More people,more erosion? Land use,soil erosion and soil productivity in Murang'a district,Kenya

Intensification of land use can become a threat to agricultural sustainability if they lead to increased soil erosion. This study examines land‐use changes, soil and water conservation, soil erosion and soil productivity in the Highlands of Kenya. In addition, it examines farmers' perception of livelihood changes. Land‐use changes were determined from interpretations of aerial photographs taken in 1960 and 1996. Additional information on land use, soil and water conservation and livelihood changes were obtained from discussions and interviews with farmers, as well as from field verifications of the most recent aerial photographs. Soil samples were analysed and soil erosion assessed according to the PLUS classification scheme. The results indicate that substantial changes in land use, such as introduction of coffee and high‐yielding maize, and fragmentation of land holdings have taken place. Less land was conserved in 1996 as compared to 1960. Moreover, SWC practices have changed from fanya chini terraces and shifting cultivation to bench terraces and permanent cultivation. Rates of soil nutrients (organic C, N and K) and maize‐yield levels decreased significantly with increasing erosion. Farmers' perception of livelihood changes was differentiated according to farmers' off‐farm resource 60 per cent of the farmers depended on income from the land and thought livelihoods were better in the 1960s. It is concluded that more efforts to decrease soil erosion and investments in land and labour are necessary to sustain soil productivity and hence secure rural livelihoods. Copyright © 2000 John Wiley & Sons, Ltd.     

Farmers' perceptions of soil erosion and soil fertility loss in Southern Ethiopia

Data and information about farmers' perceptions of soil degradation were collected using household survey, focus group discussion and field observations. The results indicate that farmers in the Sidama zone of southern Ethiopia are able to identify soil erosion and fertility loss indicators, take a holistic view of soil degradation and have a broad knowledge of the reasons for soil degradation. They perceive soil degradation mainly by reduced yields, soil changing in appearance and becoming stoney or coarse. The most frequently mentioned soil erosion indicator was soil becoming coarse and stony, followed by rill formation, dissection of fields and gullies and topsoil removal. The most important perceived indicator of soil fertility loss was reduced crop yield, followed by poor crop performance and yellowing of the crop. Farmers also have knowledge of solutions; however, participation in soil conservation activities is minimal because of the immediate threat of food insecurity. Any programme designed to address soil degradation in the region will have to be cognisant of farmers' knowledge and holistic view of soil degradation, and be integrated with aid measures to guarantee food security. Copyright © 2007 John Wiley & Sons, Ltd.     

Participatory soil and water conservation planning using an erosion mapping tool in the central highlands of Kenya

Despite several approaches that aimed at mobilising East African farmers to embrace soil and water conservation (SWC) activities, farmers hardly responded since they were seldom involved in the planning of SWC activities. Two tools that employ farmers' participation were developed and applied at Gikuuri catchment in Kenya. The first tool involved farmers to map soil erosion using their own indicators and determine the soil erosion status at catchment scale. This formed the basis upon which they undertook to plan for SWC measures at catchment scale. Farmers also predicted crop yield losses based on the soil erosion status. Farmers widely approved the soil erosion status map since their own indicators and perceptions were used. The second tool provided cash flow trends for a variety of SWC activities and farmer situations. Farmers can use land with a high, moderate or low erosion status and often have rather different socio‐economic settings. The net benefits over 5 yr for bench terraces, fanya juu terraces and grass strips were illustrated to assist farmers in making informed decisions on SWC adoption. The two tools increased awareness on the need for collective actions among farmers and showed fields that cause run‐on on downslope fields. The improved awareness of erosion problems and the related financial consequences increased farmers' willingness to share the investment costs for cut‐off drains. Copyright © 2007 John Wiley & Sons, Ltd.     

Participatory soil and water conservation planning using a financial analysis tool in the West Usambara highlands of Tanzania

Despite decades of soil and water conservation (SWC) efforts in Tanzania, the adoption of the recommended SWC measures by farmers is minimal. In the past, SWC plans did not incorporate farmers' knowledge, and the economics of SWC was not given much attention at the planning stage. This research evaluated the applicability of two tools for participatory soil erosion mapping using farmers' indicators of soil erosion and financial analysis of SWC measures at the planning stage. The two tools were evaluated in Kwalei catchment in the West Usambara highlands, Tanzania. The participatory soil erosion‐mapping tool uses farmers' indicators of soil erosion to identify, classify and map soil erosion at the catchment level. The financial analysis tool involves farmers in a stepwise analysis of the costs and benefits of SWC measures before the implementation. The erosion‐mapping tool increased farmers' awareness on the severity of soil erosion problems, and they realised the need for SWC plans at both field and catchment scales. With the financial analysis tool farmers participated in the cost and benefits analysis and were able to select SWC options that were feasible under their socio‐economic situation. The two tools were able to demonstrate that farmers' participation in SWC planning increases the acceptance of SWC measures because they solve problems that are perceived by themselves. The financial analysis tool demonstrated how farmers could make selection of SWC measures that are feasible under their biophysical and economic condition if they are informed about the costs and benefits. Copyright © 2006 John Wiley & Sons, Ltd.     

基于PSR模型的粤北山区农户行为对水土流失的影响研究

[目的]了解农户自身行为对水土流失影响,为保护和改善粤北山区生态环境、实现精准贫困和区域可持续发展提供依据。[方法]以贫困胁迫下的粤北山区农户行为为研究对象,采用参与式农村评估(PRA)进行农户调查,并通过"压力—状态—响应(PSR)"模型建立粤北山区农户行为对水土流失影响评价指标体系,从农户行为视角出发,结合层次分析法确定各指标权重,定量评价农户行为对水土流失影响程度。[结果](1)由于薪柴依赖度降低、坡耕地比重下降等因素,2012—2016年农户行为对水土流失影响的压力值逐渐降低;(2)虽然农户区水土流失状态值降低,但农户水土保持状态增加,总状态值稍有增加;(3)农户和政府对水土流失治理响应值逐渐增加;(4)综合PSR值,最终农户行为对水土流失影响值稍微降低,生态环境有所好转。[结论]粤北山区农户对水土流失影响压力值降低,状态值增加,最终农户行为对水土流失影响值稍有降低,农户行为对水土流失影响减小。     

Farmers' knowledge and perceptions of soil erosion and conservation measures in the Central Highlands,Kenya

A lack of appreciation of Kenyan farmers' knowledge and their perceptions of soil erosion and soil conservation measures was the reason for low adoption of recommended technologies. This research was carried out to identify the criteria that farmers used to distinguish farm‐types and to use these types to evaluate different knowledge levels and perceptions of soil erosion and existing soil and water conservation (SWC) measures in the Central Highlands of Kenya. Community meetings and semi‐structured household surveys were carried out in a small catchment, with 120 households. Results partly support the idea of using farmer‐developed criteria to distinguish among land managers with reference to a farm‐type classification. Criteria distinguishing three classes of land managers (good, moderate and poor) were significant with regard to the following land husbandry practices: use of hybrid or recycled seed and use of organic and/or inorganic fertilizers. Farmers were aware of on‐going soil erosion and of several erosion control measures. Whereas a majority of farmers preferred grass‐strips as a SWC measures, they did not recognize agroforestry as a form of SWC measure. Farmers perceived that SWC measures could successfully increase crop yields and soil‐water retention, and increase land value. In general, farmers did not perceive that SWC measures successfully prevented erosion phenomena, given the evidence of on‐site erosion indicators. They attributed the continued erosion to high rainfall, steep slopes, lack of maintenance and poorly designed SWC measures. They did not consider poor soil‐cover, up‐down tillage and tall trees to be the causes of erosion. Farmers faced several constraints in adopting SWC measures: lack of labour, tools, capital and know‐how to construct the measures. Copyright © 2005 John Wiley & Sons, Ltd.     

Soil Conservation in Europe: Wish or Reality?

Nearly all of Europe is affected by soil erosion. A major policy response is required to reverse the impacts of erosion in degraded areas, particularly in light of the current climate change and water crisis. Soil loss occurs not because of any lack of knowledge on how to protect soils, but a lack in policy governance. The average rate of soil loss by sheet and rill erosion in Europe is 2·46 Mg ha⁻¹ yr⁻¹. To mitigate the impacts of soil erosion, the European Union's Common Agricultural Policy has introduced conservation measures which reduce soil loss by water erosion by 20% in arable lands. Further economic and political action should rebrand the value of soil as part of ecosystem services, increase the income of rural land owners, involve young farmers and organize regional services for licensing land use changes. In a changing World of 9 billion people with the challenge of climate change, water scarcity and depletion of soil fertility, the agriculture economy should evolve taking into account environmental and ecological aspects. © 2016 The Authors Journal of Land Degradation & Development Published by John Wiley & Sons Ltd.     

Mechanical soil conservation with contour ridges: Cure for,or cause of,rill erosion?

Based on the results of an erosion damage assessment in Southern Zimbabwe, where mechanical conservation work has been carried out since the 1940s, this paper describes the impact of mechanical conservation systems on processes leading to rill erosion. In a study of a catchment area, it was found that influxes of water from roads and waterways as well as contour ridges that were originally designed to control rill erosion had a major role in the formation of rills. Existing rills and depressions which cause water concentration, siltation of contour drains and overflowing of contour ridges were the main factors leading to excessive rill erosion. The study showed that particularly during a highly erosive year like 1992/93, the damage due to rill erosion can be excessive, causing an abrupt degradation. It is concluded that the present conservation system is insufficient to control rill erosion effectively and is often the cause of this erosion. Effective control of rill erosion is a pre-condition for optimal implementation of land management systems such as conservation tillage. Therefore, an integrated approach to land husbandry must be developed jointly with farmers and promoted in order to improve crop production and sustainable management of natural resources. This should consider improved mechanical conservation as well as agronomic and biological soil and water conservation techniques.     

Wind erosion: the perspective of grass-roots communities in the Sahel

Under the harsh conditions prevailing in the West African Sahel, farmers must deal with a range of environmental and socio-economic issues that constrain agriculture. Although scientific evidence indicates that wind erosion is potentially a major land degradation process, little is known about the Sahelian farmer's perception of the relative importance of wind erosion as a constraint to agricultural production. A village-level survey was therefore undertaken to assess farmers' views about the relative importance of perceived constraints to agricultural production in 41 villages across Niger. During the interviews, the communities' views were also recorded regarding the causes and consequences of wind erosion as well as known wind erosion control measures. Wind erosion ranked eighth overall and was listed by male farmers among the top 10 constraints in 54 per cent of the villages. It was perceived by male farmers to be a moderate to high constraint in 39 per cent of the villages but was not considered important by female farmers. Wind erosion ranked third among environmental constraints, behind drought and soil fertility. Wind erosion related health problems were generally of more concern than crop damage or loss of topsoil by wind erosion. Deforestation, removal of crop residue and land-clearing practices were identified by farmers as major contributors to soil losses by wind. To address this issue, at least 10 different low-cost technologies are currently being implemented by farmers, including leaving crop residue in the field, mulching and natural regeneration of vegetation. The survey results indicate that farmers are well aware of the overriding importance of their management practices, as opposed to climatic factors, on the current extent of wind erosion. Copyright © 2001 John Wiley & Sons, Ltd.     

Farmland degradation in the mountains of Nepal: a study of watersheds ‘with’ and ‘without’ external intervention

Amidst growing concerns about farmlands conservation, this paper examines the status of farmlands in two mountain watersheds ‘with’ and ‘without’ external intervention, located in the western hills of Nepal. Information was obtained from a household survey and group discussions conducted during April to September 1999. The severity of soil erosion from farmers' perspectives, density of landslides, soil nutrient balance and change in crop yield have been adopted as indicators of the status of the land. Results of the analysis indicate that land resources in both watersheds are undergoing degradation, though the causes and extent of degradation vary from one type of land to another. Upland crop terraces, locally called bari, are undergoing degradation most seriously under the combined influence of severe soil erosion, landslide and the depletion of soil nutrients. In particular, soil erosion has severely affected nearly half of the upland crop terraces in both watersheds due to a number of natural and anthropogenic factors ranging from weak geological structure to arable agriculture. Landslide and nutrient depletion have affected all types of farmlands except homesteads in both watersheds. Overall, the extent and intensity of land degradation is relatively high in the non‐project area, as farmers were not provided with necessary technical and financial support. A broad strategy has been outlined for effective conservation of farmlands. Copyright © 2002 John Wiley & Sons, Ltd.     

三峡库区水土保持工程农户参与行为调查

[目的]研究三峡库区水土保持工程农户参与程度、参与阶段性特征及主要影响因素,为区域水土保持生态环境建设提供决策参考。[方法]采用参与式农户评估法调查了113户农户,并通过深度访谈重点了解农户对水土保持的相关诉求,运用二元逻辑回归模型分析了农户参与水土保持工程的主要影响因素。[结果](1)库区农户对水土保持的认知度和对水土保持工程的满意度均不高。(2)库区农户多以有偿投工方式参与水土保持工程;农户参与程度低,以零参与和低度参与为主,中度参与和高度参与仅占12%。水土保持工程规划设计、施工、后期管护三阶段农户参与比例分别为19%,42%和2%。(3)参与工程能否挣钱和农户对水土保持的认知是影响农户参与水土保持工程的主要因素。农户参与工程收入越多、水土保持认知度越高,其参与水土保持工程积极性越大。[结论]三峡库区农户水土保持认知度偏低,农户参与水土保持工程偏少,参与阶段主要集中在施工期,不利于水土保持工程的开展和效益发挥。今后要加强水土保持宣传和教育,改革农户参与激励机制,增强水土保持工程实用性和适宜性,以更好发挥水土保持工程的作用。     

Farmers' perceptions of the role of scattered vegetation in wind erosion control on arable land in Burkina Faso

This paper describes the results of a survey on farmers' perceptions of the effect of woody natural vegetation on wind erosion. Sixty farmers were interviewed in three villages in northern Burkina Faso. The farmers mentioned that the presence of woody vegetation between the crops could benefit yield, but feared competition between the natural vegetation and the crop. Vegetation in a field was considered to increase deposition and decrease erosion on that field. The most important vegetative characteristics that affect wind erosion were, according to the farmers, vegetation's shape, porosity, flexibility and arrangement of the vegetation in the field. At present, most farmers do not apply this knowledge to the management of the natural woody vegetation on their fields. Copyright © 2005 John Wiley & Sons, Ltd.     

Erosion modelling approach to simulate the effect of land management options on soil loss by considering catenary soil development and farmers perception

The prevention of soil erosion is one of the most essential requirements for sustainable agriculture in developing countries. In recent years it is widely recognized that more site‐specific approaches are needed to assess variations in erosion susceptibility in order to select the most suitable land management methods for individual hillslope sections. This study quantifies the influence of different land management methods on soil erosion by modelling soil loss for individual soil‐landscape units on a hillslope in Southern Uganda. The research combines a soil erosion modelling approach using the physically based Water Erosion Prediction Project (WEPP)‐model with catenary soil development along hillslopes. Additionally, farmers' perceptions of soil erosion and sedimentation are considered in a hillslope mapping approach. The detailed soil survey confirmed a well‐developed catenary soil sequence along the hillslope and the participatory hillslope mapping exercise proved that farmers can distinguish natural soil property changes using their local knowledge. WEPP‐model simulations show that differences in soil properties, related to the topography along the hillslope, have a significant impact on total soil loss. Shoulder and backslope positions with steeper slope gradients were most sensitive to changes in land management. Furthermore, soil conservation techniques such as residue management and contouring could reduce soil erosion by up to 70 percent on erosion‐sensitive slope sections compared to that under tillage practices presently used at the study site. The calibrated model may be used as a tool to provide quantitative information to farmers regarding more site‐specific land management options. Copyright © 2008 John Wiley & Sons, Ltd.     

Assessment of soil erosion hazard in Kilie catchment,East Shoa,Ethiopia

This paper reports on a field study conducted in Kilie catchment, East Shoa Zone, Ethiopia to assess the rate of soil erosion by employing a soil loss prediction model (Universal Soil Loss Equation) integrated with in remote sensing and geographical information systems (RS/GIS), environment and gully measurement techniques. The final soil erosion risk map was produced after multiplication of the six factors involved in the USLE and RS/GIS. Gully measurement showed that the erosion rate is higher for the upland areas than the lowlands due to inappropriate soil and water conservation measures, free grazing by animals and conversion of hillside areas into farmlands. About 97·04 per cent of the study catchment falls within a range of 0–10 t ha⁻¹ yr⁻¹ sheet/rill erosion rate. We found that 2·17 per cent of the study area in the uplands has a soil erosion rate falling between 10 and 20 t ha⁻¹ yr⁻¹. About 0·8 per cent of the study area in the uplands is hit by severe sheet/rill erosion rate within the range of 20–60 t ha⁻¹ yr⁻¹. Gully erosion extent in the study area was evaluated through gully measurement and quantification methods. Gully density of 67 m ha⁻¹ was recorded in the catchment. The gully to plot area ratio was found to be 0·14 on average. Hence, in the upland areas, sustainable land management practices are required in order to reduce the rate of soil erosion. Copyright © 2011 John Wiley & Sons, Ltd.     

Better land husbandry in Honduras: towards the new paradigm in conserving soil,water and productivity

Land shortages are forcing more smallholder farmers to cultivate tropical steeplands. Resulting accelerated soil erosion is being countered by the promotion of soil conservation (SC) technologies, such as cross‐slope barriers, which aim to reduce soil loss and preserve land productivity. However, farmer adoption rates tend to be low. This is often attributed to the farmers' conservatism or lack of education. Research in Honduras's steeplands demonstrates that farmers value SC, provided that it promotes agricultural production. Field research from 1995–98, involving farmed test plots on slopes greater than 35 per cent (19 degrees), demonstrates that at least one typical SC technology—live barriers of Vetiveria zizanioides (vetiver grass)—has little or no impact on maize yield. This means that farmers see little benefit from their investment in the SC method. They find that erratic rainfall, pests and diseases and a lack of economic resources are far greater threats to their livelihoods than soil erosion. Consequently, SC has a low priority. Keeping soil in place avoids major off‐farm disbenefits. However, the SC technique tested here made no discernible difference to slope foot sediment yields during the life of this study. In sum, a new approach is needed. Promoting ‘Better Land Husbandry’ strategies, which seek to combine farmers' concerns about productivity with conservationists' concerns about reducing soil erosion—often via cover‐management—seem to be the best way forward. Copyright © 2002 John Wiley & Sons, Ltd.     

Assessing the costs of land degradation: a case study for the Puentes catchment,southeast Spain

Whereas many studies point out the economic benefits of controlling land degradation through sustainable land management (SLM) approaches, there is often a lack of local adoption of SLM techniques. Analysis of the local impacts and costs of land degradation is critical for understanding farmers' responses to land degradation. The objective of this paper is to analyse the local costs of land degradation in the Puentes catchment in southeast Spain. This catchment has been identified as particularly vulnerable to erosion, yet farmers show a general lack of interest in applying erosion control techniques. The paper subsequently analyses land degradation processes in the Puentes catchment, the income derived from agriculture and several other ecosystem services, and the local costs of land degradation. Erosion is widespread in the catchment, comprising sheet and rill erosion as well as gulley erosion. Relatively high erosion rates are encountered in cropland. The most important source of local income is irrigated agriculture, with revenues of up to €1350/ha y⁻¹. Dryland agriculture, hunting and herding provide additional income. The costs of erosion on cropland, calculated with a replacement method, vary from around €5/ha y⁻¹ on slopes between five per cent and ten per cent, to around €50/ha y⁻¹ on slopes between 30 per cent and 50 per cent. Except on the steepest slopes, these costs are relatively low for the farmers, which explains the limited application of erosion control techniques in the catchment. Copyright © 2007 John Wiley & Sons, Ltd.     

野外模拟降雨条件下矿区土质道路径流产沙及细沟发育研究

为研究矿区土质道路径流产沙及细沟形态发育特征,在野外调查的基础上,设计坡度(3°、6°、9°、12°)和雨强(0.5、1.0、2.5、2.0、2.5、3.0 mm/min)2个处理,在野外建立不同坡度的道路小区,采用人工模拟降雨的方法,测定了不同处理道路径流产沙参数和细沟形态指标。结果表明:1)各坡度道路径流率为1.12~8.24 L/min,与雨强线性关系极显著,随坡度变化不显著;除0.5 mm/min雨强3°~9°坡及1.0 mm/min雨强3°坡道路径流流态为层流外,其余为紊流,雨强-坡度交互作用(I×S)对流态影响显著;阻力系数只与坡度相关。2)各坡度道路剥蚀率为0.92~324.46 g/(m2·s),与雨强、坡度和径流率呈极显著幂函数关系(R2=0.968,P0.01),道路土壤发生剥蚀的临界剪切力和临界径流功率分别为2.15 N/m2和0.41 W/(m2·s)。3)3°道路以片状侵蚀为主,6°~12°道路细沟发育,细沟宽深比、复杂度、割裂度和细沟密度分别为1.80~3.75、1.07~1.55、0.20%~10.33%和0.067~2.01 m/m2,细沟发育程度是雨强和坡度交互作用(I×S)的结果。4)6°~12°道路细沟侵蚀量占总侵蚀量比例为18.0%~57.16%,总侵蚀量与细沟宽深比、细沟复杂度、细沟割裂度和细沟密度均呈显著的函数关系(R2=0.35~0.96,P≤0.01),割裂度是影响土质道路总侵蚀量的最佳细沟形态因子。结果可为矿区土质道路水土保持工程设计及生产安全提供参数支持。