土地利用方式对桂西北石漠化地区土壤理化性质的影响

在广西壮族自治区凌云县典型石漠化地区对7种不同土地利用方式土壤理化性质进行了调查分析.结果表明,不同土地利用方式对土壤容重、含水量、总孔隙度、毛管孔隙度、非毛管孔隙度存在极显著差异(p＜0.01),有机质、全氮、全磷、全钾、速效氮、速效磷、速效钾及交换性Ca2+含量差异极显著(p＜0.01).相对阔叶林地土壤,灌木林、针叶林、退耕台地、草地、退耕坡地、农田土壤的退化程度依次增加.农田土壤质量最低,针叶林地、草地、退耕坡地、退耕台地土壤质量为中等,灌木林地与阔叶林地土壤质量较高.人为干扰是影响土壤理化性质的主导因素,干扰强度大,土壤理化性质退化严重.控制不合理的人为干扰及恢复结构良好的地上植被对改善土壤质量具有重要意义.     

Soil organic carbon,nitrogen, and phosphorus distribution in stable aggregates of an Ultisol under contrasting land use and management history

Different land‐use affects the organization of mineral soil particles and soil organic components into aggregates and the consequent arrangement of the aggregates will influence essential ecosystem functions. We investigated a continuous rubber plantation (forested), land fallowed for 10 y (fallow), 10‐y continuous arable cropping land and cropped land with top soil removed (TSR) for concentrations of C, N, and P in bulk soil and dry aggregates. Results showed that a high level of soil disturbance decreased the proportion of surface (0–15 cm) soil aggregate stability (low mean weight diameter) in TSR by 149% and arable cropping by 125% compared with the forested. Aggregate associated SOC was higher in aggregate‐size fractions of forested land‐use when compared with that in 10‐y fallow, continuous arable cropping, and TSR. For aggregate associated N, fallow and forested land‐use types concentrated higher proportion across aggregate sizes than the arable cropping and TSR. Macro aggregate fractions generally contained higher concentrations of C, N, and P compared with the micro‐aggregates. Water transmission indicators like total porosity and saturated hydraulic conductivity recorded higher values with forested and fallow land‐use than the others. We can thus conclude that long‐term soil disturbance due to cultivation and removal of top soil reduces the accumulation of soil C, N, and P in bulk soil and decreases water transmission properties. On the other hand, aggregate‐associated C, N and P accumulations are dependent on the level of soil surface disturbance and aggregate sizes.     

晋西黄土区典型林地土壤水分变化特征

选择晋西黄土区蔡家川流域5种典型林地(山杨×辽东栎天然次生林、人工油松×刺槐混交林、人工油松林、人工刺槐林、人工侧柏林)作为研究对象,在每块样地中心布设1个土壤水分观测点,采用TRIME-TDR土壤水分测定仪定位观测2016—2018年1—12月的土壤体积含水量,测定深度为200 cm,每20 cm为1个测层,每月分上、中、下旬进行土壤水分含量观测,分析不同林地类型土壤水分年内变化规律和土壤水分垂直变化规律。结果表明:(1)研究区不同林地土壤水分年内变化可以划分为稳定期(1—3月)、波动期(4—6月)、增长期(7—9月)和消耗期(10—12月)4个时期,5种林分类型的年平均土壤储水量按照从大到小的排序为天然次生林地(338.68 mm)>人工油松林地(319.74 mm)>人工侧柏林地(314.15 mm)>人工油松×刺槐混交林地(303.37 mm)>人工刺槐林地(292.03 mm),刺槐林地耗水量最大。(2)在雨季末,研究区5种林分类型林地土壤水分均得到了正向补充,且土壤水分的恢复能力大小排序为次生林地>针叶林地>混交林地>刺槐纯林。(3)研究区土壤水分垂直变化可划分为土壤水分含量速变层和土壤水分含量相对稳定层2个层次;随着土层深度增加,不同林地类型剖面平均含水量总体上先增大后减小。不同林地类型表层土壤水分含量为侧柏林地>次生林地>油松林地>油松×刺槐混交林地>刺槐林地;土壤水分的补充深度为天然林地>针叶林地>油松×刺槐混交林地>刺槐纯林。     

Nutrient concentrations and acidity in ferralitic soil under perennial cropping, fallow and primary forest in central Amazonia

The long‐term productivity on the acidic, nutrient‐poor upland soils of central Amazonia depends to a large extent on the chemical soil fertility as influenced by vegetation type and management. We compared soil and soil solution data from permanent cropping, fallow and primary forest on a Xanthic Ferralsol in central Amazonia to evaluate changes of soil fertility following forest conversion, agricultural use at different intensities and setting aside agricultural land. The agricultural systems included a perennial polyculture at two fertilizer inputs and a monoculture plantation. Soil and soil solution were collected to 2 m depth, and the soil solution was monitored over 2 years. Both soil and soil solution data showed decreasing soil fertility in the sequence: monoculture and polyculture at large input, polyculture at small input, forest and fallow. The soil solution data were more sensitive to effects of systems and fertilizer inputs on subsoil fertility. Fractionation of the N in the soil solution showed a larger proportion of dissolved organic N in the N‐poor fallow soil than in the soil under forest and agriculture. The soil under fallow, forest and low‐input agriculture had larger exchangeable acidity than that under high‐input agriculture, but the Al concentrations in the soil solution were very small because there were few cations with which to exchange and less nitrification. In high‐input agriculture, pronounced acidification peaks in the topsoil solution followed fertilization. The comparison of soil and soil solution data explained why the spontaneous vegetation thrives at very large exchangeable acidity in these soils, whereas agricultural systems often depend on liming to reduce the concentration of toxic Al in the soil.     

人为干预下喀斯特峡谷区不同土地利用类型对土壤理化性质的影响

[目的]探究人为干预下喀斯特峡谷区不同土地利用类型对土壤理化性质的影响,为岩溶山区的生态环境保护和可持续发展提供科学依据。[方法]以贵州省花江喀斯峡谷示范区生态系统土壤为研究区,选取典型喀斯特石漠化治理区域进行野外定点取样,通过室内分析的方法进行不同土地利用石漠化地区土壤理化性质比较研究。[结果](1)土壤含水量随着土层深度的增加递增,土壤含水量大小依次为:封山育林径流场坡改梯自然灌丛撂荒地,形成土壤水分的垂直变化;(2)经过改良后坡改梯通过种植花椒的田间持水量明显比草地含量高,相对于进行石漠化治理并合理耕作的坡改梯花椒地来说,荒草地的持水能力明显下降;(3)石漠化环境下土壤颗粒分散、土体结构破坏,土壤通透能力下降,孔隙的变化规律为:林地坡改梯灌草丛耕地撂荒地;(4)示范区土壤总钾偏高,与pH值呈正相关,总氮普遍低于全国农田氮含量,土壤养分不足。[结论]不同土地利用条件下土壤特征有显著差异,这种差异是基于不同石漠化等级下不同土地利用的治理措施造成的。花江示范区土壤持水效益低,土壤养分不足,不利于耕作,农业产量不高,建议花江示范区应减少耕地,多种植经济林和草地,保护天然林地。     

Effects of different land-use types on soil quality in the hilly area of Rawalakot Azad Jammu and Kashmir

Abstract

Vegetative cover plays an important role for the quality of soil especially in hilly and mountainous areas such as Azad Jammu and Kashmir where erosion is a major threat to the ecosystem and productivity. The study focuses on the impact of land-use types on soil quality by measuring the differences in chemical and physical properties at three sites in adjacently located natural forest land (forest), fallow grassland (grass) and arable land (arable). Soil samples from 0-15 and 15-30 cm depth were collected and examined for particle distribution, dry bulk density, organic matter (OM), pH, macro- and micro-nutrients. Land-use types had a significant effect on primary soil particle distribution. Highest clay content was found in forest and highest sand content in arable. Forest had relatively the highest levels of OM, macro- and micro-nutrients and arable the lowest. Most of the properties of the 0-15 cm surface level of grass were similar to those observed in the 15-30 cm level in forest. Arable exhibited lowest nutrient status and poorest physical conditions, indicating a degrading effect of arable cultivation practices on soil. Grass and arable showed, compared to forest, a 30–60% average increase in bulk density and 26–66% average decrease in OM. Regression analysis showed a significant correlation of OM with available phosphorus and potassium while it had negative correlation with dry bulk density and pH. Natural vegetation appeared to be a main contributor of soil quality as it maintained the organic carbon stock, and increased the nutrient status of soil and is therefore important for sustainable development of Azad Jammu and Kashmir and other similar areas. Furthermore, OM was shown to be an important indicator of soil quality.     

Changes in Soil Properties and Microbial Indices across Various Management Sites in the Mountain Environments of Azad Jammu and Kashmir

The mountainous region of the Himalayas is covered with forest, grassland, and arable land, but the variation in ecosystem functions has not been fully explored because of the lack of available data. This study appraises the changes in soil properties over the course of a year (spring, summer, autumn, winter) for forest, grassland, and arable soils in a typical hilly and mountainous region of Azad Jammu and Kashmir, Pakistan. Soil samples were collected from major land-cover types in the mountain region: natural forest, grassland, and cultivated land (arable). The natural forest served as a control against which changes in soil properties resulting from removal of natural vegetation and cultivation of soil were assessed. Soil samples were collected from depths of 0–15 and 15–30 cm six times during the year and examined for changes in temperature, moisture, electrical conductivity (EC), micronutrients [iron, manganese, copper, and zinc (Fe, Mn, Cu, Zn, respectively)], and microbial population. Significant differences were found in soil temperature, soil moisture, Fe, Mn, Cu, Zn, and number of bacteria, actinomycetes, and fungi among the three land-cover types. Soil under cultivation had 4–5 °C higher temperature and 3–6% lower moisture than the adjacent soils under grassland and forest. Electrical conductivity (EC) values of forest, grassland, and arable soil were 0.36, 0.30, and 0.31 dS m^?1, indicating that soil collected from the forest had 18–20% more EC than the adjacent arable and grassland soils. On average, amounts of Fe, Mn, Cu, and Zn in the soil collected from the arable site were 6.6, 5.7, 1.7, and 0.8 mg kg^?1, compared with 24.0, 12.1, 3.5, and 1.2 mg kg^?1 soil in the forest soil, showing that arable had two to four times less micronutrients than grassland and forest. Populations of bacteria, actinomycetes, and fungi in the forest were 22.3 (10⁵), 8.2 (10⁵), and 2.5 (10³), respectively, while arable land exhibited 8.2 (10⁵), 3.2 (10⁵), and 0.87 (10³). Season (temperature) and depth showed significant effects on microbial activity and nutrient concentration, and both decreased significantly in winter and in the subsurface layer of 15?30 cm. Different contents of the parameters among arable, grassland, and forest soils indicated an extractive effect of cultivation and agricultural practices on soil. Natural vegetation appeared to be a main contributor to soil quality as it maintained the moisture content and increased the nutrient status and microbial growth of soil. Therefore, it is important to sustain high-altitude ecosystems and reinstate the degraded lands in the mountain region.     

晋西黄土区长期人工林恢复对土壤水分和养分性质的影响

黄土高原地区是我国水土流失和环境问题严重的地区之一,人工植被恢复可以有效改善土壤性质,提高土壤质量,明确长期人工植被恢复后土壤水分和养分性质的响应差异,有利于进一步有效改善生态环境。选取晋西黄土区自然恢复的次生林地、人工刺槐林地、人工油松林地3种典型植被恢复类型为研究对象,通过测定土壤物理性质以及有机碳、氮磷钾元素含量等土壤养分,对比分析长期不同人工林恢复条件下的差异。结果表明:(1)次生林地、刺槐林地和油松林地在0-20 cm浅层土壤的容重分别1.15,1.04,1.06 g/cm³,次生林地的容重最大,土壤容重随着土层深度的增加而增大;(2)次生林地在浅层的土壤水分状况优于刺槐林地和油松林地,土壤水分消耗期(生长季开始前)过渡到积累期(生长期开始)时,次生林土壤水分动态变化更剧烈;(3)次生林地土壤碳储量较高,油松林地土壤氮、磷储量较高。3种林地土壤养分垂直变化差异显著,且均具有明显的表聚性,有机碳、全氮、全磷、速效氮和速效钾含量均随着土层深度的增加而减少,而速效磷含量随着土层深度的变化表现为先增大再减小。以水养条件为依据,建议在植被恢复过程中多以保育次生林为主来达到较好的水碳储量等生态效益,有利于优化晋西黄土区的林分管理,促进植被恢复和生态建设。     

Effects of exotic tree plantations of teak (Tectona grandis) and gmelina (Gmelina arborea) on a forest soil in south-western Nigeria

Abstract. The properties of soil under 15-year-old plantations of gmelina ( Gmelina arborea ) and teak ( Tectona grandis ) were compared with logged forest soil in south-western Nigeria. The soil was significantly denser in the 0–10 cm layer of plantation soil and total porosity less than that of forest soil. Organic carbon was significantly greater in the 0–10 cm layer of forest soil. Similarly, the concentrations of total N, exchangeable Ca, Mg and K were greater under forest soil, but the concentrations of available P were similar under all three ecosystems. The smaller organic carbon and nutrient content of plantation soil is mainly due to its more open organic matter and nutrient cycles and nutrient immobilization in the fast-growing exotics.     

The match between microbial community structure and soil properties is modulated by land use types and sample origin within an integrated agroecosystem

It is of global concern to adopt measures to mitigate land degradation caused by agricultural production systems. One of the strategies proposed is to replace degraded pastures with agrosilvopastoral systems which integrate three different land-use types: crop production, livestock pasture and forestry plantation (denoted iCLF). However, little is known about the differences between iCLF and other land use types in terms of soil microbial community structure. Distance matrices based on individual soil chemical properties and individual soil microbial variables were correlated by Procrustes analysis and these relationships yielded vectors of residuals depicting these correlations (matches). These vectors were used as univariate response variables in an ANOVA framework in order to investigate how the match sizes (the strength of correlation/covariance) between individual soil chemical properties and individual soil microbial variables vary across land use types (levels: iCLF; degradated pasture; improved pasture; and a native cerrado fragment) and also across sample origin within iCLF (levels: soil samples under more influence of the exotic tree forest stand; soil samples under influence of the pasture; samples within the transition between the forest stand and the pasture). We were able to obtain insights into the fact that the land use distinction can be driven by more than just individual soil chemical and microbial variables. The integration of crop, livestock and forestry promoted a dominance of fungi in this low fertility and low pH environment. P availability and the composite variable exchangeable base cations (Ca⁺², Mg⁺², K⁺) were the soil properties whose strengths of correlation (match sizes) with individual microbial variables were the most affected by land use type and sampling origin within iCLF. While the strength of the correlation between soil microbial structure variables and P availability was typically land use type dependent, the response of the microbial structure to exchangeable base cations was mainly affected by the sample origin within iCLF. Finally our results point towards the conclusion that increases in the heterogeneity of vegetation within integrated crop, pasture and forestry systems are an important driver of microbial community response to environmental changes, and may be one means by which to increase the sustainability of tropical agroecosystems.     

红壤不同利用方式下的剖面酸度特征

【目的】 作物类型及其管理模式是影响红壤酸化的主要因素之一,研究不同利用方式下红壤剖面酸度的变化特征,对红壤酸化防治具有重要指导意义。 【方法】 选取由红砂岩母质发育红壤的4种主要利用方式 (水田、旱地、果园和林地),通过分层 (0—20、20—40、40—60、60—80 cm和80—100 cm) 测定pH、交换性酸、交换性盐基总量和盐基饱和度,定量比较不同利用方式下各酸度指标在剖面上的变化特征及程度。 【结果】 在不同利用方式下,红壤剖面pH为水田 (5.69) > 旱地 (4.71) ≈ 果园 (4.74) > 林地 (4.49);交换性酸含量为林地 (6.54 cmol/kg) ≈ 旱地 (6.52 cmol/kg) > 果园 (3.51 cmol/kg) > 水田 (0.79 cmol/kg);交换性盐基总量为水田 (4.47 cmol/kg) > 旱地 (1.97 cmol/kg) > 果园 (1.26 cmol/kg) > 林地 (0.48 cmol/kg);盐基饱和度为水田 (53.14%) > 旱地 (20.87%) > 果园 (15.41%) > 林地 (4.67%)。随着土层深度的增加,红壤剖面pH值逐渐升高;不同层次间交换性酸含量无显著差异;交换性盐基总量随土壤深度增加逐渐升高,为60—100 cm (2.34 cmol/kg) > 40—60 cm (2.05 cmol/kg) > 0—40 cm (1.75 cmol/kg);水田利用方式下红壤盐基饱和度随土壤深度增加逐渐升高,为80—100 cm (33.95%) > 60—80 cm (32.27%) > 40—60 cm (31.31%) > 20—40 cm (25.47%) > 0—20 cm (21.08%)。水田、果园利用方式下红壤pH与交换性酸含量呈显著负相关,与交换性盐基总量和盐基饱和度呈显著正相关;旱地利用方式下红壤pH与交换性盐基总量呈显著正相关;林地利用方式下pH与交换性酸含量呈显著负相关。 【结论】 4种利用方式下,在0—40 cm土层,林地红壤酸度最高,其次是果园和旱地,水田红壤酸度最低,在40—100 cm土层酸度变异较小。通过改变土地利用方式,降低红壤交换性酸含量、增加交换性盐基总量和盐基饱和度可以有效降低红壤酸度。      

不同利用方式对潮棕壤交换性钾钠及盐基总量的影响

为深刻认识土地利用变化对土壤交换性离子的影响,本文对潮棕壤水稻田、玉米地、撂荒地和人工林地4种土地利用方式经过14年后,在0～150cm剖面中土壤交换性钾、钠、交换性盐基总量的剖面分布及交换性钾钠比值变化进行了比较研究。结果表明,林地和撂荒地各土层交换性K含量及土体中交换性K储量具有高于水稻田和玉米地的趋势;水稻田和撂荒地0～20cm各土层的交换性Na含量显著高于林地和玉米地;林地0～150cm深度土壤交换性Na储量显著高于其他三种利用方式(P<0.05);0～150cm深度内土壤交换性盐基总储量大小依次为林地、玉米地、撂荒地、水稻田;水稻田剖面土壤交换性K/Na随土层深度增加而增大,其他3种土地利用方式则是随土层深度增加而降低。土壤管理和植物自身的特性在土壤剖面中交换性离子的构成以及土壤交换性盐基库的重建等方面可能起到重要作用。     

Soil ecological study on dynamics of K,Mg, and Ca,and soil acidity in shifting cultivation in Northern Thailand

Abstract

Soil degradation caused by excessive land use is presently one of the major constraints on sustainable agriculture in the mountainous area of northern Thailand. In order to obtain basic information about soil fertility problems involved in the transition from traditional shifting cultivation to more intensive upland farming, the dynamics of K, Mg, and Ca, and soil acidity in the farming systems of both Karen and Hmong/Thai peoples were investigated. In the fields that lay fallow for more than 5 y, the soils were highly acidic and poor in exchangeable bases, mainly due to the fact that the fallow vegetation rapidly absorbed inorganic bases (K, Mg, and Ca) in the soils. In the fields both under fallow and cropping within 3 y after the slash and burn practice, the high acidity observed in the soils at the fallow stage seemed to be alleviated by ash input with high alkalinity. The aboveground biomass ranged from 9 to 10 t ha^?1 in the 8 y fallow field and the sum of inorganic bases and alkalinity, which were expected to be added to the soils with ash input, ranged from 3 to 4 kmol( + ) ha^?1 or kmol(-) ha^?1 , respectively. In the fields under continuous cultivation for more than 4 y after the slash and burn practice, the subsoils showed a more acidic nature than in the fields immediately after burning. Judging from the high concentrations of inorganic bases in the soil solution from the subsoils, the decrease of the content of exchangeable bases and resulting soil acidification might have proceeded through leaching loss of these bases. Among the exchangeable bases in the soils, Ca and Mg were generally predominant and K occurred as trace. Comparison of the total contents of the bases with the contents of exchangeable ones showed that most of Ca occurred in an exchangeable form while most of K and Mg occurred in the nonexchangeable forms in the soils. Therefore, Ca was likely to be readily depleted along with soil acidification in continuous cultivation.     

Spatial Distribution of Surface Soil Acidity,Electrical Conductivity,Soil Organic Carbon Content and Exchangeable Potassium,Calcium and Magnesium in Some Cropped Acid Soils of India

Land degradation is a global problem. Best management of degraded land can be done by evaluating the spatial variability of soil properties including chemical properties of degraded land and mapping such variations. Since, a significant portion of arable land in India is chemically degraded due to soil acidity; the present study was conducted to study the spatial variability of soil acidity (pH), electrical conductivity (EC), soil organic carbon (OC) content, exchangeable potassium (K⁺), calcium (Ca²⁺) and magnesium (Mg²⁺) contents in some cropped acid soils of India. A total of four hundred (one hundred from each series) representative surface (0–0.15 m depth) soil samples were collected from arable soils representing four soil series namely Hariharapur, Debatoli, Rajpora and Neeleswaram situated in Orissa, Jharkhand, Himachal Pradesh and Kerala states of India, respectively, and were analyzed. Soil acidity (pH between 3.90 and 6.45) showed a low variability, in contrast to other soil properties, which showed moderate variability. The coefficients of variation varied from 32.4 to 74.3, 31.2 to 50.9, 45.6 to 100, 71.9 to 93.0 and 59.0 to 79.8% for EC (mean between 0.05 and 0.09 dS m⁻¹), OC (mean between 0.29 to 1.86%), exchangeable K⁺ (mean between 39.1 and 77.7 mg kg⁻¹), Ca²⁺ (mean between 148 and 293 mg kg⁻¹) and Mg²⁺ (mean between 111 and 191 mg kg⁻¹), respectively. Soil pH and OC content were positively and significantly correlated with exchangeable K⁺, Ca²⁺ and Mg²⁺ content. Geostatistical analysis revealed that the best fit models were gaussian, exponential and spherical for different soil properties with moderate to strong spatial dependency. Copyright © 2014 John Wiley & Sons, Ltd.     

不同降雨强度下北京山区典型林地土壤水分时空变化特征

通过ECH2O土壤水分监测系统和EM50数据采集器对北京山区2种典型人工林地(栓皮栎林和油松林)土壤水分含量进行定位、长期观测、数据处理,分析不同降雨强度对不同林分类型土壤水分时空变化特征及差异性的影响。结果表明:(1)栓皮栎林地和油松林地日平均土壤储水量随降雨量显著变化,月平均土壤储水量随降雨量的增加呈上升趋势。(2)在垂直方向上,栓皮栎和油松林地0—40cm土层土壤储水量的增加率随雨强增加而降低,栓皮栎林地土壤储水量平均增加率(94.17%)大于油松(84.19%),而40—100cm土层土壤储水量的增加率随雨强增加均呈现增加趋势,且油松林地土壤储水量平均增加率(15.81%)大于栓皮栎林地(5.83%)。(3)栓皮栎与油松林地相同土层土壤储水量差异性显著(p0.05),同一林地不同土层土壤储水量也到达差异性显著(p0.05)。从栓皮栎和油松林地的土壤水分时空变化特征来看,2种林地土壤储水量分布不同。在造林树种选择时,可以考虑将油松和栓皮栎2个树种进行混交。研究结果将为北京山区植被建设和管理提供参考和理论依据。     

Effect of land use on some soil properties related to the risk of loss of soil phosphorus

Although land use clearly modifies soil properties, the intensity of the modifications depends on the management procedures and also on the soil properties themselves. To enable construction of models that describe soil nutrient losses, extensive databases corresponding to soils under different land use must be made available. Analysis of 404 samples of soils (from Galicia, NW Spain), under different types of use revealed that most of the soil properties underwent changes in the following order: forest use (least modified) ‐ grassland ‐ arable (most modified). Decreases in the contents of organic matter, extractable oxides and P‐adsorption capacity followed the same order, as did increases in the contents of available P (total, inorganic and organic), P desorbed with distilled water, and degree of P saturation. In general, in all of the soils, independently of their use, the amount of P desorbed (whether total P, molybdate reactive P or particulate P) was more closely related to the degree of P saturation than to the levels of P extracted with bicarbonate. Copyright © 2007 John Wiley & Sons, Ltd.     

长白山地丘陵区不同土地利用方式土壤动物群落生态分布特征

在长白山地丘陵区选择次生落叶阔叶林、灌木林、采伐迹地以及耕地四种土地利用方式,对其土壤动物群落的组成、多样性和分布特征进行研究。结果表明:不同土地利用方式土壤动物群落的水平分布呈现明显的差异。采伐迹地中型土壤动物个体密度和耕地中型土壤动物类群数季节变化明显。次生落叶阔叶林和灌木林土壤动物分布随土层加深急剧减少,采伐迹地和耕地垂直分布递减和缓。同一季节土壤动物的丰富度指数和多样性指数在不同土地利用方式差异显著。土壤动物的多样性表现为灌木林最高,耕地最低。不同土地利用方式影响土壤动物群落的生态分布,其中pH、土壤有机质、有效磷和速效氮是影响长白山地丘陵区不同土地利用方式土壤动物群落分布的主导因子。     

南方典型红壤区旱地与水田土壤酸度的剖面差异性

为探明红壤区不同耕地利用类型下土壤酸度的剖面变化特征及其主要影响因素,选取江西省余江县和湖南省祁阳县的典型水田、旱地两种耕地利用类型下、第四纪红色黏土母质发育的红壤,分5层(0～20、20～40、40～60、60～80和80～100 cm)测定土壤pH、交换性铝、交换态盐基阳离子及有机质含量等指标,分析剖面酸度特征及其相互关系。结果表明：土壤pH均随土层深度的增加呈增加趋势,不同耕地利用类型下以水田剖面p H较高,范围为5.80～6.43,旱地剖面p H较低,范围为4.68～5.41。土壤交换性铝含量以水田含量较低,范围为0.16～1.56 cmol/kg,旱地的含量较高,范围为4.22～7.02 cmol/kg,水田的交换性铝含量随土层深度的增加呈降低趋势,旱地则呈现相反的变化趋势。0～20 cm土层的交换性铝与有机质含量呈显著负相关,40～100 cm土层的交换性铝与交换态盐基阳离子含量呈显著负相关。耕地利用类型是影响土壤酸度的主要因素之一,旱地土壤酸度强于水田。增加耕层土壤有机质含量可能是减缓酸化、降低交换性铝含量的策略之一。     

Assessment of the postagrogenic transformation of soddy-podzolic soils: Cartographic and analytic support

The results of experimental studies of the postagrogenic transformation of loamy soddy-podzolic soils on the southern slope of the Klin-Dmitrov Moraine Ridge are discussed. A chronosequence of soils (arable soils (cropland)-soils under fallow with meadow vegetation-soils under secondary forests of different ages-soils under a conventionally initial native forest) was examined, and the stages of the postagrogenic transformation of the automorphic soddy-podzolic soils were identified. The differentiation of the former plow horizon into the A1 and A1A2 horizons (according to the differences in the humus content, texture, and acidity) served as the major criterion of the soil transformation. A stage of textural differentiation with clay depletion from the uppermost layer was identified in the soils of the 20- to 60-year-old fallows. The specificity of the postagrogenic transformation of the soils on the slopes was demonstrated. From the methodological point of view, it was important to differentiate between the chronosequences of automorphic and semihydromorphic soils of the leveled interfluves and the soils of the slopes. For this purpose, a series of maps reflecting the history of the land use and the soil cover pattern was analyzed. The cartographic model included the attribute data of the soil surveys, the cartographic sources (a series of historical maps of the land use, topographic maps, remote sensing data, and a digital elevation model), and two base maps: (a) the integral map of the land use and (b) the map of the soil combinations with the separation of the zonal automorphic, semihydromorphic, and erosional soil combinations. This scheme served as a matrix for the organization and analysis of the already available and new materials.     

Soil capability as a predictor of cropland change in Alberta,Canada from 1988 to 2010

Understanding the mutual influences between cropland use and soil characteristics is important in anticipating and planning for food production, environmental protection and resource sustainability. Numerous studies focus on the relationship between crop rotations and soil characteristics at a microscale, but fewer studies focus on the relationships between soil capability and cropland use and change at a medium scale. We explore how soil capability has influenced cropland changes over 22 yr, using statistical and land use transition analysis. Landsat images from the years 1988, 2002 and 2010 were used to map cropland changes by soil capability class within a pilot site in Alberta, Canada. Between the late 1980s and 2010: (i) the area of annual crops increased substantially while that of forest and summer‐fallow decreased; (ii) changes in cropland use among annual crops, perennial crops and summer‐fallow differed substantially depending on soil capability; and (iii) a transition from annual crops and summer‐fallow to perennial crops was more likely on land of poorer soil capability, whereas the transition from perennial crops and summer‐fallow to annual crops was more likely on land with higher soil capability. The changes in land use practices identified in this study indicate that producers are actively intensifying production on their best land to optimize profitability while simultaneously reducing the intensity of production on poorer land for either financial or environmental reasons, or both.