肯尼亚的土壤保持

<正>1 概况肯尼亚是一个东非国家,位于东经31°~41°的赤道地区。国土面积;582 648km~2,现有人口大约为420万。农业是肯尼亚经济的支柱,可耕种面积占国土面积的1/5。因为人口以每年略高于3%的速度高速增长,所以肯尼亚需要在有限的土地资源上扩大农业生产以保证农业对国民经济的有效支持。通过保护水土资源,这一设想可能得以继续。     

土壤保持与土壤管理

土壤保持是经常涉及到与风蚀、水蚀有关的主要的土地退化活动.土壤保持是一个较为广泛的问题.不仅关系到主要侵蚀活动,而且也关系到影响着土壤肥力总体保持的较为缓慢的、连续不断的隐伏过程.土壤紧实,土壤有机质、土壤养分含量和微生物活动能力减少,都是土壤保持专家应予关心的问题.土壤保持往往被认为是用以防止土地退化的一些技术,缺乏农学知识的土木工程师经常持己看法,而又使这种看法得以强化.对农民来说土壤保持会被认为是不可理解、不适合当地条件的不必要的花费.在国际土壤研究与管理委员会的观点看来.土壤保持是土壤管理实践能力维持方面的一部分,既无需破坏表土地上层.还要与耕作制度相结合及适宜生境的特性.土壤保持问题涉及国际土壤研究与管理委员会(IBSRAMS)的三个主要目标,首先是关于以供养农业为目的的热带土地的开垦.另一方面还涉及酸性带土壤管理和森林土壤的管理.     

埃塞俄比亚土壤保持研究

为了改进农业生产,埃塞俄比亚农业部正做出极大努力进行土壤保持.到目前为止,社区森林土壤保持开发部在过去的十年中对一百多万公顷的土地实施了土壤保持措施.但在这个农业生态因素具有很大变异性的国家里,通过对地方问题的发现而研究出的系统性的方法是十分缺乏的,结果土壤保持工作没有得到预想的效果.为了填补这一空白.由瑞士政府提供资金由伯尔尼大学和社区森林土壤保护开发部负责实施的土壤保持研究计划在1981年开始实施.这个研究项目包括埃塞俄比亚的沃洛,哈勒尔盖,锡达莫、谢野哇、戈贾姆和厄立特里亚六个试验基地,覆盖了埃塞俄比亚高原的六个最主要的农业气候带.现在,这个项目已经对科学理解埃塞俄比亚土壤冲蚀过程作出了重大贡献,并且就田间改进土壤保持措施提出了有用的建议.供研究开发人员使用的埃塞俄比亚土壤保持指南在社区森林土地开发部的协助下已经设计出来并出版了.     

论森林与土壤保持

本从森林土壤抗蚀性，林木根系对土壤固持作用，森林改良土壤作用，降低径流侵蚀力等方面论述了森林防止土壤侵蚀的良好功能，并从森林覆盖率，林地利用方式等与土壤侵蚀的关系阐明了森林的保土作用，对充分认识森林的水土保持作用，推动森林的保护和绿化事业具有重要意义。     

杭州湾南岸农业生态系统土壤保持功能及其生态经济价值评估

文章运用土壤通用流失方程(USLE)研究了杭州湾南岸农业生态系统的土壤保持功能,并评价了其经济价值.研究表明,由林地、水田和旱地组成的杭州湾南岸农业生态系统的土壤保持量为5.67×105 t/a,其经济价值为20.35×105元/a,其中减少土壤废弃的经济价值为12.33×105元/a,保持土壤养分价值为4.92×105元/a,减少泥沙淤积价值为3.10×105元/a.     

黄骅市土壤保持价值年内动态特征

掌握不同生态系统类型土壤侵蚀和土壤保持量的年内动态变化,对于区域水土保持重点及时序安排具有积极的指导作用。本研究在GIS支持下,运用通用土壤流失方程(USLE)对河北省黄骅市不同生态系统年内土壤侵蚀与保持量进行计算,并利用市场价值法、机会成本法对各生态系统类型年内各月的土壤保持价值进行测算,研究黄骅市土壤保持价值年内动态特征。研究表明,黄骅市全年各月土壤保持价值分配不均,年内动态特征与土壤保持量的季节动态变化规律一致,8月达到最大峰值,1—3月、10月、12月价值均为零,5—8月呈增加趋势,5—9月土壤保持价值占全年土壤保持价值的82.47%。从各生态系统类型来看,草地8月的单位面积土壤保持价值最大,为128.87元·hm?2;水域9月的单位价值最小,为11.23元·hm?2。从土壤保持价值构成来看,年内各土壤保持功能单位面积贡献价值大小排序为:减少土壤养肥流失价值减少淤泥淤积价值减少废弃土地价值。研究区各生态系统类型的土壤保持价值具有明显随季节变化的规律,在雨季受暴雨等短期大量降水的影响,土壤潜在的侵蚀量增大,而生态系统的土壤保持功能和价值在此过程得以发挥作用。     

淮阴市土壤有机质含量及其保持措施

本文对淮阴市所辖各县主要土壤的有机质含量及其保持措施进行了研究和讨论。     

我国土壤有机质和有机肥料研究现状

本文简要的回顾了四十年来我国在土壤有机质的组成、性质、转化，有机肥对植物生长的直接作用和间接作用等方面的一些研究工作，讨论了有机质的组成、性质与成土因子的关系，指出了我国应坚持有机肥与无机肥配合的这一施肥制度。     

基于FRN技术的我国不同地区典型土壤保持措施的有效性评价

选择中国西南-东北样带4个典型土壤侵蚀区,包括位于长江上游的西昌,黄土高原延安,北方风蚀区的丰宁和东北黑土区的拜泉,应用环境放射性核素(FRN)技术研究了不同土壤保持措施在减少土壤侵蚀、改善土壤质量方面的作用。在西昌,137Cs和210Pbex的测定结果表明,不同植被覆盖结构减少土壤侵蚀的作用为:灌木>有地被物的乔木>草类>无地被物的乔木;在延安,利用137Cs示踪技术对坡地景观的产沙量估算结果表明,梯田和林草地相对于坡耕地产沙量分别减少了49%和80%,林草地的土壤有机质、碱解氮和速效磷含量相对于坡耕地分别增加了255%、198%和18%,梯田土壤有机质、碱解氮和速效磷含量分别增加了121%、103%和162%,而土壤容重分别降低了1.6%和6.4%;在丰宁,对7Be的测定结果表明,与传统耕作方式相比,4年免耕+作物高留茬(50～56cm)和免耕+作物低留茬(25cm)分别使土壤侵蚀速率下降44%和33%;在拜泉,通过137Cs测定结果发现,坡改梯使土壤流侵蚀降低14%,等高耕作使土壤侵蚀量减少了34%。研究结果说明,灌木林覆盖、林草复合结构是控制西南侵蚀山地土壤侵蚀的优选生物配置措施,梯田和林草复合结构在控制黄土高原土壤侵蚀和改善土壤质量方面有重要作用,免耕+高留茬措施是我国北方风蚀区防治土壤侵蚀退化的有效措施,等高耕作应当成为防治东北黑土区土壤侵蚀的关键措施。     

水土保持功能评价及其在水土保持区划中的应用

随着国家对生态文明建设的日益重视,以及国家及地方主体功能区规划的实施,对于水土保持的功能研究也越来越多.结合全国水土保持规划工作的需要,提出水土保持功能的概念、类型确定原则和功能类型,阐述了水土保持基础功能和社会经济功能的评价方法,以及各基础功能的评价指标体系.以太行山东部山地丘陵区为例,举例说明水土保持功能评价的过程和结果.对全国水土保持区划三级区基础功能进行统计分析,明确各功能的区域比例,提出8个一级区水土保持工作主要方向,维护和提高区域水土保持功能将成为水土保持工作的重点和方向.     

水土保持与发展我国持续农业的关系

对我国土壤侵蚀的严重性,阐明了持续农业的内在涵义,从农业土地和农业经济的损失两个方面,着重叙述了土壤侵蚀对我国持续农业的危害;系统分析了水土保持与发展我国持续农业的内在联系。最后,从水土保持角度提出了发展我国持续农业的主要策略和措施。     

Integrating biophysical and socio‐economic aspects of soil conservation on the Loess Plateau,China. Part II. Productivity impact and economic costs of erosion

Using the simulation model described in Part I, this paper examines the impact of erosion on soil productivity, how the impact varies according to initial soil conditions and organic matter management and the economic cost of erosion measured as net present value. The reference crop is winter wheat grown in Chunhua in the southern Loess Plateau. Biomass yield is plotted over 100 years for four erosion scenarios represented by 0, 9, 27 and 47 per cent slopes, three initial soil conditions indicated by 0·5, 1 and 2 per cent organic matter, and two management levels determined by high or low levels of reincorporation of organic residues. Calculations of soil productive half‐life (time to half initial yield) and whole‐life (to equilibrial yield) are presented. The principal findings are that decline in soil productivity is caused by both erosion and insufficient return of organic matter. By increasing organic matter input, erosion damage is offset and soil productive life prolonged, but this is a costly strategy. If yield decline caused by erosion is isolated, erosion control is more important on a high organic matter input system. A maximum soil productive half‐life of 600 years is achieved with no erosion, high initial organic matter and return of organic residues; minimum half‐life of 10 years is with high erosion, low initial organic matter and little return of residues. In between, there are complicated interactions that significantly affect the economic cost of erosion and hence the decisions farmers make in investing in conservation practices. Copyright © 2000 John Wiley & Sons, Ltd.     

我国数字水土保持建设基本思路

在分析我国水土保持信息化建设现状的基础上,提出我国数字水土保持建设的目标、任务、内容和布局等。我国数字水土保持建设目标是建立健全水土流失治理措施的监测体系,建成良好的信息管理、传输与发布的技术平台,形成良好的信息服务体系,全面提高水土保持决策能力。主要内容包括技术标准、信息基础设施、水土保持数据库、业务应用服务和信息共享平台、应用信息系统和环境建设6个方面。     

我国水土保持区划的回顾与思考

 水土保持区划是水土保持工作中重要的基础工作。分析水土保持区划的定位、发展历史和现状,讨论我国水土保持区划存在的问题,探讨我国水土保持区划的特点、区划原则、指标设置原则和区划方法,初步提出了我国水土保持区划的框架。     

对我国水土保持区划与规划中若干问题的认识

 土壤侵蚀分类分区、水土保持区划、水土流失重点防治区划分和生态自然修复区划是水土保持规划的重要基础工作。水土保持规划是以土壤侵蚀分类分区为科学依据,在大区域区划的原则指导下进行的,弄清土壤侵蚀分类分区、各类区划与规划之间的关系是做好水土保持前期工作的关键问题。因此,针对我国现行的水土保持区划和规划中存在的问题,着重从分析水土保持区划和规划的区别及联系入手,说明其相互关系,并提出相应的对策。     

Integrating biophysical and socio‐economic aspects of soil conservation on the Loess Plateau,China. Part I. Design and calibration of a model

A principal challenge in erosion control is the integration of the many technical and non‐technical issues that affect the acceptance of soil conservation measures by land users. This first paper in a three‐part series considers the main criteria at farm level: biophysical efficiency; productivity and sustainability; and socio‐economic acceptability. A model is developed to integrate these various components into a decision‐making framework for soil conservation at the farm level. With the particular conditions of the Loess Plateau in China, land degradation comprises a number of key biophysical and socio‐economic variables. The model components therefore include available water storage capacity of the soil as an index of productivity, the organic matter and mineral soil balance to reflect the major changes to the soil when eroded, and cost‐benefit analysis to determine the economic wisdom of devoting household resources to land improvement. The model is calibrated using data from the Nihegou Catchment near Chunhua in the southern part of the Loess Plateau. Through simulation runs, this model enables a better understanding of erosion–productivity–time relationships. Although relatively simple, the model successfully encompasses the processes of greatest significance to agricultural development in this part of China. Copyright © 2000 John Wiley & Sons, Ltd.     

关于我国水土保持顶层设计若干重要关系的思考

水土保持涉及农业、林业、水利、国土、环保等部门以及生产建设各行业,任务艰巨、关系复杂.做好其顶层设计十分重要.水土保持顶层设计就是在全国水土保持规划的指导下,构建自上而下的水土保持规划体系,并通过不断协调各种关系和调整实施方案,最终达到既定的长远性、战略性总体目标和任务.2015年国务院以国函[2015]160号文批复了《全国水土保持规划(2015-2030)》,明确水土保持目标和任务.据此,针对水土保持面临的新形势和新问题,审视水土保持的区域、部门、行业特点,科学分析中央与地方、部门与行业、区域内部及区域之间、经济与生态、保护与利用等各种重要关系,提出水土保持落实顶层设计,分级实施全国水土保持规划的对策与建议,重点是建立相关部门的协作协调合作机制,健全我国水土保持规划体系,落实水土流失防治目标与任务,完善和拓展投入机制.     

Evaluation of soil health in organic vs. conventional farming of basmati rice in North India

Conventional agricultural practices that use excessive chemical fertilizers and pesticides come at a great price with respect to soil health, a key component to achieve agricultural sustainability. Organic farming could serve as an alternative agricultural system and solve the problems associated with the usage of agro‐chemicals by sustainable use of soil resources. A study was carried out to evaluate the impact of organic vs . conventional cultivations of basmati rice on soil health during Kharif (rainy) season of 2011 at Kaithal district of Haryana, India, under farmers' participatory mode. Long‐term application of organic residues in certified organic farms was found to improve physical, chemical, and biological indicators of soil health. Greater organic matter buildup as indicated by higher soil organic carbon content in organic fields was critical to increase soil aggregate stability by increasing water holding capacity and reducing bulk density. Proper supplementation of nutrients (both major and micro nutrients) through organic residue addition favored biologically available nutrients in organic systems. Further, the prevalence of organic substrates stimulated soil microorganisms to produce enzymes responsible for the conversion of unavailable nutrients to plant available forms. Most importantly, a closer look at the relationship between physicochemical and biological indicators of soil health evidenced the significance of organic matter to enzyme activities suggesting enhanced nutrient cycling in systems receiving organic amendments. Enzyme activities were very sensitive to short‐term (one growing season) effects of organic vs . conventional nutrient management. Soil chemical indicators (organic matter and nutrient contents) were also changed in the short‐term, but the response was secondary to the biochemical indicators. Taken together, this study indicates that organic farming practices foster biotic and abiotic interactions in the soil which may facilitate in moving towards a sustainable food future.     

Interactions between soil conservation and dryland farming of heterogeneously eroding areas in Loess Hills,China

The unidirectional impacts of soil conservation on dryland farming and local livelihood have been well studied. However, there are gaps in literature regarding the interactions among factors, such as labor force and financial capital, in response to soil conservation, as well as the influence of such interactions on the relationships between environmental projects and agricultural development. By combining the Chinese Soil Loss Equation (CSLE) model and statistical analyses, this study investigated the spatio-temporal characteristics of soil erosion while also identifying the controlling factors that affect crop and livestock farming. The aim was to reveal how these factors interacted to influence agriculture in two case study areas between 2000 and 2017. The results showed that soil erosion substantially declined as a consequence of soil conservation, while the output from crop farming increased, indicating that there was a synergy between soil conservation and dryland farming in both the districts, over time; and factors facilitating crop farming, such as labor force, agricultural machinery, and irrigation, appeared to exert an adverse effect on livestock farming in both areas, implying a tradeoff between livestock and crop farming in the context of programs such as the Grain for Green Program (GGP) in the Loess Hills. Such a tradeoff is a result of the competition for cropland and labor that exists due to grazing prohibition and rural-urban migration. Therefore, policy-related resolutions are required to address the land use conflicts and migration-related rural labor losing due to implementation of the GGP in the Loess Hills.