Analyzing the hydrologic effects of region-wide land and water development interventions: a case study of the Upper Blue Nile basin

In the drylands of the Upper Blue Nile basin, high climate variability and land degradation are rampant. To enhance adaptive capacity in the region, various soil and water conservation interventions have been implemented. Moreover, water resources development schemes such as the Grand Ethiopian Renaissance Dam should be implemented by 2025. We modeled the effects of these interventions on surface runoff in the basin for both current and future (2025) basin conditions, using the runoff coefficient method in a spatially explicit approach. Under current conditions, we observed high spatial variability of mean annual runoff. The northeastern Blue Nile-1 sub-basin produces the highest mean annual runoff (391 mm or 10 × 10⁹ m³), whereas the northwestern Blue Nile-2 sub-basin produces the lowest mean annual runoff (178 mm or 0.2 × 10⁹ m³). The basin generates a total annual runoff volume of 47.7 × 10⁹ m³, of which about 54 % comes from cultivated land. The strong association between land use and topography masked the direct effect of rainfall on runoff. By 2025, total annual runoff yield could decrease by up to 38 % if appropriate basin-wide soil and water conservation interventions and the Grand Ethiopian Renaissance Dam are implemented. However, the full effects of most physical structures will only last for 1 or 2 years without regular maintenance. The improved understanding of the dynamics of the Upper Blue Nile basin’s hydrology provided by the present study will help planners to design appropriate management scenarios. Developing the basin’s database remains important for a holistic understanding of the impacts of future development interventions.     

Assessment of adoption and impact of rainwater harvesting technologies on rural farm household income: the case of rainwater harvesting ponds in Rwanda

Rainwater harvesting is increasingly viewed as a major strategy for enhancing agricultural productivity and boosting farm income in many drought-prone areas. While this technology is being promoted in many developing countries, there is conflicting evidence in the literature about its impact on welfare of farm households. This study uses propensity score matching and discrete choice regression techniques to assess the impact of rainwater harvesting ponds on farm household income and factors that influence adoption of such technologies in Rwanda. It finds that households with rainwater harvesting ponds have significantly higher income than their counterparts of comparable observable characteristics. It further finds evidence that increase in farm income occurs via increased input use and that household size, asset endowments and participation in farmer organizations condition adoption of rainwater harvesting ponds. The study concludes that adoption of rainwater harvesting technologies has positive benefits on farm households. It discusses the policy implications that adoption of rainwater harvesting ponds presents a pathway for reducing rural poverty.     

Analysis of farm-level adoption of soil nutrient management technology by paddy farmers in Karnataka,India

Adoption of soil test-based nutrient management is important for achieving sustainable development of agriculture. The present study analysed the factors influencing the adoption of soil nutrient management technology package comprising adoption of soil test and recommended fertiliser by paddy farmers in the southern Indian state of Karnataka by using field survey data. Bivariate probit model was used to estimate the sequential adoption decisions on soil test and fertiliser application technologies. The study results showed that farmers’ training on fertiliser application and education had positive and significant effect on adoption of soil nutrient technology package. The likelihood of adoption of soil test technology decreases with increase in distance measured from farm to soil test laboratory. Availability of fewer family labour increases the probability of adoption of soil nutrient management technology. These results have significant policy implications for provision of soil testing facilities nearer to villages and for conducting periodical training programmes for encouraging the farmers to adopt soil test-based nutrient management.     

Adoption and adaptation of natural resource management innovations in smallholder agriculture: reflections on key lessons and best practices

Many smallholder farmers in vulnerable areas continue to face complex challenges in adoption and adaptation of resource management and conservation strategies. Although much has been learned from diverse experiences in sustainable resource management, there is still inadequate understanding of the market, policy and institutional failures that shape and structure farmer incentives and investment decisions. The policy and institutional failures exacerbate market failures, locking smallholder resource users into a low level equilibrium that perpetuates poverty and land degradation. Improved market access that raises the returns to land and labor is often the driving force for adoption of new practices in agriculture. Market linkages, access to credit and availability of pro-poor options for beneficial conservation are critical factors in stimulating livelihood and sustainability-enhancing investments. Future interventions need to promote joint innovations that ensure farmer experimentation and adaptation of new technologies and careful consideration of market, policy and institutional factors that stimulate widespread smallholder investments. Future projects should act as ‘toolboxes’, giving essential support to farmers to devise complementary solutions based on available options. Addressing the externalities and institutional failures that prevent private and joint investments for management of agricultural landscapes will require new kinds of institutional mechanisms for empowering communities through local collective action that would ensure broad participation and equitable distributions of the gains from joint conservation investments. Readers should send their comments on this paper to: BhaskarNath@aol.com within 3 months of publication of this issue.     

网络嵌入与风险感知对农户绿色耕作技术采纳行为的影响分析——基于湖北省615个农户的调查数据

基于社会嵌入理论，利用湖北省615个农户调查数据，运用结构方程模型实证分析网络嵌入与风险感知对农户绿色耕作技术采纳行为的影响路径及其群组差异。研究发现：（1）当前采用绿色耕作技术的农户比例相对较小，其中以秸秆还田覆盖技术采用率相对较高，而深松、有机肥、生物农药等采用率略低；（2）网络嵌入和风险感知对农户绿色耕作技术采用行为具有显著的正向影响，同时风险感知在结构嵌入对农户绿色耕作技术采纳行为的影响中具有中介效应；（3）相比受教育程度与家庭年收入，家庭实际经营土地面积在网络嵌入对农户绿色耕作技术采纳行为影响中的作用更为明显。鉴于此，建议应积极推进农地适度规模经营，并鼓励建立内嵌于当地农技推广站、以种植大户为先导的绿色适用技术推广与讨论网络，确保绿色耕作技术落到田间地头。同时，政府应加强灾害预警与田间学校建设，通过宣传教育与培训指导，强化农户绿色生产意识，引导农户推行绿色生产方式。     

Social and ecological facets of pest management in Honduran subsistence agriculture: implications for IPM extension and natural resource management

In subsistence farming systems of the developing world, adoption of resource-conserving practices such as integrated pest management (IPM) is often strikingly low. This has partially been ascribed to researchers’ limited understanding of how technologies develop at the interface of the systems’ social and ecological components. In Honduras (Central America), there exists concern about limited adoption and diffusion of IPM technologies in certain smallholder production systems. In this study, we determine social and ecological drivers of IPM adoption in subsistence maize production in the country’s hillside environment. Honduran small-scale maize production is typified by a key insect pest (the fall armyworm, Spodoptera frugiperda) being partly kept at bay through action of a diverse natural enemy complex, including ants, social wasps, carabid beetles, and spiders. Local agricultural landscapes, primarily shaped through shifting cultivation, provide key resources to maintain this natural enemy diversity. These local ecological conditions and related natural enemy abundance strongly influence farmers’ agroecological knowledge and pest management practices. In the meantime, farmer practices are also affected by local communication networks, which help validate and spread IPM concepts and technologies. Based on our findings, we advocate a holistic approach to improve IPM extension through mapping of agroecological opportunities, visualization of regional patterns in farmer knowledge, and associated priority setting. Local IPM capacity could be built through institutional strengthening and adaptive comanagement, while IPM training should be linked with natural resource management initiatives. These approaches may eventually improve the way IPM is delivered to small-scale farmers who operate in the ecologically diverse environments of the tropics.     

南方沙化土地治理中的农户行为实证研究

我国南方亚热带沙化土地在成因、危害和治理方式上均与北方沙地有很大不同，以沙化土地水土流失治理典型区周边的农户为研究对象，通过实地调研村域基本情况，走访村落中的农户群体与关键人物，获得问卷与访谈数据，对农户沙地治理与利用行为、生态意识、生态认知、农业生产方式等进行了统计分析，从人口特征分异上考察各类农户群体的行为和意识差异，运用Logistic二值回归模型验证农户治理行为的显著影响因子，研究结果表明，农户沙地行为和生态意识在人口特征和土地利用方式上都有显著差异，其中年龄、学历、实际耕种规模、农业损失、沙地活动是影响农户参与沙地造林意愿和行为的主要因素。研究结论对改善沙地生态治理模式和优化环境政策具有一定参考意义，生态治理中的农户行为具有进一步研究的价值     

Rainfall trends,land use change and adaptation in the Chaco salteño region of Argentina

Regional change under agricultural expansion in the Chaco of Argentina is determined by interactions of rainfall change, infrastructure development, socio-economic actions and values, and the social perceptions of change. Our study focused on adaptation in the socio-environmental system which is the key to understanding opportunities, uncertainties and risk in the context of historical change. Change in land use from extensive grazing through mixed farming and on to industrial-scale soybean production was made possible by a trend of increasing rainfall that reduced the risk of crop failure from drought since the 1970s. Rainfall change coincided with a period in which the Chaco forest was suffering extensive degradation from long-term extractive use. The degradation aided agricultural expansion since the degraded state of the ecosystem justified public policies of deforestation. In parallel to these resource-based processes, public policy changed in the late 70s and 80s toward favoring privatization of state land and exclusion of small producers. This permitted the land concentration needed for industrial-scale production. Technological innovation in both water and land resource management reinforced the process of concentration because small producers rarely have the financial or educational capital to develop or implement emerging technologies. One of the results of the intensification and expansion of agriculture is that soil surface sealing, waterlogging and flood risk are now effective at a landscape scale. To address these risks, private enterprise and government efforts must now come together toward innovative policies in integrated landscape management.     

基于SWAT模型的太湖西北部30a来氮磷的输出特征

随着工业的迅速发展和农业生产方式的转变,使得太湖富营养化现象日趋严重,对流域内生态环境构成极大的威胁。以研究区6个时期土地利用数据和30a逐日降雨数据为模型的主要输入变量,利用SWAT模型分别对研究区内6个不同时期营养盐输出进行模拟研究,得到研究区内30a时间尺度(1984~2013年)营养盐输出情况。根据模型输出结果探究研究区内营养盐输出与降雨量、径流量以及土地利用变化的关系。以2009~2013年宜兴站径流数据和水质数据作为模型的率定和验证数据,总氮(TN)和总磷(TP)在模型率定期确定系数R2为0.76和0.92,纳什效率系数Ens为0.76和0.79,验证期确定系数R2为0.66和0.95,纳什效率系数Ens为0.6和0.54,模拟结果较好。结果表明:营养盐输出与降雨在时间是呈现较强的相关性,但是在空间上降雨与营养盐输出相关性不明显;土地利用类型与营养盐输出密切相关,耕地和建设用地是研究区主要的营养盐输出源,土地利用类型空间分布与TN、TP空间分布相关系数分别为0.74和0.73。将为太湖流域非点源污染控制和治理提供理论支撑及数据基础。     

基于多层次非线性Tobit模型的集体行动对农户水土保持技术采用的影响研究

利用黄土高原区农户微观调研数据，运用多层次非线性Tobit模型实证分析了集体行动与农户水土保持技术采用之间关系的主效应和生态补偿对集体行动与农户水土保持技术采用程度之间关系的调节效应。结果表明：（1）集体行动对任何一种类型的水土保持技术均产生显著正向影响；（2）生态补偿对集体行动与农户水土保持技术采用程度之间的关系具有调节作用，但不同类型的水土保持技术，其调节作用的方向不一致，对于劳动密集型的水土保持技术具有正向调节作用，对于资本密集型的水土保持技术具有负向调节作用。基于此提出以下政策建议：增强农户的集体行动参与能力和规模、细化补偿金额和年限的标准、制定技术属性差异化的生态补偿政策等。     

空间异质性下农户水土保持耕作技术采用行为研究 ——基于黄土高原3省6县的实证

利用黄土高原山西、陕西和甘肃3省的1 237户农户的调查数据，分析了农户采用水土保持耕作技术的空间差异，运用Heckman样本选择模型，研究了3省农户水土保持耕作技术的采用行为及其影响因素的差异。结果表明：（1）农户所采用的水土保持耕作技术在3省之间存在明显的区域差异，山西省农户秸秆还田技术和深松耕技术采用率较高，陕西省农户对少免耕和沟垄种植技术采用率相对较高，甘肃省农户采用较多的技术分别为秸秆还田、残茬覆盖、地膜覆盖和深松耕技术。（2）家庭收入对3省农户水土保持耕作技术的采用和采用程度都有显著的正向影响；非农收入占比对3省农户水土保持耕作技术的采用有显著的正向影响；家庭养殖对3省农户水土保持耕作技术的采用程度有显著的负向影响。（3）降水量对3省农户水土保持耕作技术的采用有显著的负向影响；地块类型对山西和陕西两省农户水土保持耕作技术采用和采用程度有显著的负向影响，对甘肃省的农户影响不显著。（4）社会网络对3省农户水土保持耕作技术的采用程度有显著的正向影响；技术推广促进了农户水土保持耕作技术的采用；政府补贴对山西和甘肃两省的水土保持耕作技术的采用程度有显著的正向影响，对陕西省农户水土保持耕作技术的采用程度影响不显著。     

邻里效应与农技推广对农户稻虾共养技术采纳的影响分析——互补效应与替代效应

稻虾共养生态农业技术可以带来良好的经济、生态和社会效应,但由于有效技术来源不足、较高的技术与经济风险给农户采纳带来多重约束。以稻虾共养技术为例,利用湖北省与江苏省605份农户调研数据,通过理论与实证分析了邻里效应与农技推广对农户稻虾共养技术采纳的影响及二者的互补与替代效应。研究发现:(1)邻里观察性学习、交流感受均显著正向促进农户稻虾共养技术采纳。(2)通过农资企业的经营性农技推广显著正向影响农户稻虾共养技术采纳。(3)对农户稻虾共养技术采纳的影响上,观察性学习、社会规范均与农技推广存在部分替代效应,邻里农户交流感受与农技推广存在部分替代与互补效应。基于上述研究结论,该文认为应该有效结合邻里效应与农技推广的互补与替代效应,提高各农技推广主体的运行效率和实际影响力,进而提高农户的采纳规范性和效率。     

Land use Systems and Erosion in the Uplands of the Central Coast, Vietnam

Soil erosion is a significant problem in the uplands of the Central Coast, Vietnam. It affects the livelihood of farmers and could hinder the long-term economic development efforts in the uplands. Yet, trapped in poverty, upland farmers, especially the ethnic minority, are still mining the soil using erosive land use systems to meet their urgent needs. This study demonstrates that the level of soil erosion varies across the typical land use systems. The fruit tree-based agroforestry (AF) system is least erosive and most financially profitable. The choice of land use system is influenced by farmers' attributes, land plot characteristics, and policy-related variables. The set of policy variables is important in explaining land use choice by upland farmers. Promoting the switch to AF system and the adoption of soil conservation is of great importance to reducing soil erosion and sustaining development in the uplands. However, it is a very challenging task.     

Impact of peri-urban agriculture on runoff and soil erosion in the rapidly developing metropolitan area of Jakarta,Indonesia

Negative effects of land use change on water resources are among the most important environmental problems widely found in rapidly developing urban areas. Preserving green open spaces, including peri-urban agriculture, has been emphasized in urban planning to maintain or enhance the water catchment capacity of a landscape. However, the effect of agriculture on water-related landscape functions varies depending on the type, distribution, and management of farmland. This paper analyzes the dynamics of agricultural land and its effect on runoff and soil erosion, in order to support agricultural land management in Jabodetabek Metropolitan Area (JMA) with Indonesia’s capital Jakarta at its core. In 2012, agricultural land in JMA covered 53% of the total area, mostly located in the peri-urban zone. Peak Flow and Universal Soil Loss Equation (USLE) models were used to quantify the increase of runoff and soil erosion in the three most important water catchment areas in JMA caused by an expansion of dryland agriculture and mixed gardens from 1983 to 2012. Critical zones, which generate most of the runoff and soil erosion, were identified in each of the catchment areas. While reforestation of farmland in these zones will be only an option on steep slopes given the great food demands and rural livelihood, adoption of soil and water conservation practices can make a substantial contribution to reduce flood risks and conserve the productivity of agricultural land. A specific set of policy incentives is recommended considering agricultural land use types distribution and their impact on runoff and soil erosion.     

自我剥削、禀赋效应与农地流转潜在市场发育——兼论经济欠发达地区小农户生产方式转型

以家庭均包制为主要经营特征的农村土地制度曾一度引致农户农业生产积极性的提高和农业生产效率的快速增长,但由此导致的细碎化小规模的农地经营特征和农业生产成本的上升却造成了农地经营的自我剥削现象普遍存在,加之传统的村庄惯习和土地占有关系诱致的农户对农地的禀赋效应,共同导致农户农地经营的自我剥削属性与土地的市场处置行为呈现出内在运行机制不一致性。为此,本文采用引入交叉项的Probit模型,并利用江西省丰城市和遂川县的706户农户调查数据经验分析了小农户的自我剥削和农地禀赋效应对农地流转潜在市场发育的影响。理论分析表明,农地经营的自我剥削特征与农地市场化具有一致性倾向,但农地的人格化财产属性引致的农户禀赋效应造成了农户农地经营自我剥削感知度的下降,并削弱了要素经营属性与市场配置行为的匹配。经验分析结果发现,小农户低效率农地经营导致的自我剥削与农地禀赋效应分别激励农地流转市场的潜在供给和需求。同时,农地禀赋效应弱化了自我剥削对农地流转潜在需求和供给的诱发作用。为此,本文认为降低农户的土地禀赋效应是欠发达地区小农户转型的总体方向,它为农地由小农户流向生产大户和培育部分小农户成为新型农业经营主体提供保障。文章主要从家庭决策的利益导向化、农地流转市场与劳动力市场发展的不一致性及农村制度供给等维度提出了经济欠发达地区小农户转变农业生产方式,跳出自我剥削陷阱的政策建议。具体措施包括:1切实保障小农户的基本权益,提高他们在家庭资源配置中的预期收益;2在初次规模经营补贴、农业基本补贴机制转变、经营者生产奖励、专业技能培训、市场信息供给等层面加大投入力度,同时完善农村社会保障体系,以降低小农户转型的难度与风险。     

Determination of radionuclide levels in rainwater using ion exchange resin and γ-spectrometry

The evaluation of radioactivity accidentally released into the atmosphere involves determining the radioactivity levels of rainwater samples. Rainwater scavenges atmospheric airborne radioactivity in such a way that surface contamination can be deduced from rainfall rate and rainwater radioactivity content. For this purpose, rainwater is usually collected in large surface collectors and then measured by γ-spectrometry after such treatments as evaporation or iron hydroxide precipitation. We found that collectors can be adapted to accept large surface (diameter 47 mm) cartridges containing a strongly acidic resin (Dowex AG 88) which is able to quantitatively extract radioactivity from rainwater, even during heavy rainfall. The resin can then be measured by γ-spectrometry. The detection limit is 0.1 Bq per sample of resin (80 g) for ¹³⁷Cs. Natural ⁷Be and ²¹⁰Pb can also be measured and the activity ratio of both radionuclides is comparable with those obtained through iron hydroxide precipitation and air filter measurements. Occasionally ²²Na has also been measured above the detection limit. A comparison between the evaporation method and the resin method demonstrated that 2/3 of ⁷Be can be lost during the evaporation process. The resin method is simple and highly efficient at extracting radioactivity. Because of these great advantages, we anticipate it could replace former rainwater determination methods. Moreover, it does not necessitate the transportation of large rainwater volumes to the laboratory.     

Synergistic vulnerabilities: climate variability and fire management policy increase farming challenges in southeastern Mexico

Agricultural fire for land preparation is central in the livelihoods of subsistence farmers practicing shifting cultivation. Achieving a good agricultural burn, one in which the biomass is thoroughly consumed within the chosen area, depends on specific weather conditions. Fire use decisions are also shaped by institutions that define the timing and rules for fire use but also constrain the alternatives and shape adaptive capacities. Global and regional climate changes interact with the institutional framing of fire management affecting local fire use and burn outcomes. These effects are documented and analyzed to suggest adaptations to existing governance systems. We examined subsistence farmers’ socio-ecological vulnerability in the Calakmul municipality, located in southeastern Mexico. Using interviews with farmers and government agents, as well as participatory mapping and observation of agricultural burns, we studied fire management knowledge, practices and burn outcomes. Our results describe a continuum of burn outcomes covering good agricultural burns, uncontrolled burns leading to wildfires and “malquemados” literally poorly burned areas. Malquemados represent unsuccessful combustion associated with excess moisture that results in scorched vegetation. We discuss how unexpected early rains trigger effects that cascade through space and the ecological, economic and cultural domains. We argue that fire management has been historically approached from a conservation standpoint yet agricultural fire use and wildfire prevention should also be addressed from a rural development perspective. This shift in fire management would lead to the proper inclusion of the entire array of burn outcomes in studies and policies addressing farmers’ vulnerability amplified by synergistic effects between climate variability and institutional change.     

The relationship between climate and streamflow in the Namoi Basin

The Namoi River Basin (42 000 km²) is located in the Murray-Darling Basin, west of the Great Australian Dividing Range in northeast New South Wales (NSW), and includes some of the most fertile agricultural lands in Australia. One of the environmental concerns for this basin is erosion and its effects on downstream water quality. Models that relate climate, land use, and these concerns require measurements of climate (rainfall and temperature) and streamflow. These measurements were examined as a preliminary to the modelling. The residual mass technique was used to examine the temporal variation of annual rainfalls over the approximately 100 years of available data, and significant spatial variations were found in annual rainfall trends over the catchment. Streamflow was examined at key river gauging stations. The impact of recent large-scale irrigation operations was clearly observed. The impact of changing land use and land management on runoff ratios was examined for eight subcatchments. Temperature variations were examined for the four major towns in the catchment. The duration of the temperature data is too short to make any comments about long-term trends. Significant variations were observed in an east to west direction.     

Linking agricultural adaptation strategies,food security and vulnerability: evidence from West Africa

Adaptation strategies to reduce smallholder farmers’ vulnerability to climate variability and seasonality are needed given the frequency of extreme weather events predicted to increase during the next decades in sub-Saharan Africa, particularly in West Africa. We explored the linkages between selected agricultural adaptation strategies (crop diversity, soil and water conservation, trees on farm, small ruminants, improved crop varieties, fertilizers), food security, farm household characteristics and farm productivity in three contrasting agro-ecological sites in West Africa (Burkina Faso, Ghana and Senegal). Differences in land area per capita and land productivity largely explained the variation in food security across sites. Based on land size and market orientation, four household types were distinguished (subsistence, diversified, extensive, intensified), with contrasting levels of food security and agricultural adaptation strategies. Income increased steadily with land size, and both income and land productivity increased with degree of market orientation. The adoption of agricultural adaptation strategies was widespread, although the intensity of practice varied across household types. Adaptation strategies improve the food security status of some households, but not all. Some strategies had a significant positive impact on land productivity, while others reduced vulnerability resulting in a more stable cash flow throughout the year. Our results show that for different household types, different adaptation strategies may be ‘climate-smart’. The typology developed in this study gives a good entry point to analyse which practices should be targeted to which type of smallholder farmers, and quantifies the effect of adaptation options on household food security. Subsequently, it will be crucial to empower farmers to access, test and modify these adaptation options, if they were to achieve higher levels of food security.