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   土壤 在 自然地理学和测绘学 分类中 的翻译结果: 查询用时:1.243秒
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土壤     
相关语句
  soil
    Study on the Measuring Theory & Method of Dielectric Characteristics for Unsaturated Soil
    非饱和土壤介电特性测量理论与方法的研究
短句来源
    The Study on Nitrogen Supply of Soil after Long-term Different Fertilizing Experiments
    长期不同施肥土壤供氮特性研究
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    Study on mechanism of water and solute transport in soil with macropores
    水及溶质在有大孔隙的土壤中运移机制研究
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    STUDY ON SOIL FERTILITY OF KOREAN PINE PLANTATIONS
    红松人工林土壤肥力的研究
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    Study on the Law and Models of Soil Erosion in Red Soil Watershed
    红壤小流域土壤侵蚀规律与模型研究
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  soils
    Dissimilatory Nitrate Reduction to Ammonium in Submerged Soils
    淹水土壤中硝态氮异化还原成铵过程的研究
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    Study on Soil Air CO_2 Concentration and Soil CO_2 Evolution in Farmland Soils
    农田土壤空气CO_2动态和土壤——大气界面CO_2释放的研究
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    Study on Fixed Ammonium in Soils and Effect Factors on It
    土壤固定态铵及其影响因素的研究
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    Study on Labile Organic Carbon Pool in Forest Soils
    森林土壤活性有机碳库的研究
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    Study on N_2O Emissions and Nitrogen Transformation in Leaching Solution in Cracking Paddy Soils
    裂缝条件下稻田土壤中N_2O的释放和氮溶质运移的机理研究
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更多       
  the soil
    Remote Sensing and GIS Based Study on the Soil Wind Erosion in China
    基于遥感和GIS的中国土壤风力侵蚀研究
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    Preliminary study on the content and transformation of the soil nutrients in the community of Stipa glandis and aneurolepidium chinensis
    羊草和大针茅植物群落土壤养分含量与转化规律的初步研究
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    The Soil Resource Evaluation of Daian District
    大连地区土壤资源评价
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    STUDIES ON THE BIOLOGY AND THE APPLICATION OF THE CROPPING SYSTEM ON THE UPLAND RED SOIL IN SOUTHEAST CHINA Ⅳ.The Dynamic Analysis of the Soil Microflora and Enzyme Activity in the Grass—Planted Sloping Wasteland of Red Soil
    中国东南部红壤旱地种植系统的生物学及其应用研究——Ⅳ红壤荒坡种草的土壤微生物区系与土壤酶活性的动态分析
短句来源
    THE DYNAMIC ANALYSIS OF THE SOIL MICROFLORA AND ENZYME ACTIVITY IN THE GRASS—PLANTED SLOPING WASTELAND OF RED SOIL
    红壤荒坡种草的土壤微生物区系与土壤酶活性的动态分析
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更多       
  matter of soil
    The resultsshowed that NAS could reduce the nitrification rate, lower the N03-Ncontent, and increase the content of total N and organic matter of soil. During the incubation, NAS was effective in promoting theimmobilization of inorganic nitrogen in the former while improving themineralization of organic nitrogen in the later.
    试验表明,NAS能降低土壤的硝化速率,减少NO_3-N的含量,在培养前期能促进土壤中无机氮的固定,后期能促进土壤有机氮的矿化,并且能显著提高土壤的全氮及有机质含量。
短句来源
    (3) Through photosysthesis transforming CO2 into organic matters, micro-algae can increase the content of soil organic matter. On the 90th day, the content of organic matter of soil samples under illumination condition was 2-3 times more than that of the beginning.
    (3)土壤微藻通过光合作用将二氧化碳合成为有机物,增加土壤的有机质含量,在90天的实验期内,有微藻生长的土样内的有机质含量是对照组的2-3倍。
短句来源
    The results show that after harvesting, the pH value of soil increases, the organic matter of soil and soil nutrient(N、P、K) obviously increases in the early days and soon afterwards fast decreases to the level which is lower than that before harvesting.
    结果表明:森林采伐后,土壤pH值增加,土壤有机质和土壤养分(N、P、K)初期表现为明显增加,随后又迅速减少,以至低于采伐前水平。
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      soil
    An antibiotic producing strain Streptomyces violaceusniger was isolated from soil sample, characterized and studied for antibacterial and antifungal activity profile.
          
    These points can be estimated by introducing the soil factor (Ks) and tree species factor (Kt) to potential evapotranspiration with the Penman formula.
          
    Root biomass, length, and the number of roots in every diameter class, for each soil layer and for each plant species, are regarded as observation variables.
          
    The results show that most of the vertical distributions of plant roots belong to the type wherein the roots are concentrated in the topsoil layer (0-20 cm), far more than those in the lower soil layers.
          
    Ecological Benefit of Reforestation in a Severely Degraded Red Soil Region
          
    更多          
      soils
    Baldcypress should not be planted in drought-stricken soils.
          
    Characteristics of the temperature coefficient, Q10, for the respiration of non-photosynthetic organs and soils of forest ecosys
          
    The temperature coefficient, Q10 (fractional change in rate with a 10°C increase in temperature) describes the temperature sensitivity of soils, roots, and stems, as well as their possible performance in global warming processes.
          
    The differences between woody organisms of stems, roots, and soils excluding roots were statistically significant (p>amp;lt;0.05), indicating that heterotrophic respiration from microorganism activity may be more sensitive to global warming.
          
    The contents of aggregates of over 0.25 mm in two shrub land soils in the upper layer (0-20 cm) increased by 4.6% and 14.1% compared with farmland.
          
    更多          
      the soil
    These points can be estimated by introducing the soil factor (Ks) and tree species factor (Kt) to potential evapotranspiration with the Penman formula.
          
    (2) Soil aeration and the soil air regime improved.
          
    Three years after 50% thinning and 100% clear-cutting, the loss of carbon storage in the soil (0-60 cm) of cutover areas was 16.14 and 45.15%, respectively.
          
    Carbon storage in unburnt soil (0-45 cm) reached 73.36 t/hm2, which was 15.20 t/hm2 higher than that in the soil of burnt areas.
          
    A total of 20.7% of carbon storage in the soil (0-45 cm) of burnt areas was lost 40 days after burning.
          
    更多          
      matter of soil
    Both the clay minerals and organic matter of soil contribute to the adsorption of organic compounds on soil but the clay minerals bentonite and montmorillonite play a major role in their adsorption on soil.
          
    For the other field, it's simply a matter of soil type.
          


    A.The Soils Since the goological formation of this mountainous area is quite uniform,a vertical distribution of soils is obviously observed. At the top of the mountain with an elevation of 8,500 feet,the podzolic soil is found. The process of podzolization is clearly shown by the translocation of clays,organic matter, and active aluminum from an upper to lower layer.The gray brown podzolic soil is distributed in areas ranging from 7,000 to 8,500 feet in elevation.It is developed under forest and has a...

    A.The Soils Since the goological formation of this mountainous area is quite uniform,a vertical distribution of soils is obviously observed. At the top of the mountain with an elevation of 8,500 feet,the podzolic soil is found. The process of podzolization is clearly shown by the translocation of clays,organic matter, and active aluminum from an upper to lower layer.The gray brown podzolic soil is distributed in areas ranging from 7,000 to 8,500 feet in elevation.It is developed under forest and has a surface covering of leaf litter and a surface soil with high content of organic matter.In places at an elevatin from 3,900 to 7,000 feet the yellow podzolic soil is dominant.At an elevation below 3,000 foot the red podzolic soil and the sketetal soil are fonnd. The analytical data of the soils of this area may be summarized as follows: 1.pH values of the soils:In the whole area,since the parent rock (gneiss) is poor in basic constituents,soils are all acid in reaction.The pH of the different horizons of the soils ranges from 4.0 to 5.5.The A_0 and A_1 horizons are usually less acid than B horizon,the A and B horizons are much more acid than the parent rock.This shows the leaching process of the soils under such a humid atmosphere. 2.Organic Matter of the soils:The organic matter content of the soils in this area is greatlg influenced by the kind of the vegetation cover.At an elevation of 8,500 feet, the soil developed under forest has 38.92% of organic matter in the A_1,while that under grass has only 11.08% of organic matter in the corresponding horizon.However as the vegetation cover is constant,the dopth of the A_1 and its organic matter content are evidently affected by the elevation.At an elevation of 3,000 feet,the A_1 horizon of the red podzolic soil is only 1 cm.in depth,and it has 3.37% of organic matter.At an elevation of 8,500 feet,howerver,the A_1 horizon of the podzolic soil is 7 cm.in depth, and it has 11.08% of organic matter.In addition,deposition of organic matter in the B horizon is clearly found in the podzolic soil,but it has not been seen in soils found at lower elevation. 3.Active aluminum of the soils:All the soils in this area are high in active aluminum. They contain from 20 to 16 p.p.m.of active aluminum.The content of active aluminum in the different horizons of the same profile has a very close relationship with the pH values of the corresponding horizon.The less acid the reaction the smaller is the amount of acitve aluminum.The active aluminum of the soil is usually higher in amount than that of the parent rock from which the soil is derived. 4.Available calcium magnesium,and potassium of the soils:All the soils are general- ly low in available calcium,magnesium,and potassium.The comparatively high content of these elements in the A horizon is derived from the leaves of the vegetation which are grown on that soil. 5.Available phosphorus of the soils:All the soils of this area are low in available phosphorus. 6.Available nitrate:All soils in this area are very low in nitrate. B.The Vegetation 1.The plants growing on soils of this area are most calcifuge species which are acid- loving (Vaughan and Wishe,1937).As far as the chemical analysis of the soil is concer- ned,those species may be assumed as not only acid-loving,buy also active aluminum- loving (Hutchinson,1943). 2.The distribution of the calcifuge plants In this area is apparently affected by the local climate in terms of elevation.Some of them (temperate plants) are confined to high elevation,others(tropical plants) being limited to low elevation,Two groups of the plants may be given as follows.Many of them are of the same species as those found in southwestern China (Hou,1944). (a) Plants mainly ocurring in areas at elevations from 7,000 to 8,500 foot (temperate plants): Pteridophyta: Destaedtia Scabra (Wall.) Moore Diranopteris linearis Under. Hicrioptris glauea Under. Hymenophyllum crispatum Wall. Hymenophyllum exsertum Wall. Lidsaya cultrata Sw. Lycopodium clavatum L. Plagiogyria pyphylla (Kunze) Mett. Pteridium aquilinum Wightianum Trym Pteris aspericaulis Wall. Flowering Plants: Castanopsis tribuloides A.DC. Lindera pulcherrima Bth. Osbeckia crinata Bth. Rhododendron arboreum Sm. Rhododendron grande Wight Pieris formosana D.Don Vaccinium refersceda HK. Vaccinium serrasum Wight (b) Plants mainly ocurring in areas at elevation from 1,000 to 3,000 feet (tropical plants): Pteridophyta: Adiantum philippense L. Blechnum orientale L. Aglaoorpha coronaus Copel Lycopodium cernum L. Nephrolepsis cordifolia Presl Tectaria spp. Polypodium ucidum Roxb. Flowering plants: Oxyspora paniculate DC. Themeda arundinacea Ridl.

    1945年10月中旬,作者留印三月另一周,曾作三次野外调查,计包括印缅边区、恒河平原及喜马拉雅山东南麓等三区,茲先将大吉岭区调查结果,草成此文。调查区域大吉岭位于喜马拉雅山东南麓,在我国西藏边境,全区是山地,海拔自1000到9000尺不等,主为酸性的片麻岩地层,在拔海6500尺地点,年平均气温为56.3℉.,年雨量为122寸。土壤灰壤——灰棕壤组合:在拔海8500尺左右的山顶,灰壤见于草地上,而灰棕壤则发育在森林之下。灰棕壤——灰化黄壤组合:在拔海7000—8000尺地带,森林下仍是灰棕壤,而草地上则为灰化黄壤。灰化黄壤——粗骨土组合:在拔海1000—3000尺地带,片麻岩生成灰化红壤,酸性砂岩生成砾质土。全区土壤特征可归纳如下: (1)土壤 pH 值:全区因土壤母质为酸性片麻岩,各类土壤剖面亦为酸性反应;pH 值约自4.0至5.5。A_1层之 pH 值恒较 B 层为大,而土壤剖面内之 A 层及 B 层均较母岩之酸度为高。 (2)土壤有机质:从土壤有机质分析结果观之,显示植物种类对于土壤有机质之含量高低...

    1945年10月中旬,作者留印三月另一周,曾作三次野外调查,计包括印缅边区、恒河平原及喜马拉雅山东南麓等三区,茲先将大吉岭区调查结果,草成此文。调查区域大吉岭位于喜马拉雅山东南麓,在我国西藏边境,全区是山地,海拔自1000到9000尺不等,主为酸性的片麻岩地层,在拔海6500尺地点,年平均气温为56.3℉.,年雨量为122寸。土壤灰壤——灰棕壤组合:在拔海8500尺左右的山顶,灰壤见于草地上,而灰棕壤则发育在森林之下。灰棕壤——灰化黄壤组合:在拔海7000—8000尺地带,森林下仍是灰棕壤,而草地上则为灰化黄壤。灰化黄壤——粗骨土组合:在拔海1000—3000尺地带,片麻岩生成灰化红壤,酸性砂岩生成砾质土。全区土壤特征可归纳如下: (1)土壤 pH 值:全区因土壤母质为酸性片麻岩,各类土壤剖面亦为酸性反应;pH 值约自4.0至5.5。A_1层之 pH 值恒较 B 层为大,而土壤剖面内之 A 层及 B 层均较母岩之酸度为高。 (2)土壤有机质:从土壤有机质分析结果观之,显示植物种类对于土壤有机质之含量高低,有密切的关系,在拔海8500尺之地带,发育于森林下的灰棕壤,表土含有机质38.92%,而同处草类和蕨类植物发育下的灰壤的表土,仅含有机质11.08%,但在相同的植物环境下,拔海高度或局部气候,也是支配土壤有机质含量的重要因素,例如在拔海3000尺地带,长有草类的灰化红壤,仅有极薄之有机质层,该层有机质含量为3.37%,而在拔海8500尺地带,长有草类的灰壤,则有较厚层有机质,其含量为11.08%。 (3)可溶性铝质:全区土壤含有高量可溶性铝,大约自20至160 p.p.m.,其含量与 pH 值高低相关,土壤 pH 值愈酸,可溶性铝含量就愈高。 (4)可溶性钙镁及钾质:全区土壤之可溶性钙,镁及钾等之含量均较低,但就同一土壤剖面而言,富于有机质的 A。或 A_1层的钙镁和钾质,常较 B 层为高,此点显示此等成份是来自植物遗体,亦即指示土壤中有机质与肥力之关系。 (5)全区土壤有效磷含量均甚低。 (6)全区土壤硝酸态氮之含量均极低,并有下淋现象。植物本文所论植物,仅以作者所采集而经各专家鉴定为限,其中以蕨类植物为主。本区的土壤都是酸性反应,所见的植物是以嫌钙性者为主,这些嫌钙性植物与拔海高度的关系很显著,兹将常见的植物种类,叙述如下: (一)主分布于拔海7000—8500尺地带的植物: 蕨类植物 Dennstaedtia scabra(Wall.)Moore Dicranopteris linearis Under. Hicriopteris glauca Under. Hymenophyllum crispatum Wall. Hymenophyllum exsertum Wall. Lindsaya cultrata Sw. Lycopodium clavatum L. Plagiogyria pycniphylla(Kunze)Mett. Pteridium aquilinum Wightianum Trym. Pteris aspericaulis Wall.种子植物 Castanopsis tribuloides A.DC. Lindera pulcherrima Bth. Osbeckia crinata Bth. Rhododendron arboreum Sm. Rhododendron grande Wight Pieris formosana D.Don Vaccinium referesceda HK. Vaccinium Serrasm Wight(二)主分布于1000—3000尺地带的植物: 蕨类植物Adiantum philippense L.Blechnum orientale L.Aglaomorpha coron(?)us copelLycopodium cernuum L.Nephrolepsis cordifolia PresslTectaria spp.Polypodium lucidum Roxb.种子植物Oxysoira paniculata DC.Themedra arundinacea Ridl.

    The mode of genesis of plate-like structure of soils under different conditions may be different.Broad field observation reveals that soils favoring plate-like structure formation generally have an easy access to an abundant but intermittant supply of water,low content of raw organic matter as well as of humus,indefiniteness but not being too sandy in tex- ture,and weakness in structural stability. The present paper reports the evidences gathered from the field obser, vation and laboratory experiments showing...

    The mode of genesis of plate-like structure of soils under different conditions may be different.Broad field observation reveals that soils favoring plate-like structure formation generally have an easy access to an abundant but intermittant supply of water,low content of raw organic matter as well as of humus,indefiniteness but not being too sandy in tex- ture,and weakness in structural stability. The present paper reports the evidences gathered from the field obser, vation and laboratory experiments showing that plate-like structure can be developed through the effect of alternate wetting and drying processes. Laboratory experiments have shown that the degree of perfection of the development of plate-like structure as evidenced both from the horizontal natural crackings and from the volume of swelling of the soil body in- creases with increase in the number of cycles of alternate wetting and drying.(Plate Ⅰ.)In order to assure the effectiveness of the processes, both drying and wetting should be carried out as thorough as possible. A mechanism explaining the formation of plate-like structure is pro- posed.According to the suggested mechanism,swelling of the soil as a result of wetting affords the necessary conditions for the formations of plate-like structure,while the actual development of structural plates is accomplished through the drying processes.The greater the rate of drying, the better the conditions for the development of plate-like structure. The horizontal axis of the structural plates as demonstrated by the laboratory experiments runs parallelly to the contour of the drying sur- face.The development of plate-Iike structure is greatly hindered by exerting pressure on the surface upon wetting.Microscopic examination of the structural units reveals that no definite orientation of the individual soil particles are noticeable and the horizontal crackings separating layers of structural plates were seen to be discontinuous and of non-uniform in dimension. The following is a brief account of the mechanism of plate-like struc- ture formation through the effect of alternate wetting and drying processes: The evaporation of water from the saturated soil leads first of all to the formation of a thin crust on the very surface of evaporation.This leaves,beneath the crust a series of cracking spaces parallel to the surface due to the shrinkage of the soil while drying.Further drying compels water to evaporate from below the surface into these cracking spaces. Thus a second layer of laminated dry soil may form below the first layer of the surface crust.As evaporation continues on,the process repeats itself with decreasing intensities because part of water will be lost inevitably through the few connections that may exist between adjacent layers of structural plates.The layers developed below the surface crust are of course somewhat different in nature because the conditions of drying pre- vailing here are different.Thus the drying out of the soil below the surface usually proceeds in a much more restricted rate——a fact,that may explain the presence of structural plates in the underlying layers which are absent in the surface crust.On rewetting the soil,the particles or aggregates in cracking spaces then may serve as wedges to push layers of structural plates further apart as a result of swelling. This theory may afford explanations to the facts that in the laboratory experiments better development of plate-like structure is always accom- panied by the greater extent of swelling of the soil and the latter in turn can be augmented by increasing the number of cycles of alternate wetting and drying processes.The proposed mechanism also suggests that not only should both wetting and drying be thorough enough so as to assure the formation of as many horizontal crackings and structural plates as possible, but also the rate of drying should be great enough to check as much as possible the lose of water through capillary action.It is also evident ac- cording to the supposition given above that any factor inhibiting the swelling of the soil,(such as pressure exerted upon the surface)will make it impossible to develope plate-like structure through alternate wetting and drying processes.As further evidences to support the suggested mechanism, it is worth while to point out the facts that plate-like structure usually occurs near the soil surface and that structural plates run always parallelly to the surface of evaporation. The soils that are most liable to the formation of plate-like structure according to this mechanism are those medium in texture,and low in organic matter and colloid contents. The plate-like structure thus developed is believed to be temporary in the sense that it will be easily disintegrated by either mechanical forces as practiced in the usual cultivation processes or by prolonged flooding followed by imcomplete drying.

    一、片状结构形成的原因很多,但在地表常见的一种可能不是沉积、水冻或压力等原因造成,而系常经干湿变异的结果。二、在干湿变异条件下产生的片状结构分布地区甚广,可能其形成与土壤种类无直接关系。凡地面少植被、原缺乏结构的土壤,如不受人为翻动,露于地面一定时期后,多半会产生不同明显程度的片状结构。三、土壤在干湿变异条件下产生片状结构可能为一简单的机械作用。即土块湿润时膨胀,体积变大,再经干燥,体积不能恢复,留下横向裂隙于土中,遂成片状结构。在所研究的各因子中,干湿变异次数多、干湿变异程度大以及干湿变异中脱水速率快均能促使土块膨胀,所以能使片状结构形成更为明显。如对土块施以压力,不予膨胀,虽土块具有各方面生成片状结构的良好条件,仍不能形成片状结构。对田间具片状结构土块的试验中,说明它可能与室内人工片状结构有相同的成因,一方面也说明了这种结构的不稳定,易于破坏,但如条件适合,形成也不困难。四、此种片状结构因系土块干燥时产生横向裂隙所形成,所以结构横轴生成的方向主要决定于水分的蒸发面而经常与之平行。这种关系在野外具体表现为结构横轴常与地表平行,在室内的几项试验结果与此也相符合。此外结构横轴...

    一、片状结构形成的原因很多,但在地表常见的一种可能不是沉积、水冻或压力等原因造成,而系常经干湿变异的结果。二、在干湿变异条件下产生的片状结构分布地区甚广,可能其形成与土壤种类无直接关系。凡地面少植被、原缺乏结构的土壤,如不受人为翻动,露于地面一定时期后,多半会产生不同明显程度的片状结构。三、土壤在干湿变异条件下产生片状结构可能为一简单的机械作用。即土块湿润时膨胀,体积变大,再经干燥,体积不能恢复,留下横向裂隙于土中,遂成片状结构。在所研究的各因子中,干湿变异次数多、干湿变异程度大以及干湿变异中脱水速率快均能促使土块膨胀,所以能使片状结构形成更为明显。如对土块施以压力,不予膨胀,虽土块具有各方面生成片状结构的良好条件,仍不能形成片状结构。对田间具片状结构土块的试验中,说明它可能与室内人工片状结构有相同的成因,一方面也说明了这种结构的不稳定,易于破坏,但如条件适合,形成也不困难。四、此种片状结构因系土块干燥时产生横向裂隙所形成,所以结构横轴生成的方向主要决定于水分的蒸发面而经常与之平行。这种关系在野外具体表现为结构横轴常与地表平行,在室内的几项试验结果与此也相符合。此外结构横轴形成的方向是否与土块湿润时水分进行的方向有关,还待进一步的研究解决。五、通常所见的片状结构每每愈至土壤深处愈不明显,推测其原因可能是下层土壤具有以下特性:①干湿变异程度小,②干燥时脱水速率慢,③受到上部土层的压力,湿时不易膨胀,是几方面生成上的不利条件综合影响下的结果。六、片状结构容易在冲积母质的土壤上、滨海盐土地带以及碱土地区等处表土上发现,这可能与:地势平坦,水分易于停积;植被稀疏;土壤缺乏结构;或下层坚实,水分常积于上部,使表土能充分湿润等因子有关。在灰化土及生草灰化土地区,A_2 层中的片状结构结构是否具有上述同样的成因,还不能肯定,但有些条件很值得注意,如 A_2层缺乏有机质,没有良好结构;下面有一坚实的B 层,水分易在此停积;一般 A_2层距地表不远;同时在质地方面含粉砂较多,说明其片状结构也可能是干湿变异的结果。七、质地在片状结构的形成上也可能是影响较大的因子之一,工作中初步的印象是含粉砂或细砂较多的土壤易于形成,土块内粘结力过强时不易形成,但迄无充分证据,还有待进一步的研究。

    Experiments were conducted in 1955—1957 to determine the merits of the use of gravel as a soil mulch material instead of a mixture of sand and gravel widely used in Kansu.The results showed that(1)the effect of the gravel mulch on the soil temperature was as favorable as that of the sand-gravel mulch,(2) the gravel mulch was more effective in retaining soil moisture and(3)the growth and yield of the wheat grown on gravel mulched soil were slightly higher than those on sand-gravel mulched soil. The possibility...

    Experiments were conducted in 1955—1957 to determine the merits of the use of gravel as a soil mulch material instead of a mixture of sand and gravel widely used in Kansu.The results showed that(1)the effect of the gravel mulch on the soil temperature was as favorable as that of the sand-gravel mulch,(2) the gravel mulch was more effective in retaining soil moisture and(3)the growth and yield of the wheat grown on gravel mulched soil were slightly higher than those on sand-gravel mulched soil. The possibility of lengthening the effective period of the gravel mulch and of operating of farm machineries in gravel mulched fields is discussed.

    甘肃砂田在战胜干旱与保证作物高额而稳定的产量方面具有特殊功效。但是它也具有寿命短促与机械化困难等两个严重的缺点。这两个缺点产生的基本原因在于耕作过程中砂石容易和土壤混合之故。为了改进这种缺点,我们提出用直径5毫米以上的砾石来代替砂石混合物作为土壤覆盖层。根据三年来的试验结果,证明:(1)纯砾石层覆盖下的土壤温度并不低于砂石混合层(见表1);(2)纯砾石层的保存土壤水分的作用大于砂石混合层,这主要由于在纯砾石层覆盖之下,土壤水分的蒸发率小,而雨水的渗漏速度大之故(见表2和表3);(3)利用纯砾石层代替砂石混合层对于作物的生长与产量并无不利的影响。对于利用这种改良方法能够延长砂田使用年限与进行机械化耕作的可能性也加以讨论。

     
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