Impacts of Low-Cost Land Certification on Investment and Productivity

New land reforms are again high on the policy agenda and low-cost, propoor reforms are being tested in poor countries. This article assesses the investment and productivity impacts of the recent low-cost land certification implemented in the Tigray region of Ethiopia, using a unique household and farm-plot-level panel data set, with data from before and up to eight years after the reform. Alternative econometric methods were used to test and control for endogeneity of certification and for unobserved household heterogeneity. Significant positive impacts were found, including effects on the maintenance of soil conservation structures, investment in trees, and land productivity.     

浅谈软土地区基坑工程开挖与支护要点

本文根据有关的研究成果和多年的工程实践经验,详细分析了软土基坑支护的一些问题。     

Gliricidia sepium Carbon Inputs and Soil Carbon Pools in a Costa Rican Alley Cropping System

Alternative land management practices, including agroforestry, help to maintain levels of soil organic matter (SOM) and can facilitate soil carbon (C) sequestration for mitigating atmospheric CO₂ emissions. This study quantified C inputs and determined the changes of the soil C pool in a 19-year-old Gliricidia sepium alley cropping system, studied at two fertiliser levels (tree prunings only [? N], and tree prunings plus chicken manure [+ N]), and was compared to a sole crop system. Carbon input from tree prunings ranged from 455 to 457 g C m^{? 2} y^{? 1}, whereas C inputs from crop residues were similar between alley- and sole crops ranging from 121 to 159 g C m^{? 2}y^{? 1}. The soil organic C (SOC) pool in the alley crop was 16–23% higher than the sole crop. In the 19th year of alley farming, SOC was significantly higher (p < 0.05) in the alley crop (3.2%) compared to the sole crop (2.4%), and was also greater compared to that at the time of establishment of the agroforestry system (2.8%). Gross SOC turnover to a 20-cm depth ranged from 12 to 14 years in the + N and ?N alley crops compared to 49 and 50 years in the + N and ?N treatments for the sole crops. Residue stabilisation efficiency in the alley crops was 39% and 55% in + N and ?N treatments respectively.     

软土地基上高速公路路基扩建加宽中的关键问题研究

高速公路路基扩建加宽问题是现阶段高速公路建设过程中面临的重要问题之一。本文主要分析软土地基上高速公路路基扩建加宽中涉及的关键问题。     

应用型人才培养过程中工程力学的教学研究

目前，在高等教育工程力学课程的教学过程中，一些高校简单地合并理论力学与材料力学的教学内容，造成该课程的某些章节重复，部分传统理论与计算方法不适用于工程实践。因此，必须对该课程体系中的内容进行精简和舍弃，以新的理念构建一套具有时代意义的工程力学知识教学体系，由此突出机械专业人才培养过程中的实用性和应用性。     

外墙饰面砖返碱防治方法

传统的外墙饰面砖施工方法是用水泥浆黏结和填缝,由于材料、施工等因素的影响,瓷砖出现返碱现象,极大地破坏了建筑装饰效果。文章分析了瓷砖返碱的成因,并提出相应的预防措施。     

预制桩填土复合地基的设计与施工

论述了小预制方桩与压实填土复合地基在大型污水处理池中的设计与施工应用情况，提出了粘性填土分层压实、具有不小于80kPa承载能力的观点，如桩端土层良好，则可大幅度提高复合地基的强度。     

考虑应力作用影响的黄泛区粉土土水特征曲线分析与预测

为了研究应力作用对土水特征曲线的影响，采用应力关联土水特征仪测定不同应力下粉土的脱湿-吸湿曲线，讨论应力变化对粉土土水特征的影响规律，并利用应力与孔隙比的关系提出考虑应力作用的粉土土水特征曲线预测方法。研究发现：试样在应力逐渐增加时不易脱水，但更易吸水，非饱和粉土的持水能力随着正应力的增大而增强；脱湿曲线与吸湿曲线并不重合，有明显的回滞现象，并且吸湿曲线饱和度的变化比脱湿曲线更加剧烈；随着正应力的增大，滞回圈面积减小，滞回特性减弱。此外，将预测曲线与测得的试验曲线对比, 可知提出的考虑应力的土水特征曲线预测方法具有较好的预测精度。     

福州市饮用水源保护区水土流失风险评价

选择植被覆盖度、地形坡度和土地利用类型来进行水土流失的风险度评价;试验区域为福州市第二饮用水源地山仔库区和塘坂库区;利用Landsat-7ETM 的影像,在计算归一化差分植被指数NDVI的基础上估算水源地保护区的植被覆盖度;利用栅格数字高程模型DEM,计算地表坡度;利用土地利用类型图获取保护区各地土地利用类型的分布;根据水利部部颁标准,对植被覆盖度、坡度和土地利用类型进行分级,建立水土流失风险评价模型,并在ArcGIS 9.0软件支持下,对上述各因子进行叠加分析,得到保护区水土流失评价风险评价;结果表明研究区内生态环境总体保护较好,但存在一定的水土流失现象,生态环境保护还需进一步加强.     

Social capital and soil conservation: evidence from the Philippines*

The formation of social capital is hypothesised to enhance collective efforts for soil conservation. The Landcare Program in the southern Philippines promotes simple conservation practices in upland environments by supporting community landcare groups and municipal landcare associations, thus augmenting social capital. A study was conducted in 2002–2003 to evaluate the Landcare Program, using a mix of quantitative and qualitative techniques. In the present paper, the relationship between social capital formation and adoption of soil conservation in the Municipality of Lantapan is investigated. It is concluded that the Landcare Program as a whole created a valuable stock of bridging social capital, rapidly accelerating the adoption of contour farming measures, but that on‐going support is needed to maintain this capital stock.