南亚热带丘陵赤红壤水分性能变化及其机理

对丘陵赤红壤水分性能变化的研究结果表明,与地带性自然坡被下丘陵赤红壤比较,次生植被或人工植被下丘陵赤红壤水分笥能变劣,表现在导水性降低,120min饱和渗水量减少,自然赤红壤比耕型赤红壤的减幅大,持水能力下降,在同样吸水力下,土壤持水量较少,供水能力下降,在同样吸力段,表土释放的水量较少,亚表土在低吸力段释放水量较少,通径分析结果表明,养分贫疹化,特别是贫有机质化,是丘陵赤红壤水分性能降低的主要内在因素。     

广西雅长细叶云南松分布区土壤的肥力特性

根据调查研究结果,分析了林区土壤的肥力特点。该林区土壤属褐红壤,具有一定的钙质土性质,有机质有特殊的幂积方式,腐殖化过程强,其肥力水平高于赤红壤,在有林情况下,不低于同纬度的红壤。     

坡地赤红壤物理退化及其机理研究：I土壤结构退化研究

通过比较研究,探讨了坡地红壤结构退化过程的特征,结果表明,与地带性自然植坡下的坡地赤红壤比较,次生植被或人工植被的下坡地赤红壤结构退化现象明显,表现在表土砂化,即沙粒含量相对增加,粘粒含量相对减少;土壤结构稳定性下降,主要体现在较大业径水稳性团聚体减少,土壤孔隙性变差,主要体现在容重增加和较大孔径孔隙减少,对自然赤红壤而言容重增加,较大孔隙减少更为明显,对耕型赤红壤而言,土壤结构稳定性下降,表土砂     

福建赤红壤旱地与红土壤旱地水分特性的比较

释放80％的有效水时赤红壤旱地的t值（当释放的土壤有效水占有效水库容的比率为80％时的土壤水吸力值）较小，表明赤红壤旱地持水性较红壤旱地更差，植物更容易受到干旱的协迫。赤红壤旱地贮水库容比红壤旱地少，赤红壤旱地的比水容量达到10^-2数量级（难效水）在－19kPa～-30kPa就开始出现，而红壤旱地出现在－30kPa以下，表明赤红壤旱地的失水速度愉，保水供水性能弱于红壤旱地。最后，讨论了影响旱地土壤水分性质的因素。     

福建三个垂直带谱中土壤氧化铁的研究

应用穆斯堡尔谱分析、化学分析和光学显微镜分析，对福建三条最有代表性的土壤垂直带谱中的粗粒及粘粒氧化铁矿物进行研究。结果表明，赤铁矿从黄壤－黄红壤－红壤－赤红壤逐渐增多而针铁矿逐步减少，粗粒原生矿物组合类型从复杂趋向简单。铁的游离度及晶胶比从黄壤－黄红壤－红壤逐渐升高而活化度逐渐下降，但赤红壤例外，这可能与其成土年龄有关。本文还讨论了土壤分类的有关问题。     

南亚热带丘陵土壤水分循环及其有效性的研究：I.赤红壤水 …

阐述了南亚热带低山,丘陵,台地赤红壤总库容,贮水库容,通透库容的占有情况,探讨了水库容的有效性以及不同利用方式的赤红壤有效水库容与无效库容的差异,并对影响赤红壤水分有效性的因素作了分析。结果表明,赤红壤贮水库容小,尤其是有效水库容小,赤红壤水分有效性主要与土壤有机质相关。     

坡地赤红壤不同利用模式对土壤磷和酶的影响

试验采用广东东莞花岗岩发育的坡地赤红壤为样品进行研究表明 :在坡地赤红壤的 4种利用模式中 ,旱地种植花生 ,荔枝可以有效地改善土壤的酸性 ,提高土壤肥力 ;提高土壤Al-P和Fe -P的含量 ,减少O -P的所占的比例 ,提高坡地赤红壤磷酸盐的有效性 ;增加土壤表层的脲酶和蛋白酶的活性 ,可能使土壤的磷酸酶的活性降低     

福建赤红壤旱地土壤水分特性及调控

福建不同母岩上发育的赤红壤旱地土壤水总库容在熟化度大致相当的情况下相差不大。玄武岩上发育的赤红壤旱地贮水库容、有效水库容分别比花岗岩发育的赤红壤旱地贮水库容、有效水库容要高 ,前者的保水性强于后者。不同利用方式主要通过影响土壤的有机质状况及熟化度 ,进而影响土壤结构 ,导致土壤持水容量不同。赤红壤旱地的比水容量达到 10 2 数量级在 - 10kPa～ 30kPa就开始出现 ,而红壤旱地出现在- 30kPa以下 ,表明赤红壤旱地的失水速度快 ,保水供水性能弱于红壤旱地。为此 ,福建省赤红壤旱地土壤水分调控管理的方向和措施有 :增加降水入渗、调整农业结构 ,采用复合农业技术、增施有机肥和改进灌溉等。     

广西富硒土壤中氧化铁对Se（Ⅳ）吸附解吸的影响机制

为探究游离氧化铁对富硒土壤吸附解吸Se(Ⅳ)的影响机理,以广西富硒赤红壤、红壤为研究对象,通过等温吸附解吸实验,比较去除游离氧化铁前后土壤对Se(Ⅳ)的吸附解吸特征,同时运用Zeta电位、扫描电镜-能谱分析和傅里叶红外光谱技术分析其机理。结果表明：Langmuir和Freundlich等温吸附方程均能较好地拟合供试土壤吸附Se(Ⅳ)过程,相关系数在0.920～0.995之间。供试土壤最大吸附量由高到低依次为：赤红壤(1 399 mg·kg^–1)、红壤(1 336 mg·kg^–1)、去氧化铁赤红壤(444 mg·kg^–1)、去氧化铁红壤(352 mg·kg^–1)。去除游离氧化铁后,红壤、赤红壤的Zeta电位分别由–24.42、–18.06 mV变为–33.06和–26.43 mV,且比表面积减小。红壤、赤红壤及其去氧化铁土对Se(Ⅳ)的解吸率在2%～7%之间,去氧化铁土的解吸率高于红壤、赤红壤。红外光谱分峰拟合分析可知,土壤主要通过-OH、Fe-O、C=O等含氧基团与硒发生反应,土壤去除氧化铁后,Fe...     

赤红壤旱地钾素的生物耗竭

盆栽试验赤红壤在连续种植条件下，钾耗竭处理的生物产量迅速下降，土壤供钾水平陡降至“最低值”，表明赤红壤钾素耐耗竭的能力较弱，该能力与缓效钾的释放有关，研究还显示，赤红壤钾素耗竭的负效应远大于水稻土，对补充钾素的需要更为迫切，即使是供钾水平较高者也是如此。     

岩溶坡地不同利用类型土壤入渗性能及其影响因素

为了探讨岩溶坡地不同土地利用类型土壤入渗性能差异及其影响因素,该文利用环刀法测定了不同利用类型石灰岩土壤的入渗过程曲线,并分析了孔隙状况、颗粒组成和土壤结构等对入渗的影响。结果表明：土地利用类型对岩溶坡地土壤入渗性能影响较大,初始入渗速率和稳定入渗速率均表现为灌丛＞果园＞草地＞旱地。灌丛地表下层（＞15～30 cm）平均稳定入渗速率8.11 mm/min,最小值4.22 mm/min;旱地地表下层平均稳定入渗速率0.46 mm/min,最小值仅0.13 mm/min。旱地表层以下存在显著的入渗阻滞层。岩溶坡地土壤入渗性能与有机质、水稳性团聚体和孔隙度有显著相关性。非毛管孔隙在入渗初期的作用大于后期,＞0.25 mm水稳性团聚体含量是影响稳定入渗速率的重要因素。该文为进一步研究岩溶坡地旱涝灾害、水土保持和水资源开发利用等提供了理论依据。     

Humus and nitrogen in soddy-podzolic soils of different agricultural lands in Perm region

Heavy loamy soddy-podzolic soils (Eutric Albic Retisols (Abruptic, Loamic, Cutanic)) under a mixed forest, a grass–herb meadow, a perennial legume crop (fodder galega, Galéga orientalis), and an eightcourse crop rotation (treatment without fertilization) have been characterized by the main fertility parameters. Differences have been revealed in the contents of humus and essential nutrients in the 0- to 20- and 20- to 40-cm layers of soils of the studied agricultural lands. The medium acid reaction and the high content of ash elements and nitrogen in stubble–root residues of legume grasses favor the accumulation of humic acids in the humus of soil under fodder galega; the C_HA/C_FA ratio is 0.95 in the 0- to 20-cm layer and 0.81 in the 20- to 40-cm layer (under forest, 0.61 and 0.41, respectively). The nitrogen pool in the upper horizon of the studied soddy-podzolic soil includes 61–76% nonhydrolyzable nitrogen and 17–25% difficultly hydrolyzable nitrogen. The content of easily hydrolyzable nitrogen varies depending on the type of agricultural land from 6% in the soil under mixed forest to 10% under crop rotation; the content of mineral nitrogen varies from 0.9 to 1.9%, respectively. The long-term use of plowland in crop rotation and the cultivation of perennial legume crop have increased the content of hydrolyzable nitrogen forms but have not changed the proportions of nitrogen fractions characteristic of this soil type.     

SOIL ORGANIC CARBON STOCK AND FRACTIONS IN RELATION TO LAND USE AND SOIL DEPTH IN THE DEGRADED SHIWALIKS HILLS OF LOWER HIMALAYAS

The proportional differences in soil organic carbon (SOC) and its fractions under different land uses are of significance for understanding the process of aggregation and soil carbon sequestration mechanisms. A study was conducted in a mixed vegetation cover watershed with forest, grass, cultivated and eroded lands in the degraded Shiwaliks of the lower Himalayas to assess land‐use effects on profile SOC distribution and storage and to quantify the SOC fractions in water‐stable aggregates (WSA) and bulk soils. The soil samples were collected from eroded, cultivated, forest and grassland soils for the analysis of SOC fractions and aggregate stability. The SOC in eroded surface soils was lower than in less disturbed grassland, cultivated and forest soils. The surface and subsurface soils of grassland and forest lands differentially contributed to the total profile carbon stock. The SOC stock in the 1.05‐m soil profile was highest (83.5 Mg ha⁻¹) under forest and lowest (55.6 Mg ha⁻¹) in eroded lands. The SOC stock in the surface (0–15 cm) soil constituted 6.95, 27.6, 27 and 42.4 per cent of the total stock in the 1.05‐m profile of eroded, cultivated, forest and grassland soils, respectively. The forest soils were found to sequester 22.4 Mg ha⁻¹ more SOC than the cultivated soils as measured in the 1.05‐m soil profiles. The differences in aggregate SOC content among the land uses were more conspicuous in bigger water‐stable macro‐aggregates (WSA > 2 mm) than in water‐stable micro‐aggregates (WSA < 0.25 mm). The SOC in micro‐aggregates (WSA < 0.25 mm) was found to be less vulnerable to changes in land use. The hot water soluble and labile carbon fractions were higher in the bulk soils of grasslands than in the individual aggregates, whereas particulate organic carbon was higher in the aggregates than in bulk soils. Copyright © 2012 John Wiley & Sons, Ltd.     

种植草本植物狗牙根改良滨海黏性盐碱地的研究

为探明不同轮作模式对宁夏南部山区旱地农田土壤肥力和谷子产量的影响，基于连续8年定位试验，研究了谷子连作（R0）、谷子–小麦–糜子轮作（R1）、谷子–胡麻–豌豆轮作（R2）和谷子–豌豆–马铃薯轮作（R3）处理对谷子产量及土壤物理和化学性质的影响。结果表明：经过两个轮作周期后，与R0处理相比，R2处理谷子产量增加13.10%，R1处理产量略有降低，R3处理产量显著降低（P<0.05）。各轮作模式均有利于降低土壤容重，提高土壤田间持水量，并且R1和R2处理土壤容重显著低于R0处理；除R3处理外，R1和R2处理有利于增加土壤孔隙度，与R0处理相比增幅分别为15.09%和21.18%。各轮作模式均有利于增加土壤>0.25 mm大团聚体总量，其中R1和R2处理可以显著降低土壤中<0.25 mm和2~0.25 mm团聚体数量（P<0.05），并显著增加>2 mm团聚体比例。各轮作模式土壤有机质含量均高于R0处理，土壤全量养分含量差异不明显；各轮作模式均有利于增加土壤微生物生物量碳、氮和有效磷含量，同时R2处理还有利于增加土壤碱解氮、速效钾和微生物生物量磷含量。综上，轮作有利于旱地土壤有机质积累，降低土壤容重，增加大团聚体数量，提高土壤微生物生物量，但不同轮作模式间存在差异，其中，R2处理更有利于增加谷子产量、改善土壤结构、培肥土壤，可以作为宁夏南部山区雨养农业旱作区的优选作物轮作模式进行推广。     

Soil penetrating quality in cultivated and forested coastal plain sands of Southern Nigeria

Conversion of natural forest to intensive cultivation makes to soil susceptible to flooding, declining fertility and loss of organic matter (OM) and reduced water movement into and within the soil. We studied infiltration rates and related soil penetrating indicators of forested and cultivated soils in humid tropical coastal plain sands in Southern Nigeria. Results showed that mean-weight diameter (MWD) and water stability of aggregates were higher in forested than cultivated soils. Stable aggregates > 1.00 mm were 16.5% and 31.1% respectively, for cultivated and forested soils at 0–15 cm depth, indicating formation of more macro-aggregates in forested soil. Soil disturbance through cultivation decreased hydraulic conductivity and increased bulk density of the soil. Infiltration rate attained after 2 hours was higher in forested soil. Temporary infiltration rate of 178 mm hr^?1 at initial time in cultivated soil was followed by very low infiltration rate of 7 mm hr^?1 after 2 hours. Soil organic matter (SOM), saturated hydraulic conductivity, MWD and total sand correlated positively with infiltration rates are r = 0.76, 0.61, 0.57 and 0.51 respectively. Changes in these parameters are dependent on surface soil disturbance by cultivation. Cultivation of forest decreased infiltration rates and water transmission properties of the soil.     

THE EFFECT OF CULTIVATION ON THE STRUCTURE AND OTHER PHYSICAL CHARACTERISTICS OF GRASSLAND AND ARABLE SOILS (194–970)

Cultivating grassland changes the physical state of the soil. The paper describes observations and measurements made in the field and the laboratory on a wide range of soils (with series names) in England over a period of 25 years. Dry sieving showed that natural weathering of grassland aggregates after three months'exposure was very considerable. The drawbar-pull on ploughing soil recently out of grass, as compared with old arable, increased with the number of years out of grass. The number of earthworms per hectare on old grassland was 6 to 9 times that on old arable of the same soil series: after three years'cultivation it was reduced by about a half. The possibility of erosion by wind increased with the number of years out of grass. Old arable land on gentle slopes had its resistance to flowing water (sheet erosion) much increased by as little as 2 years under grass. The apparent densities of soils were at a minimum under old grass and increased under cultivation. On some soils arable for many decades, the apparent densities were near those considered limiting for root penetration. The volurne of water per cent in the soil at the sticky point decreased as the years out of grass increased, suggesting a decrease in the number of days the soil could be cultivated without smearing. The water-stability of soil aggregates decreased as the number of years after ploughing old grassland increased. Whatever the texture, on ploughing old grassland, the water stability of air-dry aggregates feil sharply in the first – years and then approached the value corresponding to that of old arable soils more slowly, apart from soils of low clay content in which it differed little from old arable land after 2 years. Measurement of changes in water stability and field observations in a 6-course rotation (3 years ley, 3 years cereal) on a loam which had been in a similar rotation for about a decade after old grassland, suggested that this balance was probably right for maintaining such a soil at a good cropping level. Puddling (poaching) by animals of wet arable loam soils overlying clay resulted in gleying to the surface: ferrous iron was detected chemically. On putting down to grass there was little increase in water stability of the aggregates after 4 years. The reduction in the total pore space caused by harvesting machinery and also as a result of some years'cultivation of grassland was considerable. The ease of penetration of soils when taking cores was compared by counting the number of blows to drive in a corer: the number was much less in a soil recently out of old grass compared with old arable. The root development of cereals was poor in old arable silt soils very unstable to wetting and drying and with few visible biopores (> 10–00 μm). On soils with many visible pores, root development was much greater and yields with similar rates of nitrogen were double. The total N in the soils feil when old grassland was ploughed, sometimes by as much as 75 per cent in about 20 years. There was sometimes a significant corre-lation between total N and the reduction in water-stable aggregation during the years following ploughing grassland: the correlation coefficient was much higher on ploughing old grassland rather than leys. The N level dropped much more quickly in the first few years after ploughing old grassland than later. All single-property measurements give only a limited assessment of the physical state of a soil. Soils can be assessed satisfactorily only by making a range of measurements appropriate to the farming System.     

不同利用方式下红壤结构的形成

本文应用顺序脱胶法,对砖红壤、赤红壤和红壤在不同利用方式下的水稳性团聚体的有机和无机胶结物组成进行了分析研究。水稳性团聚体共分>5,3-1,1-0.5和<0.25毫米四级。结果表明,红壤开垦后随着粘粒活度的增加和无机胶结物含量的降低,土壤团聚体的水稳性和土壤结构系数逐渐降低。但是,一旦采用合理的施肥和管理方法,这些物理参数又会逐步恢复和增加。此外,还研究了土壤结构稳定性与土壤地带性的关系。作者认为在中亚热带的红壤上施用有机物料以增强它的结构稳定性比热带砖红壤上施用更为重要。     

高聚物对土壤结构改良的研究 Ⅲ.聚丙烯酰胺对赤红壤的改良研究

研究了不同离子类型 (中性、阴离子和两性 )聚丙烯酰胺对赤红壤的改良作用。实验结果显示 ,聚丙烯酰胺能够提高赤红壤 >0 .2 5mm水稳性团粒结构数量 ,降低土壤容重 ,增大土壤的毛管持水量和渗透系数 ,提高土壤的含水量 ;在施用量为 0 .0 0 5 %— 0 .2 0 0 %的范围内 ,改良剂对赤红壤的改良效果随其施用量的增大而增强 ;聚丙烯酰胺的离子类型和分子量及其施用方式和添加剂对土壤的改良效果有显著影响     

Dynamics of soil organic carbon and nitrogen associated with physically separated fractions in a grassland-cultivation sequence in the Qinghai-Tibetan plateau

This study is aimed at quantifying organic carbon (C) and total nitrogen (N) dynamics associated with physically separated soil fractions in a grassland-cultivation sequence in the Qinghai-Tibetan plateau. Concentrations of organic C and N of soil, free and occluded particulate organic matter (OM), and aggregate- and mineral-associated OM in different land uses are increased in the following order: 50 years cultivation < 12 years cultivation ≤ native grassland. The prolonged cropping of up to 50 years markedly affected the concentrations of free and occluded particulate OM and mineral-associated OM. After wet-sieving, 43% of native grassland soil mass was found in >1−10 mm water-stable aggregates that stored 40% of bulk soil organic C and N; only 16% and 7% of soil mass containing 16% and 7% of bulk soil organic C and N was >1−10 mm water-stable aggregates of soils cultivated for 12 years and 50 years, respectively. This indicated that losses of soil organic C and N following cultivation of native grassland would be largely related to disruption of >1–10 mm size aggregates and exposure of intra-aggregate OM to microbial attack. Organic C and N concentrations of soil aggregates were similar among aggregate size fractions (>0.05−10 mm) within each land use, suggesting that soil aggregation process of these soils did not follow the hierarchy model. The increase of the C-to-N ratio of free and occluded particulate fractions in the cultivated soils compared to the grassland soil indicated a greater loss of N than C.     

不同利用方式旱地红壤水稳性团聚体及其碳、氮、磷分布特征

针对江西红壤地区不同利用方式引起的土壤质量和肥力的相应变化,研究了不同肥力水平、不同利用方式下红壤旱地水稳性团聚体含量及其养分分布规律。研究表明,荒地土壤中>5 mm水稳性团聚体含量显著高于其他利用方式,花生地和果园土壤则以0.25～0.053 mm的水稳性团聚体为主。各肥力水平下,菜地土壤中除>5 mm水稳性团聚体外,各粒级团聚体中有机碳、全氮和全磷含量均显著高于花生地、果园和荒地土壤。说明菜地土壤长期大量施肥,导致土壤碳、氮、磷养分含量均相对丰富。不同利用方式旱地红壤中,有机碳、全氮主要分布在>5 mm、5～2 mm和2～1 mm的较大粒径水稳性团聚体中。说明随着团聚体粒径增大,其有机碳含量增加,土壤全氮的消长趋势和有机碳一致。土壤全磷较均匀地分布在水稳性团聚体中,如高肥力菜地和荒地土壤各粒级团聚体中全磷含量间均无显著性差异。各利用方式旱地红壤中2～1 mm和1～0.5 mm的水稳性团聚体含量与土壤有机碳、全氮和全磷含量间均达到了极显著正相关。