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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Seasonality in river export of nitrogen : A modelling approach for the Yangtze River
Chen, Xuanjing ; Strokal, Maryna ; Kroeze, Carolien ; Ma, Lin ; Shen, Zhenyao ; Wu, Jiechen ; Chen, Xinping ; Shi, Xiaojun - \ 2019
Science of the Total Environment 671 (2019). - ISSN 0048-9697 - p. 1282 - 1292.
Diffuse and point sources - MARINA model - Nitrogen - Sub-basins - Water quality - Yangtze River

In China, many estuaries suffer from eutrophication problems such as green tides and hypoxia. This is often a result of human activities on land leading to increased nutrient exports by rivers. River pollution shows seasonal trends that are not well understood. Therefore, the main objective of this study is to improve our understanding of the seasonal variation in river export of dissolved inorganic nitrogen (DIN) by source and at the sub-basin scale. To this end, we modified the existing MARINA model 1.0 (Model to Assess River Input of Nutrient to seAs) to account for seasonality in river export of DIN, and applied it to the Yangtze River. The resulting MARINA model version 1.1 takes a mass-balance approach and accounts for seasonality in human activities (e.g., crop planting and fertilization) and meteorology. The model distinguishes four seasons: winter (December–February), spring (March–May), summer (June–August) and fall (September–November). Our results for Yangtze indicate that N inputs to land and river export of DIN to sea are higher in summer and lower in winter. In spring, summer and fall, diffuse sources from agriculture contribute 43–85% to DIN export. In spring and fall, use of synthetic N fertilizers in cropland is an important source of DIN. In summer, both atmospheric N deposition and synthetic N fertilizers dominate. Animal manure is typically applied on land in spring and fall, contributing then to DIN. In winter, point sources of animal manure are responsible for 34–74% of DIN river export. In general, more DIN is exported to the sea from activities in middlestream and downstream sub-basins. Our results can serve as an example for other large rivers worldwide, and support the formulation of effective strategies to reduce seasonal eutrophication.

Fertile cities: Nutrient management practices in urban agriculture
Wielemaker, Rosanne ; Oenema, Oene ; Zeeman, Grietje ; Weijma, Jan - \ 2019
Science of the Total Environment 668 (2019). - ISSN 0048-9697 - p. 1277 - 1288.
Fertilizer use - Nitrogen - Organic matter - Phosphorus - Potassium - Urban farming

Cities are increasingly targeted as centers for sustainable development and innovation of food systems. Urban agriculture (UA) is advocated by some as a multi-faceted approach to help achieve urban sustainability goals as it provides possible social, economic and environmental benefits. The role of UA in restoring resource cycles receives increasing attention, especially with regard to assimilating urban waste. However, there is little information on how nutrients are managed in UA in industrialized countries. To examine nutrient management in UA, data was collected from a total of 25 ground-based UA initiatives in the Netherlands on i) preferences for types of fertilizers, and ii) quantity and quality of fertilizers used including nutrient composition and organic matter content. The main inputs at urban farms were compost and manure, high in organic matter content. The total nutrient inputs were compared to nutrient demand, based on crop nutrient uptake, in order to determine nutrient balances. Results show that mean nutrient inputs exceeded mean crop demand by roughly 450% for total nitrogen, 600% for phosphorus and 250% for potassium. Mean inputs for plant-available nitrogen were comparable to crop uptake values. The surpluses, particularly for phosphorus, are higher than fertilizer application limits used for conventional farming in The Netherlands. While nutrient input calculations were subject to several uncertainties, e.g., due to lack of accuracy of the data supplied by the farmers, results show a salient indication of over-fertilization and thus a suboptimal nutrient use. If UA continues to expand across cities these observed nutrient surpluses may pose a risk for local surface waters and groundwater as well as soil quality. The need to improve nutrient management in UA is evident. Soil tests, harvest logging and book keeping of nutrient inputs would improve data quality and may help balance nutrient inputs with nutrient outputs.

Does the use of digestate to replace mineral fertilizers have less emissions of N2O and NH3?
Verdi, L. ; Kuikman, P.J. ; Orlandini, S. ; Mancini, M. ; Napoli, M. ; Marta, A. Dalla - \ 2019
Agricultural and Forest Meteorology 269-270 (2019). - ISSN 0168-1923 - p. 112 - 118.
Biogas - Digestate - Greenhouse gasses - Maize - Nitrogen - Static chambers

Digestate is considered a sustainable opportunity to reduce environmental impact from fertilization, due to high content of nitrogen easily available for plants and for the low impact of its production. We tested liquid fraction of digestate from anaerobic digestion of pig slurries and urea, to assess the emissions of nitrous oxide and ammonia from soil on silage maize (Zea mays L.). Nitrogen rate was the same for both treatments (150 kg/ha) spread replacing common methods. Emissions measurements were performed immediately after fertilization using a static chamber method with a portable gas analyser. Measurements were performed daily during the first week, and twice per week until no emissions from the soil were observed. Cumulative nitrogen emissions show that digestate can be an efficient method to reduce nitrogen losses (2.87 kg N/ha/25 days and 3.76 kg N/ha/25 days for digestate and urea respectively). However, the two fertilizers emitted different kind of gases: compared to urea, digestate emitted the 23% of nitrous oxide more, on the other hand urea emitted 66% of ammonia more than digestate. Crop yield obtained under the two fertilization methods did not significantly differ in terms of dry matter (DM) (13.63 t DM/ha and 13.24 t DM/ha for digestate and urea, respectively) (significance factor α > 0.5).

Fertilizer response and nitrogen use efficiency in African smallholder maize farms
Ichami, Stephen M. ; Shepherd, Keith D. ; Sila, Andrew M. ; Stoorvogel, Jetse J. ; Hoffland, Ellis - \ 2019
Nutrient Cycling in Agroecosystems 113 (2019)1. - ISSN 1385-1314 - p. 1 - 19.
Kenya - Meta-analysis - Nitrogen - Soil responsiveness - Spatial variability

Improving fertilizer recommendations for farmers is essential to increase food security in smallholder landscapes. Currently, blanket recommendations are provided across agro-ecological zones, although fertilizer response and nutrient use efficiency by maize crop are spatially variable. We aimed to identify factors that could help to refine fertilizer recommendation by analyzing the variability in fertilizer response (FR) and the agronomic nitrogen use efficiency (N-AE). A literature search for on-farm studies across Kenya and Sub-Sahara Africa (SSA), excluding Kenya, yielded 71 publications. The variability in FR was studied using a meta-analysis whereas key factors that influence FR and N-AE were studied with linear regression models. On average, the FR was 2, but it varied considerably from 1 to 28.5 (excluding outliers). In SSA, 18% of the plots were non-responsive plots with an FR < 1. The main factors affecting N-AE for Kenya were P-Olsen, silt content, soil pH, clay and rainfall, whereas only soil pH, exchangeable K and texture were important for SSA. However, our study indicates that available data on soil, climate and management factors could explain only a small part (< 33%) of the variation in FR and N-AE. Soil pH, P-Olsen, silt content, and rainfall had significant but low levels of power in explaining variation in FR and N-AE. Our findings indicate that strategies to refine fertilizer recommendation should include information on soil types and soil properties.

Agricultural nitrogen and phosphorus emissions to water and their mitigation options in the Haihe Basin, China
Zhao, Zhanqing ; Qin, Wei ; Bai, Zhaohai ; Ma, Lin - \ 2019
Agricultural Water Management 212 (2019). - ISSN 0378-3774 - p. 262 - 272.
Crop-livestock system - Haihe Basin - Nitrogen - NUFER - Phosphorus - Water pollution

Agricultural nitrogen (N) and phosphorus (P) emissions to water bodies remain largely unknown in China, mainly due to the lack of reliable data sources and quantification tools. In this study, we constructed a grid-based NUFER (NUtrient Flow in food chains, Environment and Resources use) model in order to quantify a high-resolution agricultural N and P emissions to water bodies in Haihe Basin in 2012, based on data collected from county-level statistics, farm interview, and spatial data of topography, climate, soil texture, and land use. We also explored the mitigation strategies in 2030 via scenario analysis. The results showed that total agricultural N emission to water bodies in Haihe Basin was 1079 Gg N in 2012, of which cropland contributed 54%; total agricultural P emission to water bodies was 208 Gg P, livestock contributed 78%. There were large spatial variations in agricultural N and P emissions. Overall, the plain areas accounted for around 80% of the total agricultural N and P emissions to water in 2012. The highest N and P emission intensities were 10 t N km−2 and 2 t P km−2, respectively. N and P emissions were significantly related to anthropogenic factors (such as the livestock density and cropland) in the plain areas; whereas in mountainous areas, both anthropogenic and natural factors (e.g., slope deviation and soil texture) significantly affected N and P emissions. Our scenario analysis suggests that agricultural N and P emissions can be reduced by up to 45% and 77%, respectively for N and P in 2030, via improved agricultural and environmental policies, technologies and managements. The prohibition of direct animal manure discharge to the water system seems to be the most effective measure to mitigate the emissions. Our study provided a high-resolution agricultural N and P emissions to the water bodies of Haihe Basin and identified the most effective options to reduce these emissions in highly intensified agricultural areas.

Spatio-temporal dynamics in the dissolved nutrient waste plume from Norwegian salmon cage aquaculture
Jansen, H.M. ; Broch, O.J. ; Bannister, R. ; Cranford, P. ; Handå, A. ; Husa, V. ; Jiang, Z. ; Strohmeier, T. ; Strand, Ø. - \ 2018
Aquaculture Environment Interactions 10 (2018). - ISSN 1869-215X - p. 385 - 399.
Atlantic salmon - Farm scale - Nutrients - Nitrogen - Integrated multitrophic aquaculture - IMTA - pelagic - Environmental impact
The aim of this study was to define the waste plume dynamics around a salmon farm in Norway. Systematic water sampling and numerical modeling were implemented to define nutrient concentrations in the upper water column at long-term (seasonal) and short-term (between and within days) time scales. Nutrient enhancement was observed for ammonium only, while the concentrations of orthophosphate and organic wastes were never higher than the background values. The spatial magnitude of cage effluent dispersion was limited. Empirical results detected enhanced concentrations up to 100 m down-current of the farm when fish biomass was high. Model results showed that the zone of influence could occasionally reach to >1000 m. In the first year of production, when fish biomass was low, no enhancement was detected, and in April and September of the following year, average ammonium concentrations were respectively 0.2 and 0.8 µM above the background concentrations. Taking the ambient seasonal variability into account, this resulted in 1.6 times higher concentrations for both sampling months. The measured short-term temporal variability in nutrient concentrations near the cages varied up to 2 times from day to day and were 3.5 times higher in the evening compared to the morning. As seasonal investigations were performed in the morning, maximum enhancement was likely underestimated. The rapid decrease in nutrient concentrations with increasing distance from the cages suggests that the farm studied here is currently not causing significant degradation of surface water quality. Results of this study contribute to evaluating the potential for ecological mitigation of waste nutrients and provide directions for design of optimized integrated multi-trophic aquaculture facilities
Cereal yield gaps across Europe
Schils, René ; Olesen, Jørgen E. ; Kersebaum, Kurt Christian ; Rijk, Bert ; Oberforster, Michael ; Kalyada, Valery ; Khitrykau, Maksim ; Gobin, Anne ; Kirchev, Hristofor ; Manolova, Vanya ; Manolov, Ivan ; Trnka, Mirek ; Hlavinka, Petr ; Paluoso, Taru ; Peltonen-Sainio, Pirjo ; Jauhiainen, Lauri ; Lorgeou, Josiane ; Marrou, Hélène ; Danalatos, Nikos ; Archontoulis, Sotirios ; Fodor, Nándor ; Spink, John ; Roggero, Pier Paolo ; Bassu, Simona ; Pulina, Antonio ; Seehusen, Till ; Uhlen, Anne Kjersti ; Żyłowska, Katarzyna ; Nieróbca, Anna ; Kozyra, Jerzy ; Silva, João Vasco ; Maçãs, Benvindo Martins ; Coutinho, José ; Ion, Viorel ; Takáč, Jozef ; Mínguez, M.I. ; Eckersten, Henrik ; Levy, Lilia ; Herrera, Juan Manuel ; Hiltbrunner, Jürg ; Kryvobok, Oleksii ; Kryvoshein, Oleksandr ; Boogaard, Hendrik ; Groot, Hugo de; Lesschen, Jan Peter ; Bussel, Lenny van; Wolf, Joost ; Zijlstra, Mink ; Loon, Marloes P. van; Ittersum, Martin K. van - \ 2018
European Journal of Agronomy 101 (2018). - ISSN 1161-0301 - p. 109 - 120.
Barley - Crop modelling - Grain maize - Nitrogen - Wheat - Yield potential

Europe accounts for around 20% of the global cereal production and is a net exporter of ca. 15% of that production. Increasing global demand for cereals justifies questions as to where and by how much Europe's production can be increased to meet future global market demands, and how much additional nitrogen (N) crops would require. The latter is important as environmental concern and legislation are equally important as production aims in Europe. Here, we used a country-by-country, bottom-up approach to establish statistical estimates of actual grain yield, and compare these to modelled estimates of potential yields for either irrigated or rainfed conditions. In this way, we identified the yield gaps and the opportunities for increased cereal production for wheat, barley and maize, which represent 90% of the cereals grown in Europe. The combined mean annual yield gap of wheat, barley, maize was 239 Mt, or 42% of the yield potential. The national yield gaps ranged between 10 and 70%, with small gaps in many north-western European countries, and large gaps in eastern and south-western Europe. Yield gaps for rainfed and irrigated maize were consistently lower than those of wheat and barley. If the yield gaps of maize, wheat and barley would be reduced from 42% to 20% of potential yields, this would increase annual cereal production by 128 Mt (39%). Potential for higher cereal production exists predominantly in Eastern Europe, and half of Europe's potential increase is located in Ukraine, Romania and Poland. Unlocking the identified potential for production growth requires a substantial increase of the crop N uptake of 4.8 Mt. Across Europe, the average N uptake gaps, to achieve 80% of the yield potential, were 87, 77 and 43 kg N ha−1 for wheat, barley and maize, respectively. Emphasis on increasing the N use efficiency is necessary to minimize the need for additional N inputs. Whether yield gap reduction is desirable and feasible is a matter of balancing Europe's role in global food security, farm economic objectives and environmental targets.

Nutrient use efficiencies, losses, and abatement strategies for peri-urban dairy production systems
Wei, S. ; Bai, Z.H. ; Qin, W. ; Wu, Z.G. ; Jiang, R.F. ; Ma, L. - \ 2018
Journal of Environmental Management 228 (2018). - ISSN 0301-4797 - p. 232 - 238.
Dairy farms - Manure management - Nitrogen - NUFER model - Nutrient cycling - Phosphorus

Manure management is an important aspect of urban livestock production that has a profound impact on metropolitan living. Data were collected from 28 dairy farms in peri-urban Beijing and analysed to determine farm nitrogen and phosphorus flows and costs associated with various manure management options to reduce nutrient losses. Dairy production in peri-urban Beijing was characterized by its use of high protein diets (16.3–17.0% crude protein), high reliance on imported feeds (92–98%), and low manure recycling (3.0–10.8%). Farms of 900–2000 cattle showed lower use efficiencies than farms of <900 cattle. Costs of manure handling ranged from 0.1 to 1.0 Yuan kg−1 milk. Among various manure treatment options, biogas digesters with aerobic lagoons had the lowest N losses and costs, justifying their investments. In conclusion, peri-urban dairy production systems were contrasting with traditional systems and within their own systems in nutrient use efficiency and losses, which was mainly decided by their farm size. To improve the nutrient use efficiencies and reduce losses, farmers and managers of peri-urban dairy production system should have a full awareness of different feed intake and manure management.

Simulation of soil organic carbon effects on long-term winter wheat (Triticum aestivum) production under varying fertilizer inputs
Ghaley, Bhim B. ; Wösten, Henk ; Olesen, Jørgen E. ; Schelde, Kirsten ; Baby, Sanmohan ; Karki, Yubaraj K. ; Børgesen, Christen D. ; Smith, Pete ; Yeluripati, Jagadeesh ; Ferrise, Roberto ; Bindi, Marco ; Kuikman, Peter ; Lesschen, Jan Peter ; Porter, John R. - \ 2018
Frontiers in Plant Science 9 (2018). - ISSN 1664-462X
Crop productivity - DAISY model - Grain yield - Long-term experiment - Nitrogen - Pedotransfer functions - Plant available water

Soil organic carbon (SOC) has a vital role to enhance agricultural productivity and for mitigation of climate change. To quantify SOC effects on productivity, process models serve as a robust tool to keep track of multiple plant and soil factors and their interactions affecting SOC dynamics. We used soil-plant-atmospheric model viz. DAISY, to assess effects of SOC on nitrogen (N) supply and plant available water (PAW) under varying N fertilizer rates in winter wheat (Triticum aestivum) in Denmark. The study objective was assessment of SOC effects on winter wheat grain and aboveground biomass accumulation at three SOC levels (low: 0.7% SOC; reference: 1.3% SOC; and high: 2% SOC) with five nitrogen rates (0–200 kg N ha−1) and PAW at low, reference, and high SOC levels. The three SOC levels had significant effects on grain yields and aboveground biomass accumulation at only 0–100 kg N ha−1 and the SOC effects decreased with increasing N rates until no effects at 150–200 kg N ha−1. PAW had significant positive correlation with SOC content, with high SOC retaining higher PAW compared to low and reference SOC. The mean PAW and SOC correlation was given by PAW% = 1.0073 × SOC% + 15.641. For the 0.7–2% SOC range, the PAW increase was small with no significant effects on grain yields and aboveground biomass accumulation. The higher winter wheat grain and aboveground biomass was attributed to higher N supply in N deficient wheat production system. Our study suggested that building SOC enhances agronomic productivity at only 0–100 kg N ha−1. Maintenance of SOC stock will require regular replenishment of SOC, to compensate for the mineralization process degrading SOC over time. Hence, management can maximize realization of SOC benefits by building up SOC and maintaining N rates in the range 0–100 kg N ha−1, to reduce the off-farm N losses depending on the environmental zones, land use and the production system.

Relationship between home-field advantage of litter decomposition and priming of soil organic matter
Lonardo, D.P. di; Manrubia, M. ; Boer, W. de; Zweers, H. ; Veen, G.F. ; Wal, A. van der - \ 2018
Soil Biology and Biochemistry 126 (2018). - ISSN 0038-0717 - p. 49 - 56.
C-plant litter - Carbon cycling - Home field advantage - Nitrogen - Priming effect - Soil organic matter

Home field advantage (HFA; acceleration of plant litter decomposition in soils that receive their indigenous litter) and priming effects (PE; short-term changes in the turnover of soil organic matter caused by the addition of fresh organic carbon) are two aspects of decomposition processes that are driven by the composition and functioning of soil decomposer communities. Physicochemical similarity between added organic compounds and soil organic matter fractions has been indicated as an important steering factor of PE. It is unknown whether PE, like litter decomposition, experience HFA, i.e., whether PE are higher than expected in soils receiving their own litter due to specialization of the decomposer community. Here we studied both HFA and PE by measuring litter- and SOM-derived carbon (C) fluxes after the addition of fresh plant litter. We reciprocally incubated three 13C labelled litter types (maize, bent and beech) in soils from ecosystems where these litters are abundantly produced (e.g., arable sites, grasslands and forests), with and without the addition of mineral nitrogen (N). Generally, respiration of both litter-derived and SOM-derived C were lowest when beech litter was added, and were lower in forest soils than in arable or grassland soils. N addition generally slightly increased the respiration of litter-derived C, but had no effect on SOM-derived C. All litter types induced a positive PE in all soils. HFA effects were not significantly different from zero, but were significantly higher in grasslands than in maize fields amended with nitrogen. We found a positive relationship between litter and priming HFA, indicating that the rates of both litter decomposition and PE may be affected in the same manner by home combinations of plant and litter versus away combinations. This positive relationship disappeared when N was added. Our results provide a first indication that the extent to which indigenous soil microbes are specialized to breakdown home litter, not only accelerates or decelerates the decomposition of litter, but affects the breakdown of SOM in the same way. This could imply that a specialized litter decomposer community driving HFA can further accelerate soil C mineralization via enhanced induction of PE. Therefore, the impact of specialized decomposer communities on the dynamics of soil C pools may be bigger than expected from HFA of litter decomposition alone.

A comparison of disaggregated nitrogen budgets for Danish agriculture using Europe-wide and national approaches
Kros, Johannes ; Hutchings, Nicholas J. ; Kristensen, Inge Toft ; Kristensen, Ib Sillebak ; Børgesen, Christen Duus ; Voogd, Jan Cees ; Dalgaard, Tommy ; Vries, Wim de - \ 2018
Science of the Total Environment 643 (2018). - ISSN 0048-9697 - p. 890 - 901.
Agricultural soils - Budgets - Disaggregation - Modelling - National - Nitrogen

Spatially detailed information on agricultural nitrogen (N) budgets is relevant to identify regions where there is a need for a reduction in inputs in view of various forms of N pollution. However, at the scale of the European Union, there is a lack of consistent, reliable, high spatial resolution data necessary for the calculation of regional N losses. To gain insight in the reduction in uncertainty achieved by using higher spatial resolution input data. This was done by comparing spatially disaggregated agricultural N budgets for Denmark for the period 2000–2010, generated by two versions of the European scale model Integrator, a version using high spatial resolution national data for Denmark (Integrator-DK) and a version using available data at the EU scale (Integrator-EU). Results showed that the national N fluxes in the N budgets calculated by the two versions of the model were within 1–5% for N inputs by fertilizer and manure excretion, but inputs by N fixation and N mineralisation differed by 50–100% and N uptake also differed by ca 25%, causing a difference in N leaching and runoff of nearly 50%. Comparison with an independently derived Danish national budget appeared generally to be better with Integrator-EU results in 2000 but with Integrator-DK results in 2010. However, the spatial distribution of manure distribution and N losses from Integrator-DK were closer to observed distributions than those from Integrator-EU. We conclude that close attention to local agronomic practices is needed when using a leaching fraction approach and that for effective support of environmental policymaking, Member States need to collect or submit high spatial resolution agricultural data to Eurostat.

Drought and soil fertility modify fertilization effects on aphid performance in wheat
Tamburini, Giovanni ; Gils, Stijn van; Kos, Martine ; Putten, Wim van der; Marini, Lorenzo - \ 2018
Basic and Applied Ecology 30 (2018). - ISSN 1439-1791 - p. 23 - 31.
Agricultural intensification - Cereals - Climate change - Grain aphid - Nitrogen - Soil organic matter - Water availability

Agricultural intensification and climate change are expected to affect pest performance through excessive inputs of chemical fertilizers and increased probability of extreme drought events. Potential interactive effects of fertilization and water availability on aboveground pest performance may depend on soil fertility because of its effect on nutrient availability. In a greenhouse experiment, we examined the effects of inorganic fertilization on the performance of the grain aphid (Sitobion avenae, F.), an important pest of wheat, under different conditions of soil fertility and water availability. We found soil fertility and water availability to influence the positive effects of inorganic fertilizers on aphid growth, i.e. fertilization promoted faster aphid development time and higher fecundity and biomass under low fertility and under well-watered conditions. Moreover, although increased soil fertility favored aphid growth under well-watered conditions, it simultaneously sustained plant development. The current practices promoting soil fertility do not have direct negative consequence on crop protection under conventional cropping systems.

Reducing external costs of nitrogen pollution by relocation of pig production between regions in the European Union
Grinsven, Hans J.M. van; Dam, Jan D. van; Lesschen, Jan Peter ; Timmers, Marloes H.G. ; Velthof, Gerard L. ; Lassaletta, Luis - \ 2018
Regional Environmental Change 18 (2018)8. - ISSN 1436-3798 - p. 2403 - 2415.
European Union - External cost - Nitrogen - Pig industry - Spatial optimization

This paper tests the hypothesis that relocation of pig production within the EU27 can reduce the external costs of nitrogen (N) pollution. The external cost of pollution by ammonia and nitrate from agriculture in the European Union (EU27) in 2008 was estimated at 61–215 billion € (0.5 to 1.8% of the GDP). Per capita it ranged from more than 1000 € in north-west EU27 to 50 € in Romania. The average contribution of pig production was 15%. Using provincial data (224 NUTS2 regions in EU27), the potential reduction of external N cost by relocation of pig production was estimated at 14 billion € (10% of the total). Regions most eligible for decreasing the pig stock were in western Germany, Flemish region, Denmark, the Netherlands and Bretagne, while Romania is most eligible for increasing pig production. Relocating 20 million pigs (13% of the total EU stock) decreased average external costs per capita from 900 to 785 € in the 13 NUTS2 regions where pigs were removed and increased from 69 to 107 € in 11 regions receiving pigs. A second alternative configuration of pig production was targeted at reducing exceedance of critical N deposition and closing regional nutrient cycles. This configuration relocates pigs within Germany and France, for example from Bretagne to Northern France and from Weser-Ems to Oberbayern. However, total external cost increases due to an increase of health impacts, unless when combined with implementation of best N management practices. Relocation of the pig industry in the EU27 will meet many socio-economic barriers and realisation requires new policy incentives.

Animal manure use in vegetable production in the Netherlands
Haan, J. de; Geel, W. van - \ 2018
In: 5th International Symposium on Ecologically Sound Fertilization Strategies for Field Vegetable Production. - International Society for Horticultural Science (Acta Horticulturae ) - ISBN 9789462611887 - p. 73 - 80.
Manure - Nitrogen - Organic matter - Phosphate - Regulations - Vegetables
Application of animal manure in vegetables, when used right, can improve soil quality, crop production and financial returns on the long term. Use of animal manure closes nutrient and carbon cycles and contributes to several ecosystem services. The composition of animal manure varies considerably depending on animal species, housing system and feeding of animals. It is important to account for the composition of the manure when using it in vegetable production. Important aspects are the right selection of manure type, matching crop needs in nutrients and organic matter, and the right application of manure in time and place with minimum emissions. Animal manure is ample available in the Netherlands. It is widely used to cover nutrient needs and to sustain soil fertility in the intensive crop rotations in the Netherlands. Manure use in the Netherlands is severely restricted by legislation on nitrogen and phosphorus to prevent emissions to ground and surface water. Processing of animal manure is emerging to be able to use more manure in crop production efficiently next to other advantages for the animal farmer. Important processing techniques developed are 1) anaerobic digestion and 2) separation of manure in a liquid and a solid fraction combined with reversed osmosis making mineral concentrates. The value of animal manure for arable and vegetable crop production is difficult to calculate, especially for organic matter as it affects multiple processes in soil and plant growth. A first estimation of the value of animal manure for arable and vegetable farming on sandy soils is made based on a long-term experiment with different organic matter input treatments. Total value of slurry in the Netherlands is estimated between € 35 and 57 t-1 or € 430 and 2240 ha-1 based on input of 60 kg ha-1 of phosphate with slurry.
Plant species occurrence patterns in Eurasian grasslands reflect adaptation to nutrient ratios
Roeling, Ineke S. ; Ozinga, Wim A. ; Dijk, Jerry van; Eppinga, Maarten B. ; Wassen, Martin J. - \ 2018
Oecologia 186 (2018)4. - ISSN 0029-8549 - p. 1055 - 1067.
Niche - Nitrogen - Phosphorus - Species composition - Stoichiometry
Previous studies of Eurasian grasslands have suggested that nutrient ratios, rather than absolute nutrient availabilities and associated productivity, may be driving plant species richness patterns. However, the underlying assumption that species occupy distinct niches along nutrient ratio gradients remains to be tested. We analysed plant community composition and nutrient status of 644 Eurasian wet grassland plots. The importance of nutrient ratios driving variation in species composition was analysed using ordination methods (DCA and CCA). Subsequently, we assessed the niche position and width along the most important nutrient ratio gradient [N:P] for each species. We found that the N:P ratio explained part of the variation in species composition independent from conventional explanatory variables. The N:P ratio explained less variation than soil moisture or pH, but more than productivity or the availability of N and P separately, highlighting its importance for grassland species composition. Species occupied distinct niches along the N:P gradient, and species’ niche widths decreased toward extreme nutrient limitation. After correcting for niche position, there was no overall difference in niche width between endangered and non-endangered species. Surprisingly, endangered species with niche optima at the extreme P-limited end of the gradient had broader niches than their non-endangered counterparts. As species occupied distinct niches along a nutrient ratio gradient, future grassland conservation efforts may benefit from targeting changes in nutrient ratios, i.e. the balance between N and P, rather than only focussing on a general reduction in nutrient availability. However, what management interventions can be used for this purpose remains unclear.
Feasibility of coupled empirical and dynamic modeling to assess climate change and air pollution impacts on temperate forest vegetation of the eastern United States
McDonnell, T.C. ; Reinds, G.J. ; Sullivan, T.J. ; Clark, C.M. ; Bonten, L.T.C. ; Mol-Dijkstra, J.P. ; Wamelink, G.W.W. ; Dovciak, M. - \ 2018
Environmental Pollution 234 (2018). - ISSN 0269-7491 - p. 902 - 914.
Acidification - Biodiversity - Climate change - Forest understory - Nitrogen
Changes in climate and atmospheric nitrogen (N) deposition caused pronounced changes in soil conditions and habitat suitability for many plant species over the latter half of the previous century. Such changes are expected to continue in the future with anticipated further changing air temperature and precipitation that will likely influence the effects of N deposition. To investigate the potential long-term impacts of atmospheric N deposition on hardwood forest ecosystems in the eastern United States in the context of climate change, application of the coupled biogeochemical and vegetation community model VSD+PROPS was explored at three sites in New Hampshire, Virginia, and Tennessee. This represents the first application of VSD+PROPS to forest ecosystems in the United States. Climate change and elevated (above mid-19th century) N deposition were simulated to be important factors for determining habitat suitability. Although simulation results suggested that the suitability of these forests to support the continued presence of their characteristic understory plant species might decline by the year 2100, low data availability for building vegetation response models with PROPS resulted in uncertain results at the extremes of simulated N deposition. Future PROPS model development in the United States should focus on inclusion of additional foundational data or alternate candidate predictor variables to reduce these uncertainties. Climate change and elevated N deposition were simulated to be important factors for determining habitat suitability for plants, and are expected to interact with changes in soil chemistry.
Relationships between leaf mass per area and nutrient concentrations in 98 Mediterranean woody species are determined by phylogeny, habitat and leaf habit
Riva, Enrique G. de la; Villar, Rafael ; Pérez-Ramos, Ignacio M. ; Quero, José Luis ; Matías, Luis ; Poorter, Lourens ; Marañón, Teodoro - \ 2018
Trees-Structure and Function 32 (2018)2. - ISSN 0931-1890 - p. 497 - 510.
Functional traits - Leaf economics spectrum - Nitrogen - Phosphorus - Phylogenetic independent contrast (PIC) - Stoichiometry
Key message: This study reinforces the existence of the leaf economics spectrum in Mediterranean woody species, and demonstrates the strong influence of phylogeny, leaf habit and environmental context as main drivers of variability in structural and nutrient traits of leaves. Abstract: Leaf structural and nutrient traits are key attributes of plant ecological strategies, as these traits are related to resource-use strategies and plant growth. However, leaf structure and nutrient composition can vary among different habitats, leaf habits or phylogenetic groups. In this study, we measured 13 leaf traits (one structural—leaf mass per area, LMA—and 12 nutrient traits) in 98 Mediterranean woody species growing over a wide range of environmental conditions, with the final aim of discerning the main causes of leaf trait variability. The variance decomposition results show that phylogeny, leaf habit and habitat type affected in several ways the structural and nutrient traits studied. Leaf nutrient concentrations are strongly positively correlated amongst themselves, and negatively correlated with LMA, in accordance with the “leaf economics spectrum”. We found that leaf habit and phylogeny were important causes of variation in LMA and in a broad number of leaf nutrients (i.e., C, N, Mg, S, K), while other micronutrients seemed to be more dependent on the environment (i.e., Cu and Mn). In summary, our study reinforces the existence of the leaf economics spectrum in a broad pool of Mediterranean woody species, and demonstrates the strong influence of phylogeny, leaf habit and environmental context as the main drivers of variability in some leaf structural and nutrient traits.
Sink-source relationship during rice grain filling is associated with grain nitrogen concentration
Wei, Huanhe ; Meng, Tianyao ; Li, Xiaoyun ; Dai, Qigen ; Zhang, Hongcheng ; Yin, Xinyou - \ 2018
Field Crops Research 215 (2018). - ISSN 0378-4290 - p. 23 - 38.
Grain filling - Model - Nitrogen - Oryza sativa - Source/sink ratio
High grain nitrogen (N) concentration in crops may require to translocate more N from the vegetative tissues, cause faster plant senescence, alter sink-source balance during grain filling, and ultimately lower grain yield. Previous studies have shown that indica hybrid rice (IH) have shorter grain-filling period, and lower biomass and grain yield, compared with japonica/indica hybrid rice (JIH) and japonica conventional inbred rice (JC) in China. We hypothesise that these are caused by early senescence and poor sink-source balance after heading in IH as a result of its high grain N concentration. In this study, two JIH, two JC, and two IH varieties were grown in 2013 and 2014 at Ningbo, and in 2015 and 2016 at Yangzhou, China, and the observed dynamics of grain and crop biomass were fitted to mathematical equations to quantify sink-source relationships during grain filling. Compared with JC and IH varieties, JIH varieties showed higher sink growth and source capacity and 7.5–21.6% higher grain yield across years and sites. In JIH and JC genotypes, total source during grain filling was higher than the total sink value, whereas opposite was observed for IH genotypes. Source-sink difference, source/sink ratio, and grain-filling duration all negatively (P < 0.01) correlated with grain N concentration at maturity. Compared with JIH and JC, IH accumulated more N in grains and translocated more N from leaf during the period from heading to maturity. We conclude that early senescence and poor sink-source balance after heading of IH was linked to its high grain N concentration, and sink-source relationships during rice grain filling were associated with grain N concentration. Further breeding and cultivation programmes should aim at improving sink-related traits in JIH and JC genotypes, whereas for IH varieties, whether yield was set by sink size or by any limited availability of pre-heading reserves remains to be further examined.
Can our global food system meet food demand within planetary boundaries?
Conijn, J.G. ; Bindraban, P.S. ; Schröder, J.J. ; Jongschaap, R.E.E. - \ 2018
Agriculture, Ecosystems and Environment 251 (2018). - ISSN 0167-8809 - p. 244 - 256.
Food system - GHG emission - Land use - Nitrogen - Phosphorus - Planetary boundaries - Sustainability
Global food demand is expected to increase, affecting required land, nitrogen (N) and phosphorus (P) inputs along with unintended emissions of greenhouse gasses (GHG) and losses of N and P. To quantify these input requirements and associated emissions/losses as a function of food demand, we built a comprehensive model of the food system and investigated the effects of multiple interventions in the food system on multiple environmental goals. Model outcomes are compared to planetary boundaries for land system change, climate change and the global N and P cycles to identify interventions that direct us towards a safe operating space for humanity. Results show a transgression of most boundaries already for 2010 and a drastic deterioration in the reference scenario for 2050 in which no improvements relative to 2010 were implemented. We defined the following improvements for 2050: reduction of waste, less consumption of animal products, higher feed conversion efficiency, higher crop and grassland yields, reduction of N and P losses from agricultural land and reduction of ammonia (NH3) volatilization. The effects of these measures were quantified individually and in combination. Significant trade-offs and synergies in our results underline the importance of a comprehensive analysis with respect to the entire food system, including multiple measures and environmental goals. The combination of all measures was able to partly prevent transgression of the boundaries for: agricultural area requirement, GHG emission and P flow into the ocean. However, global mineral N and P fertilizer inputs and total N loss to air and water still exceeded their boundaries in our study. The planetary boundary concept is discussed in relation to the selected variables and boundary values, including the additional necessity of eliminating the dependency of our food production on finite P reserves. We argue that total N loss is a better indicator of the environmental impacts of the global N cycle than fertilizer N input. Most measures studied in this paper are also on the agenda of the United Nations for Sustainable Development, which gives added support to their implementation.
Balanced N and C input recommendations for rain-fed maize production in northern China based on N balances and grain yields
Wang, Xiaobin ; Cai, Dianxiong ; Zhao, Quansheng ; Xie, Xiaohong ; Hoogmoed, Willem B. ; Oenema, Oene - \ 2018
Journal of the Science of Food and Agriculture 98 (2018)3. - ISSN 0022-5142 - p. 872 - 883.
Carbon - Dryland - Maize - Nitrogen - Rain-fed farming

BACKGROUND: This study aimed to assess longer-term (1993-2009) effects of combined applications of fertiliser, maize stover, and cattle manure on maize yields, partial nitrogen (N) and carbon (C) balances, and water and N-use efficiencies, to guide N and C input recommendations for rain-fed maize production in northern China. RESULTS: The field trial, with three factors at five levels and 12 treatments, was conducted at Shouyang Dryland-Farming Experimental Station, Shanxi, China. Data analysis revealed higher N balances but lower C balances significantly occurred in a dry year than in a wet year. Positive N balances related to higher N inputs resulted in higher soil available N, even downward to deep layers with increasing N inputs, while positive C balances due to higher C inputs could be benefit to increase soil organic C. Based on partial N balances and grain yields, N and C inputs at ranges of 100kg N ha-1 and 1.9-2.9Mg C ha-1 could be recommended for target yields of 6.7-7.2Mg ha-1 in rain-fed maize production. CONCLUSION: The study suggests that N balances close to neutral be given priority to improving N-use efficiency, and more positive C balances also be important for sustaining target yields and soil fertility levels.

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