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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Bepaling samenstelling van vaste mest met NIRS
Rietra, R.P.J.J. ; Oenema, O. - \ 2017
Wageningen : Wageningen Environmental Research (Wageningen Environmental Research rapport 2837) - 27
dierlijke meststoffen - stikstof - fosfor - nabij infrarood spectroscopie - referentienormen - analyse - betrouwbaarheid - analytische methoden - animal manures - nitrogen - phosphorus - near infrared spectroscopy - reference standards - analysis - reliability - analytical methods
On the role of soil organic matter for crop production in European arable farming
Hijbeek, Renske - \ 2017
University. Promotor(en): Martin van Ittersum, co-promotor(en): Hein ten Berge. - Wageningen : Wageningen University - ISBN 9789463436632 - 211
soil fertility - soil fertility management - soil management - soil conservation - organic matter - soil organic matter - nitrogen - nitrogen fertilizers - green manures - manures - straw - soil carbon sequestration - cover crops - crop yield - yields - meta-analysis - food security - europe - drivers - barriers - bodemvruchtbaarheid - bodemvruchtbaarheidsbeheer - bodembeheer - bodembescherming - organische stof - organisch bodemmateriaal - stikstof - stikstofmeststoffen - groenbemesters - mest - stro - koolstofvastlegging in de bodem - dekgewassen - gewasopbrengst - opbrengsten - meta-analyse - voedselzekerheid - europa - chauffeurs - barrières

The aim of this thesis was to improve understanding of the role of organic inputs and soil organic matter (SOM) for crop production in contemporary arable farming in Europe. For this purpose, long-term experiments were analysed on the additional yield effect of organic inputs and savings in mineral fertiliser. In addition, a farm survey was conducted to find drivers and barriers for the use of organic inputs and to assess if arable farmers in Europe perceive a deficiency of SOM.

The findings in this thesis suggest that at least on the shorter term, on average, there seems to be no immediate threat from a deficiency of SOM to crop production in arable farming in Europe. The long-term experiments showed that with sufficient use of only mineral fertilisers, on average, similar yields could be attained over multiple years as with the combined use of organic inputs and mineral fertiliser. This was reflected in the farm survey, in which a large majority of farmers indicated not to perceive a deficiency of SOM. Analysis of long-term experiments also showed that more mineral fertiliser N was saved when using farmyard manure at high N rates (with mineral fertiliser application) than at low N rates (without mineral fertiliser application), based on comparisons at equal yield.

Specific crops and environments did benefit from organic inputs and more SOM in terms of crop production. Long-term experiments showed that organic inputs give benefit to crop production in wet climates and on sandy soils. In addition, farmers perceived a higher deficiency of SOM on steep slopes, sandy soils, wet and very dry climates. The additional yield effect of organic inputs was significant for potatoes. More in general, farmers who cultivated larger shares of their land with specialized crops (including potatoes, sugar beets, onions and other vegetables) than cereals perceived a higher deficiency of SOM. It seems that while the functions of SOM can be replaced with technical means to a large extent (e.g. tillage, use of mineral fertilisers), there are limits to this technical potential when environmental conditions are more extreme and crops are more demanding.

The farm survey revealed that farmers perceive a trade-off between improved soil quality on the one hand and increased pressures from weeds, pests and diseases and financial consequences on the other hand when using organic inputs. If policies aim to stimulate the maintenance or increase of SOM, more insight is needed into the conditions that regulate the pressures of weeds, pests and diseases in response to organic inputs. Financial consequences (at least on the short term) should also be accounted for. More importantly however, benefits from SOM for crop production cannot be taken for granted. Only in specific situations such benefits will exist. If European policies on SOM aim to include benefits for crop production, focus should be on areas with more extreme environmental conditions (very dry or wet climates, steep slopes, sandy soils), or cropping systems with more specialized or horticultural crops rather than cereals.

Genetic diversity of potato for nitrogen use efficiency under low input conditions in Ethiopia
Getahun, Baye Berihun - \ 2017
University. Promotor(en): Richard Visser, co-promotor(en): Gerard van der Linden. - Wageningen : Wageningen University - ISBN 9789463436595 - 219
solanum tuberosum - potatoes - genetic diversity - nitrogen - plant breeding - ethiopia - nutrient use efficiency - aardappelen - genetische diversiteit - stikstof - plantenveredeling - ethiopië - nutriëntengebruiksefficiëntie

Potato is a prime food security crop for smallholder farmers in the highland part of North western Ethiopia. In this region, nutrient availability, especially nitrogen (N) is a major constraint for crop productivity. To obtain insight in the possibility of improving potato for growth under low N input conditions in Ethiopia, we evaluated CxE diploid back cross population, modern European and Ethiopian potato cultivars and local Ethiopian cultivars for their ability to grow and produce tubers under low and high N input conditions. The experiments were conducted under rainfed and irrigation conditions. Eighty-eight Dutch cultivars and 9 Ethiopian cultivars were evaluated in three locations in North-western Ethiopia, in 2013 and in 2015. The two years represent two different growth seasons: rain-fed (June-October 2013) and irrigated cultivation (February-June 2015). Similarly 100 CxE diploid back cross potato genotypes were evaluated in both rainfed and irrigation production seasons in 2014. The Growth of the plants was monitored throughout the growth cycle using canopy cover measurements, with modelled canopy characteristics, and other agronomic traits were measured as per the description. The effect of season and location was further investigated by a GGE Biplot genotype-by-environment interaction analysis, and genetic factors determining phenotypic traits and yield were identified through QTL mapping and association mapping. Ethiopian cultivars showed a remarkable, environment-dependent difference in utilisation of the canopy for tuber production. While total photosynthetic capacity was higher in Ethiopian cultivars than in Dutch cultivars in rainfed production season at Injibara, tuber production was higher in Dutch cultivars. This low radiation use efficiency was not observed in the other rain-fed location (Debre-Tabor). A Genotype by Environment analysis using GGE biplots demonstrates that, Irrespective of the N levels and locations, rainfed production season test environments were grouped as one mega environment and irrigation production season test environments as the other mega environment, indicating most of the variation for yield and nitrogen use efficiency (NUE) in the dataset may be caused by the effect of rain-fed vs irrigation season. Further trials are needed to confirm this result. The QTL mapping with the CxE diploid population and GWAS analysis with the Dutch cultivars discovered both season-environment and N-specific QTL as well as constitutive QTLs. Overall, N availability affects Dutch and Ethiopian cultivars differentially, with strong environmental interaction on canopy and yield traits. Rainfed and irrigated seasons in Ethiopia may require different breeding programs for improved yield under varying fertilizer levels. Both constitutive and environment-specific QTLs were identified that may be targets for breeding prorgams towards improved yield under Ethiopian cultivation conditions.

Modelling of ammonia volatilisation in fertilised and flooded rice systems
Khairudin, Nurulhuda - \ 2017
University. Promotor(en): Nurul Khairudin, co-promotor(en): Karel Keesman; Mohamad Pauzi Zakaria. - Wageningen : Wageningen University - ISBN 9789462576698 - 209
oryza - flooded rice - ammonia - volatilization - modeling - dynamic modeling - flooded land - nitrogen - natte rijst - ammoniak - vervluchtiging - modelleren - dynamisch modelleren - overstroomde gronden - stikstof

In flooded rice systems that are broadcast with urea, significant amounts of nitrogen (N) may be lost to the atmosphere in the form of ammonia (NH3). Many models with different complexities with regards to describing the process of NH3 volatilisation and the overall N dynamics in the systems are available. However, given the differences in local conditions, both too simple and too complex models may not be able to predict NH3 volatilisation correctly or may lead to large prediction uncertainties. Therefore, the main objective of this thesis is to provide a framework to determine an appropriate process-based model with corresponding uncertainty characteristics for estimating NH3 volatilisation in fertilised and flooded rice systems.

As a first step in the selection of a model for a specific application, an overview on the modelling concepts and the performance of 14 models developed to simulate N dynamics in flooded soil systems is given. Next, in order to understand differences in modelling concepts for a specific process, co-validation was conducted at single process level: urea hydrolysis, NH3 volatilisation, and floodwater pH. Then, a new process-based model for estimating NH3 volatilisation in fertilised and flooded rice systems, which is of a complexity appropriate for scarce soil N data, is presented and evaluated with field observations. For the flooded rice systems in the Philippines, conceptualisation of the two-step urea hydrolysis, partitioning between ammonium and NH3, and a time-varying rate coefficient of NH3 volatilisation in the proposed model improved the prediction of the net NH3 loss. Subsequently, a set-membership parameter estimation approach with soft-error-bounds was used to characterise the uncertainty in the parameter estimates in the proposed model. The set-membership approach is appropriate for poor quality data sets as it allows simultaneous consideration of the different sources of uncertainty affecting the model prediction, such as uncertainty in the model structure, parameters, and observations. Findings of this study can be used as criteria for stakeholders to make an informed selection of models, to modify the existing models for a specific purpose, and to interpret model-output responses critically.

BEN: Bedrijfsspecifieke bemesting met kunstmest stikstof : resultaten 2014 en 2015
Verloop, Koos ; Hilhorst, Gerjan ; Oenema, Jouke ; Gielen, Jaap - \ 2017
Wageningen : Wageningen UR Livestock Research (Rapport / Koeien en kansen nr. 77) - 38
melkveehouderij - bemesting - kunstmeststoffen - stikstof - graslanden - akkerbouw - wetgeving - nederland - dairy farming - fertilizer application - fertilizers - nitrogen - grasslands - arable farming - legislation - netherlands
From harmful to useful algae
Blaas, Harry - \ 2017
University. Promotor(en): Carolien Kroeze. - Wageningen : Wageningen University - ISBN 9789463430357 - 117
algae - algae culture - adverse effects - nitrogen - phosphorus - rivers - eutrophication - waste water treatment - europe - algen - algenteelt - nadelige gevolgen - stikstof - fosfor - rivieren - eutrofiëring - afvalwaterbehandeling - europa

Eutrophication of coastal waters is a worldwide phenomenon. This study focuses on eutrophication in the coastal waters of Europe. Eutrophication is mainly a result of the increased transport of nutrients from watersheds by rivers to the coastal waters. Nutrient losses from watersheds are generally from agriculture, sewage, atmospheric deposition and from natural sources. In case of an overload of nutrients in the coastal waters, algal blooms may develop which increase the risk of hypoxia, fish mortality, and loss of biodiversity.

Algae can also be useful. They are increasingly considered an interesting product. For instance, micro-algae can be grow on land to produce proteins, lipids and fatty acids. Some studies indicate that micro-algae can be an important feedstock in the future for, for instance, the production of biodiesel. Moreover, macro-algae can be produced in seawater in sea farms. Macro-algae can be edible, or be used as a feedstock. By yielding macro-algae, nutrients are removed from the water, reducing coastal eutrophication.

The objective of this study is to analyse past and future trends in nutrient export by rivers to European seas with a focus on the role of algae. Three types of algae will be distinguished: (1) harmful algal blooms in coastal seas, (2) cultivation of micro-algae on land for the production of proteins, lipids and fatty acids, and (3) cultivation of multi cellular algae in seaweed farms for human consumption or other products.

To meet the objective the following research questions are addressed:

RQ1 To what extent do N and P loads exceed levels that minimize the risk of harmful algal blooms, and what are the relative shares of sources of N and P in rivers of the European Union?

RQ2 What are the potential consequences of large-scale land-based production of biodiesel from cultivated micro-algae in Europe for coastal eutrophication?

RQ3 Would it possible to cultivate and process micro-algae in a factory, and what is the environmental performance?

RQ4 To what extent can seaweed farming in combination with nutrient management in agriculture and waste water treatment reduce the potential for coastal eutrophication?

These questions are answered through model analyses. The Global NEWS (Nutrient Export from WaterSheds) model simulates river export of nutrients as function of human activities on land. It includes more than 6000 rivers worldwide. It can be used to quantify nutrient flows from land to sea for the years 1970, 2000, 2030 and 2050. For future years four scenarios have been implemented. One of these scenarios is named Global Orchestration and mostly used as a reference in this thesis. This scenario assumes a globalised world, with a reactive approach towards environmental problems. The model was released in 2010, has been validated for the years 1970 and 2000. The nutrients considered in the model are nitrogen (N) and phosphorus (P). In this thesis Global NEWS is used to calculate transport of nutrients to the coastal waters of Europe. The model uses ICEP (Indicator for Coastal Eutrophication Potential) values at the river mouths as an indicator for potentially harmful effects of nutrient enrichment. These ICEP values reflect the ratio of nitrogen and phosphorus to silica in coastal seas. A positive ICEP value indicates that nitrogen or phosphorus levels are too high, favouring conditions for potentially harmful algae to bloom.

In chapter 2 Global NEWS is used to calculate the transport of nutrients and ICEP values for 48 European rivers for the years 2000 and 2050. The model calculates a positive ICEP for 38 rivers in the year 2000, and for 34 rivers in the year 2050. This indicates that current policies are not so effective in reducing the river transport of nutrients. For polluted rivers the anthropogenic sources of the nutrients are investigated. For most rivers the dominant polluting sources are agriculture or sewage. The results indicate that a basin-specific policy is needed to reduce the risks of coastal eutrophication.

In chapter 3 the focus is on useful algae: micro-algae cultivation on land for, for instance, biodiesel production. The consequences of large-scale production of biodiesel on nutrient export by rivers to the European coastal waters are investigated. A scenario is developed assuming that a production of 0.4 billion m3 diesel from cultivated micro-algae. The cultivation is assumed to be in the open air, for instance in ponds or in closed tube systems. Such production levels would need a land surface area as large as Portugal. The Global NEWS model is used to calculate the amount of waste water from micro-algae production that will be transported to the coastal waters in this scenario. The results indicate that large-scale cultivation of micro-algae on land can become a source of nutrient pollution in rivers. In the scenario with large-scale micro-algae cultivation the future transport of nitrogen and phosphorus is considerably higher than in the reference scenario. To ensure sustainable production of biodiesel from micro-algae it is important to develop cultivation systems with low nutrient losses to the environment.

Chapter 4 presents a design of a factory for the cultivation and processing of micro-algae in an environmentally sound way. The factory does not use fossil fuels and applies maximum recycling of water and nutrients. In this factory it is possible to produce lipids, carbohydrates, proteins and minerals. The factory can be built on any piece of land, so there is no need to use arable land. The factory is independent of weather and climate. Energy can be delivered by wind mills. In this chapter an example of producing diesel in the factory is shown. In the 12 stories factory with a cultivation area of 1 hectare, 810 ton micro-algae can be cultivated per year. This is enough for the production of 386 ton diesel per year.

Chapter 5 focuses on mitigation of eutrophication in European coastal waters. A scenario is presented assuming different types of measures. The scenario first assumes that nutrient use efficiencies in agriculture are higher than today, and that waste water treatment in sewage systems is improved. In addition, it assumes that all excess N and P in coastal waters is harvested in seaweed farms producing edible macro-algae. In our scenario for 2050 there is seaweed farming in the coastal waters of 34 rivers mouths in Europe .NEWS The areas needed to ensure that ICEP values remain below 0 (low potential for coastal eutrophication) range between 0 and 952 km2 per river mouth.

This thesis shows that algae can be both harmful and useful. River export of nutrients can lead to coastal eutrophication increasing the risks of harmful algal blooms. On the other hand, micro-algae can be produced without environmental harm on land, and macro-algae can be useful in reducing pollution levels in coastal seas. This thesis could serve as a basis for environmental policies to stimulate the production of these useful algae. The methods to mitigate algal blooms and to use algae in a sustainable way in this thesis are also useful for other parts of the world.

Closing the nutrient loops in (peri-)urban farming systems through composting
Nigussie, Abebe - \ 2017
University. Promotor(en): Thomas Kuijper; A. de Neergaard, co-promotor(en): S. Bruun. - Wageningen : Wageningen University - ISBN 9789463430050 - 144
urban agriculture - farming systems - nutrients - composting - refuse - sewage - waste treatment - vermicomposting - soil quality - nitrogen - ethiopia - stadslandbouw - bedrijfssystemen - voedingsstoffen - compostering - vuilnis - rioolwater - afvalverwerking - vermicompostering - bodemkwaliteit - stikstof - ethiopië

Organic amendments are used to improve soil fertility and maintain agricultural fields in a productive state. Despite these benefits, the use of organic amendments is limited in many developing countries. The overall objective of this thesis is therefore to provide a better understanding of current waste management practices in developing countries and ensure sustainable crop production via the biotransformation of urban waste into a high-quality soil amendment. First, I aimed at determining the causes for the limited use of organic amendments in small-scale urban farming systems. I interviewed 220 urban farmers in Ethiopia and found that competition for agricultural waste between fuel, feed and soil amendment is a major cause for the limited use of organic amendments. I demonstrated that allocation of agricultural waste for soil amendment is linked with farmers’ livelihood strategies. I also studied variation in compost demand among different farmer groups, and the socio-economic variables which explained these variations.

Gaseous losses of ammonia and greenhouse gas (GHG) emissions occur during composting of nitrogen-rich urban waste. Several technologies could reduce these losses. However, these technologies are inadequate to fit within the broader farming systems because they are expensive. The second aim of this thesis was to develop low-cost methods to mitigate N losses and GHG emissions from composting, while retaining its fertilising value.

Composting by earthworms (vermicomposting) is proposed as a low-cost strategy for minimising N losses and GHG emissions. Using a wide range of substrate qualities (C:N ratio, labile C sources) and other factors (earthworm density, amount of input, and moisture), I showed that vermicomposting reduced N losses and GHG emissions compared with traditional thermophilic composting, but the magnitude of the earthworm effect varied between substrates. Earthworms also change the quantity and composition of dissolved organic carbon during composting. Another low-cost strategy is to delay the addition of N-rich substrates during composting. I demonstrated that addition of nitrogen-rich substrate after the thermophilic phase reduced N losses. Delayed addition of N-rich substrates increased N2O emissions, but reduced CH4 emissions. Delayed addition resulted in compost that was as stable and effective at completely eradicating weed seeds as traditional composting.

In conclusion, urban waste compost should be considered as alternative source for soil amendment, particularly in developing countries with competition for agricultural waste. Technologies such as vermicomposting and delayed addition of N-rich substrate are recommended to increase or maintain the nitrogen content of compost, reduce N losses and mitigate GHG emissions.

Notitie Bemestingswaarde van digestaten
Schroder, J.J. - \ 2016
Wageningen UR Livestock Research, Commissie Bemesting Grasland en Voedergewassen - 5 p.
bemesting - digestaat - samenstelling - stikstof - fosfaat - berekening - fertilizer application - digestate - composition - nitrogen - phosphate - calculation
‘Digestaat’ is een algemene benaming voor meststoffen afkomstig uit vergistingsinstallaties. Teneinde de biogasproductie te vergroten, kunnen, naast dierlijke mest, koolstofrijke producten worden toegevoegd. Omdat de samenstelling en afbreekbaarheid van die toegevoegde co-producten betekenisvol verschilt, zal ook de bemestingswaarde van digestaten sterk verschillen. Een gemiddelde van zoveel mogelijk analyse-uitkomsten van digestaten zegt daarom weinig over de bemestingswaarde van een individuele partij. Meer nog dan bij dierlijke mest verdient het daarom de voorkeur om een mestmonster te nemen en daarin op zijn minst de gehalten aan P2O5, totaal-N en ammonium-N (NH4-N) te bepalen.
Stikstof blijkt behalve essentieel voedingselement ook signaalstof : aansturing van processen, zoals een hormoon
Heuvelink, E. ; Kierkels, T. - \ 2016
Onder Glas 13 (2016)9. - p. 20 - 21.
glastuinbouw - voedingsstoffenbehoeften - stikstof - plantenontwikkeling - greenhouse horticulture - nutrient requirements - nitrogen - plant development
Er is geen voedingselement waarvan de plant zoveel nodig heeft als stikstof. Het gehalte kan wel 5% van de drogestof uitmaken. Behalve als essentieel onderdeel van veel plantonderdelen en inhoudsstoffen, wordt ook steeds meer duidelijk dat stikstof een signaalstof is, die processen aanstuurt, bijna zoals een hormoon.
Procesindicatoren PAS : rapportage 2016
Smits, N.A.C. ; Mucher, C.A. ; Ozinga, W.A. ; Waal, R.W. de; Wamelink, G.W.W. - \ 2016
Wageningen : Wageningen Environmental Research (Wageningen Environmental Research rapport 2771) - 61
stikstof - indicatoren - monitoring - ecologisch herstel - habitats - vegetatie - nitrogen - indicators - ecological restoration - vegetation
In het kader van het Programma Aanpak Stikstof (PAS) is in 2016 doorgewerkt aan een aantal onderwerpen rondom de ecologische onderbouwing van het PAS, waaronder de procesindicatoren. Binnen de PAS-monitoring is afgesproken dat het proces van natuurherstel ook op korte termijn gevolgd wordt om zo snel mogelijk de effectiviteit van de herstelmaatregelen in kaart te brengen. Hiervoor zijn de PAS-procesindicatoren ontwikkeld. Deze procesindicatoren zijn vooral bedoeld om een indicatie van het herstelproces te geven. Deze procesindicatoren kunnen verschillen per habitattype en per maatregel, maar ook per gebied. Om die redenen is een flexibel systeem ontworpen met diverse parameters: luchtfoto’s, abiotische metingen, vegetatie en soorten. De huidige rapportage betreft de verslaglegging van de ontwikkelde systematiek van PAS-procesindicatoren.
Monitoring van effecten van evenwichtsbemesting op de grondwaterkwaliteit van het Natura 2000-gebied Boetelerveld
Kuiters, A.T. ; Corporaal, A. ; Weijters, M.J. ; Bobbink, R. - \ 2016
Wageningen : Wageningen Environmental Research (Wageningen Environmental Research rapport 2772) - 72
bemesting - grondwaterkwaliteit - natura 2000 - habitats - stikstof - fertilizer application - groundwater quality - nitrogen
In het kader van het Programma Aanpak Stikstof (PAS) worden in en rondom het Natura 2000-gebied Boetelerveld maatregelen genomen om de effecten van een overmaat aan stikstof te mitigeren. Daarnaast vinden brongerichte maatregelen plaats. Een van de maatregelen is evenwichtsbemesting. Gedurende twee jaar is gekeken naar de uitspoeling van nutriënten in enkele agrarische percelen grenzend aan de oostzijde van het gebied, waar in 2014 is gestart met evenwichtsbemesting. Daarbij is gekeken naar de chemische samenstelling van het grondwater (150-200 cm) en naar veranderingen in de chemische samenstelling van het bodemwater onder de bewortelingszone (50 cm) van percelen met reguliere bemesting en van percelen waar evenwichtsbemesting is toegepast. Daarmee kan een beeld worden gekregen van wat op de langere termijn het effect van evenwichtsbemesting zal zijn op de kwaliteit van het grondwater (150-200 cm). Ook is gekeken naar de huidige kwaliteit van de habitattypen waarvoor het gebied is aangewezen en is een vergelijking gemaakt met de situatie in 2004.
Simulation nitrogen-limited crop growth with SWAP/WOFOST : process descriptions and user manual
Groenendijk, Piet ; Boogaard, Hendrik ; Heinen, Marius ; Kroes, J.G. ; Supit, Iwan ; Wit, Allard de - \ 2016
Wageningen : Wageningen Environmental Research (Wageningen Environmental Research rapport 2721) - 59
crops - growth - soil - nitrogen - organic matter - mineralization - leaching - simulation models - nitrates - gewassen - groei - bodem - stikstof - organische stof - mineralisatie - uitspoelen - simulatiemodellen - nitraten
This report describes a soil nitrogen module (Soil-N), which is combined with the agro-hydrological model, SWAP, and the crop growth model, WOFOST. The core of the Soil-N module is a description of the nitrogen cycle, which is coupled to the organic matter cycle based upon the RothC-26.3 model. Nitrogen can be supplied to the soil as different types of fertilizer applications and through mineralisation of organic nitrogen. Ammonium and nitrate balances are calculated including uptake by plant roots, de-nitrification and leaching of nitrate. Data exchange is on a daily base. The partitioning of nitrogen within crops and the nitrogen contents of crop residues are calculated by WOFOST and passed to the Soil-N module. SWAP generates the data for establishing the water balance of the soil compartment for which the Soil-N perform the simulations. Nitrogen uptake by the crop is calculated as the minimum of the demand by the crop and the availability of nitrogen in the soil. The crop production rate is reduced when the mineral nitrogen stock is limited. Nitrogen-fixation is based on a simple approach. An improved sub-model for phenological stages of soybean was implemented. Increasing atmospheric CO2 concentrations can be accounted for. The innovated integrated model was tested using data sets from The Netherlands, China and Argentina, for which examples are given. This new model can be used as a tool in studies, in which both water and nitrogen can be limited for crop growth.
Towards improving the manure management chain
Hou, Yong - \ 2016
University. Promotor(en): Oene Oenema, co-promotor(en): Gerard Velthof. - Wageningen : Wageningen University - ISBN 9789462579620 - 215
manures - manure treatment - livestock - excretion - nitrogen - mitigation - methane - european union - mest - mestverwerking - vee - excretie - stikstof - mitigatie - methaan - europese unie

Animal manures are major sources of nutrients and organic matter, to be used to fertilize crops and improve soil quality. However, when not properly managed, these manures release considerable amounts of ammonia (NH3), nitrous oxide (N2O) and methane (CH4) into the air, and nitrogen (N) and phosphorus (P) to water bodies, which create a range of unwanted environment impacts. Nutrient losses from manure depend on the management activities and techniques used at different stages of the whole manure management chain, from animal feeding up to manure application to land. The trade-offs and co-benefits of emission mitigation measures and manure treatment technologies are as yet poorly understood, especially when taking the whole manure management chain into account. Moreover, the effects of combinations of measures and technologies have not been well analyzed, and analyses at national scales are lacking. The overall objective of this PhD thesis research is (i) to enhance the quantitative insight into the effects of emission mitigation measures and treatment technologies on emissions of NH3, N2O and CH4, and the recovery of N and P from animal manure in the whole management chain, and (ii) to explore the effects of combinations of measures and technologies to mitigate these emissions and to increase the N and P recovery.

In Chapter 2, methodologies for estimating N excretion factors for the main animal categories in member states of the European Union (EU) were reviewed. In Chapter 3, a transparent and uniform methodology for estimating annual feed use and N excretion per animal category for all countries of the EU-27 was developed, based on the energy and protein requirements of the animals and statistics of feed use and composition, animal number and productivity. In Chapter 4, firstly the impacts of a suite of NH3 mitigation measures on emissions of NH3, N2O and CH4 at individual stages of the manure management chain were analyzed by means of a meta-analysis of published data. Secondly, the overall impacts of alternative combinations of mitigation measures on emissions from the whole chain were evaluated through scenario analysis. Chapter 5 reports on an integrated assessment of the effects of manure treatment on NH3, N2O and CH4 emissions from manure management chains in EU-27 at the national level for 2010, using the model MITERRA-Europe. Whole-chain effects of implementing twelve treatment technologies in EU-27 on emissions and N and P recovery were further explored through scenario analyses. Chapter 6 reports on a survey conducted under various stakeholder groups with expertise in the domain of manure treatment in four European countries that have regions of high animal density. The survey addressed questions related to i) which factors facilitate and hinder the implementation of treatment technologies in practice, ii) which technologies have the most potential for successful adoption, and iii) how farm characteristics and the scale of the treatment operation affect priorities for adoption. The main conclusions of this PhD thesis are as follows:

In EU-27, the amounts of N and P in manure are as large as or larger than the total amounts of fertilizer N and P used annually. However, there is a huge spatial variation in manure production. Nutrient excretion factors per animal category also vary between countries, as a result of variations in feed use and animal productivity. Clearly, for accurate inventories of national emission there is a need for estimating nutrient excretion using country-specific feed use data.

Increasing the effectiveness of measures to mitigate NH3 and GHG emissions from animal manure requires proper combination of measures in the manure management chain. Lowering the dietary protein content in animal feed is an effective measure to reduce NH3 emissions and other N emissions at all stages of the manure management chain. Other measures may reduce emissions of a specific gas or emissions source, by which there is a risk of unwanted trade-offs in the manure management chain. Joint adoption of these measures with low-N feeding strategies and slurry acidification can greatly decrease the risk of pollution swapping.

Implementation of manure treatment is on average still limited in EU-27. Effects of manure treatment on NH3 and GHG emissions are therefore relatively small at EU level. Increasing the implementation of treatment technologies, including acidification, incineration and thermal drying, or optimized combinations of treatment technologies, can significantly contribute to achieving NH3 and GHG emission targets of EU environmental policies. Implementation of manure treatment technologies provides opportunities to improve the use of plant nutrients in manures, because of the release of manure products with different N/P ratios. Applying acidification technology and optimized combination of NH3 emission mitigation measures increase the N recovery from animal manure, and can decrease the demand of mineral fertilizers. However, some technologies decrease the N and P recovery and/or decrease the availability of the N and P in manure products to plants.

Implementation of manure treatment in practice is forced by the pressure from EU environmental regulations, and is hindered by financial barriers. To encourage the adoption of manure treatment, policies must be economically appealing to attract new adopters (farmers and industries). Long-term financial support schemes (e.g. subsidies) seem to be necessary, especially with the current low prices for fossil fuels. Outreach strategies are required to convey the knowledge to stakeholders from both the supply and the demand side, with respect to the economic, technical and environmental aspects of manure treatment technologies.

Landbouw en de KRW-opgave voor nutriënten in regionale wateren : het aandeel van landbouw in de KRW-opgave, de kosten van enkele maatregelen en de effecten ervan op de uit- en afspoeling uit landbouwgronden
Groenendijk, Piet ; Boekel, Erwin van; Renaud, Leo ; Greijdanus, Auke ; Michels, Rolf ; Koeijer, Tanja de - \ 2016
Wageningen : Wageningen Environmental Research (Wageningen Environmental Research rapport 2749) - 149
kaderrichtlijn water - voedingsstoffen - oppervlaktewater - oppervlaktewaterkwaliteit - stikstof - fosfaten - uitspoelen - landbouw - oppervlakkige afvoer - water framework directive - nutrients - surface water - surface water quality - nitrogen - phosphates - leaching - agriculture - runoff
Het doel van de Europese Kaderrichtlijn Water is duurzame bescherming van ecosystemen en watervoorraden. Een deel van de regionale waterlichamen voldoet nog niet aan de normen voor stikstof- en fosforconcentraties die behoren bij een goede ecologische toestand. Om af te wegen welke maatregelen kunnen bijdragen aan het realiseren van de KRW-doelen, is inzicht nodig in de herkomst van stikstof en fosfor in het oppervlaktewater. In dit onderzoek is het aandeel van de landbouw in de overschrijding van de normen voor de stikstof- en de fosforconcentratie in regionale waterlichamen berekend met modellen. In deze analyse zijn verschillende brontermen onderscheiden die niet afzonderlijk te meten zijn (kwel, nalevering bodem, na-ijling uit overschotten in het verleden) en alleen met modellen zijn te berekenen. Vervolgens zijn van een viertal maatregelen (vervanging uitspoelingsgevoelige gewassen in het zuidelijke zandgebied, bodemverbetering, verbetering nutriëntenbenutting en drainage) de effecten op de uit- en afspoeling van stikstof en fosfor geschat. Ook zijn gevolgen voor het gebiedsgemiddelde financieel saldo geschat. Om te voldoen aan de normen voor stikstof- en fosforconcentraties in regionale waterlichamen, moet de uit- en afspoeling uit landbouwgronden landelijk gemiddeld met respectievelijk 12─17% en 12–38% worden verminderd, afhankelijk van de wijze waarop de uit- en afspoeling wordt vertaald naar een aandeel in de overschrijding van de concentratienormen. Tussen regio’s doen zich grote verschillen voor. Door een combinatie van de doorgerekende maatregelen lijkt in de zandgebieden een groot deel van de opgave voor reductie van de stikstofuitspoeling gerealiseerd te kunnen worden, terwijl de opgave voor het reduceren van de uit- en afspoeling van fosfor slechts voor een klein deel gerealiseerd kan worden met deze maatregelen. Voor fosfor zijn andere en/of aanvullende maatregelen nodig die voorkomen dat de opgehoopte voorraad fosfaat in de bovengrond kan uitspoelen naar het oppervlaktewater en/of maatregelen met een zuiverende werking in het oppervlaktewater.
Vergelijking tussen gangbaar en emissieloos teeltsysteem : waterefficiënte Emissieloze Kas
Os, Erik van; Ruijven, Jim van; Janse, Jan ; Beerling, Ellen ; Staaij, Marieke van der; Kaarsemaker, Ruud - \ 2016
Bleiswijk : Wageningen UR Glastuinbouw (Rapport GTB 1406) - 62
paprika's - capsicum annuum - teelt onder bescherming - kasgewassen - glasgroenten - glastuinbouw - emissiereductie - emissie - stikstof - fosfaat - voedingsstoffen - pesticiden - sweet peppers - protected cultivation - greenhouse crops - greenhouse vegetables - greenhouse horticulture - emission reduction - emission - nitrogen - phosphate - nutrients - pesticides
Stricter legislation forces growers to decrease discharge of water with nitrogen, phosphate and plant protection products. A demonstration was set-up to compare emission free cultivation with a traditional growing method. Goal was to achieve a comparable yield and quality. Essential differences were disinfection of rainwater, ring pipes for drip irrigation, no discharge of first drain in cultivation, a filter without rinsing and weekly analysis of the nutrient solution. It appeared that production and quality were similar as were other climate parameters. Water use was higher in emission free crop, discharge was 4% in traditional crop realizing 152 kg N discharge per ha per year, which was more than the allowed 133 kg. Specific end cultivation strategy is useful to decrease nitrogen and phosphate stored in slabs and stock containers.
Bronnen van nutriënten in het oppervlaktewater in het beheergebied van Wetterskip Fryslân : studie naar de herkomst en beïnvloedbaarheid van stikstof en fosfor in het oppervlaktewater voor zes polders in het beheergebied van Wetterskip Fryslân
Boekel, E.M.P.M. van; Groenendijk, P. ; Renaud, L.V. - \ 2016
Wageningen : Alterra, Wageningen-UR (Alterra-rapport 2727) - 50 p.
oppervlaktewater - voedingsstoffen - stikstof - fosfor - modellen - oppervlaktewaterkwaliteit - mestbeleid - friesland - surface water - nutrients - nitrogen - phosphorus - models - surface water quality - manure policy
Om inzicht te krijgen in de herkomst en beïnvloedbaarheid van stikstof en fosfor in het oppervlaktewater in het beheergebied van Wetterskip Fryslân zijn met de ECHO-methodiek stofbalansen opgesteld voor een zestal polders. De beïnvloedbaarheid van bronnen is afgeleid conform de werkwijze die wordt toegepast door de Nutriëntenwerkgroep Rijn-West. Daarnaast is het effect van het mestbeleid op de nutriëntenbelasting van het oppervlaktewater in beeld gebracht op basis van uit het landelijke STONE-model afgeleide resultaten voor de uitspoeling bij gebruiksnormen van het 5e Nitraat Actieprogramma (5e NAP). Uit de resultaten blijkt dat het grootste deel (46 −74%) van de stikstof- en fosforbelasting van het oppervlaktewater afkomstig is van beïnvloedbare bronnen (actuele bemesting en nalevering bodem) met een effect op de korte en lange termijn. Bronnen met een direct effect (voornamelijk inlaatwater) dragen voor 5 − 45% bij aan de totale nutriëntenbelasting. De stikstofbelasting van het oppervlaktewater is voor 7 − 22% afkomstig van niet of moeilijk te beïnvloeden bronnen, voor fosfor ligt dit tussen 1 en 12%. Het doorrekenen van het mestbeleid (5e NAP) resulteert in een reductie van de uit- en afspoeling tussen 1,9 en 9,1%. Voor de totale nutriëntenbelasting ligt de reductie als gevolg van de maatregelen in het 5e NAP tussen 1,1 en 7,7%.
Examining growth, yield and bean quality of Ethiopian coffee trees : towards optimizing resources and tree management
Bote, Adugna - \ 2016
University. Promotor(en): Niels Anten, co-promotor(en): Jan Vos; F.L. Ocho. - Wageningen : Wageningen University - ISBN 9789462578319 - 138
coffea - coffea arabica - trees - growth - yields - quality - radiation - nitrogen - agroecosystems - bomen - groei - opbrengsten - kwaliteit - straling - stikstof - agro-ecosystemen

Coffee (Coffeaarabica L.)bean production and quality are determined by a diversity of interacting factors (e.g. shade, nitrogen, crop traits). Bean yield increases with increase in radiation, but adequate fertilizer suppliesare needed to sustain the productivity. This thesis analysed coffee tree growth, bean production and bean quality in relation to different degrees of exposure to radiation and nitrogen supply. Growth of leaves and branches and properties of leaves such as specific leaf area, nitrogen content per unit leaf area and light-saturated rate of photosynthesis were determined. Radiation interception and nitrogen uptake were also determined as were radiation use efficiency and apparent nitrogen recovery. Tree biomass and coffee bean yield responded positively to both radiation and nitrogen supply. Abundant bean yield to the detriment of vegetative growth, however, resultedin biennial bearing in coffee trees. Effects of fruit load on coffee treegrowth and productivity were studied for two consecutive years and the resultshowed that competition between fruit growth and vegetative growth predisposed the trees for biennial bearing. Reduced vegetative growth when fruit load is high reduces the number of flower bearing nodes and hence yields in the next season. Coffee quality is a sum of favourable characteristics that satisfies requirements of different actors in the coffee chain and is the factor determining the price on the coffee market. This study has also examined coffee quality attributes in relation to radiation and nitrogen, fruit load manipulation, and genotype by environment (different altitudes) interactions. The result indicated that factors and conditions that support non-limiting supply of resources for bean to grow and a sufficient long period of maturation promote coffee bean quality. Overall, the study gained further understanding of coffee tree growth, yield and bean quality responses to aforementioned factors and explored traits that underlie the patterns. Further works are required to use the traits and describe the behaviour of coffee trees in different agro-ecosystems.

Effect Ca- en Mg-meststoffen op bodemkwaliteit en grasproductie op veengrond
Deru, Joachim ; Eekeren, Nick van; Lenssinck, F.A.J. ; Bloem, J. - \ 2016
V-focus 13 (2016)3. - ISSN 1574-1575 - p. 29 - 31.
veengronden - graslanden - stikstof - calciummeststoffen - magnesiummeststoffen - indicatoren - bodemkwaliteit - duurzaam bodemgebruik - landbouwkundig onderzoek - peat soils - grasslands - nitrogen - calcium fertilizers - magnesium fertilizers - indicators - soil quality - sustainable land use - agricultural research
Uit onderzoek in 2010 blijkt dat het gemeten stikstofleverend vermogen van veengraslanden varieert tussen 170 en 340 kg N per ha, en dat de verhouding tussen calcium (Ca) en magnesium (Mg) in de bodem hier een belangrijke voorspeller voor is. In het kader van het project ‘Bodemindicatoren voor duurzaam bodemgebruik in de veenweiden’ hebben het Louis Bolk Instituut, het Veenweiden Innovatiecentrum en WUR-Alterra onderzocht of er ook een oorzakelijk verband is tussen de Ca/Mg-verhouding en het stikstofleverend vermogen. Verschillende calcium- en magnesiummeststoffen zijn hiervoor getoetst.
Voederbieten : minder stikstofverliezen na scheuren grasland
Pijlman, J. ; Hilhorst, G.J. ; Gerner, L. ; Kessel, T. van - \ 2016
V-focus 13 (2016)2. - ISSN 1574-1575 - p. 32 - 33.
voederbieten - graslanden - mineralen - stikstof - oppervlaktewater - grondwater - maïs - melkveehouderij - fodder beet - grasslands - minerals - nitrogen - surface water - groundwater - maize - dairy farming
In het project Vruchtbare Kringloop Achterhoek en Liemers werken 250 melkveehouders aan het verbeteren van de mineralenbenutting op bedrijfsniveau en het beperken van verliezen naar oppervlakte- en grondwater. Wat betreft stikstof zijn de verliezen het hoogst bij maisteelt op gescheurd grasland. In de Kennisgroep Bodem van het project heeft melkveehouder Arjan Freriks de handschoen opgepakt om dit probleem op te lossen met de teelt van voederbieten.
Development of a breeding strategy for nitrogen use efficiency in spinach (Spinacia oleracea L.)
Chan Navarrete, J.R. - \ 2016
University. Promotor(en): Edith Lammerts van Bueren, co-promotor(en): Oene Dolstra; Gerard van der Linden. - Wageningen : Wageningen University - ISBN 9789462577961 - 161 p.
spinacia oleracea - spinach - plant breeding - nitrogen - nutrient use efficiency - genetic mapping - nitrogen fertilizers - fertilizer application - genetic diversity - nitrogen response - spinazie - plantenveredeling - stikstof - nutriëntengebruiksefficiëntie - genetische kartering - stikstofmeststoffen - bemesting - genetische diversiteit - stikstofrespons

Spinach (Spinacia oleracea L.) is one of the most consumed leafy vegetables worldwide and it is considered to be highly nutritious. Spinach is a short-cycle leafy crop that has a high demand for nitrogen in order to rapidly come to a harvestable product that has the required dark green colour within a reasonable harvest window. In commercial production of spinach the recovery of N is poor, which may result in environmental pollution. To increase sustainability of both organic and conventional spinach cultivation there is a need to reduce the dependency on high levels of nitrogen. Growers therefore urgently need cultivars with a satisfactory yield under reduced N input conditions. Nitrogen use efficiency (NUE), defined as the ability to produce high biomass per unit N applied, is low in spinach. The present study aims to evaluate spinach genotypes for selectable traits under varying N supply and provide tools and knowledge to facilitate the development of varieties with good yield, quality and stability under low N input. To minimise environmental variation affecting the identification of traits related to NUE a screening method was developed using a hydroponics system. The genetic diversity for NUE related traits was first studied with 24 commercial cultivars under contrasting levels of N supply based on the Ingestad model with a steady-state N application. This demonstrated that the hydroponics screening strategy as a pre-screening tool enabled reliable detection of heritable variation among cultivars for NUE-related traits under optimal as well as suboptimal N input. Shoot dry weight and leaf area were preferred selectable traits for the detection of heritable differences contributing to NUE in spinach. The effect of N application strategy was examined in seven cultivars grown under hydroponics conditions with low and high N levels supplied either as a single bulk N application resembling N fertilization in field cultivation, or a steady-state N application according to Ingestad. The latter application strategy provided more stable and reproducible conditions for determination of genetic differences in NUE under low N conditions for a short-cycle leafy vegetable crop. Several tools for molecular genetic evaluation of NUE in spinach were provided as well, including a SNP marker set for marker-assisted breeding, a genetic mapping population with a corresponding genetic map, and the identification of two major QTL regions contributing to growth under low N conditions. With these tools, an efficient strategy for breeding for NUE efficiency in spinach would include screening under controlled conditions at high and low N using leaf area, biomass and root to shoot ratio as selectable traits, and QTL identification of genetic factors that can be targeted and combined using marker-assisted selection. An in depth genotype by environment interaction analysis using six field trials showed that environmental factors like temperature, soil, and management strongly influence nitrogen availability in the soil in a short cycle crop like spinach. This severely complicates selection and breeding for NUE of spinach under field conditions, and emphasizes the importance of performing trials under better controllable conditions for genetic dissection of NUE and discovery of genetic factors contributing to NUE. It also underscores the importance of validating these findings in various field trials. Multi-environment field trials with different levels of N fertilization will then allow selection of cultivars that combine stable performance under various low input growing conditions with high yields under more favorable conditions.

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