北疆常年膜下滴灌棉田土壤盐分年内及年际变化特征研究

针对膜下滴灌棉田土壤次生盐渍化问题,从年内变化与年际变化两个方面,分析新疆典型绿洲区膜下滴灌棉田土壤盐分演变特征。研究结果表明:在年内,土壤盐分整体随生育期的顺延而呈下降趋势,其中5月上旬(苗期)、7月中旬(花铃期)、9月中旬(收获期)土壤盐分呈现积盐趋势;膜下滴灌4~12 a的棉田土壤存在稳定积盐层,其深度大约在60~150 cm范围内,其盐分值基本保持在0.6%上下;60 cm以上土层基本处于脱盐状态,其盐分值保持在0.2%~0.4%左右,属于非盐化土壤;膜下滴灌15 a的棉田,土壤盐分随生育阶段变化幅度较大,呈现中度盐化土特征。在年际间,膜下滴灌最初1~6 a,土壤盐分呈现持续脱盐趋势,尤其20 cm以下土层脱盐效果较为明显;实施膜下滴灌6~7 a,土壤盐分变化趋于稳定状态,各棉田出现稳定积盐层,其深度大约在80~100 cm土层,积盐层盐分值大部分保持在0.25%上下,属于非盐化土。     

秦王川灌区土壤次生盐渍化预测及防治

本文在论述秦王川盆地水文地质条件及土壤盐渍化现状的基础上，对引大通河水入秦王川工程灌水后土壤次生盐渍化极易产生的盆地南部，建立起地下水流数学模型，并对灌后土壤次生盐渍化进行也预测，提出了相应的防治对策。     

甘肃秦王川灌区土壤盐分特征及次生盐渍化预测

在秦王川灌区水文地质条件和土壤盐分含量特征调查研究的基础上,采用有限差分法建立了预测模型,对灌溉实施后1～5年间地下水位及其埋深变化进行了预测。结果表明,地下水位呈普遍抬升趋势,可导致约2000ha土地产生次生盐渍化。如果不及时采取防治措施,土壤次生盐渍化面积还会进一步扩大。     

河套灌区西部土壤盐渍化分异特征及其主控因素

由于长期引黄灌溉,河套灌区土壤广泛次生盐渍化,严重影响了区域经济和生态良性发展。通过对河套灌区西部临河区土壤盐渍化现状进行系统调查分析,查明了研究区内土壤盐渍化程度、类型及其分布特征,讨论了区域土壤盐渍化的主要影响因素和成因。结果表明：（1）研究区内50%以上的土壤发生了不同程度次生盐渍化,呈斑块状分布,北部及东南部土壤盐渍化较严重,尤其是总干渠和黄济渠两侧的洼地;土壤主要盐分类型为SO₄-Na和SO₄·Cl-Na型。（2）研究区浅层地下水的总溶解固体（TDS）含量平均值为2.13 g·L^-1,属于微咸水,平均水位埋深为4.65 m,65%的调查点埋深小于3 m。（3）长期地表漫灌和冬季压盐引起的地下水位抬升和强烈的蒸发浓缩作用是形成高TDS地下水的直接原因,而较高的地下水盐度、浅层地下水位抬升和强烈的潜水蒸发引起的盐分上升是冲积平原土壤盐渍化的主要控制因素。     

种植枸杞对次生盐渍化土壤活性有机碳和碳库管理指数的影响

以次生盐渍化弃耕地为对照,研究种植枸杞对次生盐渍化土壤有机碳、活性有机碳、非活性有机碳及碳库管理指数的影响。结果表明:与弃耕地相比,4 a、7 a、11 a枸杞地0~100 cm土壤有机碳分别增加41.6%、46.5%、51.1%,活性有机碳分别增加57.1%、57.9%、54.4%,非活性有机碳分别增加24.0%、33.2%、47.3%,增加量在0~10 cm和60~80 cm土层最为明显;次生盐渍化土地种植枸杞后碳库活度和碳库活度指数有所增加,碳库指数和碳库管理指数明显增加,土壤质量得到改善。土壤总有机碳、活性有机碳、非活性有机碳和碳库指数与土壤肥力提高、含盐量和p H的降低密切相关,可作为表征次生盐渍化土壤质量改善的指标。     

层次分析法在新疆平原灌区土壤盐渍化研究中的应用

本文结合新疆平原灌区土壤盐渍化形成、治理以及现状,利用层次分析法,探讨了灌区内部土壤盐渍化的发生原因和治理措施的有效性。结果表明:干旱荒漠化气候和土壤历史积留盐分是灌区内土壤盐渍化的主导因子,贡献率达69.3%;地下水水位过高是引起土壤盐渍化的重要原因,贡献率11.1%;不完善的排水系统和不合理的灌溉方式也是土壤盐渍化的重要因素。各个治理措施组合权重的分配格局相对均衡,其中建立现代化的排水系统和通过平整土地、植树造林治理土壤盐渍化的效益较高,组合权重达31%。层次分析法可为灌区土地资源的管理、土壤盐渍化的治理提供定量依据。     

不同栽培模式下甜菜和籽粒苋对次生盐渍化土壤的抑盐效应

针对甘肃省秦王川引大灌区的土壤次生盐渍化愈发严重的农业和生态问题,以露地平播为对照(CK),研究了垄沟露地(R)、垄沟覆膜(R+P)两种栽培模式下耐盐作物甜菜和籽粒苋对该地区次生盐渍化土壤的p H值、盐分离子(Na~+、Ca~(2+)、Cl~-、SO_4~(2-))含量和电导率(EC)及植物电导率、成苗率和产量的影响。结果表明,种植耐盐作物对次生盐渍化土壤的脱盐改良效应十分明显,配合R、R+P的栽培模式效果更加显著;R+P模式下耕种一季作物后,与CK相比,种植甜菜和籽粒苋的土壤盐分离子浓度分别下降4.8%~7.4%和4.7%~6.5%,土壤电导率分别下降16.7%~28.6%和12.8%~30.9%,甜菜和籽粒苋叶片电导率分别下降22.9%和14.9%;R+P模式下籽粒苋成苗率显著提高,但栽培模式对两种作物的产量无显著影响。     

托克逊绿洲开发利用水资源的环境效应分析

本文论述了托逊绿洲水资源开发利用现状和所取得的成就,对水资源开发过程中出现的环境退化问题(土地沙漠化、草场资源退化、土壤次生盐渍化等)作了分析,并就如何合理利用水资源,改善绿洲生态环境,使其趋于良性发展,提出了相应对策。     

黄淮海平原高水肥改良中低产田耕地质量动态评估

为研究黄淮海平原地区改良中低产田进程中广泛采取的高水肥措施对耕地综合质量发展的影响,在河南封丘布置田间小区试验,通过测产、采样和分析,研究不同施肥方案和不同肥料处理下的耕地土壤及作物的质量动态,评估各处理的利弊权重.结果表明:优化施肥和高水肥措施有利于提高作物根系吸水能力、增加作物对土壤氮素的利用、提高耕地作物产量和品质、抑制土壤碱性增加.但是当前施肥制度尤其在高肥处理下耕地土壤有板结现象;优化施肥方案中的高肥处理不利于底层土壤脱盐,易引发土壤次生盐渍化;高水肥措施下土壤保肥能力较差.针对不同施肥处理的利弊权重提出以优化施肥技术和高水肥措施为技术主导进行中低产田改良,增加耕地作物产量和改善品质,同时需配合土壤次生盐渍化防控措施、土壤培肥措施和农艺措施,除弊扬利,实现耕地综合质量的全面、持续提升.     

吐鲁番市非灌溉期农田土壤盐分特征分析

对吐鲁番市的大河沿河、塔尔朗河、煤窑沟和黑沟上、中、下游灌区进行土样采集,测定吐鲁番市沿四条河流在非灌溉期内(3月、10月)土壤含盐量及主要离子含量,并分析土壤盐渍化类型、程度及土壤盐分与主要离子之间的相关关系。结果表明:研究区土壤有部分出现盐渍化趋势,且土壤次生盐渍化趋势较高;吐鲁番市土壤含盐量高低与各离子(即CL-、CO3-、HCO3-、SO42-、K+、Na+、Ca2+、Mg2+)含量大小有密切的关系;土壤盐分剖面分布具有表聚型;四条河流灌溉区土壤盐渍化类型的主要成分为硫酸盐渍土。     

土壤冻融温度影响下棉田水盐运移规律

以新疆北部常年膜下滴灌棉田为研究对象,探讨整个冻融过程中温度对土壤水盐运移规律的影响。研究结果表明：气温对土壤温度的影响随着土壤深度的增加而不断减小,滞后时间不断延长,并且气温对冻土的消融速度远远快于冻结速度,上层冻土消融速度快于下层。土壤水分受温度的影响较大,在冻结期,土壤水分从非冻结层向冻结层缓慢运移;在消融期,下层土壤水分在蒸发作用下不断向上运移。通过监测分析得知,温度间接影响盐分运移,在冻结期,土壤水分运移缓慢,土壤盐分运移变化较小;在消融期,土壤水分运移较为活跃,土壤盐分运移变化较大。在温度快速上升的情况下,土壤水分不断上移, 120～150 cm土壤盐分迅速向上扩散,上层土壤盐分不断增加,威胁膜下滴灌棉田可持续种植。     

银川平原植被空间分异研究

土壤盐渍化是制约银川平原内部植被生长最主要的生态环境地质问题,根本的影响因素则是土壤中的水盐运移与水盐平衡,而地形及微地貌条件对于土壤中的水盐运移过程具有控制作用,从而影响植被的生长和发育。文中以银川平原为研究对象,借助遥感数据中的植被指数方法定量地描述该地区植被的生长状况和空间分布,通过与数字高程模型的空间叠加与复合分析,合理地揭示了银川平原由于土壤盐渍化在不同地貌中的发育特点而产生的植被空间分异规律。     

鲁北平原咸水滴灌对土壤水盐分布和棉花产量的影响

鲁北平原是山东省重要的粮棉油生产基地,合理利用微咸水和咸水资源是亟待解决的问题。通过田间小区试验,以淡水滴灌处理为对照,设置不同矿化度咸水滴灌处理,研究全地膜覆盖条件下,咸水滴灌对棉花农田土壤水盐分布和产量的影响。结果表明,灌出苗水可以明显降低棉田主要根层土壤EC值,降低率在26．8％～29．0％之间。咸水滴灌减少了棉花对土壤水分的吸收,主要影响土层在40～100 cm,灌溉水矿化度越高,影响越大。与淡水滴灌相比,滴灌补灌矿化度6g·L-1以下的咸水对棉花产量没有明显的影响,而滴灌8g·L-1的咸水在降水偏少的年份能明显降低棉花产量。从土壤盐分的积累来看,利用滴灌补灌一次6g·L-1以下的咸水,通过黄河水和夏季降水淋洗土壤盐分,不会造成棉花根系分布层土壤盐分的积累。该研究结果可为鲁北平原区咸水利用提供科学依据。     

关中农田土壤物理状态与分析

针对关中农田土壤通气、透水能力下降,抗不良环境能力减弱,生产成本逐年递增的实际问题,以关中11个县区农田土壤为研究对象,以土壤耕作层厚度、容重及团聚体特征为指标,开展了现代利用强度及土壤管理模式下农田土壤物理状态及其退化特征研究。结果表明:关中地区土壤发生学层次厚度尽管很厚,但受下层土体紧实化的影响,农田土壤耕作层普遍浅薄,疏松良好的土壤耕作层厚度变化在5~21 cm。调查范围内耕作层厚度在20 cm左右的仅占18%,10~15 cm之间的占64%,10 cm占18%左右。关中地区农田0~20 cm耕层土壤容重变化在1.04~1.34 g·cm~(-3),平均容重为1.21 g·cm~(-3),属于良好物理状态;而20~40 cm土壤容重变化在1.46~1.70 g·cm~(-3)之间,平均容重为1.58 g·cm~(-3),属于很紧实土壤状态。约36%的农田在20~40 cm处容重达到或超过了1.60 g·cm~(-3)的极限容重值。用干、湿筛技术测定的土壤团聚体的组成,关中农田1~5 mm的"(质量)优势团聚体"、团聚体的几何均重直径(GMD)、标准化平均当量直径(NMWD)以及土壤结构系数(Kctp)均显示,耕作层土壤团聚状态处于良好级别,其下层64%的土壤团聚状态较差,关中农田土壤团聚体水稳定性差,各地土壤团聚体状态以及稳定性差别明显。结论:关中地区农田土壤耕层变浅薄,是因为20~40 cm土层紧实化程度增大和犁底层上移与变厚所致;20~40土壤容重已经增大到极限值;0~20 cm土壤团聚体状态良好,但稳定性不强是引起其下层土壤紧实化的重要原因。关中农田土壤亚表层紧实化问题普遍,有愈加严重的发展态势。从空间上紧实化土层具有很强的隐蔽性,难以被人们所觉察,属于隐型土壤物理退化特征,不可小觑。     

干旱区绿洲土壤盐分空间异质性及人为驱动力分析

通过对渭干河-库车河三角洲绿洲土壤含盐量空间异质性及人为驱动力分析,结果表明:土壤含盐量在0-10cm、10-30cm和30-50cm具有一致的空间分布格局,在绿洲的东部、南部和东南部含量分布相对较高,绿洲西部和西北部的含量分布偏低,而在绿洲北部和西南部,土壤含盐量具有中等水平的空间分布。人口的增长以及人类不合理的经济活动致使绿洲部分区域受人为活动影响严重,灌区地下水位上升、土壤弃耕严重,致使盐分在土壤中急剧增加,表聚强烈。因此,改变不合理的经济增长方式,研究先进的农业种植技术,有效控制人口增长速度以及制定相应的盐渍化防治措施是目前渭干河-库车河三角洲绿洲急需解决的首要问题。     

Voetrot bij planten en stekken vanPelargonium

Summary In thePelargonium region of Lent in the Netherlands heavy losses of cuttings and plants are due to a basal stem rot. These losses can be prevented by improved cultural methods. Cuttings are to be rooted after treatment with -naphthaleneacetic (NAA) 0,1% in powdered charcoal in light soil. Watering of these succulent plants must be limited during the whole growing period. However, for these plants which are sensitive to salt, limited water supply may lead to excessive salt concentrations due to water ascending from the subsoil. This problem and the problem of temporary water annoyance can be solved by draining and washing out of the soil.     

隔沙层对盐碱地土壤水盐运动的影响

在80~100 cm范围土层设置沙层,对土壤电导率和含水量进行为期6个月的观察,分析隔沙层对土壤水盐运动的影响。结果表明:80~100 cm层沙层在大降雨量时能够提高土壤含水量;降雨量小,蒸发强烈的5~7月份,隔沙处理能够使土壤积盐程度较对照减少50%~70%;隔沙层延缓沙层以上土壤水分的下渗,从而提高降雨对土壤盐分的淋洗作用。当降雨量接近蒸发量的时候,隔沙处理土壤就能明显脱盐,而在此雨量下,对照只能保证土壤不发生积盐或少量积盐。雨季结束之后,隔沙处理土壤脱盐率较对照提高10%~35%,并能够使土壤脱盐过程持续到10月份,对植物生长十分有利。     

土内保墒措施在黄土高原对油松生长的影响

在黄土高原地区,研究了不同土内保墒措施对渍松幼林土壤水分状况,土壤物理才林分生长的影响。结果表明,土壤内施用保水剂、绿肥和锯末保墒材料后,土壤含水量和土壤孔隙度等有明显提高;且显著提高了油松幼林的地径和树高生长量,与对照相比,施用保水剂使树高和地径生长量分别提高了７６％和７５％,绿肥分别提高了８２％和８８％,锯末分别提高了５１％和５０％。土壤内施用保水剂时,要半保水剂和土壤充分混匀,且施入后要进行     

Soil water and salt distribution under furrow irrigation of saline water with plastic mulch on ridge

Furrow irrigation when combined with plastic mulch on ridge is one of the current uppermost water-saving irrigation technologies for arid regions.The present paper studies the dynamics of soil water-salt transportation and its spatial distribution characteristics under irrigation with saline water in a maize field experiment.The mathematical relationships for soil salinity,irrigation amount and water salinity are also established to evaluate the contribution of the irrigation amount and the salinity of saline water to soil salt accumulation.The result showed that irrigation with water of high salinity could effectively increase soil water content,but the increment is limited comparing with the influence from irrigation amount.The soil water content in furrows was higher than that in ridges at the same soil layers,with increments of 12.87% and 13.70% for MMF9(the treatment with the highest water salinity and the largest amount of irrigation water) and MMF1(the treatment with the lowest water salinity and the least amount of irrigation water) on 27 June,respectively.The increment for MMF9 was gradually reduced while that for MMF1 increased along with growth stages,the values for 17 August being 2.40% and 19.92%,respectively.Soil water content in the ridge for MMF9 reduced gradually from the surface layer to deeper layers while the surface soil water content for MMF1 was smaller than the contents below 20 cm at the early growing stage.Soil salinities for the treatments with the same amount of irrigation water but different water salinity increased with the water salinity.When water salinity was 6.04 dS/m,the less water resulted in more salt accumulation in topsoil and less in deep layers.When water salinity was 2.89 dS/m,however,the less water resulted in less salt accumulation in topsoil and salinity remained basically stable in deep layers.The salt accumulation in the ridge surface was much smaller than that in the furrow bottom under this technology,which was quite different from traditional furrow irrigation.The soil salinities for MMF7,MMF8 and MMF9 in the ridge surface were 0.191,0.355 and 0.427 dS/m,respectively,whereas those in the furrow bottom were 0.316,0.521 and 0.631 dS/m,respectively.The result of correlation analysis indicated that compared with irrigation amount,the irrigation water salinity was still the main factor influencing soil salinity in furrow irrigation with plastic mulch on ridge.     

Soil Fertility Variability and Constraints on Village Scale Transects in Northern Burkina Faso

Soil variability has a profound impact on crop yields in low-input agriculture. The objectives of this study were to examine soil fertility variability and to identify potential soil constraints relating to farmers' conditions for agricultural production in the Sahelian zone of northern Burkina Faso. Surface soil (0-20 cm) and subsoil (20-100 cm) were sampled from 25 pedons on village-scale transects embracing three genetic soil units: two generations of sandy dune soils showing incipient development; a complex unit of clayey pediplain soils with duplex properties showing both alkaline and acid subsoil reaction; and hydromorphic, clayey valley bottom soils. Particle size distribution, pH, electrical conductivity, cation exchange capacity, exchangeable base cations and acidity, soluble base cations, organic carbon, nitrogen, total and available phosphorus, moisture constants, and bulk density were determined. Contents of organic carbon, total nitrogen, total and available phosphorus,and exchangeable potassium are low in all soils and are presumably major constraints.The sodium influenced clayey soils show high absolute variability; properties that vary are subsoil clay (5.8-38.5%), pH (5.8-10.0), cation exchange capacity (4.49-24.81 cmolc kg1), exchangeable sodium percentage (0-26), as well as electrical conductivity, structure, consistency, and available water holding capacity. The sandy soils are homogeneous and not as acid as elsewhere in the Sahel, presumably due to a dust influx. The soil fertility is generally low but highly variable, implying that constraints within production units may consist of multiple com binations of adverse chemical and physical properties, conceptually consistent with the low and variable millet yields. The variability also implies that soil character ization depends on the design of soil sampling, that average values are of doubtful use, that application of chemical fertilizers will produce very different results, and that there is no general scheme for correcting soil fertility. The application of lives tock manure will continue to be the best strategy for sustaining soil productivity.