关于侵蚀土壤退化及其机理

本文首先对土壤退化的涵义作了概要介绍，并根据土壤退化不同成因，将之区分为受自然因素影响的和受人为因素与自然因素双重影响的两种土壤退化类型；文中就土体构型变化、养分循环失衡、理化性质劣化和逆向发育等方面，重点阐述了侵蚀土壤退化的过程及机理。     

金沙江干热河谷典型区土壤退化机理研究——土壤侵蚀对土壤退化的作用

云南省金沙江干热河谷典型区土壤侵蚀普遍而严重 ,对土壤退化有关键性影响。通过对该区不同退化土壤的侵蚀状况 ,从土壤侵蚀对土壤退化的空间分布格局 ,土壤侵蚀对土壤退化类型的发生和作用机制 ,探讨了土壤侵蚀对土壤退化的作用和影响。结果表明 :(1)侵蚀和水土流失是造成土壤退化的要因 ,不同侵蚀类型及其强度控制了土壤退化的空间分布 ;(2 )土壤侵蚀对土壤退化的作用机制主要是 :不同土壤侵蚀强度 ,决定了土壤退化发生类型的数量和程度 ;通过对该区几类主要土壤退化类型发生机制进行分析 ,看出土壤侵蚀是以冲刷剥蚀、搬运扩散和沉积掩埋等作用为主 ,造成和加速了土壤退化的发生和发展。     

土壤退化时间序列的构建及其在我国土壤退化研究中的意义

我国土壤退化发生广、发展快,后果严重,很多问题亟待解决,加大其研究力度势在必行。显而易见,人们对土壤特性与土壤退化过程了解得越详细,对土壤退化的评估与防治也会越好。因此迫切需要建立大量土壤退化时间序列来明确土壤退化过程中时间因素的作用并帮助人们正确理解和认识土壤退化与人为作用之间的关系。为了得到可靠的结果,土壤退化时间序列的建立需包括起始土壤相似性判定与退化土壤绝对或相对年龄的验证两个重要过程。本文详细论述了土壤退化时间序列的构建过程及应注意的问题,并探讨了土壤时间序列在我国土壤退化研究中的意义,旨在为土壤退化时间序列的正确建立与应用提供较为详尽的参考。     

吉林省西部土壤退化特征及机理分析

以吉林省西部土壤退化典型地区大安市和长岭县为例，研究、分析了该地区土壤退化特征及机理。该地区的土壤退化主要表现为营养成分的减少，有害的盐碱成份的增加。造成土壤退化的原因既有自然因素也有人为因素，自然因素是土壤退化的基础和潜在因素，人类不合理活动是土壤退化的诱发因素和主要因素。借助于GIS，SPSS技术，揭示了土壤化学成分在水平、垂直方向的动态变化和分布规律。该区的土层结构复杂，土壤剖面含盐量的分布呈“T”形、正“梯”形、负“梯形”和“柱”形等形态。     

土壤侵蚀退化研究进展

从土壤物理退化、化学退化和生物学退化等3个方面回顾了国内外的土壤退化过程研究的历史与现状，全总结了国内外在土壤侵蚀退化形成的过程、机理、影响因素以及评价土壤退化的指标方法等方面的最新研究进展，最后提出了土壤退化过程和防治方法研究中存在的主要问题，并从多学科交叉的角度和土壤侵蚀退化机理研究及定量动态监测度来展望土壤侵蚀退化研究的进一步发展方向。     

福建省长汀县水土流失区土壤退化及其恢复研究

土壤退化是指在不利的自然条件和人类对土壤的不合理利用等因素影响下,造成水土流失,导致土壤物理、化学和生物学性质的下降过程。本文通过对长汀县不同侵蚀强度水土流失区的土壤调查,分析其土壤退化的因子,并对长汀强度侵蚀区治理2～3年、10年、15年和30年的样地进行布点调查、取样分析其土壤理化性质,来研究水土流失治理区土壤恢复过程。     

农村居民点整理不同阶段农户参与行为影响因素分析

为探讨农村居民点整理中农户参与行为机制及其影响因素,该文基于江苏省5县531个农户的调研数据,实证分析了不同农村居民点整理阶段农户参与行为特征及其影响因素的差异。结果表明:1)不同农村居民点整理阶段,显著影响农户参与行为的因素存在较大差异。2)所有因素中,农户整理内容认知对农户整体参与行为、决策制定参与行为影响分别在5%及1%的水平上显著;农户参与能力认知对农户决策制定参与行为、施工建设参与行为的影响分别在1%及10%的水平上显著;来自外部环境中的政府支持度对农户整体参与行为的影响在5%的水平上显著,对农户施工建设参与行为以及后期管护参与行为的影响则均在1%的水平上显著。3)农户受教育年数以及家庭年收入均未对任何类型的农户参与行为产生显著影响。建议未来应制定差别化政策激励农户全过程参与,并着重于信息公开制度的完善、农户参与能力的提升、参与程序的制定以及参与外部制度环境的建设。     

西藏“一江两河”地区土壤退化特征

西藏“一江两河“地区日趋严重的土壤退化是由其生态环境的脆弱性、地貌结构的特殊性，特别是人类影响和干预的广泛性、非合理性决定的。在阐述土壤退化类型、特征的基础上，就土壤退化的发生机制进行了综合分析。     

合作社发展模式下农户实施农业标准化的效益分析

本文通过对吉林、浙江、陕西3个省份16个县市的农户进行调研．运用描述统计分析方法和Logistic回归模型，分析了合作社发展模式下农户实施农业标准化的影响因素以及效益，结果表明，劳动力的投入、文化素质和培训、经验借鉴、生产认证、产品销售渠道、政府资金支持等因素对农户的比较价格优势和比较效益优势具有不同程度的影响．在此基础上提出了相应的政策建议。     

黄河三角洲典型生态脆弱区土壤退化遥感反演

黄河三角洲是典型的生态环境脆弱区,土壤质量不高,盐渍化状况普遍,快速准确掌握该区土壤退化状况,对退化土壤恢复重建、可持续利用具有重要意义。该研究选择黄河三角洲垦利县为研究区,以2008年实测数据为依据,通过建立土壤退化评价指标体系,以参评因素权重与隶属度值加权组合构建土壤退化综合指数,在GIS支持下对土壤退化进行了综合评价;采用与实测同时相的TM影像数据,结合不同程度退化土壤光谱特征、土壤退化综合指数与波段灰度值的相关性分析,筛选土壤退化敏感波段,进而构建土壤退化敏感光谱指数,并建立基于敏感光谱指数的土壤退化综合指数反演模型,最终筛选出拟合程度最高的指数模型作为研究区土壤退化的反演模型,对模型进行精度分析,并利用2008年遥感影像验证反演结果;将该反演模型应用于2011年和2013年的遥感影像,并对研究区2008-2013年的土壤退化状况及动态变化进行了分析。结果显示:基于土壤退化综合指数评价结果,研究区土壤退化程度从沿海到内陆呈现由高到低过渡的趋势;TM1、TM2、TM3波段为土壤退化敏感波段,基于此3个波段组合的土壤退化光谱指数构建的土壤退化遥感反演模型有较高的精度,R2为0.7182,其验证均方根误差、相对误差和决定系数分别为0.0241、3.66%和0.6724,反演结果与同年基于实测数据的综合评价结果相一致;研究区2008-2013年土壤退化状况总体变化不大,有逐渐改善趋势。     

红壤丘陵区农户水土保持投资行为研究--以江西省余江县为例

通过对余江县3个乡镇的农户访谈式调查,对农户水土保持行为机理进行了分析。研究表明农户兼业行为、传统生产习惯、农业经营规模、农业劳动力状况、水土流失现状与家庭经济条件等因素对农户水土保持行为有较大影响。通过相关性分析,建立了多元线性回归模型。模型运行结果表明,农户水土保持行为主要受到非农收入比例、从事农业生产的时间、从事农业人口数量、经营土地面积、水土流失减产损失、家庭人均收入以及距离城市远近等因素的影响。非农收入比重高的农户,水土保持投入的积极性不高。农业人口多的农户,或者受家族传统影响较勤劳的农户,其水土保持投资也多。据此,提出了激励农户水土保持投资行为和改善水土流失治理现状的相关建议。     

The economics of soil productivity: local,national and global perspectives

Soil degradation is a mounting problem on many smallholder lands in developing countries. Economic analysis has been an important tool in addressing this problem, beginning with assessments of the financial attractiveness of investing in soil conservation works. Data compiled from 67 studies of the financial attractiveness of conservation technologies suggest that many can provide positive net returns at the farm level (64·2 per cent). While such studies have made a valuable contribution, economists have been exploring additional applications of economics to the problem, such as the development of new perspectives under the guise of ecological economics. As a result, this paper argues it is an opportune time to assess progress in the field of economic analysis of soil degradation and to consider the policy ramifications of this research. Key issues are grouped into farm‐level considerations, national policy linkages and global issues. A number of policy implications emerge. Clearly, devising effective incentives at the farm or community (collective action) level must be a priority. As part of this effort, even more attention should be paid to the influence of macroeconomic and sectoral policies on soil productivity. Since soil degradation is also a problem with global ramifications, there is a clear rationale for intervention at the international level via mechanisms such as international transfers. Copyright © 2004 John Wiley & Sons, Ltd.     

Determinants for adoption of physical soil and water conservation measures by smallholder farmers in Ethiopia

Adoption rates of soil and water conservation measures remain below the expected levels in Ethiopia despite the considerable investments in reducing land degradation and improving soil fertility. This constitutes one of the key research agendas in the country. This paper underscores the need for investigating the factors hindering or facilitating the adoption of soil and water conservation measures. The study results presented in this paper are based on cross-section data collected from 408 households in eastern Ethiopia, including field observations of 790 plots selected using a multi-stage sampling procedure. A multivariate probit model was employed to analyse the determinants of adoption of three soil and water conservation measures (stone bund, soil bund, and bench terracing) at the plot level. The study findings reveal that household, socioeconomic, and institution characteristics were the key factors that influenced the adoption of soil bund, stone bund, and bench terracing conservation measures. Furthermore, there was a significant correlation among the three soil and water conservation measures, indicating that the adoption of these measures is interrelated. In particular, the results show that there was a positive correlation between stone bunds and soil bunds. However, the correlations between bench terracing and stone bunds as well as bench terracing and soil bunds were negative (implying substitutability). These results imply that the Government and other relevant organizations that are responsible for reducing land degradation in order to increase agricultural production should support the establishment and strengthening of local institutions to facilitate the adoption of soil and water conservation measures.     

Upland Farming System Erosion Yields and Their Constraints to Change for Sustainable Agricultural Conservation Practices: A Case Study of Land Use and Land Cover (LULC) Change in Indonesia

In the upper catchments of Southeast Asia, land use change from forest to agricultural systems generated land degradation and conflicts between uplanders and lowlanders. More sustainable cropping systems are proposed to upper‐catchment farmers. Grass fodder strip (GFS) is an effective anti‐erosion practice, and it involves lower costs for farmers. However, labour and cash constraints are sometimes preventing farmers to implement it. To evaluate farms' current impact and adaptation capacities, we need a comprehensive understanding of farm and farm household characteristics that influence their activities. This paper proposes an approach that combines farm household surveys and modelling of farm erosion yield to help project planners and policy makers to identify such farmers in a data‐scarce environment. We developed two farm typologies—one based on both farm and farm household characteristics and one based on their erosion yield and constraints. We calculated erosion yields on plot level by using revised universal soil loss equation method and identified their constraints. We found that a typology based on farm constraints and calculated farm erosion was a good complement to identify farmers who are generating the highest erosion yields and would be able to change their production systems. This methodology is mainly useful at the beginning of conservation projects, when very few hard data are available. Copyright © 2016 John Wiley & Sons, Ltd.     

江苏典型农户农业生态系统能量分析

本文对实行家庭联产承包责任制后的典型农户农业生态系统进行了能量的投入产出分析,从能量的角度提出了该系统的基本特征,并在此基础上对整个农村的能量的合理流动作了分析和探讨。     

Social and economic factors affecting the adoption of soil and water conservation in West Usambara highlands,Tanzania

Accelerated soil erosion is one of the major constraints to agricultural production in many parts of the Tanzanian highlands. Although several soil and water conservation technologies have been developed and promoted, the adoption of many recommended measures is minimal and soil erosion continues to be a problem. This research was conducted in order to determine the social and economic factors that influence adoption of soil and water conservation (SWC) measures in the West Usambara highlands, Tanzania. For this research a household survey, group discussions and transect walks were undertaken. A total of 104 households were interviewed and several fields were visited during the transect walks. Data was analysed with the use of cross‐tabulation, cluster analysis, factor analysis and chi‐squared methods. The results obtained indicate that involvement in off‐farm activities, insecure land tenure, location of fields and a lack of short‐term benefits from SWC are among the major factors that negatively influence adoption of SWC measures. Membership in farmer groups, level of education, contacts with extension agents and SWC programmes were found to be positively influencing the adoption of SWC measures. Recommendations to facilitate adoption of different SWC measures include: integration of social and economic factors into SWC plans; the creation of more awareness among farmers of soil‐erosion effects and long‐term benefits of SWC; the development of flexible SWC measures to cater for different farm patterns and a participatory approach to SWC at catchment level rather than at individual farmers' fields. Copyright © 2004 John Wiley & Sons, Ltd.     

Aggregate stability in organically and conventionally farmed soils

A range of factors that influence aggregate stability and soil erodibility were analysed for soils sampled from land managed under contrasting agricultural methods. These included: an organic farm; a conventional farm that incorporated organic fertilizers; a conventional farm that only used inorganic fertilizers; and a non-cultivated control site. The stability of aggregates that compose the bulk soil structure (macroaggregates), and aggregates that were mobilized from the soil by simulated rainfall and surface runoff (microaggregates), were evaluated in terms of the soil fragmentation fractal dimension, organic carbon content and ATP (adenosine 5'-triphosphate; a signature of live biomass) concentration. The results were used to interpret the existing physical condition of the soils, the (microbial) processes that contribute to that physical structure, and how both pedogenic processes and existing soil quality are influenced by agricultural methods. The soils sampled for this study were demonstrated to be multi-fractal in nature: soils with greater bulk density were composed of more stable macro-aggregates, which, in turn, fragmented into larger, more stable micro-aggregates, rendering the entire soil structure less erodible. Soil erodibility and sustainable soil management should therefore be approached at multiple scales. The primary control on both macro- and micro-aggregate stability was determined to be the organic matter input to the soil, as represented by measurements of organic carbon and ATP. Organic content was greatest for the non-cultivated soil, which reflects the degradation of organic reserves in cultivated soils. For cultivated soils, it was not possible to differentiate aggregate stability for soils managed under organic or conventional (i.e. using biological and inorganic fertilizers) farming practices, but aggregates of soils that only received artificial fertilizers consistently exhibited less stability.     

The role of social capital in the promotion of conservation farming: the case of ‘landcare’ in the Southern Philippines

‘Social capital’ refers to the relationships of trust, communication, and cooperation that facilitate collective action in a community. It is particularly relevant to soil conservation in developing countries, which requires collective efforts to raise awareness of soil degradation, provide effective training in soil conservation practices, and implement soil conservation measures on individual farms. The Landcare Program in the Southern Philippines promotes simple conservation practices in upland environments through establishing and supporting community landcare groups and municipal landcare associations, thus augmenting the social capital of farmers in these locations. An evaluation of the Landcare Program in Barangay Ned, South Cotabato, based on a survey of 313 farm households and case studies of nine landcare groups, shows that, despite extreme isolation and difficult working conditions, farmers responded by rapidly forming landcare groups and a landcare association, and adopting contour barriers on their maize farms. They utilized the bonding social capital inhering in their local communities to build stocks of bridging social capital, linking them to information, training and resources from outside their immediate locality. A logistic regression model of the factors affecting adoption of contour barriers shows that farmers who had undergone the practical, farmer‐based training provided by the Landcare Program, and who were members of a landcare group, were significantly more likely to adopt conservation measures. These results confirm the value of investing in social capital to promote soil conservation. Copyright © 2005 John Wiley & Sons, Ltd.