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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A Global Analysis of Future Water Deficit Based On Different Allocation Mechanisms
Bijl, David L. ; Biemans, Hester ; Bogaart, Patrick W. ; Dekker, Stefan C. ; Doelman, Jonathan C. ; Stehfest, Elke ; Vuuren, Detlef P. van - \ 2018
Water Resources Research 54 (2018)8. - ISSN 0043-1397 - p. 5803 - 5824.
integrated assessment model - irrigation - socioeconomic development - water demand - water scarcity - water-food-energy nexus

Freshwater scarcity is already an urgent problem in some areas but may increase significantly in the future. To assess future developments, we need to understand how future population growth, agricultural production patterns, energy use, economic development, and climate change may impact the global freshwater cycle. Integrated models provide opportunities for quantitative assessment. In this paper, we further integrate models of hydrology and economics, using the models IMAGE and LPJmL, with explicit accounting for (1) electricity, industry, and municipal and irrigation water use; (2) intersectoral water allocation rules at the 0.5° × 0.5°grid scale; and (3) withdrawal, consumption, and return flows. With the integration between hydrology and economy we are able to understand competition dynamics between the different freshwater users at the basin and grid scale. We run model projections for three Shared Socioeconomic Pathways (SSPs), more efficient water use, and no expansion of irrigated areas to understand the competition dynamics of these different allocation mechanisms. We conclude that (1) global water withdrawal is projected to increase by 12% in SSP-1, 26% in SSP-2, and 29% in SSP-3 during 2010–2050; (2) water deficits (demand minus allocated water) for nonagricultural uses are small in 2010 but become significant around 2050; (3) interannual variability of precipitation results in variability of water deficits; (4) water use efficiency improvements reduce water withdrawal but have little impact on water deficits; and (5) priority rules at the local level have a large effect on water deficits, whereas limiting the expansion of irrigation has virtually no effect.

Deriving spatially explicit water uses from land use change modelling results in four river basins across Europe
Huber García, Verena ; Meyer, Swen ; Kok, Kasper ; Verweij, Peter ; Ludwig, Ralf - \ 2018
Science of the Total Environment 628-629 (2018). - ISSN 0048-9697 - p. 1079 - 1097.
change detection - iCLUE model - irrigation - land use model - River Basin Management Plan - water scarcity
The objective of this study is to provide spatially distributed water use maps at a high spatial and thematic resolution as detailed input data for further modelling purposes. The maps were derived on the basis of official water statistics and land use maps to represent the current conditions in four European river basins affected by water scarcity (Adige, Ebro, Evrotas and Sava) and allow setting up reference scenarios. The present land use distribution was modelled based on CORINE data with the land use change model iCLUE. Modelling the land use allows to create dynamic land and water use maps adapted to the needs of eventual scenario analyses compared to using only observed land use maps. The availability of several CORINE datasets allowed calibrating and validating the results of the iCLUE model carrying out a three map comparison. Sectoral water uses were attributed to different land use classes and by this means located in space. Both the location and the magnitude of urban and agricultural water uses can be derived from the final maps. The created maps together with the corresponding land use data provide a coherent set of information crucial to most environmental modelling activities and often missing at this spatial and thematic resolution. This work also aims at visualizing and validating the water use statistics provided by official institutions such as the River Basin Management Plans. The results show that in some cases they are not consistent and underline the importance of harmonised data collection regarding water statistics, as otherwise comparisons within one study area and with others are hampered. This study is embedded in the EU-FP7 GLOBAQUA project which analyses the effects of stressors, such as changes of land and water use, on aquatic ecosystems in areas suffering water scarcity.
Carbon dioxide fertilization offsets negative impacts of climate change on Arabica coffee yield in Brazil
Verhage, Fabian - \ 2017
Arabica coffee yield simulation model - productivity - elevated CO2 concentration - carbon dioxide fertilization - climate change impact assessment - global warming - irrigation
This collection unites the most important files used to assess the impact of climate change on Arabica coffee in Brazil under a RCP4.5 scenario by 2040-2070, as described by Verhage, Anten & Sentelhas (2017). These files are provided to encourage the further verification, development and application of the Arabica coffee yield simulation model. In addition, the collection includes a short description and try-out of the agro-ecological zoning model, developed by Doorenbos & Kassam (1979) for the Food and Agriculture Organization (FAO), applied on Arabica coffee. This model was excluded from the final study, but the work might still be of use to other researchers.
Becoming an Engineer or a Lady Engineer : Exploring Professional Performance and Masculinity in Nepal’s Department of Irrigation
Liebrand, Janwillem ; Udas, Pranita Bhushan - \ 2017
Engineering Studies 9 (2017)2. - ISSN 1937-8629 - p. 120 - 139.
Engineering - gender - irrigation - masculinities - Nepal - water
In this article, using the Department of Irrigation in Nepal as a case study, we argue that professional performance in irrigation engineering and water resources development is gendered and normalised as ‘masculine’. In Nepal, the masculinity of professional performance in irrigation engineering is located in intersections of gender, class, caste, ethnicity, sexuality, nationality and disciplinary education, and hinders especially female engineers to perform as a ‘normal’ engineer. Our analysis is based on interviews with male and female engineers in the department, documentation research, and ethnographic observations in the period 2005–2011. Our study suggests that professional performances and engineering identities in the organisation have always been tied to performances of masculinity. This implies that career prospects in the Nepalese irrigation department for female engineers remain grim; because for them to succeed and belong, they have to reconcile the near incommensurable: a performance of a ‘lady engineer’ with that of a ‘normal’ engineer.
Modelling the dynamic interactions between food production and ecosystem services : a case study in Benin
Duku, C. - \ 2017
University. Promotor(en): Lars Hein, co-promotor(en): S.J. Zwart. - Wageningen : Wageningen University - ISBN 9789463431613 - 141
ecosystem services - modeling - food production - case studies - hydrology - irrigation - forests - woodlands - climatic change - nature conservation - food security - benin - ecosysteemdiensten - modelleren - voedselproductie - gevalsanalyse - hydrologie - irrigatie - bossen - bosgebieden - klimaatverandering - natuurbescherming - voedselzekerheid

Given the high levels of food insecurity and the loss of vital ecosystem services associated with deforestation, countries in sub-Saharan Africa (SSA) face a major dilemma. How can they produce enough food in a changing climate to feed an increasing population while protecting natural forests and woodlands that provide a wide array of ecosystem services beneficial to livelihoods? Thus, the objectives of this thesis are twofold. First, to further enhance the understanding of the dynamic interactions between food production, and natural and semi-natural ecosystems with a case study in Benin. Second, to further enhance the understanding of how hydrological ecosystem services can be captured in an accounting framework. Understanding hydrological ecosystem services is key to understanding the multi-directional relationship between food production and ecosystem services supply from natural and semi-natural ecosystems. First, I examine how a spatially explicit ecohydrological model can be used to analyse multiple hydrological ecosystem services in line with the ecosystem accounting framework. The hydrological ecosystem services include crop water supply for rainfed agriculture, household water supply (both groundwater supply and surface water supply), water purification, and soil erosion control. Second, I develop a general modelling approach for analysing the effects of deforestation on the availability of water for irrigation at the watershed level, and I apply the approach to the Upper Oueme watershed in Benin. Third, I analyse the impact of climate change on agricultural intensification options. Finally, I quantify trade-offs between per capita food availability and protecting forests and woodlands at different levels of yield increases taking into account climate change, population growth. This thesis shows that the integration of hydrological ecosystem services into an accounting framework can provide relevant information at appropriate scales suitable for decision-making. It is empirically feasible to distinguish between service capacity and service flow of hydrological ecosystem services. This requires appropriate decisions regarding physical and mathematical representation of ecohydrological processes, spatial heterogeneity of ecosystems, temporal resolution, and required model accuracy. This thesis also shows that opportunities for irrigation expansion depend on conservation of forests and woodlands in the headwaters of the rivers feeding the irrigation scheme. Opportunities for agricultural intensification in SSA are likely to diminish with climate change, hence increasing pressure to expand cultivated areas in order to meet increasing food demand. Climate change will lead to substantial reductions in; exploitable yield gaps for major food crops, rainfed cropland areas that can support the cultivation of two or more crops per year, and water availability for irrigation expansion. Furthermore, in the far future crop yields will have to increase at a faster rate than has been recorded over the past two and half decades in order to maintain current levels of per capita food availability. Failure to achieve the required levels of yield increases is likely to lead to the conversion of substantial areas of forests and woodlands for crop cultivation. Based on the results of this thesis, four main recommendations to help address the dual challenge of food security and ecosystem protection in Benin and the larger SSA region are made: (i) promote a precautionary approach to forest and woodland conservation, (ii) promote cross-sectoral policy coherence and consultations, (iii) promote the development of satellite ecosystem accounts consistent with national accounts, and (iv) identify, evaluate and implement adaptation and resilience measures to reduce agricultural vulnerability to climate change.

SWAP version 4
Kroes, J.G. ; Dam, J.C. van; Bartholomeus, R.P. ; Groenendijk, P. ; Heinen, M. ; Hendriks, R.F.A. ; Mulder, H.M. ; Supit, I. ; Walsum, P.E.V. van - \ 2017
Wageningen : Wageningen Environmental Research (Wageningen Environmental Research report 2780) - 243
agrohydrology - irrigation - drainage - surface water - soil water - water management - simulation models - salinization - agrohydrologie - irrigatie - oppervlaktewater - bodemwater - waterbeheer - simulatiemodellen - verzilting
Theory description and user manual
Role of reservoir operation in sustainable water supply to Subak irrigation schemes in Yeh Ho River Basin
Yekti, Mawiti Infantri - \ 2017
University. Promotor(en): E. Schultz, co-promotor(en): I. Nyoman Norken; László Hayde. - Leiden : CRC Press/Balkema - ISBN 9781138065437 - 250
irrigation systems - irrigation - water supply - sustainability - basin irrigation - indonesia - rivers - irrigatiesystemen - irrigatie - watervoorziening - duurzaamheid (sustainability) - kombevloeiing - indonesië - rivieren

A Subak irrigation scheme, primarily in Bali, Indonesia concerns an irrigation system of which the construction, operation and management are based on agreed principles of technology, management of agriculture and religious community. Subak systems have been well known since the 9th Century. As a manifestation of the Cultural Landscape of Bali Province the Subak schemes are since June, 2012 included in the World Heritage List of UNESCO. These systems are managed by a Subak Association based on the Tri Hita Karana philosophy - harmony between human beings and God, harmony between people and nature, and harmony between people and people.

The problem of insufficient water in the dry season developed in the Yeh Ho River Basin. Because of this the main objective of this study was to develop an optimal reservoir operation strategy in relation to the water supply of the Subak irrigation schemes, capable to support agricultural productivity at upstream, midstream and downstream level. Based on a Generic Algorithm the RIBASIM model was applied using the dependable 80% of discharge and shifting the start of land preparation. The results provide evidence that the cropping pattern of the fifth scenario results in an overall optimal agriculture production of the Subak schemes. The recoverable flow considered in the river basin scheme model plays an important role in the optimisation. Nevertheless, if a normal hydro-climate occurs, the other scenarios, especially the first scenario, can be applied as well. This reflects the applicability of the Tri Hita Karana philosophy on harmony among people and harmony among people and nature.

Optimization of productivity and quality of irrigated tomato (Solanum lycopersicum L.) by smallholder farmers in the Central Rift Valley area of Oromia, Ethiopia
Gemechis, Ambecha O. - \ 2017
University. Promotor(en): Paul Struik, co-promotor(en): B. Emana. - Wageningen : Wageningen University - ISBN 9789463431576 - 262
solanum lycopersicum - irrigation - crop production - optimization - photosynthesis - chlorophyll - gas exchange - water use efficiency - crop yield - ethiopia - irrigatie - gewasproductie - optimalisatie - fotosynthese - chlorofyl - gasuitwisseling - watergebruiksrendement - gewasopbrengst - ethiopië

Tomato (Solanum lycopersicum L.) is a vegetable crop with high potential to contribute to poverty reduction via increased income and food security. It is widely grown by smallholders, has high productivity and its demand is increasing. Ethiopia produced about 30,700 Mg of tomatoes on 5,027 ha annually in 2014/2015. Average yields are only 6.1 Mg ha-1, below the world average yields. There is both a need and a potential to increase tomato production per unit area.

The aim of this thesis is to analyze the irrigated tomato production systems of smallholder farmers in Ethiopia, to survey and characterize the tomato in selected ecoregions and seasons, and to identify yield-limiting or yield-reducing factors and opportunities to enhance yield by using a combination of surveys and field experiments. Field experiments on optimization of yield and quality of field-grown tomato were carried out at Ziway, Ethiopia, for two seasons to study the impact of different irrigation practices applied, based on local empirical practices, deficit irrigation, or crop water requirement.

This thesis begins with a survey of tomato production systems. The survey details the area and production in various zones and for each of these zones yield- determining, yield-limiting, and yield-reducing factors and opportunities for improving yield and quality are indicated. It also avails area, production and yield data for each growing season and typifies the production systems in these zones. Low temperature (cold) from October-January and shortage of improved seeds are recognized as yield-determining factors, whereas insufficient water and nutrient (fertilizer) supply proved to be yield-limiting factors across zones. Late blight (Phytophthora infestans), Fusarium wilt (Fusarium oxysporum) and different pests and weeds are identified as yield-reducing factors in the zones. Experienced growers who have access to extension service recorded significant yield increment. Farmers Research Groups improved actual average yield with the use of improved technology (improved varieties and quality seed), and better efficiencies of water and fertilizer use. This study quantified influences of irrigation systems and strategies on growth-determining tomato features. Variation in irrigation systems and strategies accounted for variation in growth and dry matter accumulation. Greater performance for yield-related traits was obtained with drip irrigation based on crop water requirement for tomato varieties. Examination of plants showed also that local empirical irrigation is responsible for the occurrence of Phytophthora root rot, whereas deficit irrigation proved cause for occurrence of Fusarium wilt (Fusarium oxysporum), blossom end rot and broome rape (Orobanche ramosa) on roots or leaves, stems or fruits.

The experiments on irrigation scheduling with different irrigation systems and strategies gave useful indications on the possibility to improve commercial yield (CY) and water use efficiency. Promising results on CY and agronomical water use efficiency of tomato were achieved with drip irrigation based on crop water requirement, while for the biological water use efficiency higher value was obtained with deficit drip irrigation in both seasons. The findings indicate that the CY was decreased significantly for deficit by 50% in drip irrigation and deficit by 50% in furrow irrigation in both seasons. Mean CY for drip irrigation according to crop water requirement increased by 51% and 56% compared with deficit drip irrigation, whereas furrow irrigation based on crop water requirement increased by 52% and 54% compared with deficit furrow in Experiments 1 and 2, respectively. However, water use efficiency decreased with the increasing water volume.

Simultaneous measurements of rate of photosynthesis based on gas exchange measurements and the thylakoid electron flux based on chlorophyll fluorescence were used to investigate physiological limitations to photosynthesis in leaves of deficit irrigated tomato plants under open field situations. Combined leaf gas exchange/chlorophyll fluorescence measurements differentiated the treatments effectively. Reduction in rate of photosynthesis, stomatal conductance and the maximum quantum efficiency of photosystem II varied across seasons of all varieties, whereas leaf temperature was increased by deficit irrigation in all varieties. Among varieties studied, Miya was found relatively tolerant to deficit irrigation. Stomatal limitation of rate of photosynthesis increased significantly as a result of water stress suggesting a strong influence of the stomatal behaviour.

We also determined the influence of irrigation systems and strategies on water saving and tomato fruit quality. Using deficit drip irrigation was the best management strategy to optimize water use and tomato quality. Fruit dry matter content, acid content and total soluble solids were significantly higher with deficit drip irrigation than with other treatments.

From this thesis it appeared that agro-climatic conditions, access to resources and culture all contribute to the relatively low yields of tomato in the Central Rift Valley of Ethiopia. The thesis also proved that significant advances can be made in yield, quality and resource use efficiency.

Modernisation strategy for National Irrigation Systems in the Philippines : Balanac and Sta. Maria River Irrigation Systems
Delos Reyes, Mona Liza Fortunado - \ 2017
University. Promotor(en): E. Schulz, co-promotor(en): Guillermo Q. Tabios; K. Prasad. - Leiden : CRC Press/Balkema - ISBN 9781138067745 - 416
irrigation systems - crop yield - design - irrigation - water supply - philippines - irrigatiesystemen - gewasopbrengst - ontwerp - irrigatie - watervoorziening - filippijnen

The performance of publicly funded canal irrigation systems or more commonly called national irrigation systems (NIS) in the Philippines remained below expectations despite considerable system rehabilitation and improvement efforts. The continued suboptimal performances were attributed to technical, managerial, institutional and policy issues and constraints, and in recent years, to climate change. Irrigation modernisation is recognized as strategic option to improve the irrigation system performance. It is defined as a process of technical, management and institutional transformation to improve irrigation services to farmers.

The main objective of the research study was to formulate a strategy for developing a modernisation plan for national irrigation systems in the Philippines. The research methodology was framed with deliberately selected assessment and characterization procedures, which were adoptively modified and integrated to critically analyse the state of coherence among the three fundamentals of irrigation system water delivery: design, operation and water supply; and to identify solutions for any inconsistency. It included, among others an analysis of the process, nature and impacts of rehabilitation projects; diagnostic assessment of the irrigation systems; revalidation of design assumptions on water balance parameters; characterization of irrigation management, service and demands; and identification of options for improvements.

The developed methodology for examining the different aspects of planning and operations of NIS with an end view of modernising the systems provides a more comprehensive and applicable methodology for drawing up of a more relevant plan for NIS modernisation. The knowledge gained on case study systems provides a sound basis for planning of appropriate modernisation solutions for the case study systems and in cases of ungauged, small-scale NIS. The methodology developed in this study could serve as a blueprint for modernisation program for NIS.

Agricultural intensification in Nepal, with particular reference to systems of rice intensification
Uprety, Rajendra - \ 2016
University. Promotor(en): Thomas Kuijper, co-promotor(en): Harro Maat. - Wageningen : Wageningen University - ISBN 9789462579651 - 190
rice - oryza sativa - nepal - asia - south asia - intensification - livelihoods - livelihood strategies - farming systems - farming - crop management - fertilizers - nutrients - irrigation - varieties - rijst - azië - zuid-azië - intensivering - middelen van bestaan - strategieën voor levensonderhoud - bedrijfssystemen - landbouw bedrijven - gewasteelt - kunstmeststoffen - voedingsstoffen - irrigatie - rassen (planten)

This thesis deals with agricultural intensification in Nepal. The initial focus of the study was the System of Rice Intensification (SRI), as introduced in Nepal from 2001. The multiple factors affecting SRI adoption, modification and dissemination together with the option to apply SRI in different combinations of its components result in a variety of SRI applications. For the same reason the effect of SRI on overall agricultural and livelihood development of Nepalese farmers has to be evaluated within the variety of farming systems in which it is applied.

Despite government policies to promote rice cultivation, national rice production is declining. Farmer livelihood strategies, as reflected in rice farming systems, and field management strategies were influenced by several agro-ecological and socio-economic factors. Livelihood and field management strategies of rice farmers are interconnected. In the study presented here four livelihood strategies and three kinds of field management strategies are distinguished. Two livelihood strategies can be characterized as more intensive and more productive; the other two are less intensive and less productive. Livelihood strategies are more family resource-based strategies, while farmers’ field management strategies are more context-dependent. Field management strategies were characterized by forms of nutrient management. Intensive management strategies had most similarities with SRI. But rice intensification is not achievable as a general strategy.

Government policies (fertiliser subsidies) encourage increased fertiliser use. Study results didn't show any significant effect of volume of fertilisers on rice yield but the combined use of organic manure and mineral fertilisers resulted in the highest average rice yields. Irrigation management is another important factor for rice production. Field management is influenced by the reliability of water which was better in farmers' managed irrigation system. Choice of rice varieties influenced the overall rice farming system and cropping intensity and preference of varieties for rice cultivation by scientists and by farmers were different in eastern Nepal. Most popular varieties were those not recommended by science and policy and were disseminated farmer to farmer.

The introduction of SRI in Morang district resulted in several changes in rice farming, but only part of the farmers have adopted such technologies, and adoption has been only in part of their fields. Other farmers have incorporated some SRI practices in their conventional practices. After the introduction of SRI, farmers further tested, re-packaged or hybridized SRI methods to make SRI ideas suitable for their agro-ecological and socio-economic environments. In order to reform Nepalese rice farming, we need to recognize that different farmers, with different livelihood strategies, and with access to different kinds of fields, need different forms for agricultural intensification. High-intensive farmers prefer to use modified SRI methods where there is good irrigation and drainage facilities. There are many possibilities for improvement of the existing nutrient management practices of rice farmers in Nepal. Nutrient management will be useful to increase rice production because the majority of farmers currently use fertilisers non-judiciously. The SRI-recommended practices (younger seedlings, early weeding, use of organic manure, and alternate wetting and drying (AWD) irrigation) will be useful to improve the nutrient use efficiency of rice farmers. Cost-reduction strategies and less labour-intensive cultivation practices will be appropriate options to improve existing rice farming system of Nepal. Participatory cultivar selection and dissemination will be better strategies to introduce new, promising rice cultivars among rice farmers.

Crop intensification options and trade-offs with the water balance in the Central Rift Valley of Ethiopia
Debas, Mezegebu - \ 2016
University. Promotor(en): Martin van Ittersum, co-promotor(en): Huib Hengsdijk; Katrien Descheemaeker. - Wageningen : Wageningen University - ISBN 9789462578616 - 178
cropping systems - intensification - water balance - crop production - land use - climatic change - crop yield - water use - irrigation - ethiopia - teeltsystemen - intensivering - waterbalans - gewasproductie - landgebruik - klimaatverandering - gewasopbrengst - watergebruik - irrigatie - ethiopië

The Central Rift Valley (CRV) of Ethiopia is a closed basin for which claims on land and water have strongly increased over the past decade resulting in over-exploitation of the resources. A clear symptom is the declining trend in the water level of the terminal Lake Abyata. The actual productivity of most cereals in the CRV is less than 2 t ha-1 associated with low input use and poor crop management. Consequently, there are two major development objectives in the CRV, i.e. producing sufficient food for the increasing population, while at the same time ensuring efficient use of limited water and land resources under variable and changing climate conditions. The low productive cereal systems and a declining resource base call for options to increase crop productivity and improve resource use efficiency in order to meet the growing demand for food.

In this thesis, the recent impacts were quantified of climate change, land use change and irrigation water abstraction on water availability of Lake Abyata of the CRV. The trends in lake levels, river discharges, basin rainfall, temperature and irrigation development (ca. 1975-2008) were analysed and the additional evapotranspiration loss resulting from temperature change and irrigated land were computed. We also analysed land use change (1990-2007) and the associated changes in runoff. Results showed that temperature has increased over 34 years (p<0.001) whereas annual rainfall has not changed significantly. Consequently, increased evapotranspiration consumed 62 and 145 Mm3 of additional water from lakes and land surface, respectively, during 1990-2007. Furthermore, an estimated 285 Mm3yr-1 of water was abstracted for irrigation in 2009 of which approximately 170 Mm3yr-1 is irrecoverable evapotranspiration loss. In addition, surface runoff has increased in the upper, and decreased in lower sub-basins of the CRV associated with extensive land use change (1990-2007).

We analysed a large number of data from farmers’ fields (>10,000) and experimental data across the CRV from 2004-2009 to quantify the gaps (Yg) between actual (farm) and experimental (water-limited potential - Yw) yields of maize and wheat in homogenous farming zones. We found that the average (2004-2009) yield gap of maize and wheat ranged between 4.2-9.2 t ha-1, and 2.5-4.7 t ha-1, respectively, across farming zones. The actual N and P application in farmers’ fields was low, as about 46% of maize and 27% of wheat fields did not receive fertilisers. We calibrated, validated and used the Agricultural Production System Simulator (APSIM) model to explore intensification options and their trade-offs with water losses through evapotranspiration. Variety selection and N fertilization were more important for yield gap closure than crop residue management and planting density, and the magnitude of their effect depended on soil type and climate. There was a trade-off between intensification and water use through evapotranspiration, as increasing yield comes at the cost of increased transpiration. However, this trade-off can be minimized by choosing location-specific N levels at which both water use efficiency (WUE) and gross margin are maximised. These application rates varied between 75 and 250 kg N ha-1 across locations and soils, and allowed producing 80% of Yw of maize and wheat. Climate change was projected to lower Yw of maize and wheat by ca. 15-25% and 2-30%, respectively, compared to current climate conditions.

An automated gridded simulation framework was developed to scale up the promising intensification options from field scale to basin scale. We then aggregated basin scale production and identified trade-offs between production and water use for different land use scenarios. This procedure allowed designing land use scenarios based on a spatially explicit optimization of WUE and gross margin per grid cell. Consequences of land use scenarios for food production and water use at basin level were evaluated. Results of the different land use scenarios demonstrated that crop intensification options for which WUE and gross margin are maximised can meet the projected food demand (year 2050) of the growing population in the CRV while at the same time saving large areas of the currently cultivated land. In the intensification scenarios total water loss through evapotranspiration from agricultural land is reduced compared with water loss from current cultivated land and low crop productivity levels.

It is concluded that the current land use together with climate change and water abstraction for irrigation negatively affected the basin level water balance in CRV over the past decade. Furthermore, the scope for further expansion of farmland to increase food production is very limited. The focus should, therefore, be towards intensification also because the existing yield gaps are huge and hence the scope for intensification is large. Model-based exploration of intensification options can be used to prioritize promising options, to close the yield gap and for quantifying trade-offs. Scaling up of promising options allows to assess whether the food demand of the growing population can be met while at the same time saving the less productive land and water per unit agricultural product.

Territorial pluralism: water users’ multi-scalar struggles against state ordering in Ecuador’s highlands
Hoogesteger, Jaime ; Boelens, Rutgerd ; Baud, Michiel - \ 2016
Water International 41 (2016)1. - ISSN 0250-8060 - p. 91 - 106.
Ecuador - irrigation - resistance - scale - territorial pluralism - water reforms - water user organization
Effect of water use by smallholder farms in the Letaba basin : a case study using the SIMGRO model
Querner, E.P. ; Froebrich, J. ; Clercq, Willem de; Jovanovic, Nebo - \ 2016
Alterra, Wageningen-UR (Alterra-report 2715) - 49 p.
hydrology - models - groundwater - surface water - irrigation - farming systems - limpopo - south africa - hydrologie - modellen - grondwater - oppervlaktewater - irrigatie - bedrijfssystemen - zuid-afrika
For the Letaba basin situated in the South African part of the Limpopo basin, a hydrological study was carried out in order to quantify the effect of smallholder farming on river flows. Important was to study the consequences of improved agricultural systems on the river flows, in particular for the Kruger National Park situated in the lower part of the Letaba basin. The SIMGRO model was used in this study, which integrates groundwater and surface water. The model was calibrated, and furthermore a comparison of measured discharges and groundwater levels against calculated discharges and groundwater levels, revealed that the model is suiTable for practical analysis. For the smallholders farms different scenarios were defined with different levels of crop yield. An increase in crop yield has consequences on more water use as irrigation and crop water use. Because the area covering smallholder farming is only 0.5% of the basin, the effects of changes in water use are relatively small. In a scenario, the weather conditions for 2050 were analysed. This reveals that discharges will go down by 30% on average, which means a substantial reduction of the water resources.
Orchideeënteelt moet nog wennen aan hergebruik gietwater : zoektocht naar teeltkundige grenzen
Staalduinen, J. van; Kromwijk, J.A.M. - \ 2015
Onder Glas 2015 (2015)1. - p. 9 - 11.
glastuinbouw - potplanten - orchidaceae - hergebruik van water - afvalhergebruik - drainagewater - emissie - normen - irrigatie - greenhouse horticulture - pot plants - water reuse - waste utilization - drainage water - emission - standards - irrigation
Tot voor kort was hergebruik van gietwater in de teelt van potorchideeën niet aan de orde. Bedrijfshygiëne en de vrees voor teruglopende waterkwaliteit hield verduurzaming van de teelt op dit punt lang tegen. Strengere emissienormen dwingen ook deze gewasgroep om te investeren in waterontsmetting en hergebruik. Dankzij kennisopbouw door een praktijknetwerk en concreet onderzoek koerst de sector naar verduurzaming. Het ‘laaghangende fruit’ is eenvoudig te plukken, maar er moet nog veel gebeuren om aan de normen voor 2015 en 2016 te kunnen voldoen.
Flexibility in land and water use for coping with rainfall variability
Siderius, C. - \ 2015
University. Promotor(en): Ekko van Ierland; Pavel Kabat, co-promotor(en): Petra Hellegers. - Wageningen : Wageningen University - ISBN 9789462576063 - 222
rain - land use - water use - climatic change - food production - sustainable agriculture - irrigation - rainfed agriculture - regen - landgebruik - watergebruik - klimaatverandering - voedselproductie - duurzame landbouw - irrigatie - regenafhankelijke landbouw
Low cost drip irrigation in Burkina Faso : unravelling actors, networks and practices
Wanvoeke, M.J.V. - \ 2015
University. Promotor(en): Margreet Zwarteveen; Charlotte de Fraiture, co-promotor(en): J.P. Venot. - Wageningen University : Wageningen - ISBN 9789462576117 - 144
irrigatie - irrigatiesystemen - kosten - waterbeheer - waterbeleid - druppelbevloeiing - burkina faso - irrigation - irrigation systems - costs - water management - water policy - trickle irrigation

Title: Low cost drip irrigation in Burkina Faso: Unravelling Actors, Networks and Practices

In Burkina Faso, there is a lot of enthusiasm about Low Cost Drip Irrigation (LCDI) as a tool to irrigate vegetables, and thus improve food security, solve water scarcity and reduce poverty. Already for more than ten years, development cooperation donors, policy makers, and kit designers have invested in the technology, funded its dissemination, and encouraged farmers to adopt it. Yet, there are only very few farmers who are using the technology in their fields. This study shows that this is because the funds for paying the technology mostly do not come from them, but from external donors. For LCDI promoters and disseminators, LCDI is also importantly a tool to survive or make profits. For this, they need to continuously re-assert the success of the technology through reports and stories. Farmers agree to play this game, as they hope and do receive other benefits by associating themselves with LCDI projects.

Beter systeem voor bepalen waterschade
Hack-ten Broeke, M.J.D. ; Kroes, J.G. ; Bartholomeus, R. ; Dam, J.C. van; Bakel, J. van - \ 2015
H2O : tijdschrift voor watervoorziening en afvalwaterbehandeling 2015 (2015)oktober. - ISSN 0166-8439 - p. 43 - 46.
waterbeheer - irrigatie - irrigatiebehoeften - oogstschade - regenschade - modellen - scenario-analyse - landbouw - zouttolerantie - water management - irrigation - irrigation requirements - crop damage - rain damage - models - scenario analysis - agriculture - salt tolerance
Een nieuw instrument voor het bepalen van schade bij landbouwgewassen als gevolg van te veel water, te weinig water of te veel zout: hoe moet dat er uitzien? En kan zo’n instrument bruikbaar zijn voor het doorrekenen van klimaatscenario’s? De Waterwijzer Landbouw moet het antwoord worden op deze vragen.
Waterefficiënte en emissieloze kas voor vruchtgroenten werkt : Onderzoekers en partners tonen aan
Rodenburg, J. ; Beerling, E.A.M. - \ 2015
Onder Glas 12 (2015)1. - p. 50 - 51.
glastuinbouw - teeltsystemen - emissiereductie - steenwol - groeimedia - groenten - vruchtgroenten - doelstellingen - waterzuivering - irrigatie - hergebruik van water - greenhouse horticulture - cropping systems - emission reduction - rockwool - growing media - vegetables - fruit vegetables - objectives - water treatment - irrigation - water reuse
2027 komt snel dichterbij. In dat jaar is het (nagenoeg) emissieloos telen verplicht voor alle glastuinbouwbedrijven. Technisch gezien moet dat mogelijk zijn, meent onderzoeker Ellen Beerling. Nu al zijn diverse technieken voorhanden die deze doelstelling voor veel teelten mogelijk maken. Een langdurige praktijkdemonstratie moet aantonen dat emissieloos telen zeer goed mogelijk is.
Water geven naar behoefte komt stapje dichterbij : Het mysterie van de verdwenen stikstof
Kierkels, T. ; Voogt, W. - \ 2015
Onder Glas 12 (2015)5. - p. 20 - 21.
glastuinbouw - potplanten - plantenvoeding - nutriëntenuitspoeling - stikstof - irrigatie - meting - voedingsstoffenbalans - sensors - vochtmeters - waterbehoefte - greenhouse horticulture - pot plants - plant nutrition - nutrient leaching - nitrogen - irrigation - measurement - nutrient balance - moisture meters - water requirements
De variatie in uitspoeling van mineralen is groot tussen verschillende chrysantenbedrijven. Voor een deel ligt dat aan ondernemersbeslissingen. Om goed te kunnen sturen op minimale uitspoeling en maximale productkwaliteit zijn goede tools nodig. Een betere vochtsensor is zeer welkom, geeft teler Jos Ammerlaan aan.
Beheersing emissie grondgebonden kasteelten
Voogt, W. ; Balendonck, J. ; Janse, J. ; Swinkels, G.L.A.M. ; Winkel, A. van - \ 2015
Bleiswijk : Wageningen UR Glastuinbouw (Rapport GTB 1363) - 38
teelt onder bescherming - snijbloemen - emissie - beslissingsondersteunende systemen - biologische landbouw - irrigatie - lysimeters - sensors - water - voedingsstoffenbalans - voedingsstoffen - optimalisatie - protected cultivation - cut flowers - emission - decision support systems - organic farming - irrigation - nutrient balance - nutrients - optimization
To make growers to be in control of the emission, a decision support system is developed for irrigation in soil grown crops. In 2013-2014 the implementation was continued and several greenhouse crops were monitored. As was found earlier, the organic greenhouse growers are able to control irrigation in a way that emission is reduced to a minimum. The results obtained at (conventional) flower growers show sometimes high emission of nitrogen. This is due at one hand to high irrigation surpluses but also to high fertilisation of nitrogen. Better tuning of the water- and nitrogen supply to the crop demand is necessary. For these stapes growers need better soil-moisture sensors.
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