耐盐植物对土壤物理性质改善明显。主要表现在：土壤容重的逐年减少，土壤孔隙度明显增加。改善的土层顺序为0-20cm＞20-40cm＞40-60cm。与对照相比，柽柳、苇状羊茅、油葵0-20cm土层，土壤容重分别降低了14.04%、15.73%和10.11%，土壤孔隙度增加了15.05%、18.50%和10.45%。对土壤物理性状改善能力为：柽柳＞苇状羊茅＞油葵。苇状羊茅和油葵对0-40cm土层物理性状改善明显，柽柳对0-60cm土层物理性状改善明显。土壤水分分布表明，耐盐植物作用下，表现出明显的抑制春季土壤返盐，增加秋季盐分向下淋洗；土壤的初始入渗速率和稳定入渗速率均得到不同程度的增加，入渗由强到弱的顺序为柽柳＞苇状羊茅＞油葵。三种耐盐植物作用下的土壤，通过物理性质的改善，与植物的覆盖、对水分的吸收，改变了土壤水盐的运动方向，抑制了盐分的上升，且盐分向下淋洗作用增强，利于土壤耕层排盐。（2）耐盐植物作用下土壤有机质均呈增加趋势，增幅顺序为柽柳＞苇状羊茅＞油葵。各土层的盐分呈现波动状降低，后一年春季大于前一年秋季，即春季返盐现象较为严重。土壤返盐程度为0-20cm＞20-40cm＞40-60cm。土壤全盐含量降低为0-20cm＞20-40cm＞40-60cm、柽柳＞苇状羊茅＞油葵。耐盐植物根系作用区土壤营养成分均呈现波动状变化趋势，播种前高于收获后；柽柳对土壤中的碱解氮总体具有富集作用，而苇状羊茅和油葵对碱解氮消耗较大，需要及时施用氮可提高其改良效果。柽柳和油葵可以促进土壤中缓效磷向速效磷转化，而种植苇状羊茅需要及时施磷肥可提高其改良效果。油葵作用下的土壤含钾量略有上升，苇状羊茅和柽柳作用下的土壤则呈现相反趋势。这主要是由于经过改良后的土壤物理性质得到改善，土壤固持的钾素得到释放，因此盐碱土中的钾的释放、肥力的发挥与全盐含量密切相关；碱化度变化均随治理时间的延长呈现波动状减少趋势。油葵第一个生长期亚表层出现代换性钠离子“聚集”现象，表明浅层翻耕、耙磨对土壤洗盐效果不明显，改善土壤的通透性才是洗盐的前提条件。（3）耐盐植物对盐碱土微生物环境有明显的改善作用。对微生物环境的改善能力由强到弱的顺序为柽柳＞苇状羊茅＞油葵。土壤全盐、容重和碱化度均与土壤细菌、真菌呈显著负相关。说明盐碱胁迫不利于土壤微生物环境的良好发展。有机质、速效钾分别与碱解氮、速效磷、真菌、放线菌呈显著正相关，表明增加土壤有机肥可提高土壤微生物数量，改善土壤微生物环境。由此可知，盐碱地改良目标就是降低盐分含量、容重，增加土壤通透性和土壤肥力，从而改善土壤理化性质和微生态环境。（4）试验结果表明，土壤全盐含量与耐盐植物出苗（返青）率呈线性负相关。从连续3年的出苗（返青）率可以看出，土壤含盐量逐渐减少，土壤结构逐渐改善；从相对生长速率（RGV）和自由水与束缚水比值综合来看，三种植物的耐盐性能为：苇状羊茅＞柽柳＞油葵。一年生经济作物作为研究对象，其生物量的增加可更清楚地反映治理效果。（5）初步得出各盐基离子在植物根茎叶中的分配比例（Cl-在柽柳、苇状羊茅和油葵体内根茎叶分配比例分别为：1.7:1:7.0、0.5:1:2和0.3:1:0.3；Ca2+分别为：1.5:1:4、4.7:1:2、1:1:5；K+分别为：1.4:1:2.1、0.6:1:1.5和0.2:1:1；Na+分别为：1.3:1:2.2、5:1:1.3和2.5:1:0.8）。柽柳对Na+的主动吸收、运输能力很强，柽柳更适合在含Na+高的盐碱土上种植。计算出耐盐植物对土壤盐分的主动吸收量。计算出三种耐盐植物（柽柳，苇状羊茅和油葵）的“吸收运移脱盐率”（分别为0.8%、2.0%和4.3%）和“增渗抑蒸脱盐率”（分别为81.1%、65.9%和46.8%）。所以，土壤盐分的降低不但与水分的淋洗有关，而且与耐盐植物的吸收亦有密切关系。植物对盐分的主动吸收、运移，使其在众多改良措施具有不可替代性。测试得出柽柳对盐碱土土壤性质影响的“作用范围”，并提出柽柳的密植度及种植方式——株行距80cm×80cm，且为“品”字形交错栽植为宜。综上所述，种植耐盐植物是盐碱土改良的有效途径，即可以改良土壤理化、微生物性质，又可对盐分的主动吸收、运移，且可产生一定的经济效益，具有不可替代性。另外，复合耐盐植物改良措施、耐盐植物与耕作措施相结合等措施将会取得更为显著的改良效益。更多还原

【Abstract】 Soil salinity is one of forth major hazards of the world. Remediation and utilizationsaline-alkali soil is one of the hot issues for a long time in the world’s areas of governancedegraded land. And remediation and utilization saline-alkali soil is a long time, complex andsystematic engineering, and the core is to reduce the harmful soil salinity, and to improve thesoil environment for crop growth. Traditional technology can not solve the problem of theimprovement saline-alkali soil and continued to increase its agricultural productivity. Explorenew saline-alkali soil improvement techniques become an urgent difficult scientific problemsto be solved. At present, the halophyte availability as the core technology is generallyconsidered a breakthrough of remediation and efficient utilization saline-alkali soil in thefuture.The objective of this article was to investigate further the effects and mechanisms ofdifferent halophytes growing in a saline-alkali soil.A saline-alkali soil was planted with threerepresentative halophyte (Tamarix ramosissima Ledeb. Festuca arundinacea Schreb.Helianthus annuus) monocultures in the north region of Yin Chuan City, Ning Xia Province,uncultivated soil was used as a control for comparison. The field experiment was conductedfor3years (2008-2010), and soil chemical and physical properties, soil salt content,microbiological properties, halophyte absorption and transportation salt and biologicalresponse of halophyte were systematically investigated and analyzed. Main results lie below:(1) Soil physical properties was mproved clearly. Soil bulk density decreas, soil porosityincreased improved significantly. Soil layer of improvement was0-20cm＞20-40cm＞40-60cm. With planting Tamarix ramosissima Ledeb. Festuca arundinacea Schreb.Helianthus annuus, in0-20cm depth soil layer, soil bulk density were debased by14.04%,15.73%,10.11%and soil porosity were increased by15.05%,18.50%,10.45%. Ability ofimproving soil physical was in the order of Tamarix ramosissima Ledeb.＞Festucaarundinacea Schreb.＞Helianthus annuus. With planting Festuca arundinacea Schreb.andHelianthus annuus, physical properties of0-40cm depth soil improved clearly and so as to0-60cm depth soil with planting Tamarix ramosissima Led.. The soil moisture profiles showthat halophytes inhibiting salt movement to the soil surface in spring and enhancing salt leaching through the soil profile in autumn. The initial soil infiltration rate and the stable soilinfiltration rate increased significantly, and in the order of Tamarix ramosissima Ledeb.＞Festuca arundinacea Schreb.＞Helianthus annuus.. Halophytes improved soil physicalproperties, increased soil surface coverage and absorpted soil water, so changed soil watermovment, which could be shown to affect the soil by inhibiting salt movement to the soilsurface and enhancing salt leaching through the soil profile, and will help cultivated soil saltdrainage.(2) Soil organic matter showed an increasing trend, in the order of Tamarix ramosissimaLedeb.＞Festuca arundinacea Schreb.＞Helianthus annuus. Soil salinity showed fluctuatingchanges which could be shown that sailt content in spring was higher than that in the lastautum, because salt back to the soil surface was more serious in spring. The same can be seenthat the degree of salt backing was in the order of0-20cm＞20-40cm＞40-60cm, and the totalsalt content of soil reduce in the same order with halophyte-reclamation. The sequence ofreducing the total salt content was Tamarix ramosissima Ledeb.＞Festuca arundinaceaSchreb.＞Helianthus annuus. Soil nutrients in halophyte roots depth showed fluctuatingchanges, that is soil nutrients in spring was higher than that in the last autum. Availibal N inthe soil with planting Tamarix ramosissima Ledeb was higher than that before reclaimation,but Festuca arundinacea Schreb and Helianthus annuus consumpted more available N, andalso explained that application N fertilizer during growing season could enhance reclamationeffects. Tamarix ramosissima Ledeb and Helianthus annuus could promote the slowlyavailable P translating to available P in the soil, but P fertilizer would be applicated to theFestuca arundinacea Schreb to increase its reclamation effects. Under Helianthus annuus,available K increase slight, but decreased in soil with planting Tamarix ramosissima Ledeband Festuca arundinacea Schreb. Soil physical properties was improved and soil retentionK was released that could be absorpted and utilizated by halophyte. Therefore, releasing Kand fertility were both closely relating to the total salt content. With thehalophyte-reclamation time gone, ESP%changes showed a fluctuating decreasing trend. Inthe first growing season, substitution Na+in20-40cm depth soil under Helianthus annuusshowed by the "clustering" phenomenon, therefor shallow plouge and rake little halpe to soilsalt drainage. Improve the permeability of the soil is a prerequisite of washing salt.(3) With planting halophyte, microbial environment of saline-alkali soil was improvedsignificantly. The ability of improvement was in the order of Tamarix ramosissima Ledeb.＞Festuca arundinacea Schreb.＞Helianthus annuus. Salt content, bulk dencity and ESP%allcorrelate to bacteria and fungi negativly in soil. Salinity stress is bad to soil microbialenvironment development. Organic matter, available K correlate to both fungi andactinomyces negativly in soil respectively, reducing salt content, bulk dencity and application organic fertilizer can increase soil microbial quantity and improve the soil microbialenvironment.(4) The test result show that soil total salt content and halophyte emergence (reviving)rate was a negative linear correlation. Emergence (reviving) rate in three consecutive yearsshowed that soil salt content was gradually reduced, and soil structure was graduallyimproved. The relative growth velocity (RGV) together with the ratio of free water and boundwater showed that salt tolerance of this three types of halophytes are Festuca arundinaceaSchreb.＞Tamarix ramosissima Ledeb.＞Helianthus annuus. The increase of biomass annualcash crops can be more clearly reflect the treatment effect.(5) The distribution of salt ions in root, stem and leaf of halophyte was ensured (In theorder of Tamarix ramosissima Ledeb, Festuca arundinacea Schreb and Helianthus annuus,distributions of Cl-in root, stem and leaf of halophyte was1.7:1:7.0,0.5:1:2and0.3:1:0.3,Ca2+was1.5:1:4,4.7:1:2and1:1:5, K+was1.4:1:2.1,0.6:1:1.5and0.2:1:1, Na+was1.3:1:2.2、5:1:1.3and2.5:1:0.8respectively). The capacity of Tamarix ramosissima Lede.absorption and transport Na+was strongest in this three types of halophyte, so Tamarixramosissima Ledeb. is more suitable for cultivation in the saline-alkali soil full of Na+. Theactive absorption of halophytes to soil salinity was calculated, and (Tamarix ramosissimaLedeb, Festuca arundinacea Schreb, Helianthus annuus)“AM desalination rate”(0.8%,2.0%and4.3%) and “EPIE desalination” rate (81.1%,65.9%and46.8%) were calculated. Thereforthe reduction of soil salinity is not only relating to the leaching of water but also to absorptionof halophyte. With the active of absorption and migration salt of halophyte,halophyte-reclamation is irreplaceable in a number of reclamation measures. Test showedTamarix ramosissima Ledeb reclamation scope of soil properties, which would proposeTamarix ramosissima Lede planting mode——80×80cm, and the “品”shaped staggeredplanting is appropriate.In summary, halophyte-reclamation is an effective way of saline-alkali soil improvement,which not only can improve soil physical, chemical and microbiological propoties, but alsocan absorb and migrate the salt, and which also can produce some economic benefit. Therefor,halophyte-reclamation is irreplaceable. In addition, the complex halophyte-reclamation,halophyte-reclamation cooperating to farming measures would made more significantreclamation effects.更多还原