Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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    Water conservation under scarcity conditions : testing the long-run effectiveness of a water conservation awareness campaign in Jordan
    Zietlow, Kim J. ; Michalscheck, Mirja ; Weltin, Meike - \ 2016
    International Journal of Water Resources Development 32 (2016)6. - ISSN 0790-0627 - p. 997 - 1009.
    Behavioural determinants - environmental awareness - Jordan - long-run impact analysis - water conservation - water scarcity

    This study measures the long-run effect of the Abu Tawfeer media campaign in Jordan. Based on a representative sample (N = 367) conducted five years after the end of the campaign, a multivariate instrumental variable regression analysis shows that the campaign only marginally changed people’s water conservation awareness and behaviour. The rigorous methodological approach allows disentangling the distinct channels through which the effect of the conservation campaign was transmitted. Moreover, this is one of the first studies that comprehensively examines the role of awareness in determining water conservation behaviour.

    The urban harvest approach as framework and planning tool for improved water and resource cycles
    Leusbrock, I. ; Nanninga, T.A. ; Lieberg, K. ; Agudelo, C. ; Keesman, K.J. ; Zeeman, G. ; Rijnaarts, H. - \ 2015
    Water Science and Technology 72 (2015)6. - ISSN 0273-1223 - p. 998 - 1006.
    waterbeschikbaarheid - waterbeheer - hulpbronnenbeheer - innovaties - urbanisatie - afvalwater - watergebruik - waterzekerheid - hulpbronnenbehoud - waterbescherming - stedelijke gebieden - water availability - water management - resource management - innovations - urbanization - waste water - water use - water security - resource conservation - water conservation - urban areas
    Water and resource availability in sufficient quantity and quality for anthropogenic needs represents one of the main challenges in the coming decades. To prepare for upcoming challenges such as increased urbanization and climate change related consequences, innovative and improved resource management concepts are indispensable. In recent years we have developed and applied the Urban Harvest Approach (UHA). The UHA proposes to model and quantify the urban water cycle on different temporal and spatial scales. This approach allowed us to quantify the impact of the implementation of water saving measures and new water treatment concepts in cities. In this paper we will introduce the UHA and present for urban water cycles. Furthermore, we will show first results for an extension to energy cycles and highlight future research items (e.g., nutrients, water-energy-nexus). Key words | Resource cycles, Water management, Water-Energy Nexus, Decision-Support
    Comparing groups of Brazilian cattle farmers with different levels of intention to use improved natural grassland
    Rossi Borges, J.A. ; Oude Lansink, A.G.J.M. - \ 2015
    Livestock Science 178 (2015). - ISSN 1871-1413 - p. 296 - 305.
    planned behavior - conservation practices - dairy farmers - water conservation - risk perception - adoption - management - decisions - attitudes - technologies
    This study used the Theory of Planned Behavior (TPB) to analyze the intention of Brazilian farmers to use improved natural grassland. The TPB hypothesizes that the adoption of an innovation is driven by the intention to use it, which in turn is determined by three socio-psychological constructs: attitude, subjective norm, and perceived behavioral control. These constructs are derived from beliefs. The theoretical framework and model were applied to a sample of 214 Brazilian cattle farmers. Based on the socio-psychological constructs that influence intention, two groups of farmers were identified; farmers that were willing and farmers that were unwilling to use improved natural grassland. Results showed that compared to unwilling farmers, willing farmers evaluated the use of improved natural grassland on their farms more favorably (attitude), they felt a greater social pressure upon them to adopt this innovation (social norm), and they reported a higher capability (perceived behavioral control) to use improved natural grassland. Willing and unwilling farmers also differed in their behavioral beliefs concerning the outcomes of using improved natural grassland, their normative beliefs concerning important others, and their control beliefs concerning factors that could facilitate or inhibit the use of improved natural grassland. The two groups did not differ in most of their socioeconomic characteristics, but did differ in their goals and relative risk attitudes.
    Conservation tillage of rainfed maize in semi-arid Zimbabwe: A review
    Nyakudya, I.W. ; Stroosnijder, L. - \ 2015
    Soil & Tillage Research 145 (2015). - ISSN 0167-1987 - p. 184 - 197.
    zea-mays l. - sandy soils - sustainable agriculture - water conservation - rural livelihoods - smallholder farms - southern africa - use efficiency - rainwater use - long-term
    Food security in Sub-Saharan Africa, particularly in semi-arid tropics (41% of the region; 6 months of dry season) is threatened by droughts, dry spells and infertile soils. In Zimbabwe, 74% of smallholder farming areas are located in semi-arid areas mostly in areas with soils of low fertility and water holding capacity. The dominant crop in these areas, maize (Zea mays L.), is susceptible to drought. Under smallholder farming in Zimbabwe, conventional tillage entails cutting and turning the soil with a mouldboard plough thereby burying weeds and crop residues. Seed is planted by hand into a furrow made by the plough, ensuring that crops germinate in relatively weed free seedbeds. Inter-row weed control is performed using the plough or ox-drawn cultivators and hand hoes. Conventional tillage has been criticised for failure to alleviate negative effects of long dry spells on crops and to combat soil loss caused by water erosion estimated at 50 to 80 t ha-1 yr-1. Therefore, conservation tillage has been explored for improving soil and water conservation and crop yields. Our objective was to determine the maize yield advantage of the introduced technology (conservation tillage) over conventional tillage (farmers’ practice) based on a review of experiments in semi-arid Zimbabwe. We use a broad definition of conservation tillage instead of the common definition of =30% cover after planting. Eight tillage experiments conducted between 1984 and 2008 were evaluated. Conventional tillage included ploughing using the mouldboard plough and digging using a hand hoe. Conservation tillage included tied ridging (furrow diking), mulch ripping, clean ripping and planting pits. Field-edge methods included bench terraces (fanya juus) and infiltration pits. Results showed small yield advantages of conservation tillage methods below 500 mm rainfall. For grain yields =2.5 t ha-1 and rainfall =500 mm, 1.0 m tied ridging produced 144 kg ha-1 and mulch ripping 344 kg ha-1 more than conventional tillage. Above 2.5 t ha-1 and for rainfall >500 mm, conventional tillage had =640 kg ha-1 yield advantage. Planting pits had similar performance to ripping and conventional tillage but faced digging labour constraints. Experiments and modelling are required to test conservation tillage seasonal rainfall thresholds. Constraints to adoption of conservation tillage by smallholder farmers necessitate best agronomic practices under conventional tillage while work on adoption of alternative tillage methods continues.
    Land management in the north-western highlands of Ethiopia: adoption and impact
    Akalu Teshome Firew, ; Firew, A.T. - \ 2014
    Wageningen University. Promotor(en): Leo Stroosnijder, co-promotor(en): Jan de Graaff. - Wageningen : Wageningen University - ISBN 9789462571563 - 148
    grondbeheer - landdegradatie - hooglanden - waterbescherming - bodembescherming - ethiopië - land management - land degradation - highlands - water conservation - soil conservation - ethiopia

    Abstract

    Over the last four decades, the government of Ethiopia and various a consortium of donors have been promoting different land management (LM) practices in the highlands of Ethiopia to halt land degradation. However, the adoption rate of these practices has been low. This is because investments in LM practices are influenced by various institutional, socio-economic and bio-physical factors. The main objective of this research is to investigate the impact of these different factors on investments in LM in the north-western Ethiopian highlands. It focuses on the drivers of the different stages of adoption, on profitability of LM practices, and on land quality, land fragmentation, tenure arrangements and social capital.

    We examined the drivers of the different stages of adoption of soil and water conservation (SWC) practices using an ordered probit model. The results indicate that adoption of soil and water conservation (SWC) passes through four major phases: non-adoption/dis-adoption, initial adoption, actual adoption and final adoption. Some socio-economic and institutional factors have a different effect on the respective SWC adoption phases. Final adoption depends mostly on profitability, land-related factors, social capital and perception of erosion problems.

    We also investigated the effectiveness and profitability of three SWC practices (stone bunds, soil bunds and Fanya juu bunds) using the Universal Soil Loss Equation (USLE) and Cost Benefit Analysis (CBA). The results show that SWC practices are effective in controlling soil erosion, though the profitability of these SWC methods is dependent on the site where they are used. Fanya juu and stone bunds are generally profitable under standard conditions (e.g. medium slope and average soil quality and labour costs). However, the study also shows that different underlying assumptions change the CBA results considerably and consequently also change the conclusions regarding circumstances under which SWC measures are or are not profitable.

    Besides, we assessed farmers’ perceptions about land quality, land fragmentation and tenure systems and their influence on interrelated LM (Bunds, Compost/Manure and Fertilizer) investments using a multivariate probit (MPV) model. The study shows that investments in LM practices are interdependent. For example, compost/manure and fertiliser substitute each other to a certain extent (often not used together, or used interchangeably by farmers) in the farming system of the study areas. Land quality (e.g. slope and soil fertility status), land fragmentation (parcel size and distance of parcel from homestead) and tenure arrangements influence farmers’ investments in LM practices.

    In addition, the relationship between the different dimensions of social capital and investments in LM practices was explored. The results show that the different dimensions of social capital affect LM practices differently. In particular, the cooperation and trust dimensions of social capital are associated with the intensity of investment in SWC bunds and fertiliser use. The extent of participation in formal institutions has a positive effect on the use of fertiliser and compost.

    Furthermore, we evaluated different SWC practices using Multi-Criteria Analysis (MCA) to assess their ecological, economic and social impacts. The study reveals that MCA is an effective evaluation tool that can take into account non- monetary and less quantifiable effects of SWC measures, which is not possible with Cost Benefit Analysis. The results of the analysis indicate that farmers have a range of criteria to evaluate the performance of SWC measures. The relative importance of each criterion in the selection of SWC alternatives depends to a large extent on slope categories.

    For enhancing the adoption and impacts of land management, there is a need to increase knowledge about location specific viable LM practices, to promote collective action at watershed level, to pay more attention to farmers’ preferences and to improve the capacity and capability of farmers.

    Environmental conditions and human drivers for changes to North Ethiopian mountain landscapes over 145 years
    Nyssen, J. ; Frankl, A. ; Haile, M. ; Hurni, H. ; Descheemaeker, K.K.E. ; Crummey, D. ; Ritler, A. ; Portner, B. ; Nievergelt, B. ; Moeyersons, J. ; Munro, N. ; Deckers, J. ; Billi, P. ; Poesen, J. - \ 2014
    Science of the Total Environment 485-486 (2014). - ISSN 0048-9697 - p. 164 - 179.
    land-use changes - tigray highlands - water conservation - cover dynamics - montane forest - soil-erosion - degradation - eucalyptus - rainfall - climate
    As quantitative or spatially distributed studies of environmental change over truly long-term periods of more than 100 years are extremely rare, we re-photographed 361 landscapes that appear on historical photographs (1868–1994) within a 40,000 km2 study area in northern Ethiopia. Visible evidence of environmental changes apparent from the paired photographs was analyzed using an expert rating system. The conditions of the woody vegetation, soil and water conservation structures and land management were worse in the earlier periods compared to their present conditions. The cover by indigenous trees is a notable exception: it peaked in the 1930s, declined afterwards and then achieved a second peak in the early 21st century. Particularly in areas with greater population densities, there has been a significant increase in woody vegetation and soil and water conservation structures over the course of the study period. We conclude that except for an apparent upward movement of the upper tree limit, the direct human impacts on the environment are overriding the effects of climate change in the north Ethiopian highlands and that the northern Ethiopian highlands are currently greener than at any other time in the last 145 years.
    Effects of soil bunds on runoff, soil and nutrient losses, and crop yield in the Central Highlands of Ethiopia
    Adimassu Teferi, Z. ; Mekonnen, K. ; Yirga, C. ; Kessler, A. - \ 2014
    Land Degradation and Development 25 (2014)6. - ISSN 1085-3278 - p. 554 - 564.
    water conservation - northern ethiopia - land degradation - smallholders - management - rainfall - tigray - technologies - investments - variability
    The effects of soil bunds on runoff, losses of soil and nutrients, and crop yield are rarely documented in the Central Highlands of Ethiopia. A field experiment was set up consisting of three treatments: (i) barley-cultivated land protected with graded soil bunds (Sb); (ii) fallow land (F); and (iii) barley-cultivated land without soil bund (Bc). For 3¿years (2007–2009), the effect of soil bunds on runoff, losses of soil and nutrients, and crop productivity was studied. Daily runoff and soil and nutrient losses were measured for each treatment using standard procedures while barley yield was recorded from the cultivated plots. The results showed that Sb brought about significant reduction in runoff and soil losses. Plots with Sb reduced the average annual runoff by 28¿per cent and the average annual soil loss by 47¿per cent. Consequently, Sb reduced losses of soil nutrients and organic carbon. However, the absolute losses were still high. This implies the need for supplementing Sb with biological and agronomic land management measures to further control soil erosion. Despite these positive impacts on soil quality, Sb do not increase crop yield. Calculated on a per-hectare basis, Sb even reduce crop yield by about 7¿per cent as compared with control plots, which is entirely explained by the reduction of the cultivable area by 8·6¿per cent due to the soil bunds. Suitable measures are needed to compensate the yield losses caused by the construction of soil bunds, which would convince farmers to construct these land management measures that have long-term beneficial effects on erosion control.
    Rainwater harvesting for dryland agriculture in the Rift Valley of Ethiopia
    Temesgen, B.B. - \ 2012
    Wageningen University. Promotor(en): Leo Stroosnijder, co-promotor(en): Geert Sterk. - S.l. : s.n. - ISBN 9789461732156 - 152
    dry farming - regenafhankelijke landbouw - regenwateropvang - bodemfysica - ploegen als grondbewerking - waterbescherming - landgebruik - participatie - ethiopië - dry farming - rainfed agriculture - water harvesting - soil physics - ploughing - water conservation - land use - participation - ethiopia

    The Ethiopian drylands occupy about 65% of the total land mass (close to 700,000km2) of the country. The predominantly rainfed agriculture in these drylands is highly constrained due to erratic rainfall, long dry-spells and excessive loss of rainwater through non-productive pathways (surface runoff, evaporation and deep drainage). Apart from this, deteriorated dryland soils have low infiltration and water holding capacity, shallow depths and are sensitive to crusting. Therefore, to keep in pace with the demand for food for the burgeoning population, the Ethiopian drylands should be made more productive through appropriate rainwater harvesting and management techniques. Therefore, the objective of this study was to develop appropriate rainwater harvesting and management techniques in the Central Rift Valley (CRV) drylands of Ethiopia through a participatory planning and development process.

    Primarily, an overview of the various rainwater harvesting and management techniques in sub-Saharan Africa was made. Moreover, the biophysical performances and socioeconomic implications of the most common practices were synthesized. The sub-Saharan Africa is actually the birthplace of a range of indigenous rainwater harvesting and management (RWHM) techniques. The micro-catchment and in situ RWHM techniques are more commonly applied than the macro-catchment techniques for supplemental irrigation on farm lands. Depending on rainfall patterns and local soil characteristics, appropriate application of in-situ and micro-catchment techniques could improve the soil water content of the rooting zone by up to 30%. Smart combinations of rainwater harvesting and soil improvements enable to increase crop yields by 200-600% as compared to the traditional farming without them. Following the implementation of rainwater harvesting techniques, the cereal-based smallholder farmers could shift to diversified crops, hence improving household food security, dietary status, and economic return.

    The interplay between drought vulnerability and the changing trends in land-use/cover and land management in the CRV drylands of Ethiopia was made using a combination of GIS/remote sensing, meteorological drought analyses and surveying techniques. Given late onset of rainfall seasons (for both livestock farming and crop cultivation) and long dry-spells (for crop cultivation only) as the perceived causes of drought, pastoral system was vulnerable to severe drought once in seven years while mixed crop-livestock farming was vulnerable to severe drought once in twenty eight years. Over the last 5 decades, cultivated lands increased to threefold while the dense acacia coverage declined from 42% in 1965 to 9% in 2010. Although conversion from pastoral life to mixed crop-livestock system was perceived important to cope with drought, long-term tillage using the traditional Maresha cultivation caused deteriorates of the soil water properties. Infiltration rate of the surface soil layer increases significantly immediately after conversion of acacia-based grasslands to cultivation. However, there is a weak decreasing trend in infiltration rate and a significant increase in soil evaporation with increases in cultivation durations. Thus, it was implied that improved soil management and appropriate tillage are needed to maximize rainwater use efficiency and achieve sustainable agricultural production in the CRV of Ethiopia.

    Two-year field experimentation was undertaken to calibrate and examine the role of the FAO’s AquaCrop model in simulating the effect of rainwater harvesting techniques in response to different rainfall patterns and soil fertility levels in the CRV of Ethiopia. After proper calibration of the FAO’s AquaCrop model, it was possible to simulate the effect of tied-ridges and soil fertility improvements on maize yield and water use efficiency in response to different rainfall patterns. The model simulation revealed that the effect of tied-ridges alone performed better than soil fertility improvements during below-average rainfall seasons. During above-average rainfall seasons, the combined use of tied-ridges and soil fertility improvement was found very effective to substantially improve maize yield. This is because the excess water held in the tied-ridges can be best utilized due to the enhanced water uptake capacity of maize growing in the fertilized soils. Depending on the seasonal rainfall patterns, the combined use of tied-ridges and optimum level of soil fertilizer doubles the rainwater use efficiency of maize. A field experiment during a normal rainfall in 2010 revealed that the combined use of farmyard manure (4.5 Mg ha-1) and tied-ridges increased maize yield by 47% while tied-ridges in isolation increased maize yield by 26%. Moreover, long-term simulation revealed that the effect of tied-ridges on yield improvements was higher for sowing in April than for sowing in May.

    Finally, this study enabled to develop a participatory planning approach for rainwater harvesting and management. The approach starts with investigation of the priority agro-meteorological determinants for crop production and identification of the existing knowledge and opportunities. The proposed approach also enables to plan an integrated rainwater harvesting and soil improvement techniques. The application of this new approach in the CRV implied that any effort on the introduction of new in situ rainwater harvesting techniques should assess existing tillage, hoeing and associated land management practices. The existing Dirdaro furrow system could be taken as a basis to introduce and develop tied-ridges using the Maresha-modified ridger. Overall, this approach may augment the recent efforts of dissemination of rainwater harvesting and management techniques for improved agricultural development in the vast drylands of Ethiopia.

    Socio-ecological Niches for Minimum Tillage and Crop-residue Retention in Continuous Maize Cropping Systems in Smallholder Farms of Central Kenya
    Guto, S.N. ; Pypers, P. ; Vanlauwe, B. ; Ridder, N. de; Giller, K.E. - \ 2012
    Agronomy Journal 104 (2012)1. - ISSN 0002-1962 - p. 188 - 198.
    soil fertility gradients - conservation agriculture - organic-matter - semiarid environment - water conservation - western kenya - cover crops - management - tropics - africa
    Soil fertility gradients develop on smallholder farms due to preferential allocation of inputs. A multi-location on-farm trial was conducted in Meru South, Central Kenya whose overall aim was to test minimum tillage and crop-residue retention practices in socio-ecological niches across heterogeneous smallholder farms. We identified three soil fertility classes together with the farmers, namely: good, medium, and poor. In each soil fertility class, two tillage (minimum or regular) and two crop residue (removed or retained) practices were tested for four consecutive seasons. Maize (Zea mays L.) grain yields in the good fields were above 2.5 Mg ha-1 across cropping seasons and cumulated yields were not influenced by tillage or crop residue management. The grain yields in the medium fields ranged between 1.3 and 5.4 Mg ha-1 and were greater with crop residue retention. In the poor fields, grain yield was
    Financial cost-benefit analysis of bench terraces in Rwanda
    Bizoza, A.R. ; Graaff, J. de - \ 2012
    Land Degradation and Development 23 (2012)2. - ISSN 1085-3278 - p. 103 - 115.
    west usambara highlands - soil conservation - water conservation - tanzania - adoption - farmers - policy - crop
    Bench terracing has received considerable attention from soil and water conservation (SWC) programmes involved in soil erosion control in Rwanda. It is questioned, however, whether enough attention is paid to the suitability of the soils and to the eventual financial profitability. Terraces may reduce soil erosion and increase production but they should also provide sufficient financial gains at farm level. A plot level financial cost–benefit analysis was undertaken to examine under which social and economic conditions bench terraces are financially viable in Northern and Southern Rwanda. Farmers' estimates of respective costs and potato yields from plots with subsidized and un-subsidized bench terraces, progressive terraces and plots with no terraces at all were obtained for the analysis. Costs of labour and manure were found to be the most influential for the profitability of bench and progressive terraces. While the cost–benefit analysis, using market prices, showed that bench terraces would be hardly profitable, an analysis with opportunity costs for labour and manure indicated that bench terraces and even more progressive terraces can be financially profitable. Extra measures and incentives may be required to facilitate use of labour and access to manure, as now achieved with the one cow per family policy. This paper suggests that further studies should be undertaken to determine costs and benefits of bench terraces beyond private perspective in Rwanda.
    Farmers, institutions and land conservation : institutional economic analysis of bench terraces in the highlands of Rwanda
    Bizoza Runezerwa, A. - \ 2011
    Wageningen University. Promotor(en): Erwin Bulte, co-promotor(en): Paul Hebinck. - S.l. : s.n. - ISBN 9789085859307 - 123
    ontwikkelingseconomie - boeren - institutionele economie - instellingen - landbouwgrond - bodembescherming - waterbescherming - erosie - terrassen - rwanda - oost-afrika - minst ontwikkelde landen - development economics - farmers - institutional economics - institutions - agricultural land - soil conservation - water conservation - erosion - terraces - rwanda - east africa - least developed countries
    Tillage and vegetative barrier effects on soil conservation and short-term economic benefits in the Central Kenya highlands
    Guto, S.N. ; Pypers, P. ; Vanlauwe, B. ; Ridder, N. de; Giller, K.E. - \ 2011
    Field Crops Research 122 (2011)2. - ISSN 0378-4290 - p. 85 - 94.
    contour hedgerow systems - water conservation - napier grass - andes region - leucaena-leucocephala - management-practices - spatial variability - physical-properties - northern thailand - intercrop system
    Minimum tillage and vegetative barriers can conserve soil and water resources in the steep-sloping highlands of East Africa but there has been little adoption by smallholder farmers. Soil conservation efficiency and short-term economic benefits provided by tillage and vegetative barriers were assessed over four cropping seasons to understand performance under local farming conditions. Minimum tillage was compared with regular tillage and vegetative barriers (leucaena and Napier) with no barriers. Maize and soybean yields were greater with than without vegetative barriers, except with Napier barriers when minimum tillage was practiced where strong root competition occured. Cumulatively for the four cropping seasons, Napier barriers with regular tillage conserved most soil (72%) followed by Napier with minimum tillage (53%). The least soil (1%) was conserved for minimum tillage without barriers and leucaena barriers were intermediate in decreasing soil erosion. The highest positive marginal rate of returns (MRRs) were realized under leucaena barriers with regular tillage (2.09) followed by Napier with regular tillage (1.32). Minimum tillage without barriers had the lowest positive MRRs (0.08). Future increase in the price of key inputs would have greater depressive effect on the MRRs of Napier barriers with regular tillage than leucaena barriers with regular tillage. Minimum tillage without barriers was inefficient in soil conservation particularly when rainfall was intense and had poor MRRs. Leucaena barriers conserved less soil than Napier barriers but were more economically attractive, demonstrating a clear trade-off between soil erosion that is likely to impact crop yields in the long-term and short-term economic benefits. Napier barriers with regular tillage present a win–win scenario due to efficient soil conservation and attractive economic returns provided future prices of labour and Napier cuttings remain stable.
    Chakula bila kulima? : trade-offs concerning soil and water concervation in heterogeneous smallholder
    Guto, S.N. - \ 2011
    Wageningen University. Promotor(en): Ken Giller, co-promotor(en): B. Vanlauwe; P. Pypers. - [S.l.] : S.n. - ISBN 9789085859291 - 136
    waterbescherming - bodembescherming - bedrijfssystemen - kleine landbouwbedrijven - boeren - minimale grondbewerking - voederplanten - rijgewassen - kenya - water conservation - soil conservation - farming systems - small farms - farmers - minimum tillage - fodder plants - rowcrops - kenya

    Soil and water conservation practices need to be tailored to suit the diverse local conditions in smallholder farms.Using a combination of survey methods, field experimentation over several seasons and farm scale analysis, this research explored the targeting of recommended options to field and farm types. Smallholder farmers’ in Mbeere and Meru South Districts of Central Kenya acknowledged the occurrence of soil erosionin their farms and understood the water erosion process. Trash lines were common in the low potential Mbeere area for the control of erosion, except for farmers with high resource endowment who instead preferred fanya juu and vegetation barriers. In Meru South, contour farming was popular for different farmers although the preference was for vegetative barriers with multiple benefits. Three field types on a relative scale of soil fertility were identified by the farmers: good, medium and poor. Physical and vegetative measures were more common and well maintained in good fields but rare and neglected in poor fields. Farming on sloping arable fields with no vegetative barriers lead to soil degradation and establishment of vegetative barriers curbed soil erosion. Napier grass barriers were efficient in conserving soil and water but competed with crops for available water. This competition was especially strong with minimum tillage even when the Napier was intensely harvested. Leucaena barriers had a complementary water use pattern with crops across tillage practices but were less efficient for soil and water conservation. Considering economic returns and the soil conserved, leucaena barriers had attractive and less risky economic returns across tillage practices but conserved less soil. Napier barriers with regular tillage presented a win-win scenario for farmers and environmental impacts because of simultaneous attractive economic returns and efficient soil conservation. Cumulative maize grain yields in the good fields were above 15 Mg ha-1 across cropping seasons and were not influenced by tillage and crop residue retention. The cumulative grain yields in the medium fields were above 10 Mg ha-1 across cropping seasons and were greater with crop residue retention. In the poor fields, cumulative grain yield was less than 10 Mg ha-1 across seasons and minimum tillage resulted in yield decrease while crop residue retention did not affect yields. For the poor fields, emphasis should be placed on the rehabilitation of soil physical and chemical attributes. At farm level, retention of crop residues was not viable due to use of crop residues for livestock feed. Minimum tillage was of interest to well-endowed farmers who had labour constraints. Poor farmers were interested but would not afford herbicides and had no access to sprayer pumps. Long term studies and farm scale modelling are necessary to unravel further the complexity in heterogeneous smallholder farming system for better fitting of recommended soil and water conservation options.

    The effect of long-term Maresha ploughing on soil physical properties in the Central Rift Valley of Ethiopia
    Temesgen, B.B. ; Stroosnijder, L. ; Temesgen, M. ; AdulKedir, A. ; Sterk, G. - \ 2011
    Soil & Tillage Research 111 (2011)2. - ISSN 0167-1987 - p. 115 - 122.
    tillage systems - crust formation - smallholder farmers - water conservation - faidherbia-albida - surface soil - sandy soils - management - evaporation - africa
    For thousands of years, smallholder-based crop farming in Ethiopia has been practiced with oxen ploughing using the traditional Maresha ard plough where consecutive tillage operations are undertaken perpendicular to each other. Despite its wide acceptance by smallholder farmers, long-term use of the Maresha is believed to deteriorate the soil's physical properties. This study examines the surface and subsurface infiltration, soil evaporation and penetration resistance of sandy loam soils that have been exposed to varying durations (0, 2, 7, 22 and 35 years) of cultivation after being converted from acacia-based grassland dominated by Acacia tortilis and Acacia senegal in the Central Rift Valley (CRV) of Ethiopia. The infiltration rate of the surface layer increased significantly (p = 0.05) immediately after conversion from acacia-based grassland to cultivated land. Thereafter, there was a weak decreasing trend (p > 0.05, R2 = 0.24) in infiltration rate with years of cultivation. Unlike the surface soil layer, there was no significant difference in the subsurface (below 15 cm) infiltration between the acacia-based grassland and lands cultivated for varying numbers of years. Following a rain event satisfying field capacity of the soils, the daily soil evaporation increased significantly (p = 0.05) with increased duration of cultivation. The cumulative evaporation, observed over 5 consecutive days following the last rainfall, increased by 2.4 times in the 35 years old cultivated land from the acacia-based grassland. There was also a strong correlation (R2 = 0.86) between a (the slope of the cumulative evaporation versus the square root of time) and an increase in the years of cultivation. It is, therefore, concluded that long-term Maresha cultivation along with the present soil management makes the maize crop susceptible to drought and dry-spells. Improved soil management and development of appropriate tillage are needed to maximize rainwater use efficiency and achieve a more sustained agricultural production in the drought-prone CRV of Ethiopia
    Ecosystem Goods and Services from Plantation Forests
    Bauhus, J. ; Meer, P.J. van der; Kanninen, M. - \ 2010
    London, Great Brittain : Earthscan (Earthscan forest library ) - ISBN 9781849711685 - 254
    bosplantages - bosproducten anders dan hout - meervoudig gebruik - biodiversiteit - koolstofvastlegging - waterbescherming - bosbeleid - ecosysteemdiensten - forest plantations - non-wood forest products - multiple use - biodiversity - carbon sequestration - water conservation - forest policy - ecosystem services
    This is the first book to examine explicitly the non-timber goods and services provided by plantation forests, including soil, water and biodiversity conservation, as well as carbon sequestration and the provision of local livelihoods. The authors show that, if we require a higher provision of ecosystem goods and services from both temperate and tropical plantations, new approaches to their management are required. These include policies, methods for valuing the services, the practices of small landholders, landscape approaches to optimise delivery of goods and services, and technical issues about how to achieve suitable solutions at the scale of forest stands. While providing original theoretical insights, the book also gives guidance for plantation managers, policy-makers, conservation practitioners and community advocates, who seek to promote or strengthen the multiple-use of forest plantations for improved benefits for society.
    Debating land degradation: strategy development for Bolivian mountain valleys
    Kessler, A. ; Stroosnijder, L. - \ 2010
    Land Degradation and Development 21 (2010)5. - ISSN 1085-3278 - p. 480 - 483.
    water conservation - decentralization - management - governance - resources - farmers - soil
    A debate on response strategies to rural poverty and land degradation has relevance for the core business of this journal. Based on extensive fieldwork in the mountain valleys of Chuquisaca, Bolivia, this paper discusses farming and migration in the region, and elaborates on the required components of a strategy to tackle land degradation. We argue that collective action at the micro–meso level is essential to lay the foundation for development activities and to reduce survival-driven migration rates. In order to actually change farmers into adaptive co-managers of their natural resources it is also necessary to create enabling conditions at meso-macro level. However, given the current context in Bolivia, the prospects for reducing land degradation are not good
    From Participation to Adoption: Comparing the effectiveness of soil conservation programs in the Peruvian Andes
    Posthumus, H. ; Gardebroek, C. ; Ruben, R. - \ 2010
    Land Economics 86 (2010)4. - ISSN 0023-7639 - p. 645 - 667.
    water conservation - technology adoption - developing-countries - farmers - economics - incentives - ethiopia - uncertainty - decisions - lessons
    Many efforts are made to promote soil conservation in developing countries. This paper compares the effect of two programs promoting soil conservation in Peru on the adoption decision of households. One program applies a top-down approach with soil conservation as its core activity. The other program applies a participatory approach, offering a portfolio of activities in order to improve rural livelihoods. The decisions on participation and adoption are estimated with a trivariate probit model. The results show that each program attracts different types of households and achieves different outcomes in terms of soil conservation.
    Conservation agriculture and smallholder farming in Africa: The heretics' view
    Giller, K.E. ; Witter, E. ; Corbeels, M. ; Tittonell, P.A. - \ 2009
    Field Crops Research 114 (2009)1. - ISSN 0378-4290 - p. 23 - 34.
    soil carbon sequestration - sub-saharan africa - biological nitrogen-fixation - semiarid west-africa - tillage systems - organic-matter - sustainable agriculture - cropping systems - southwestern nigeria - water conservation
    Conservation agriculture is claimed to be a panacea for the problems of poor agricultural productivity and soil degradation in sub-Saharan Africa (SSA). It is actively promoted by international research and development organisations, with such strong advocacy that critical debate is stifled. Claims for the potential of CA in Africa are based on widespread adoption in the Americas, where the effects of tillage were replaced by heavy dependence on herbicides and fertilizers. CA is said to increase yields, to reduce labour requirements, improve soil fertility and reduce erosion. Yet empirical evidence is not clear and consistent on many of these points nor is it always clear which of the principles of CA contribute to the desired effects. Although cases can be found where such claims are supported there are equally convincing scientific reports that contradict these claims. Concerns include decreased yields often observed with CA, increased labour requirements when herbicides are not used, an important gender shift of the labour burden to women and a lack of mulch due to poor productivity and due to the priority given to feeding of livestock with crop residues. Despite the publicity claiming widespread adoption of CA, the available evidence suggests virtually no uptake of CA in most SSA countries, with only small groups of adopters in South Africa, Ghana and Zambia. We conclude that there is an urgent need for critical assessment under which ecological and socio-economic conditions CA is best suited for smallholder farming in SSA. Critical constraints to adoption appear to be competing uses for crop residues, increased labour demand for weeding, and lack of access to, and use of external inputs
    Sustainable Land Management in the Tropics : Explaining the Miracle
    Burger, C.P.J. ; Zaal, F. - \ 2009
    Farnham, England : Ashgate (International Land Management Series ) - ISBN 9780754644552 - 226
    grondbeheer - klimaatverandering - erosie - tropen - bodembescherming - waterbescherming - afrika ten zuiden van de sahara - plattelandsontwikkeling - landgebruik - ontwikkelingseconomie - duurzame ontwikkeling - economische aspecten - land management - climatic change - erosion - tropics - soil conservation - water conservation - africa south of sahara - rural development - land use - development economics - sustainable development - economic aspects
    Bringing together case studies from Kenya, Benin, Cameroon and the Philippines, this volume provides a multidisciplinary overview of the economics of natural resource management in Tropical regions, at household and village level. By comparing a wide array of climatic and economic conditions, it examines the effect of location and access to the market - as well as the importance of national policies - have on soil and water conservation. The book not only analyzes the benefits of soil and water conservation based on econometric studies, but also assesses the costs involved. In doing so it challenges commonly held assumptions about poorer community's ability to finance such measures.
    Long-term strategies for flood risk management: scenario definition and strategic alternative design
    Bruijn, K. de; Klijn, F. ; McGahey, C. ; Mens, M. ; Wolfert, H.P. - \ 2008
    Delft : Flood-site - 167
    hoogwaterbeheersing - waterbescherming - waterbeheer - projecten - engeland - nederland - landen van de europese unie - waterstand - scenario planning - risicobeheersing - schelde - flood control - water conservation - water management - projects - england - netherlands - european union countries - water level - scenario planning - risk management - river scheldt
    This report reviews some mainstream existing methods of scenario development and use, as well as experiences with the design and assessment of strategic alternatives for flood risk management. Next, a procedure and methods are proposed and discussed. Thirdly, the procedure and methods are tried on the Schelde Estuary and the Thames Estuary and, finally, conclusions are drawn
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