Soil organic carbon and fly-ash distributions in eroded phases of soils in Illinois and Russia

Soil organic carbon (SOC) dynamics are affected by tillage, soil erosion and depositional processes. The objectives of this paper are to evaluate soil organic carbon and fly-ash distribution methods for identifying eroded phases of soils in Illinois and Russia and quantifying the extent of soil loss from erosion. The effect of accelerated erosion on soils is recorded on National Cooperative Soil Survey maps as phases of soil series that reflect the percentage of the original A horizon materials remaining. Identification depends on knowledge of the original A horizon thicknesses, SOC and fly-ash contents at uncultivated and uneroded sites when determining erosion phases of soil at cultivated and eroded sites. However, locating uncultivated and uneroded comparison sites with similar landscape and slope characteristics can be difficult. The amount of A horizon materials within the plow layers (Ap horizons) or topsoils are often determined by soil colors which reflect the SOC contents. Soil erosion phases based on original A horizon materials remaining in the topsoils may underestimate the extent of soil losses from topsoils and subsoils, particularly where soils have been cultivated for hundreds of years and are severely eroded. The SOC contents and soil erosion phases can be affected by losses or gains of organic C-rich sediments from tillage translocation and erosion, by management input level differences, oxidation, or as a result of land use and landscape position variations. Fly-ash was found to be more stable and act as a better indicator of soil erosion phase than SOC content.     

Restoration of surface soil fertility of an eroded red soil in southern China

To ameliorate degraded red soils and restore their productivity, it is necessary to quantitatively assess the effects of different land uses on soil fertility. In this study, surface soil samples (0–20 cm) under different land uses were collected from an 18-year ameliorative experiment site of a eroded red soil in Lanxi county, Zhejiang province of southern China. The status of surface soil fertility was quantified with a ryegrass growth test in the greenhouse and by numerical analysis of twelve important fertility indexes. The soil fertility indexes were grouped into three major factors using a factor analysis, i.e., organic matter-nitrogen-structure, acidity and phosphate. By means of principal component analysis and cluster analysis of these fertility factors, the fertility of the eroded red soil as a function of land use patterns had the following decreased order: vegetable land>paddy field, cropping arable land and ryegrass land>tea garden>citrus garden>forestland>wasteland. The result suggested that organic matter, total N, available N, and water-stable aggregates were the main characteristics for fertility restoration of the eroded red soil. Soil fertility was most rapidly restored where the soil had been used as vegetable land, and least restored when left as wasteland. The results indicated that land use strongly affected the fertility restoration of eroded red soils because of its effect on the input of nutrients and energy, thus determining the speed and direction of soil fertility evolution.     

Time and scale of gully erosion in the Jedliczny Dol gully system, south-east Poland

Key catchments of the Roztocze loess area in south-east Poland have a great potential of revealing the history of long-term soil erosion and changes in land use. The knowledge of how and when soil erosion took place in the past helps one understand the impact of land use changes on the landscapes [Bork, H.-R., 1989. Soil erosion during the past Millennium in Central Europe and its significance within the geomorphodynamics of the Holocene. Catena 15, 121–131]. The Jedliczny Dol gully system near the town Zwierzyniec in south-east Poland was investigated by using detailed field stratigraphy and radiocarbon dating of charcoal and wood.In connection with new settlements which were established between the 14th and 16th centuries, arable land was cultivated and forests were used much more intensively. As a consequence, the loess soils were strongly eroded during heavy rainfalls. Up to 4 m of colluvial sediments were deposited in the gully system during the 15th and/or 16th centuries. The thickness of the colluvial sediments indicate severe erosion which might be related to excessive timber exploitation for the local glass and iron production. With the foundation of the so-called Ordinariat Zamoyski at the end of the 16th century, some parts of the area were presumably reforested. High pressure on the land at the beginning of the 19th century enabled a second main phase of gulling before 1900.Since 1890 at the latest, almost the whole catchment is used as a forest, however, concentrated runoff on compacted forest roads can still be high after heavy rainfalls.In loess areas soil erosion caused by intensive land use, triggered by heavy rainfalls, can change the landscape drastically. These changes will continue to influence how catchments react, even if land use gets less intensive again. This knowledge should be considered regarding future, sustainable land use and recent changes in land use in the south-eastern Polish loess regions.     

Water erosion assessment using farmers' indicators in the West Usambara Mountains, Tanzania

The contribution of local knowledge to ecological sciences has not been fully exploited: there is still a gap between the recognition of farmers' knowledge as valid and an effective use of such knowledge in activities aimed at sustainable development. This study explores the use of farmers' indicators of erosion for developing a rapid tool for water erosion assessment at field level in the West Usambara Mountains (Tanzania). Two extensive field surveys were conducted in the research area concurrently. One survey consisted of applying an established erosion assessment method, the Assessment of Current Erosion Damage (ACED). According to the erosion features observed, fields were classified into five erosion classes, from very slightly eroded to very severely eroded. The second survey consisted of recording the type and number of indicators of erosion listed by farmers and present in the fields. The number of farmers' indicators per field increased with erosion intensity, from less than four in slightly eroded fields to more than eight in severely eroded fields. All farmers' indicators were positively correlated to the ACED erosion assessment classes. However, two groups of farmers' indicators could be distinguished in terms of erosion assessment: strong indicators, which were observed in more than 70% of cases in severely eroded fields, and weak indicators, which were observed more frequently in slightly and moderately eroded fields. Weak indicators appeared to be indicative of other land degradation phenomena, such as chemical fertility decline. Strong indicators and number of indicators were used to create a field erosion assessment tool in the form of a classification tree. The tree was built using one half of the field survey data and validated using the other half. The tree consisted of a hierarchical sequence of questions. Presence of rills and number of farmers' indicators were the most important factors of the tree. The validation yielded a highly significant Spearman's rho correlation coefficient (0.81). The contingency table showed that more than 80% of very severely eroded fields were correctly classified, whereas most misclassification occurred among slightly and moderately eroded fields. Farmers include land degradation phenomena and soil fertility decline in their definition of soil erosion. Soil and water conservation planning should address this broader farmers' perception by including, e.g., soil fertility improvements beside soil conservation. The distinction between strong and weak indicators of erosion is important in recommending the right intervention in the right spot, e.g., by counteracting soil erosion where strong indicators are present and by improving chemical fertility where weak indicators are present. The classification tree is of empirical nature and may need adaptation before being applied to other areas. The proposed methodology can be easily replicated and showed a high potential to provide extensionists with a field tool for erosion assessment. The classification tree was a successful example of integrating different types of knowledge for enhancing the co-operation between stakeholders involved in the erosion-control activities.     

东北黑土地保护利用研究足迹与科技研发展望

中国东北黑土是世界上最肥沃、垦殖时间较短的土壤类型之一,在保障国家粮食安全中具有非常重要的地位。本文在总结东北黑土地概况（定义、分布、土壤类型和垦殖时间）的基础上,梳理了东北黑土地的研究足迹,并提出了未来东北黑土地科技研发的方向。东北黑土地包括黑土、黑钙土、草甸土、白浆土、暗棕壤和棕壤6种土壤类型,主要分布在辽河平原、松嫩平原和三江平原。自然黑土肥力较高,但是开垦后受生态系统改变和人类活动的双重驱动,土壤肥力发了巨大变化,土壤有机质含量在垦殖初期（约30a）迅速下降,开垦50a后下降速度趋于稳定;侵蚀区黑土层受风蚀和水蚀等影响出现了不同程度的流失。有机培肥、轮作、等高种植等技术措施已经被广泛应用于黑土培肥与水土流失防治。黑土层是黑土地的标志性土层,是黑土地肥力的核心。基于黑土层保护的东北黑土地保护利用建议从以下3方面开展科学研究：（1）解析人类活动下的黑土层厚度及颜色变化过程和驱动机制,探索现代农业管理方式下维持和增加黑土层厚度的技术途径;（2）针对东北黑土地6种土壤类型耕地限制粮食生产能力的主控因子,因地制宜建立以“肥沃耕层构建”、“障碍性土层消减”和“控蚀固土增肥”为核心的东北黑土地保护利用技术模式,研发相关配套技术,探索模式的适应性及应用效果和机理;（3）以长坡为研究对象建立水土流失观测场,集中研发坡耕地控制面蚀和沟蚀的新技术和新模式。     

History, origin and extent of soil erosion on Easter Island (Rapa Nui)

The isolated Easter Island (Rapa Nui) is an outstanding example of land degradation caused by land use in a sensitive ecosystem. The focus of the investigation was placed on Poike peninsula, the most eastern part of Rapa Nui. While Poike peninsula was once supplied with fertile soils, in large areas desertification takes place today. Detailed analysis of soil profiles allowed the reconstruction of the history and of causes and effects of soil erosion and gullying in the context of land use history and cultural evolution. The results of the stratigraphic analysis prove that from the beginning of human settlement around AD 300/600 until AD 1280 the agriculture on Poike peninsula was characterised by sustainable land use and a traditional type of agro-forestry. Soil erosion was not significant. At around AD 1280 the woodland on Poike, dominated by the endemic palm Jubaea sp., was cleared by slashing and burning. Intensive farming on the upper slopes of the volcanic peninsula resulted in sheet erosion lasting until the 20th century. Settlements and ceremonial places which were built around AD 1300 on downslope areas were buried soon by sediments. Agriculture ceased around AD 1400 on downslope areas as the fertile soils were completely eroded. From AD 1400 until the late 19th century sheet erosion and the accumulation of fine-layered sediments migrated upslope. On average 8.6 Mg of soil per hectare and per year were reworked by erosion (eroded and accumulated within the catchment). Gullying began on Rapa Nui with the sudden increase in the number of sheep during the early 20th century. Gullies are still developing on the island and their ongoing enlargement created extended badlands on Poike which pose a significant problem for ecological and archaeological conservation strategies. Gullying rates exceed 190 Mg ha^{− 1} y^{− 1}.     

南方花岗岩区不同侵蚀土壤治理效果的研究

花岗岩红色风化壳广泛分布于我国南方山地丘陵区.其中的红色粘土层质地粘重且被铁铝氧化物胶结,与其下部的砂土碎屑层相比具有很强的抗蚀能力,对该区侵蚀的发展和治理具有重要意义.本研究通过对保留红色粘土层和砂石碎屑层裸露两种类型的侵蚀土壤在治理过程中保持措施的选择、植被和土壤肥力的恢复与土壤发育特点进行对比,说明了花岗岩区的侵蚀土壤在保留红土层时,土壤退化的程度轻,治理较容易,植被和土壤生产力的恢复较快;一旦红土层被侵蚀贻尽,侵蚀的速度加快,治理过程中植被和土壤生产力的恢复也慢.     

A comparison of the texture of grassland and eroded sandy soils from Shropshire, UK

In previous studies, periodic sampling of topsoils on runoff plots on sandy soils at the Hilton experimental site, Shropshire, UK, suggested erosion decreased the topsoil clay content and increased the coarse fraction. However, a comparison of soil and sediment properties suggested erosion selectively removed sand. Therefore, to cross-check the effects of erosion on soil properties, topsoil samples were collected from bare, eroded runoff plots and compared with samples from adjacent non-eroded grassland. Bare, eroded soil was stonier and particularly deficient in sand compared with grassed soil. Textural differences were very marked in the medium and coarse sands, especially the 0.5–1.0 mm fraction. On the basis of mean properties, the grassed soil was a very slightly stony loamy sand and the bare soil a slightly stony sandy loam. Soil organic matter was significantly less in the bare soils than the grassed soils and thus may have contributed to the higher erodibility of sands in bare soils.     

A participatory soil quality assessment in Northern Ethiopia's Mai-Negus catchment

Local communities often have substantial knowledge related to trends in soil quality and the associated limiting factors. Despite this, soil quality (SQ) degradation is a critical problem in Ethiopia and there is little or insufficient scientific information documenting local community experience in assessing SQ. This paper presents experiences of local communities in diagnosis of SQ and assesses the contribution of local knowledge as a strategy for sustainable development decision making within the Mai-Negus catchment of northern Ethiopia. Participatory transect-walks, group discussions and field observation which complemented by household interview were used to acquire data. Farmers identified SQ indicators e.g., crop yield, soil depth, erosion and sedimentation as their basis of categorizing the soils into high, medium and low SQ. They were also able to identify severely degraded areas (hotspots) and underlying causes. Significant variations (P ≤ 0.05) were shown between the proportions of farmers used certain SQ indicator and those who didn't while categorizing SQ. Local farmers involved in this study demonstrated their capability to suggest appropriate land management solutions for specific problems. This study demonstrates the benefit of involving local farmers in both problem identification and solution development so that anti-degradation technologies can easily be implemented and adopted.     

闽南花岗岩侵蚀区土壤退化与治理

闽南侵蚀面积达5000多平方公里,占土地面积20％强,人口密度约450人/km²。水土流失原因除了自然因素外,更主要的是人口密集,由于生产、生活和建设的需要,严重地破坏了植被,造成人为水土流失,致土壤浅化、沙化与瘠瘦化。治理经验证明:开发性治理,变水土流失区为经济作物区,不但防止了水土流失,而且扩大耕地面积并恢复提高地力,创造土地永续利用的条件。治理原则和方法是:统一规划,因地制宜,合理布局,建设成商品化的果林基地;长短结合,提高坡地利用率;工程与生物措施相结合;加强土壤管理,提高土壤肥力,增强生产后劲。     

香港土壤研究 Ⅰ.研究现状与展望

对近半个世纪以来香港地区的土壤分类、农业和园林绿地土壤的肥力以及土壤环境保护等研究工作进行了系统的回顾和介绍,为中国香港地区及其他社会经济快速发展地区的土壤资源合理利用、生态环境保护与社会可持续发展提供了科学信息。认为,高度城市化和国际化的香港地区可以结合香港高科技及新产业的发展目标,合理利用和开发土地资源,定向培育中草药产地土壤环境与教育基地;需要进一步系统研究香港地区土壤发生与系统分类、性状与特征、空间分布与变异规律,建立香港土壤基础数据库、土壤图和土壤信息与服务系统;进一步探明污染元素和有益元素的土壤地球化学背景以及持久性有机污染物的环境生物地球化学过程及其生态与健康风险,建立长期的土壤环境质量动态观测点与研究平台,以及区域尺度的土壤环境质量信息系统和定量可视化预测预警系统;研究与发展适合香港地区的有问题土壤的风险评估与修复技术体系     

Soil Structural Stability and Water Retention Characteristics Under Different Land uses of Degraded Lower Himalayas of North‐West India

The lower Himalayan regions of north‐west India experienced a severe land‐use change in the recent past. A study was thus conducted to assess the effect of grassland, forest, agricultural and eroded land uses on soil aggregation, bulk density, pore size distribution and water retention and transmission characteristics. The soil samples were analysed for aggregate stability by shaking under water and water drop stability by using single simulated raindrop technique. The water‐stable aggregates (WSA) >2 mm were highest (17·3 per cent) in the surface layers of grassland, whereas the micro‐aggregates (WSA < 0·25 mm) were highest in eroded soils. The water drop stability followed the similar trend. It decreased with the increase in aggregate size. Being lowest in eroded soils, the soil organic carbon also showed an adverse effect of past land‐use change. The bulk density was highest in eroded lands, being significantly higher for the individual aggregates than that of the bulk soils. The macroporosity (>150 µm) of eroded soils was significantly (p < 0·05) lower than that of grassland and forest soils. The grassland soils retained the highest amount of water. Significant (p < 0·05) effects of land use, soil depth and their interaction were observed in water retention at different soil water suctions. Eroded soils had significantly (p < 0·05) lower water retention than grassland and forest soils. The saturated hydraulic conductivity and maximum water‐holding capacity of eroded soils were sufficiently lower than those of forest and grassland soils. These indicated a degradation of soil physical attributes due to the conversion of natural ecosystems to farming system and increased erosion hazards in the lower Himalayan region of north‐west India. Copyright © 2013 John Wiley & Sons, Ltd.     

不同肥力水平和利用历史的红壤磷脂脂肪酸图谱

Analysis of phospholipid fatty acids(PLFAs) was used to estimate the microbial community structures of eight Chinese red soils with different fertility levels and land use histories.The total amounts of PLFAs in the soils were significantly correltaed with soil organic carbon, total nitrogen,microbial biomass C and basal respiration,indicating that total PLFA was closely related to fertility and sustainbility in these highly weathered soils.Soils of the eroded wastelan were rich in Gram-positive species .When the eroded soils were planted with citrus trees,the soil microbial population had changed little in 4 years but took up to 8-12 yearss before it reached a significantly different population,Multivariate analysis of PLFAs demonstrated that land use history and plant cover type had a significant impact on microbial community structure.Howver,the difference of soil microbial community structure in the paddy field compared to other land uses was not larger than expected in this experiment.     

Soil erosion: An important indicator for the assessment of land degradation neutrality in Russia

This review of soil erosion (SE) studies in Russia focuses on two main tasks: (i) ensuring the completeness and reliability of SE data in Russia, a large country (17.1 million km²) with a variety of natural and socio-economic causes of land degradation, (ii) assessing the possibility of including a SE indicator among the indicators of land degradation neutrality (LDN). A wide range of statistical, remote sensing, mathematical modeling data, the results of scientific and field studies obtained at different levels were analyzed. It is asserted that in Russia the total area of eroded lands and those under erosion risk occupy more than 50% of all agricultural lands, whereas soil fertility of croplands decreased in Soviet time (from 1950s to 1980s) by 30–60% only due to water erosion. However, recent scientific studies indicate a decrease in erosion rate and in the area of eroded land during the last 30–40 years as a result of abandonment of arable land and subsequent overgrown with natural vegetation. The climate change resulting in decrease of the depth of soil freezing, flow of spring runoff also adds to the decrease of soil erosion. The SE indicator was suggested as an important complement to three global LDN indicators. At national and subnational level, it can be interpreted through such indices as “Rate of soil loss” (ton ha-1 yr-1) and “Total soil loss” (1000 tons, in certain area during selected time period). At local level the set of indices can be wider and site-specific, including those obtained through remote sensing data by using the classifier of thematic applications of remote sensing technologies; the example was tested at the local site.     

Changes in soil properties across a chronosequence of vegetation restoration on the Loess Plateau of China

Soil fertility is important for vegetation growth and productivity. The relationship between vegetation and soil fertility is important for both scientific and practical reasons. However, the effects of soil fertility on vegetation development and succession are poorly documented on the Loess Plateau. In this study, we compared soil properties of the Yanhe Watershed in northern Shaanxi across five different land uses (shrubland, farmland, natural grassland, woodland and artificial grassland) and a chronosequence of soils undergoing restoration for 5, 10, 15, 20, 25, 30, 35, 40 and 45 years. We found that revegetation had a positive effect on soil bulk density decrease, total porosity and capillary porosity increase in the surface soil layers but not in the subsurface layer. Additionally, soil organic matter, total nitrogen, available nitrogen and available potassium were greater at shrubland and woodland sites compared with other land uses. Total phosphorus and available phosphorus were greater at farmland sites. Results of the study indicate that revegetation on eroded soil can produce important increases in soil fertility on older plantations and in areas with natural succession.     

南方红壤丘陵区土壤侵蚀-沉积作用对土壤酶活性的影响

土壤酶与土壤矿质营养元素循环、能量转移等密切相关。明确土壤酶对土壤侵蚀—沉积作用的响应机制,有助于进一步把握土壤侵蚀在全球碳循环中的作用。通过分析湘中红壤丘陵区松林坡面侵蚀区及沉积区土壤酶活性的变化特征,揭示了酶活性与土壤主要养分因子之间的关系,并在此基础上深入探讨了土壤侵蚀—沉积作用对土壤酶活性的影响。结果表明:沉积区绝大多数土层土壤有机碳(soil organic carbon,SOC)、全氮(total nitrogen,TN)、可溶性有机碳(dissolved organic carbon,DOC)、脲酶、酸性磷酸酶及过氧化氢酶活性均要显著高于侵蚀区。土壤沉积作用明显提高了土壤养分含量及酶活性。其次,侵蚀区与沉积区土壤养分含量及酶活性差异在侵蚀干扰较为严重的表层(0~30 cm)土壤表现较为明显,随着土壤深度的增加差异逐渐减小。侵蚀区与沉积区SOC、TN、DOC及酶活性均随土壤深度的增加呈现总体下降的趋势。相关性分析表明,土壤脲酶、酸性磷酸酶、过氧化氢酶之间及其与SOC、TN、DOC之间均存在极显著正相关关系(p0.01)。此外,偏冗余分析结果进一步表明SOC是解释土壤酶活性动态变化的主要因子,其解释量达7.5%,侵蚀诱导SOC在坡面的再分布是影响土壤酶活性的重要途径之一。     

Evaluation of soil erosion risk and identification of soil cover and management factor (C) for RUSLE in European vineyards with different soil management

Vineyards show some of the largest erosion rates reported in agricultural areas in Europe. Reported rates vary considerably under the same land use, since erosion processes are highly affected by climate, soil, topography and by the adopted soil management practices. Literature also shows differences in the effect of same conservation practices on reducing soil erosion from conventional, bare soil based, management. The Revised Universal Soil Loss Equation (RUSLE) is commonly adopted to estimate rates of water erosion on cropland under different forms of land use and management, but it requires proper value of soil cover and management (C) factors in order to obtain a reliable evaluation of local soil erosion rates. In this study the ORUSCAL (Orchard RUSle CALibration) is used to identify the best calibration strategy against long-term experimental data. Afterwards, ORUSCAL is used in order to apply the RUSLE technology from farm based information across different European wine-growing regions. The results suggest that the best strategy for calibration should incorporate the soil moisture sub-factor (S_m) to provide better soil loss predictions. The C factor, whose average values ranged from 0.012 to 0.597, presented a large spatial variability due to coupling with local climate and specific local management. The comparison across the five wine-growing regions indicates that for the soil protection management, permanent cover crop is the best measure for accomplishing sustainable erosion rates across the studied areas. Alternate and temporary cover crops, that are used in areas of limited water resources to prevent competition with vines, failed to achieve sustainable erosion rates, that still need to be addressed. This raises the need for a careful use of C values developed under different environmental conditions.     

应用数值分析试论黄土丘陵区侵蚀土壤的发展规律——以固原县为例

侵蚀土壤是水土流失历史过程中的一面镜子,在一定程度上,它反映过去的流失程度,也反映目前土壤的肥力水平.我国黄土丘陵区侵蚀土壤分布之广,侵蚀程度之烈,是世界上罕见的.研究侵蚀土壤的发展规律及其与侵蚀因子间的相互关系,对合理利用土地、制定保土措施有一定的指导意义.本文以宁夏固原县侵蚀土壤调查资料为例,并应用数值分析的结果,探讨黄土丘陵区侵蚀土壤的发展规律,为防治水土流失提供科学理论依据.     

Experiment of "No-Tillage" Farming System on the Volcanic Soils of Tropical Islands of Micronesia

The soils of southern Guam are formed from very deep; well-drained Saprolite derived from volcanic based tuff and tuff breccias. These soils suffer severe erosion as the result of rapid overland flow, wind and intensive rain events typical of southern Guam. An integrated approach to control the accelerated soil erosion was designed to include conservation tillage, crop rotation with leguminous plant, and residue management for soil surface cover.The objectives of this study are; 1) to evaluate the use of crop rotation and tillage management for increasing organic-matter content to improve the overall quality of these severely eroded soils, 2) to evaluate the effect of conservation practices on harvested yield and crop productivity of these eroded soils and, 3) to assess the effects of conservation techniques including no-tillage systems on water runoff and infiltration. This paper discusses the effect of conservation strategies and techniques on these severely eroded soils of southern Guam.