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.

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Social network analysis for facilitating the innovative water technologies towards more efficient water use in industrial zone
Tran, Trang - \ 2019
Vietnam Journal of Construction 58 (2019)4-2019. - ISSN 0866-8762 - p. 103 - 108.
Social network analysis - industrial zone - water use efficiency - network
Industrial zones (IZs) in Vietnam require a huge quantity of water for production activities to develop society an economy. However, the quality and quantity of IZ-related water resources are depleted and threatened. In order to prevent water scarcity, mismanagement and wasting of water supplies, it is necessary to develop new technologies to increase water use efficiency in the IZs. However, new technologies would be not fit with the existing socio-institutional framework so that the societal aspects could be transformed to facilitate the innovative technologies. This paper aims to analyse the existing actor network for facilitating the innovative water technologies towards more efficient water use in Hiep Phuoc IZ. Using the results from the collected data, Social Network Analysis (SNA) is applied to understand the social structure and dimension of the four networks (policy, economic, societal and research networks) that govern IZ's water flows (Borgatti et al., 2002; Domenech, 2009; Reed et al., 2009; Ashton, 2008; Steveson and Greenberg, 2000). The findings contribute insight to how the actors correlate among the four networks and their roles in facilitating the technological innovation in Hiep Phuoc Industrial Zone in the South of Vietnam.
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
Wageningen 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.

Understanding the productivity of cassava in West Africa
Ezui, Kodjovi Senam - \ 2017
Wageningen University. Promotor(en): Ken Giller, co-promotor(en): Linus Franke; A. Mando. - Wageningen : Wageningen University - ISBN 9789463430470 - 183
manihot esculenta - cassava - crop production - rainfed agriculture - drought - crop yield - water use efficiency - radiation use efficiency - fertilizers - togo - ghana - west africa - cassave - gewasproductie - regenafhankelijke landbouw - droogte - gewasopbrengst - watergebruiksrendement - stralingsbenuttigingsefficiëntie - kunstmeststoffen - west-afrika

Drought stress and sub-optimal soil fertility management are major constraints to crop production in general and to cassava (Manihot esculenta Crantz) in particular in the rain-fed cropping systems in West Africa. Cassava is an important source of calories for millions of smallholder households in sub-Sahara Africa. The prime aim of this research was to understand cassava productivity in order to contribute to improving yields, food security and farm incomes in rain-fed cassava production systems in West Africa. A long-term goal was to contribute to a decision support tool for site-specific crop and nutrient management recommendations. Firstly, we studied farmers’ perception of cassava production constraints, assessed drivers of diversity among households and analysed the suitability of farmers’ resource endowment groups to the intensification of cassava production. The results indicate that farmers perceived erratic rainfall and poor soil fertility to be prime constraints to cassava production. The agricultural potential of the area and the proximity to regional markets were major drivers for the adoption of crop intensification options including the use of mineral and organic fertilizers. While the use of mineral and organic fertilizers was common in the Maritime zone that had a low agricultural potential, storage roots yields were below the national average of 2.2 Mg dry matter per hectare, and average incomes of 0.62, 0.46 and 0.46 US$ per capita per day for the high, medium and low farmer resource groups (REGs – HRE, MRE and LRE, respectively) were below the poverty line requirement of 1.25 US$. In the high agricultural potential Plateaux zone, HRE and MRE households passed this poverty line by earning 2.58 and 2.59 US$ per capita per day, respectively, unlike the LRE households with 0.89 US$ per capita per day. Secondly, we investigated the effects of mineral fertilizer on nutrient uptake, nutrient physiological use efficiency and storage roots yields of cassava since soil fertility was a major issue across the zones. We used an approach based on the model for the Quantitative Evaluation of the Fertility of Tropical Soils (QUEFTS). This model was successfully adapted for cassava and it appropriately assessed the response of cassava to N, P and K applications, especially in years with good rainfall. Under high drought stress, the model overestimated cassava yields. Thirdly, we investigated the impact of balanced nutrition on nutrient use efficiency, yield and return on investment compared to blanket fertilizer use as commonly practiced in cassava production systems in Southern Togo, and in Southern and Northern Ghana. The balanced nutrition approach of the QUEFTS model aimed to maximize simultaneously nutrient use efficiency of N, P and K in accordance with the plant’s needs. Larger nutrient use efficiencies of 20.5 to 23.9 kg storage root dry matter (DM) per kilo crop nutrient equivalent (1kCNE of a nutrient is the quantity of that nutrient that has the same effect on yield as 1 kg of N under balanced nutrition conditions) were achieved at balanced nutrition at harvest index (HI) of 0.50 compared to 20.0 to 20.5 kg storage root DM per kilo CNE for the blanket rates recommended by national research services for cassava production. Lower benefit:cost ratios of 2.4±0.9 were obtained for the blanket fertilizer rates versus 3.8±1.1 for the balanced fertilizer rates. Our study revealed that potassium (K) was a major yield limiting factor for cassava production, especially on the Ferralsols in Southern Togo. Hence, we fourthly studied the effect of K and its interaction with nitrogen (N), phosphorus (P), and the timing of harvest on the productivity of cassava in relation to the effects of K on radiation use efficiency (RUE), light interception, water use efficiency (WUE) and water transpiration. The results suggest that K plays a leading role in RUE and WUE, while N is the leading nutrient for light interception and water transpiration. Potassium effects on RUE and WUE depended on the availability of N and harvest time. Values of RUE and WUE declined with harvest at 4, 8 and 11 months after planting. Thus, enhanced K management with sufficient supply of N during the early stage of development of cassava is needed to maximize RUE and WUE, and consequently attain larger storage root yields. Given that erratic rainfall was another major constraint to cassava production according to the results of the farm survey, and due to the inability of QUEFTS modelling to assess drought effects on cassava yield successfully, another modelling approach based on light interception and utilization (LINTUL) was used. We quantified drought impacts on yields and explored strategies to improve yields through evaluation of planting dates in Southern Togo. The evaluation of the model indicated good agreement between simulated and observed leaf area index (Normalised Root Mean Square Error - NRMSE - 17% of the average observed LAI), storage roots yields (NRMSE 5.8% of the average observed yield) and total biomass yield (NRMSE 5.8% of the average observed). Simulated yield losses due to drought ranged from 9-60% of the water-limited yields. The evaluation of planting dates from mid-January to mid-July indicated that the best planting window is around mid-February. Higher amount of cropping season rainfall was also achieved with early planting. These results contradict current practices of starting planting around mid-March to mid-April. However, the results indicate the possibility to increase cassava yields with early planting, which led to less yield losses due to drought. By contrast, late planting around June-July gave larger potential yields, and suggested these periods to be the best planting window for cassava under irrigated conditions in Southern Togo. This shows that appropriate water control and planting periods can contribute to attaining larger yields in Southern Togo. Further improvement of the LINTUL model is required towards using it to assess water-limited yield, which can be used as boundary constraint in QUEFTS to derive site-specific fertilizer requirements for enhanced cassava yield and returns on investments in West Africa.

Steering with high EC improves taste and quality of fruits : search for less water, fertilisers and discharge
Beerling, Ellen - \ 2017
horticulture - greenhouse horticulture - tomatoes - water use - water use efficiency - fertilizers - emission reduction - drainage - rockwool - irrigation systems - crop quality - cultural methods
With a little more effort you can improve even more. This is the approach behind new trials aimed at optimizing water and fertiliser use with the specific aim of reducing fertiliser emission to the environment. It sounds rather demanding until you realise that the quality of the end product can also improve, while maintaining or even increasing yield. Excess drain as an insurance policy for the cultivation is an out-dated idea.
Transition to more water efficient agriculture production in Thailand : Fact finding
Blom-Zandstra, M. ; Kempenaar, C. ; Rothuis, A.J. - \ 2016
Wageningen : Wageningen Plant Research (Report / Wageningen Plant Research 663) - 22 p.
crops - water use efficiency - water deficit - crop production - thailand - gewassen - watergebruiksrendement - watertekort - gewasproductie
Thailand will face major water scarcity problems. The question is how Thailand can remain an important producer of agriculture crops (such as rice) while facing severe water shortages in the near future. To generate “more crop per drop” a sequence of innovations need to be introduced.
Regenerating degraded soils and increasing water use efficiency on vegetable farms in Uruguay through ecological intensification
Alliaume, F. - \ 2016
Wageningen University. Promotor(en): Pablo Tittonell, co-promotor(en): Walter Rossing; Santiago Dogliotti. - Wageningen : Wageningen University - ISBN 9789462578487 - 163 p.
tillage - minimum tillage - mulches - vegetable growing - water use efficiency - degraded land - soil conservation - modeling - soil management - grondbewerking - minimale grondbewerking - groenteteelt - watergebruiksrendement - gedegradeerd land - bodembescherming - modelleren - bodembeheer

This thesis investigated alternative soil management strategies for vegetable crop systems and their hypothesized effects on increasing systems resilience by sequestering soil carbon, increasing the efficiency of water use, and reducing erosion. The goal was to contribute knowledge on and tools for the integrated assessment of soil management strategies for the ecological intensification and small-scale production systems sustainability in South Uruguay.

We performed a baseline assessment of key soil properties on cropped fields, and evaluated the impact of implementing different soil management strategies after re-design of systems in a co-innovation project. We showed evidence that even under smallholder conditions, it was possible to reverse the soil degradation. However, it was not possible to reduce erosion in cases that a pasture could not be included in the rotation. We evaluated reduced tillage and cover crop management in an experiment. In-situ grown mulching increased water capture by 9.5% and reduced runoff by 37% on average, leading to less erosion risk and greater plant available water. We also collected enough data to develop a simple, generally applicable, locally parameterizable mathematical model that accounts for the effect of soil cover on soil water dynamics. Exploration with 10 years of weather data showed that reduced tillage and mulching (RTmulch) would decrease water requirements for irrigation by 37% on average.

Finally, we scaled up the results to study the impact of RTmulch on two small horticultural family farms with different resource availabilities. By combining process-based simulation models with empirical data and expert knowledge, we quantified inputs and outputs of production activities. Adoption of RTmulch was associated with improvements of the economic and/or environmental performances. It was possible to design production activities with erosion rates below the tolerable level without sacrificing the family income too much. Average water savings of 775 m3 ha-1 yr-1 (fully irrigated rotations) to 452 (irrigating only the most profitable vegetable crops) were obtained under RTmulch compared with conventional tillage.

Reduced tillage and mulching have potential for increasing water infiltration, reducing runoff and erosion, and achieving greater efficiency of water use for vegetable crops grown in raised bed systems. These aspects are especially relevant under conditions of high rainfall variability, limited access to irrigation and high soil erosion risk. For future research, we suggest combining long-term experiments with on- farm research to capture the benefits of improving soil quality on soil productivity, while adjusting the technology to solve limitations that arise in the process. This study provides ground for testing the proposed changes on pilot farms, using a co-innovation approach combining scientific insights with farmers’ knowledge of their farms.

Exploring options for improving water and nitrogen use efficiency in crop production systems
Qin, W. - \ 2015
Wageningen University. Promotor(en): Oene Oenema, co-promotor(en): C. Hu; Marius Heinen. - Wageningen : Wageningen University - ISBN 9789462575035 - 188
gewasproductie - agrarische productiesystemen - watergebruiksrendement - stikstof - nutriëntengebruiksefficiëntie - mulchen - fertigatie - crop production - agricultural production systems - water use efficiency - nitrogen - nutrient use efficiency - mulching - fertigation

Water and nitrogen (N) are two key limiting factors in global crop production. However, the optimization of water and N use is often studied separately, and the interactions between water and N use in crop production are often neglected. Lack of systematic and quantitative understanding of the interactions between water and N use may lead to misleading and/or biased recommendations. The main objective of this thesis research was ‘to increase the understanding of interactions between water and N use in crop production’. The specific objectives were (i) to analyse water and N use and their interactions in crop yields and in water and N use efficiencies (WUE and NUE), and (ii) to explore options for increasing crop yields and water and N use efficiencies simultaneously.

In this thesis, I combined the use of literature review and meta-analysis, long-term field experiments and soil-crop modelling to quantify relationships between water and N use and their interactions in crop yields, WUE and NUE, and to explore options for improving the productivity and sustainability of two important and contrasting crop systems (i.e., annual cereal and perennial orange systems).

In arid and semi-arid regions, such as the Loess Plateau, I found that the water loss via soil evaporation was large as much as 60 to 70% of total rainfall and thereby significantly limited wheat yields. Soil mulching can effectively reduce soil evaporation thereby increasing crop yields by up to 60%. In sub-humid regions, the productivity and sustainability of rainfed wheat-soybean rotation systems can be constrained by soil fertility and other factors besides water and nutrient management. Fertilization and soil organic amendments greatly increased wheat yield and WUE, but decreased NUE.

In advanced fertigated orange production systems, a main challenge is to optimize water and N use for optimal yield while minimizing environmental pollution. Fertigation provides opportunities to simultaneously optimize water and N use in orange production systems. Optimization of water and N supply is, however, complicated in practice due to erratic and uncontrollable rainfall, which may lead to large incidental losses. Improving water and N input can significantly and simultaneously increase orange yield, WUE and NUE (by 20, 30 and 40% respectively). Importantly, even with optimal water and N input levels, fractionation (split) strategies can significantly increase orange yield and reduce N losses.

In conclusion, rainfed cereal crop yields, WUE and NUE in dryland agriculture can be increased by up to 60%, with currently available knowledge and soil mulching techniques. In many regions in the world, there is still a large gap between observed farm yield and attainable yield by best management. Given large potentials in low-performing agricultural systems, investments in knowledge and education, infrastructures and subsidies should also be prioritized for these regions. Potentially, this will significantly contribute to local and global food security at large.

Understanding factors affecting technology adoption in smallholder livestock production systems in Ethiopia : the role of farm resources and the enabling environment
Kebebe, E.G. - \ 2015
Wageningen University. Promotor(en): Imke de Boer, co-promotor(en): Simon Oosting; A.J. Duncan. - Wageningen : Wageningen University - ISBN 9789462573260 - 151
veterinaire praktijk voor kleine dieren - veehouderij - ethiopië - technologie - innovaties - dierlijke productie - watergebruiksrendement - small animal practice - livestock farming - ethiopia - technology - innovations - animal production - water use efficiency

Abstract

In response to population growth, rising income and urbanisation, the demand for livestock products, such as milk, meat and eggs is growing in Ethiopia. The growing demand for milk products offers opportunities for smallholders to realize better livelihoods. Whereas the growing demand for milk products in Ethiopia is widely recognised, the dairy sector has not been able to produce adequate milk to satisfy this demand, mainly due to low productivity of dairy animals. The use of technological inputs, such as improved breeds of dairy cows and cultivation of improved forages, is often seen as a prerequisite to increasing livestock productivity and resource use efficiency in the smallholder dairy sector. However, adoption of such technologies has been low, despite numerous efforts to disseminate the technologies in the past. This poses a question as to why the majority of smallholders have not adopted livestock technologies in the Ethiopian highlands. The overall objective of this study was understanding the factors affecting adoption of technologies that enhance the productivity of livestock production and water use efficiency in the Ethiopian highlands, with particular emphasis on dairy production. The study was intended to deepen the understanding on the role of factors at the levels of farm households, value chains and macroeconomic institutions and policies on farmers’ decision to adopt technologies. The study employed interdisciplinary approach to analyse micro and macro level constraints that affect adoption of technologies in livestock production. The findings in the empirical chapters show that low adoption of the technologies that enhance the productivity of livestock production and water use efficiency stem from farmers’ limited access to farm resources, differentials in potential welfare impacts of the technologies, lack of effective and reliable supply chains for inputs and outputs, inadequate physical infrastructure and weak institutions and policies. The findings show that smallholders have been subjected to multiple constraints. Given the multiple constraints at different scales and the associated transaction costs facing smallholders in rural Ethiopia, the returns to investment for the technologies may be too low to justify widespread adoption of the technologies. Therefore, adoption of technologies in the dairy sector requires interventions at production, storage, transportation, processing and marketing chains and at macroeconomic institutions and policies. In the short and medium term, dairy development programs in Ethiopia will have a better chance of success if they target farmers who have better resource endowments and

who are connected to better-functioning value chains rather than blanket technology scaling-up strategies targeting the majority of smallholders. Future agricultural research needs to shift the focus from predominantly developing new biophysical technologies towards social science research that assesses issues at value chain, macroeconomic institutions and policies that influence adoption of technology.

Waterbesparing door slimme en betaalbare sensor
Balendonck, J. - \ 2015
Kas techniek 2015 (2015)april. - p. 34 - 37.
teelt onder bescherming - cultuurmethoden - kunststoftunnels - irrigatie - sensors - instrumenten (meters) - waterbehoefte - vochtmeters - watergebruik - efficiëntie - watergebruiksrendement - irrigatiesystemen - protected cultivation - cultural methods - plastic tunnels - irrigation - instruments - water requirements - moisture meters - water use - efficiency - water use efficiency - irrigation systems
Onderzoekers van Wageningen UR Glastuinbouw hebben in het kader van een Partners voor Water-project laten zien dat Turkse telers met behulp van de AquaTag veel efficiënter kunnen irrigeren. Sturen op vochtsensoren is niet nieuw, maar beschikbare sensoren zijn relatief duur en meten alleen lokaal, terwijl het vochtgehalte sterk kan variëren binnen een kraanvak. Met de AquaTag is nu een goedkope en slimme oplossing voor handen.
Progress Report China Potato GAP project; Late blight control, seed quality, storage facilities and sustainability studies in Heilongjiang province and communications
Kempenaar, C. ; Kessel, G.J.T. ; Wustman, R. ; Pronk, A.A. ; Haverkort, A.J. ; Ruijter, F.J. de; Lyu, D. ; Wan, S. ; Fan, G. ; Bai, Y. ; Min, F. ; Guo, M. ; Zhang, S. ; Yang, S. ; Gao, Y. - \ 2015
Wageningen : Plant Research International (Report / Plant Research International 608) - 73
potatoes - seed potatoes - solanum tuberosum - good practices - phytophthora infestans - disease resistance - decision support systems - seed quality - land use - water use efficiency - storage - storage equipment - china - aardappelen - pootaardappelen - ziekteresistentie - beslissingsondersteunende systemen - zaadkwaliteit - landgebruik - watergebruiksrendement - opslag - voorzieningen voor de opslag
In this report we describe the mid-term results of the R&D program of the PPS Potato GAP China. The aim of the Potato GAP China PPS is to exchange information on GAP in potato production and storage, and to set up experiments and demonstration farms in China with Dutch technology and know-how. This last objective, the setup of Centres of Dutch potato Expertise in China, has not been achieved yet, but still has high priority in 2015. In this report, we describe the results of experiments, investigations and communications within the PPS in 2013 and 2014. The R&D topics are potato late blight disease monitoring and control, potato seed quality evaluation, potato storage investigation and sustainability evaluation of potato production.
Atmospheric turbulence over crops : confronting theories with observations
Boer, A. van de - \ 2015
Wageningen University. Promotor(en): Bert Holtslag, co-promotor(en): Arnold Moene; A. Graf. - Wageningen : Wageningen University - ISBN 9789462572416 - 143
turbulentie - meteorologie - atmosfeer - gewassen - watergebruiksrendement - transpiratie - modellen - eddy-covariantie - turbulente stroming - turbulence - meteorology - atmosphere - crops - water use efficiency - transpiration - models - eddy covariance - turbulent flow

Atmospheric turbulence plays a key role in hydrological and carbon cycles, and in weather and climate. Understanding and forecasting turbulence is thereby relevant for human life and environment.

We deal with some major challenges for studying atmospheric turbulence over crops. Land-atmosphere interactions are specifically complex because of surface heterogeneity. Also, boundary-layer entrainment complicates measuring and studying surface fluxes. Furthermore, the absence of high-frequency observations and of measurements of underlying soil and vegetation processes impedes studying land-atmosphere interactions.

We show the applicability of analytical footprint models over a heterogeneous land surface, and the validity of Monin-Obukhov similarity theory for a strongly-convective boundary-layer. Moreover, we present improvements on a scheme that can be used to estimate the amount of atmospheric turbulence from single-level weather data. We furthermore suggest to improve the partitioning theory that is used to distinguish soil processes from plant processes in eddy-covariance flux observations.

Agricultural water productivity optimization for irrigated Teff (Eragrostic Tef) in water scarce semi-arid region of EthiopiaAgricultural water productivity optimization for irrigated Teff (Eragrostic Tef) in water scarce semi-arid region of Ethiopia
Yihun, Y.M. - \ 2015
Wageningen University. Promotor(en): E. Schultz, co-promotor(en): T. Erkossa Jijo; A. Mehari Haile. - Leiden : CRC Press/Balkema - ISBN 9789462571709 - 82
eragrostis tef - waterbeheer - watergebruik - water - watergebruiksrendement - optimalisatie - ethiopië - water management - water use - water use efficiency - optimization - ethiopia
Physiology and genetics of root growth, resource capture and resource use efficiency in lettuce (Lactuca sativa L.)
Kerbiriou, P.J. - \ 2014
Wageningen University. Promotor(en): Edith Lammerts van Bueren; Paul Struik, co-promotor(en): Tjeerd-Jan Stomph. - Wageningen : Wageningen University - ISBN 9789462570863 - 179
lactuca sativa - slasoorten - cultivars - groei - wortels - scheuten - plantenontwikkeling - nutriëntengebruiksefficiëntie - voedingsfysiologie - watergebruiksrendement - genetische variatie - droogteresistentie - tolerantie van variëteiten - genotype-milieu interactie - biologische plantenveredeling - lettuces - growth - roots - shoots - plant development - nutrient use efficiency - nutrition physiology - water use efficiency - genetic variation - drought resistance - varietal tolerance - genotype environment interaction - organic plant breeding
Proceedings of the international symposium on growing media and soilless cultivation, Leiden, The Netherlands : June 17-21, 2013
Blok, C. ; Os, E.A. van; Voogt, W. - \ 2014
Leuven : ISHS (Acta horticulturae 1034) - ISBN 9789462610217 - 616
groeimedia - cultuur zonder grond - tuinbouw - watergebruiksrendement - growing media - soilless culture - horticulture - water use efficiency
Improving resource-use efficiency in rice-based systems of Pakistan
Awan, M.I. - \ 2013
Wageningen University. Promotor(en): Holger Meinke, co-promotor(en): Lammert Bastiaans; Pepijn van Oort. - S.l. : s.n. - ISBN 9789461737526 - 151
oryza sativa - rijst - bedrijfssystemen - hulpbronnengebruik - gebruiksefficiëntie - watergebruiksrendement - fenologie - voedselzekerheid - pakistan - rice - farming systems - resource utilization - use efficiency - water use efficiency - phenology - food security

Keywords: Aerobic rice, water productivity, pre-flowering phenology, eco-efficiency, perceptions, transformational technology, food security, resource constraints, Punjab, Pakistan.

Just like in many other parts of the world, diminishing resources of water, labour and energy threaten the sustainability of conventional flooded rice systems in Pakistan. Changing the current production system to non-flooded aerobic rice could considerably increase resource-use efficiencies. However, for subtropical conditions, such as those in South Asia, the non-conventional system is still very much in the development phase. The main objective of this study was to evaluate the aerobic rice system of the Punjab in Pakistan from a biophysical and socio-technological perspective. I employed a combined approach of experimentation and farmer surveys to contribute important information on aerobic rice crop performance, pre-flowering photothermal responses, and farmers’ perspective.

Two seasons of field experiments (2009 and 2010) at the research station of the University of Agriculture, Faisalabad–Pakistan tested local (KSK133, IR6, RSP1) and exotic (Apo, IR74371-54-1-1) genotypes against different combinations of irrigation levels (high, moderate, low) and nitrogen rates (0, 170, 220 kg N ha−1). Under aerobic conditions, the water productivity (WPg; g grain kg–1 total water input) improved significantly, showing a potential water saving of about 20%. However, this improved water productivity was at the cost of declining land productivity, as the actual production per unit area decreased. Grain yield and total aboveground N uptake were mainly limited by irrigation and not by N. The results suggest significant losses of applied N, and indicate that improvements in N use efficiency might be expected if N application is better synchronised with the N-demand of the crop.

Accurate knowledge on rice phenological development is an important feature when the aim is to better match supply and demand for further improvement in resource use efficiencies. A controlled-environment growth chamber study, aimed at estimating pre-flowering photothermal responses, gave a robust set of photoperiod-parameters and demonstrated that all four tested genotypes (KSK133, RSP1, Apo, IR74371-54-1-1) were strongly photoperiod-sensitive. The temperature range in the field experiments was too narrow to achieve convergence to a unique set of optimal temperature response parameters. Yet, sensitivity analysis clearly showed that commonly used standard cardinal temperatures (base, optimum, maximum: 8, 30, 42°C, respectively) overestimated the time to flowering. Data obtained under a wider range of temperatures should result in more accurate estimation of temperature response parameters.

To supplement the basic biophysical research, I conducted farmer surveys (n=215) in three major cropping systems viz. rice-wheat, mixed-cropping and cotton-wheat to understand farmers’ perspective about the future prospects of aerobic rice system. Most of the farmers were unaware of aerobic rice technology but expressed their keen interest in experimenting. Farmers perceived aerobic rice as a system to improve resource use efficiency particularly for labour and water but they consider it a knowledge intensive system requiring careful and timely management practices especially for weeds. The unavailability of suitable fine grain aerobic basmati varieties was identified as a major constraint for large scale adoption. Understanding farmers’ perspective helped to develop guidelinesfor the emerging aerobic rice system. The aerobic rice system is a rational approach for improving WPg and eco-efficiencies of water, labour and energy. Associated risks of crop failure can be reduced by filling the identified knowledge and technological gaps through additional research and adequate training of farmers.

Water, food and markets : household-level impact of irrigation water policies and institutions in northern China
Zhang, L. - \ 2013
Wageningen University. Promotor(en): Erwin Bulte; X. Shi, co-promotor(en): Nico Heerink. - S.l. : s.n. - ISBN 9789461735751 - 143
ontwikkelingseconomie - huishoudens - irrigatiewater - waterbeleid - watergebruik - watergebruiksrendement - instellingen - noord-china - china - azië - landbouwhuishoudens - platteland - development economics - households - irrigation water - water policy - water use - water use efficiency - institutions - northern china - asia - agricultural households - rural areas

Water is increasingly becoming a limiting factor for sustainable economic growth and development, particularly in developing countries. Besides technical innovations, water institution reforms may contribute to improving water allocation decisions. Appropriately designed water institutions can motivate water users to conserve and use water efficiently for irrigation and other uses.

In northern China, growing demands on agricultural water due to relatively low water availability and increasing grain production are putting more and more pressure on improving water resource management. The Ministry of Water Resources of the P.R. China has initiated a number of pilot projects to gain experience with the development of water-saving irrigation systems. These pilot projects focus on the construction of engineering systems as well as institutional innovations in water resource management. Analysing the household-level effects of the implemented measures is hence of great importance for further policy development.

The project ‘Building a Water-saving Society in Zhangye City’, initiated early 2002 in Zhangye City in northwest China, is the first pilot project of this kind in China. It provides a unique opportunity to examine the economic effects of changes in water policies and institutions. Minle County, the research area for this study, is located within Zhangye City. A large potato processing company was established in Minle County in 2008. After the factory started its activities, the local government intervened in the allocation of irrigation water within the region by assigning more water to a specific variety of potatoes (i.e. Atlantic potatoes) that the factory needs for processing. This further makes Minle County an interesting case for analysing the link between output market development and institutional change in irrigation water management.

The general objective of this study is to empirically investigate the household-level impacts of policies and institutional changes in irrigation water use. From this general objective, the following four specific objectives are defined and analysed in separate chapters. 1) To examine the impact of the institutional setup of Water Users Associations (WUAs) on productivity of irrigation water use by the WUA member households, based on a user-based resource governance framework. 2) To analyse the effects of a policy affecting the availability of water for different crops on farmers’ acreage allocation among crops. 3) To evaluate the internal valuation (i.e. marginal value) of irrigation water, before and after the introduction of the water policy as explained above. 4) To investigate the effects of output market development on irrigation water trading.

The information used for the empirical analyses mainly comes from two surveys that were carried out in Minle County in May 2008 and May 2010. These surveys cover information for the years 2007 and 2009, that is before and after the potato processing factory became operational. A stratified sampling approach was used for selecting the households and WUAs to be interviewed in the surveys. Additional interviews were held by the author in August 2010 with the Water Management Bureaus (WMBs) that are responsible for water allocation within the seven irrigation areas in Minle County.

Chapter 2 investigates the underlying causes of differences in WUA performance by analysing the impact of WUA characteristics on the productivity of irrigation water use. Total crop production value and household income obtained from crop production, both expressed per m3 of water, are used as dependent variables in the empirical analysis. The explanatory variables in the analysis are derived from an established user-based resource governance framework, that specifies the conditions under which user groups are expected to sustainably govern common-pool resources. These conditions are grouped into resource characteristics, group characteristics, relationships between resources and user groups, and the external environment (markets, technology). Applying a random intercept model, the estimation results show that group characteristics, particularly group size and number of water users groups, and the existing pressure on available water resources are important WUA characteristics explaining water productivity.

Chapter 3 analyses the impact of the local government intervention in irrigation water allocation on farmers’ crop planting decisions. A system of unconditional crop acreage demand functions depending on prices of variable inputs, levels of quasi-fixed inputs and prices of outputs is estimated. Two hypotheses are tested: Firstly, the government intervention results in an increase in land allocated to Atlantic potatoes and a decrease in land allocated to other crops; Secondly, among the alternative crops (i.e. other crops than Atlantic potatoes), the water policy is expected to cause a relatively small response for grain crops, because grains are mainly used for domestic consumption. The empirical results do not support the first hypothesis. The increased water allocation to Atlantic potatoes does not significantly affect the land allocated to this crop, because its planting decisions are mainly taken by village leaders instead of households. Instead, the intervention results in a shift from planting potatoes towards grains with relatively low water requirements.The second hypothesis is partly supported by the empirical results. The estimated impact of the government intervention is found to be stronger for local potato varieties than for grains, but the impact on the area planted with cash crops does not differ significantly from zero. Output prices seem to play a more important role in cash crop planting decisions than the water allocation intervention.

Chapter 4 examines the economic valuation (i.e. marginal value) of irrigation water, before and after the local government intervention in water allocation. To accomplish this, a system of translog production functions is estimated. Two hypotheses are tested: Firstly, the valuation of irrigation water is expected to be equal across different crops before the start of the new water policy. And secondly, valuation of irrigation water is expected to be lower for Atlantic potatoes as compared to the alternative crops after the water policy change. The empirical results do not support the first hypothesis. The valuation of irrigation water used on grain crops is very low, and is even below the actual water prices charged to farm households. This is probably due to self-consumption of grain by households, and to government subsidies for grain farmers that are based on the planted area with grains. The second hypothesis is supported by the empirical results, except for grains. The valuation of irrigation water used on Atlantic potatoes is lower than the value of water used on other (non-grain) crops. Moreover, the returns for irrigation water used on other crops are higher in the year after the water allocation intervention than in the year before the intervention.

Chapter 5 aims to provide insights into the impact of output market development on the trading of water use rights by farm households. Theresults of the two farm household surveys indicate that water markets have emerged at a small scale in response to the development of the potato market in Minle County. Observed water trade in the second survey, that was held after the establishment of the potato processing factory, consists mainly of the exchange of water without payment between relatives or neighbours, and seems to be meant to improve the timing of water applications to crops with different seasonal water requirements. Those who have started trading water rights tend to have more land with water use rights than other potato farmers. High transaction costs and information asymmetry between the government and water users, however, severely constrain the trading of water use rights in the region.

Chapter 6 summarizes and integrates the main findings, discusses the policy implications and the limitations of the research, and presents some suggestions for further research.

Fertilisation and water management in organic greenhouse horticulture
Voogt, Wim - \ 2012
greenhouse horticulture - fertilizer application - water management - water use efficiency - water use - nutrient leaching - organic farming
Geïntegreerde visteelt in Egypte : ‘It’s complicated’
Heijden, P.G.M. van der; Nasr Allah, A. ; Kenawy, D. - \ 2012
Aquacultuur 2011 (2012)5. - ISSN 1382-2764 - p. 18 - 25.
visteelt - aquacultuur - zoetwatervissen - irrigatiewater - landbouw - watergebruik - watergebruiksrendement - egypte - fish culture - aquaculture - freshwater fishes - irrigation water - agriculture - water use - water use efficiency - egypt
Egypte is op het Afrikaanse continent het land met veruit de grootste visteeltproductie. Het grootste deel van de aquacultuurproductie bestaat uit zoetwatervissoorten. Dat deze groei kon plaatsvinden in een land waar zoetwater beperkt aanwezig is, kan opmerkelijk genoemd worden. Nog opmerkelijker wordt het als men zich realiseert dat deze groei plaatsvindt in een land waar het viskwekers verboden is van irrigatiewater gebruik te maken, tenzij het water voor een pootvisbedrijf bestemd is. Integratie van visteelt en landbouw kan tot efficiënter watergebruik leiden, en zou in een land waar zoetwater schaars is, aangemoedigd dienen te worden. Maar niet in Egypte. Dit artikel gaat over de wetten en regels die de toepassing van geïntegreerde visteelt belemmeren, en doet verslag van de resultaten van een studie die wat cijfers over het waterverbruik door geïntegreerde bedrijven boven tafel bracht.
Living with less water: development of viable adaptation options for Riverina irrigators
Gaydon, D.S. - \ 2012
Wageningen University. Promotor(en): Holger Meinke, co-promotor(en): Jan Vos; D. Rodriguez. - S.l. : s.n. - ISBN 9789461732323 - 225
irrigatie - watergebruiksrendement - watervoorraden - bedrijfssystemen - participatieve methoden - simulatiemodellen - australië - victoria - new south wales - irrigation - water use efficiency - water resources - farming systems - participation methods - simulation models - australia

In Australia, the best use of limited national water resources continues to be a major political and scientific issue. Average water allocations for rice-cereal irrigation farmers in the Riverina region have been drastically reduced since 1998 as a consequence of high rainfall variability and prolonged periods of drought, together with political changes. This has severely impacted regional crop production during the last decade, threatening the livelihoods of many farmers and is in stark contrast to much of this region’s 100 year agricultural history, where water resources were available to farmers in steady abundance. The water ‘landscape’ has changed - bringing with it considerable social, economic and environmental consequences and forcing a rethink of how valuable water resources are best used under such variable, changed and changing conditions. This thesis presents details of investigations into on-farm adaptation options for rice-cereal farmers, using field experimentation, participatory engagement, and farming systems modelling as the major tools of research. Additionally, a major component of this work has been the development and testing of new modelling tools and decision-support structures.

Well-tested cropping systems models that capture interactions between soil water and nutrient dynamics, crop growth, climate and management can assist in the evaluation of new agricultural practices. At the beginning of this research project, all available models were lacking in at least some major element required for simulation of rice-based cropping systems. The capacity to simulate C and N dynamics during transitions between aerobic and anaerobic soil environments was added into the APSIM model, to facilitate our need to model farming system scenarios which involved flooded rice in rotation with other crops and pastures. Thorough testing against international datasets was subsequently conducted. Photosynthetic aquatic biomass (PAB – algae) is a significant source of organic carbon (C) in rice-based cropping systems. A portion of PAB is capable of fixing nitrogen (N), and is hence also a source of N for crops. To account for this phenomenon in long term simulation studies of rice-based cropping systems, the APSIM model was modified to include new descriptions of biological and chemical processes responsible for loss and gain of C and N in rice floodwater.

Using this improved APSIM model as a tool, together with participatory involvement of Riverina case-study farmers, it was demonstrated that the best on-farm cropping and irrigation strategies in years of high water availability were substantially different to those when water supplies were low. The strategies leading to greatest farm returns vary on a season-by-season basis, depending primarily on the water availability level. Significant improvements in average farm profits are possible by modifying irrigation strategies on a season-by-season basis.

The opportunities for Riverina farmers to exploit their irrigation water resources also extend beyond the farm gate. Currently there is considerable confusion amongst farmers on how to evaluate and compare on-farm and off-farm water options. Direct selling of water seasonally on the open market and even permanent sale of irrigation water entitlements are possibilities. In response to this confusion, a new conceptual framework was developed that enables quantitative comparisons between various options. The framework is based on a method regularly employed in the financial world for share portfolio analysis. Simulation modelling provided risk-return characteristics for on-farm options, and helped to elucidate circumstances under which off-farm options were viable.

A modified version of alternate wet-and-dry water management for Australian rice-growing conditions (delayed continuous flooding, DCF) was investigated via a 2 year field experiment – aimed at reducing irrigation water requirement and increasing water productivity (WP). We demonstrated up to a 17% increase in WP, and field data was generated on system performance for a range of discrete irrigation strategies. The APSIM model was then parameterized, calibrated and validated before being used to extrapolate findings from the two year experimental period to a much broader climatic record (55 years), allowing detailed investigation of optimal management strategies and a more realistic estimation of likely long-term gains in water productivity, and associated risks, from this new rice irrigation practice. Best practice guidelines were developed, and the potential impact of a changing climate on both optimal practice and likely benefits was assessed.

This thesis concludes by synthesising the approaches taken - addressing the question of whether improved rice irrigation practices, seasonally-flexible cropping and irrigation strategies and off-farm exploitation options, can in combination address the challenges of reduced irrigation water allocations in Australia’s Riverina region. Evidence is presented that the answer is yes under certain circumstances, but that limits to change exist beyond which the investigated on-farm adaptations are not enough. The thesis also proposes that the concepts and methods developed during this project are globally applicable and useful in the design of farming system adaptation options.

Keywords: irrigation, limited water resources, farming systems modelling, participatory engagement.

Handing over the sunset. External factors influencing the establishment of water user associations in Uzbekistan: Evidence from Khorezm Province
Wegerich, K. - \ 2010
Göttingen : Cuvillier Verlag - ISBN 9783869552194 - 169
watergebruik - waterbeleid - watergebruiksrendement - belangengroepen - overheidsbeleid - waterbeheer - watertoewijzing - waterbeschikbaarheid - waterverdeling - oezbekistan - associaties - water use - water policy - water use efficiency - interest groups - government policy - water management - water allocation - water availability - water distribution - uzbekistan - associations
Recently, large-scale surface-water or canal irrigation systems have been termed ‘a sunset industry’ (Rijsberman 2003). Handing over this sunset industry by means of irrigation management transfer (IMT) policies and the creation of water user associations (WUAs) has three main objectives: to increase efficiency, equity, and empowerment. The Uzbek government, together with the international organizations, the United States Agency for International Development (USAID), and the International Water Management Institute (IWMI), is currently promoting IMT and the creation of WUAs nationwide. The onset of the policy seemed to be a rational development since the former state and collective farms, which were also responsible for water management on their territories, were disintegrating, and new private farms were emerging rapidly. This study seeks to assess the potential of IMT policies by examining the broader physical, organizational, socio-economic, and political factors that might facilitate or hinder the main objectives of IMT and the creation of WUAs. These factors are addressed and analyzed separately through eight case study chapters that address questions on basin water management, the organizational capacities, and the socio-political dependencies of the district water management departments, the potential for multi-stakeholder platforms (MSPs), the politics of social network structures, and the process of land reforms. The study concludes that none of the external factors is conducive to the introduction of IMT policies and for creating WUAs. The implication is that IMT policies will not increase efficiency, equity, and empowerment, but could even worsen the water management situation. Furthermore, these policies will not increase the empowerment of either the WUAs or their members. Hence, under the current conditions, handing over the ‘sunset industry’ will not lead to a new sunrise for irrigation in Uzbekistan.
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