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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    Modeling of industrial-scale anaerobic solid-state fermentation for Chinese liquor production
    Jin, Guangyuan ; Uhl, Philipp ; Zhu, Yang ; Wijffels, René H. ; Xu, Yan ; Rinzema, Arjen - \ 2020
    Chemical Engineering Journal 394 (2020). - ISSN 1385-8947
    Chinese liquor - Heat transfer - Mathematical modeling - Product inhibition - Solid-state fermentation - Temperature modeling

    Traditional solid-state fermentation processes can give fluctuating product quality and quantity due to difficulties in control and scale up. This paper describes an engineering study of an industrial-scale anaerobic solid-state fermentation process for Chinese liquor (Baijiu) production, aimed at better understanding of the traditional process, as an initial step for future optimization. This mixed-culture fermentation is done in 0.44-m3 vessels embedded in the soil. At this scale, the fermentation is limited by product inhibition. We developed mathematical models based on the Han-Levenspiel equation for product inhibition, with parameters derived from measured data. The models accurately predicted the concentrations of starch and dry matter. A model with radial conduction into a small soil volume around the fermenter and consecutive vertical conduction into the underlying soil accurately predicted the pit temperature in the heating and cooling phases. This model is very sensitive to the values used for the enthalpies of combustion, meaning that direct measurement of the heat production rate would be preferable. In the industry practice, the fermenter volume can be from around 0.20 to 15.00 m3. The model predicts that overheating will occur not only in larger fermenters, but also in the 0.44-m3 fermenters when the soil temperature is high in summer. Our model predictions are consistent with observed behavior in the industry. Our findings can be used to improve this traditional process, as well as similar systems.

    Space-time statistical analysis and modelling of nitrogen use efficiency indicators at provincial scale in China
    Liu, Yingxia ; Heuvelink, Gerard B.M. ; Bai, Zhanguo ; He, Ping ; Xu, Xinpeng ; Ma, Jinchuan ; Masiliūnas, Dainius - \ 2020
    European Journal of Agronomy 115 (2020). - ISSN 1161-0301
    Nitrogen use efficiency (NUE) is crucial to establish efficient fertilizer application guidelines that balance crop yield, economic return and environmental sustainability. Although there are quite a few researches about the spatial and temporal variation of NUE, little work has been done on modelling NUE through deriving empirical relationships with explanatory environmental variables and exploring their relative importance quantitatively. The space-time patterns of NUE indicators (i.e., the Partial Factor Productivity of nitrogen, PFPN, and the Partial Nutrient Balance of nitrogen, PNBN) at provincial scale in China were derived and related to environmental covariates using stepwise multiple linear regression. PFPN was higher in east and south China than in central and west China and was smaller than 30 kg kg−1 yr−1 in most provinces, while PNBN was moderate in most provinces (0.41–0.50 kg kg−1 yr−1) and low (< 0.40 kg kg−1 yr−1) in south China. The national PFPN declined slightly from 32 kg kg−1 in 1978 to 27 kg kg−1 in 1995 and went up gradually to reach 38 kg kg−1 in 2015. The national PNBN decreased from 0.53 to 0.36 kg kg−1 from 1978 to 2003, thereafter stabilizing at around 0.40 kg kg−1 yr−1 between 2004 and 2015. The multiple linear regression models explained 74 % of the variance of PFPN and PNBN. The main explanatory variables of PFPN were planting area index of sugar crop (32 % of the R-square), followed by Arenosols (12 %), planting area index of oil crop (8 %), planting area index of vegetables (5 %), silt content (5 %) and total potassium (5 %). For PNBN, the variation was mainly attributed to mean annual daytime surface temperature (28 % of the R-square), planting area index of crops (beans 20 %, orchards 10 % and vegetables 9 %) and wet day frequency (5 %). The results of this study indicate that crop types, temperature and soil properties are important variables that determine NUE. These should be considered by policy makers when agricultural land development decisions are made in order to balance NUE and productivity (i.e., agronomy and environment).
    Critical transitions in Chinese dunes during the past 12,000 years
    Xu, Zhiwei ; Mason, Joseph A. ; Xu, Chi ; Yi, Shuangwen ; Bathiany, Sebastian ; Yizhaq, Hezi ; Zhou, Yali ; Cheng, Jun ; Holmgren, Milena ; Lu, Huayu - \ 2020
    Science Advances 6 (2020)9. - ISSN 2375-2548 - p. eaay8020 - eaay8020.

    Dune systems can have alternative stable states that coexist under certain environmental conditions: a vegetated, stabilized state and a bare active state. This behavior implies the possibility of abrupt transitions from one state to another in response to gradual environmental change. Here, we synthesize stratigraphic records covering 12,000 years of dynamics of this system at 144 localities across three dune fields in northern China. We find side-by-side coexistence of active and stabilized states, and occasional sharp shifts in time between those contrasting states. Those shifts occur asynchronously despite the fact that the entire landscape has been subject to the same gradual changes in monsoon rainfall and other conditions. At larger scale, the spatial heterogeneity in dune dynamics averages out to produce relatively smooth change. However, our results do show different paths of recovery and collapse of vegetation at system-wide scales, implying that hysteretic behavior occurs in spatially extended systems.

    Epigenome-wide meta-analysis of blood DNA methylation in newborns and children identifies numerous loci related to gestational age
    Merid, Simon Kebede ; Novoloaca, Alexei ; Sharp, Gemma C. ; Küpers, Leanne K. ; Kho, Alvin T. ; Roy, Ritu ; Gao, Lu ; Annesi-Maesano, Isabella ; Jain, Pooja ; Plusquin, Michelle ; Kogevinas, Manolis ; Allard, Catherine ; Vehmeijer, Florianne O. ; Kazmi, Nabila ; Salas, Lucas A. ; Rezwan, Faisal I. ; Zhang, Hongmei ; Sebert, Sylvain ; Czamara, Darina ; Rifas-Shiman, Sheryl L. ; Melton, Phillip E. ; Lawlor, Debbie A. ; Pershagen, Göran ; Breton, Carrie V. ; Huen, Karen ; Baiz, Nour ; Gagliardi, Luigi ; Nawrot, Tim S. ; Corpeleijn, Eva ; Perron, Patrice ; Duijts, Liesbeth ; Nohr, Ellen Aagaard ; Bustamante, Mariona ; Ewart, Susan L. ; Karmaus, Wilfried ; Zhao, Shanshan ; Page, Christian M. ; Herceg, Zdenko ; Jarvelin, Marjo Riitta ; Lahti, Jari ; Baccarelli, Andrea A. ; Anderson, Denise ; Kachroo, Priyadarshini ; Relton, Caroline L. ; Bergström, Anna ; Eskenazi, Brenda ; Soomro, Munawar Hussain ; Vineis, Paolo ; Snieder, Harold ; Bouchard, Luigi ; Jaddoe, Vincent W. ; Sørensen, Thorkild I.A. ; Vrijheid, Martine ; Arshad, S.H. ; Holloway, John W. ; Håberg, Siri E. ; Magnus, Per ; Dwyer, Terence ; Binder, Elisabeth B. ; Demeo, Dawn L. ; Vonk, Judith M. ; Newnham, John ; Tantisira, Kelan G. ; Kull, Inger ; Wiemels, Joseph L. ; Heude, Barbara ; Sunyer, Jordi ; Nystad, Wenche ; Munthe-Kaas, Monica C. ; Raïkkönen, Katri ; Oken, Emily ; Huang, Rae Chi ; Weiss, Scott T. ; Antó, Josep Maria ; Bousquet, Jean ; Kumar, Ashish ; Söderhäll, Cilla ; Almqvist, Catarina ; Cardenas, Andres ; Gruzieva, Olena ; Xu, Cheng Jian ; Reese, Sarah E. ; Kere, Juha ; Brodin, Petter ; Solomon, Olivia ; Wielscher, Matthias ; Holland, Nina ; Ghantous, Akram ; Hivert, Marie France ; Felix, Janine F. ; Koppelman, Gerard H. ; London, Stephanie J. ; Melén, Erik - \ 2020
    Genome Medicine 12 (2020)1. - ISSN 1756-994X
    Development - Epigenetics - Gestational age - Preterm birth - Transcriptomics

    Background: Preterm birth and shorter duration of pregnancy are associated with increased morbidity in neonatal and later life. As the epigenome is known to have an important role during fetal development, we investigated associations between gestational age and blood DNA methylation in children. Methods: We performed meta-analysis of Illumina's HumanMethylation450-array associations between gestational age and cord blood DNA methylation in 3648 newborns from 17 cohorts without common pregnancy complications, induced delivery or caesarean section. We also explored associations of gestational age with DNA methylation measured at 4-18 years in additional pediatric cohorts. Follow-up analyses of DNA methylation and gene expression correlations were performed in cord blood. DNA methylation profiles were also explored in tissues relevant for gestational age health effects: Fetal brain and lung. Results: We identified 8899 CpGs in cord blood that were associated with gestational age (range 27-42 weeks), at Bonferroni significance, P < 1.06 × 10-7, of which 3343 were novel. These were annotated to 4966 genes. After restricting findings to at least three significant adjacent CpGs, we identified 1276 CpGs annotated to 325 genes. Results were generally consistent when analyses were restricted to term births. Cord blood findings tended not to persist into childhood and adolescence. Pathway analyses identified enrichment for biological processes critical to embryonic development. Follow-up of identified genes showed correlations between gestational age and DNA methylation levels in fetal brain and lung tissue, as well as correlation with expression levels. Conclusions: We identified numerous CpGs differentially methylated in relation to gestational age at birth that appear to reflect fetal developmental processes across tissues. These findings may contribute to understanding mechanisms linking gestational age to health effects.

    Rhizosphere protists are key determinants of plant health
    Xiong, Wu ; Song, Yuqi ; Yang, Keming ; Gu, Yian ; Wei, Zhong ; Kowalchuk, George A. ; Xu, Yangchun ; Jousset, Alexandre ; Shen, Qirong ; Geisen, Stefan - \ 2020
    Microbiome 8 (2020)1. - ISSN 2049-2618
    Pathogen of Ralstonia solanacearum - Plant health - Predator-prey interactions - Protists - Rhizosphere - Secondary metabolite genes

    Background: Plant health is intimately influenced by the rhizosphere microbiome, a complex assembly of organisms that changes markedly across plant growth. However, most rhizosphere microbiome research has focused on fractions of this microbiome, particularly bacteria and fungi. It remains unknown how other microbial components, especially key microbiome predators - protists - are linked to plant health. Here, we investigated the holistic rhizosphere microbiome including bacteria, microbial eukaryotes (fungi and protists), as well as functional microbial metabolism genes. We investigated these communities and functional genes throughout the growth of tomato plants that either developed disease symptoms or remained healthy under field conditions. Results: We found that pathogen dynamics across plant growth is best predicted by protists. More specifically, communities of microbial-feeding phagotrophic protists differed between later healthy and diseased plants at plant establishment. The relative abundance of these phagotrophs negatively correlated with pathogen abundance across plant growth, suggesting that predator-prey interactions influence pathogen performance. Furthermore, phagotrophic protists likely shifted bacterial functioning by enhancing pathogen-suppressing secondary metabolite genes involved in mitigating pathogen success. Conclusions: We illustrate the importance of protists as top-down controllers of microbiome functioning linked to plant health. We propose that a holistic microbiome perspective, including bacteria and protists, provides the optimal next step in predicting plant performance. [MediaObject not available: see fulltext.]

    Relationship between energy balance and metabolic profiles in plasma and milk of dairy cows in early lactation
    Xu, Wei ; Vervoort, Jacques ; Saccenti, Edoardo ; Kemp, Bas ; Hoeij, Renny J. van; Knegsel, Ariette T.M. van - \ 2020
    Journal of Dairy Science 103 (2020). - ISSN 0022-0302 - p. 4795 - 4805.
    liquid chromatography–mass spectrometry - mammary gland - metabolomics - nuclear magnetic resonance

    Negative energy balance in dairy cows in early lactation is related to alteration of metabolic status. However, the relationships among energy balance, metabolic profile in plasma, and metabolic profile in milk have not been reported. In this study our aims were: (1) to reveal the metabolic profiles of plasma and milk by integrating results from nuclear magnetic resonance (NMR) with data from liquid chromatography triple quadrupole mass spectrometry (LC-MS); and (2) to investigate the relationship between energy balance and the metabolic profiles of plasma and milk. For this study 24 individual dairy cows (parity 2.5 ± 0.5; mean ± standard deviation) were studied in lactation wk 2. Body weight (mean ± standard deviation; 627.4 ± 56.4 kg) and milk yield (28.1 ± 6.7 kg/d; mean ± standard deviation) were monitored daily. Milk composition (fat, protein, and lactose) and net energy balance were calculated. Plasma and milk samples were collected and analyzed using LC-MS and NMR. From all plasma metabolites measured, 27 were correlated with energy balance. These plasma metabolites were related to body reserve mobilization from body fat, muscle, and bone; increased blood flow; and gluconeogenesis. From all milk metabolites measured, 30 were correlated with energy balance. These milk metabolites were related to cell apoptosis and cell proliferation. Nine metabolites detected in both plasma and milk were correlated with each other and with energy balance. These metabolites were mainly related to hyperketonemia; β-oxidation of fatty acids; and one-carbon metabolism. The metabolic profiles of plasma and milk provide an in-depth insight into the physiological pathways of dairy cows in negative energy balance in early lactation. In addition to the classical indicators for energy balance (e.g., β-hydroxybutyrate, acetone, and glucose), the current study presents some new metabolites (e.g., glycine in plasma and milk; kynurenine, panthothenate, or arginine in plasma) in lactating dairy cows that are related to energy balance and may be of interest as new indicators for energy balance.

    Optimizing rates and sources of nutrient input to mitigate nitrogen, phosphorus, and carbon losses from rice paddies
    Ding, Wencheng ; He, Ping ; Zhang, Jiajia ; Liu, Yingxia ; Xu, Xinpeng ; Ullah, Sami ; Cui, Zhenling ; Zhou, Wei - \ 2020
    Journal of Cleaner Production 256 (2020). - ISSN 0959-6526
    Enhanced-efficiency fertilizer - Greenhouse gas - Manure N - N threshold - Nutrient loss - Straw return

    Decreasing nutrient losses from excessive synthetic fertilizer inputs is the direct and valid way to address low nutrient use efficiency and the related environmental consequences. Here, we established a comprehensive database of nitrogen (N), phosphorus (P), and carbon (C) losses from rice paddy fields in China, which we used to evaluate fertilization-induced losses and the impact of environmental factors, and to mitigate losses by adopting alternative fertilization options and setting input thresholds. Our results showed that most N-loss pathways had exponential increases with additional N input. In average, 23.8% of the N applied was lost via NH3 (16.1%), N2O (0.3%), leaching (4.8%), and runoff (2.6%). Total P loss was approximately 2.7% of the input, composed of leaching (1.3%) and runoff (1.4%). C lost as CH4 accounted for 4.9% of the organic C input. A relative importance analysis indicated that climate or soil variation rather than fertilizer rate was the dominant factor driving N and P leaching, and CH4 emissions. Based on the sensitivity of multiple N-loss pathways to N fertilization, we propose upper thresholds for N inputs of 142–191 kg N ha−1 across four rice types, which would avoid dramatic increases in N losses. Compared to conventional chemical fertilization, alternative fertilization options had diverse performances: enhanced-efficiency N fertilizer reduced N loss rate by 7.8 percent points and the global warming potential (GWP, considering N2O and CH4 emissions) by 28.8%; combined manure and chemical N fertilizer reduced N loss rate by 9.0 percent points but increased the GWP by 56.9%; straw return had no effect on total N loss but almost doubled the GWP. Using nutrient sources most appropriate to site-specific conditions is demonstrated as a robust way to decrease nutrient losses. Setting nutrient input thresholds would also contribute to the mitigation of environmental pollution, especially in regions with poor fertilization recommendation systems.

    Denitrification performance and microbial communities of solid-phase denitrifying reactors using poly (butylene succinate)/bamboo powder composite
    Qi, Wanhe ; Taherzadeh, Mohammad J. ; Ruan, Yunjie ; Deng, Yale ; Chen, Ji Shuang ; Lu, Hui Feng ; Xu, Xiang Yang - \ 2020
    Bioresource Technology 305 (2020). - ISSN 0960-8524
    Bacterial community - Fungal community - PBS/Bamboo composite - RAS effluent treatment - Solid-phase denitrification

    This study explored the denitrification performance of solid-phase denitrification (SPD) systems packed with poly (butylene succinate)/bamboo powder composite to treat synthetic aquaculture wastewater under different salinity conditions (0‰ Vs. 25‰). The results showed composite could achieve the maximum denitrification rates of 0.22 kg (salinity, 0‰) and 0.34 kg NO3 -N m−3 d−1 (salinity, 25‰) over 200-day operation. No significant nitrite accumulation and less dissolved organic carbon (DOC) release (<15 mg/L) were found. The morphological and spectroscopic analyses demonstrated the mixture composites degradation. Microbial community analysis showed that Acidovorax, Simplicispira, Denitromonas, SM1A02, Marinicella and Formosa were the dominant genera for denitrifying bacteria, while Aspergillus was the major genus for denitrifying fungus. The co-network analysis also indicated the interactions between bacterial and fungal community played an important role in composite degradation and denitrification. The outcomes provided a potential strategy of DOC control and cost reduction for aquaculture nitrate removal by SPD.

    Resolving humic and fulvic acids in binary systems influenced by adsorptive fractionation to Fe-(hydr)oxide with focus on UV–Vis analysis
    Xu, Yun ; Bai, Yilina ; Hiemstra, Tjisse ; Tan, Wenfeng ; Weng, Liping - \ 2020
    Chemical Engineering Journal 389 (2020). - ISSN 1385-8947
    Acid precipitation - Adsorptive fractionation - Humic Substances - Iron-oxides - Size exclusion chromatography - UV–Vis spectroscopy

    Humic acid (HA) and fulvic acid (FA) are two operationally defined classes of natural organic matter. In the environment, both materials are present simultaneously and bind in a competitive manner to Fe-(hydr)oxides and other minerals, but their quantification in mixtures is a challenge. In this study, an UV–Vis method was developed to quantify concentrations of HA and FA without and after adsorptive fractionation by an iron oxide (goethite, α-FeOOH). In addition, the performance of the UV–Vis method was compared to that of acid precipitation and size exclusion chromatography (SEC). Among the three methodologies (UV–Vis, acid precipitation, SEC), the UV–Vis method is the most successful in quantifying the ratio of HA to FA subject to fractionation. The UV–Vis method is based on distinct differences in the UV–Vis spectra of HA and FA, including fingerprints in both the spectra shape and intensity. Adsorption to goethite decreased the specific light absorbance of HA and FA, but the changes in spectral shape were not significant enough to cover their differences. The acid precipitation method can also quantify the HA to FA ratio. But to minimize the influence of incomplete HA precipitation or co-precipitation of FA, the concentration of both HA and FA needs to be at least ~20 mgC L−1. The SEC method is not suitable to measure HA and FA after adsorption, because preferential adsorption significantly affects the shape of SEC chromatograms.

    Impact of trends in river discharge and ocean tides on water level dynamics in the Pearl River Delta
    Cao, Yu ; Zhang, Wei ; Zhu, Yuliang ; Ji, Xiaomei ; Xu, Yanwen ; Wu, Yao ; Hoitink, A.J.F. - \ 2020
    Coastal Engineering 157 (2020). - ISSN 0378-3839
    Nonstationary harmonic analysis - River discharge - Tidal amplitudes - Tidal forcing - Water levels

    The spectrum of tidal and subtidal water level variations in river deltas responds to river discharge variation, ocean tides, and human activities of many kinds. It remains a contemporary challenge to identify the main sources of changes in tidal dynamics in deltas, because of nonlinear interactions between tides and the river discharge in a changing setting. Understanding the main forcing factors controlling the evolution of mean water levels and the associated amplitudes and phases of tidal constituents can help to understand the causes of floods and the occurrence of low flows hindering navigation. Here, a nonstationary harmonic analysis tool (NS_TIDE) is applied to hydrological data from 14 stations in the Pearl River Delta (PRD) spanning the period 1961–2012. The water levels and main tidal constituent properties are decomposed into contributions of external forcing by river discharges and ocean tides, providing insight into the nonstationary tidal-fluvial processes. Significant temporal trends in mean water levels and tidal properties are observed in the PRD. Results indicate that there is spatial variability in the response of mean water levels and tidal properties to river discharge variation in the delta. The abrupt changes in bathymetry in the delta due to intensive sand excavation are likely responsible for the observed spatial variations in tidal response, which reduce the flood-dominant tidal asymmetry in this area.

    Modelling long-term impacts of fertilization and liming on soil acidification at Rothamsted experimental station
    Xu, Donghao ; Carswell, Alison ; Zhu, Qichao ; Zhang, Fusuo ; Vries, Wim de - \ 2020
    Science of the Total Environment 713 (2020). - ISSN 0048-9697
    Liming - Long-term experiments - Modelling - Soil acidification - VSD+

    Liming is widely used to reduce the impacts of soil acidification and optimize soil pH for agricultural production. Whether models can simulate the effect of liming on soil pH, and base saturation (BS), and thereby guide lime application, is still largely unknown. Long-term experimental data from a grassland (Park Grass, 1965–2012) and arable land (Sawyers Field, 1962–1972) at Rothamsted Research, UK, were thus used to assess the ability of the VSD+ model to simulate the effects of long-term fertilization and liming on soil acidification. The VSD+ model was capable of simulating observed soil pH and BS changes over time in the long-term liming experiments, except for a treatment in which sulphur (S) was added. Normalized Mean Absolute Errors (NMAE) and Normalized Root Mean Square Errors (NRMSE) of simulated and observed pH values, averaged over the observation periods varied between 0.02 and 0.08 (NMAE) and 0.01–0.05 (NRMSE). The acidity budget results for Park Grass suggest that nitrogen (N) transformations contributed most to acidity production, causing predominantly aluminium (Al) exchange in the topsoil (0–23 cm) followed by base cation (BC) release, but in the treatment with S addition, BC uptake had a nearly similar effect on acidity production. However, in Sawyers Field, the acidity budget suggested that BC uptake was the dominant cause of soil acidification, while the impacts of N transformations were limited. Liming was found to sufficiently replenish BC and decrease Al exchange in the topsoil layer. Overall, the VSD+ model can adequately reconstruct the impacts of fertilizer and liming applications on acid neutralizing processes and related soil pH and BC changes at the soil exchange complex.

    Tiara[5]arenes: Synthesis, solid-state conformational studies, host-guest properties and application as nonporous adaptive crystals
    Yang, Weiwei ; Samanta, Kushal ; Wan, Xintong ; Thikekar, Tushar Ulhas ; Chao, Yang ; Li, Shunshun ; Du, Ke ; Xu, Yun ; Gao, Yan ; Zuilhof, H. ; Sue, Andrew C.H. - \ 2020
    Angewandte Chemie 59 (2020)10. - ISSN 0044-8249 - p. 3994 - 3999.
    Tiara[5]arenes (T[5]s), a new class of five‐fold symmetric oligophenolic macrocycles, which are not accessible from the addition of formaldehyde to phenol, were synthesized for the first time. These pillar[5]arene‐derived structures display both unique conformational freedom, differing from that of pillararenes, with a rich blend of solid‐state conformations, and excellent host‐guest interactions in solution. Finally we show how this novel macrocyclic scaffold can be functionalized in a variety of ways and used as functional crystalline materials to distinguish uniquely between benzene and cyclohexane.
    Intercropping maize and soybean increases efficiency of land and fertilizer nitrogen use; A meta-analysis
    Xu, Zhan ; Li, Chunjie ; Zhang, Chaochun ; Yu, Yang ; Werf, Wopke van der; Zhang, Fusuo - \ 2020
    Field Crops Research 246 (2020). - ISSN 0378-4290
    Fertilizer N equivalent ratio (FNER) - Intercropping - Land equivalent ratio (LER) - Maize - Soybean

    Intercropping exploits species complementarities to achieve sustainable intensification by increasing crop outputs per unit land with reduced anthropogenic inputs. Cereal/legume intercropping is a classical case. We carried out a global meta-analysis to assess land and fertilizer N use efficiency in intercropping of maize and soybean as compared to sole crops, based on 47 studies reported in English and 43 studies reported in Chinese. The data were extracted and analyzed with mixed effects models to assess land equivalent ratio (LER) of intercropping and factors affecting LER. The worldwide average LER of maize/soybean intercropping was 1.32 ± 0.02, indicating a substantial land sparing potential of intercropping over sole crops. This advantage increased as the temporal niche differentiation between the two species was increased by sowing or harvesting one crop earlier than the other as in relay intercropping, i.e. with only partial overlap of the growing periods of the two species The mean fertilizer N equivalent ratio (FNER) was 1.44 ± 0.03, indicating that intercrops received substantially less fertilizer N than sole crops for the same product output. These fertilizer savings are mainly due to the high relative maize yield and the lower N input in the intercrop compared to the input in sole maize. This meta-analysis thus shows that exploiting species complementarities by intercropping maize and soybean enables major increases in land productivity with less fertilizer N use. Both LER and FNER increased as the difference in growth duration increased for maize and soybean, but were not affected by fertilizer N rate. LER increased when soil organic matter increased but FNER did not change with soil organic matter.

    Cellular RNA Hubs: Friends and Foes of Plant Viruses
    Xu, Min ; Mazur, Magdalena J. ; Tao, Xiaorong ; Kormelink, Richard - \ 2020
    Molecular Plant-Microbe Interactions 33 (2020)1. - ISSN 0894-0282 - p. 40 - 54.
    RNA granules are dynamic cellular foci that are widely spread in eukaryotic cells and play essential roles in cell growth and development, and immune and stress responses. Different types of granules can be distinguished, each with a specific function and playing a role in, for example, RNA transcription, modification, processing, decay, translation, and arrest. By means of communication and exchange of (shared) components, they form a large regulatory network in cells. Viruses have been reported to interact with one or more of these either cytoplasmic or nuclear granules, and act either proviral, to enable and support viral infection and facilitate viral movement, or antiviral, protecting or clearing hosts from viral infection. This review describes an overview and recent progress on cytoplasmic and nuclear RNA granules and their interplay with virus infection, first in animal systems and as a prelude to the status and current developments on plant viruses, which have been less well studied on this thus far.
    Negative effects of urbanization on agricultural soil easily oxidizable organic carbon down the profile of the Chengdu Plain, China
    Luo, Youlin ; Li, Qiquan ; Wang, Changquan ; Li, Bing ; Stomph, Tjeerd Jan ; Yang, Juan ; Tao, Qi ; Yuan, Shu ; Tang, Xiaoyan ; Ge, Jinru ; Yu, Xuelian ; Peng, Yueyue ; Xu, Qiang ; Zheng, Gangxun - \ 2020
    Land Degradation and Development 31 (2020)3. - ISSN 1085-3278 - p. 404 - 416.
    easily oxidized organic carbon - impact factors - negative effects - rapid urbanization - soil profile

    Soil easily oxidizable organic carbon (EOC) is directly related to CO2 density; dynamics in subsurface EOC have been observed globally in relation to rapid urbanization. However, in the context of rapid urbanization, the factors related to EOC and the response of the EOC pool to urbanization down the profile remain elusive. The aim of the current paper is to investigate possible changes in the distribution of EOC over the soil profile and the impact of land use, socioeconomic, and natural factors on these. The study used samples from 182 soil profiles (0–100 cm) taken in the peri-urban areas of the megacity Chengdu (a typical megacity with rapid urbanization). Main drivers of changes in soil EOC were analyzed by using spatial and regression analyses. Closer to the centre of the city, soil EOC levels were lower and land-use factors and socioeconomic factors contributed more to explaining variation in EOC levels in the 0–40-cm layer, whereas natural factors were most important at larger distance from the city. The effect of land-use factors and socioeconomic factors on EOC reached down to 60-cm depths. Moreover, an estimated 20% loss of EOC stock was observed close to the city in comparison with the surroundings, suggesting that the rapid process of urbanization was accompanied by a loss of EOC stock down the profile to depths of 60 cm, and the negative effects on EOC stock became more intensive as the distance to the city decreased.

    Environmental impact assessment of water-saving irrigation systems across 60 irrigation construction projects in northern China
    Chen, Xiuzhi ; Thorp, Kelly R. ; Oel, Pieter R. van; Xu, Zhenci ; Zhou, Bo ; Li, Yunkai - \ 2020
    Journal of Cleaner Production 245 (2020). - ISSN 0959-6526
    Carbon footprint - Environmental impact - Irrigation project - Life cycle assessment - Scenario - Water footprint

    With increasing water shortages partly due to increasing demands, water has become a globally relevant issue especially in arid and semi-arid regions. Water-saving irrigation technologies provide new ways for improving the efficiency of water use for agricultural production. Although efficient irrigation management could lead to water savings and increased yields, the water consumption and greenhouse gas emissions during the construction of irrigation projects also puts pressure on environmental health. However, little research has considered the environmental impact of the construction process and materials. To fill this gap, the water footprint (WF) and carbon footprint (CF) of irrigation projects were calculated using life cycle assessment (LCA) methods. The results for sixty typical irrigation projects in northern China showed that the WF accounted for only 0.2–1.5% of the total agricultural WF and 2.3–8.8% of the water saved. When the WF to construct modern irrigation systems is not considered, the water-saving effects of these systems are generally overestimated by 13%. The CF for irrigation projects was 42.0% of all agricultural activities. Due to the difficulty to obtain detailed information for irrigation projects, this paper established the relationship between financial investment or area and CF for three kinds of irrigation projects. It provided a simple quantitative method for assessing its environmental impacts. By comparing environmental impacts and production benefits under different scenarios, using drip irrigation over the long-term could increase crop yield and reduce water footprint, but carbon footprint was increased at the same time. This study suggests that it is necessary to assess the environmental impacts of irrigation construction projects from a life cycle perspective rather focusing only on yield increases and reductions in irrigation amounts.

    A network approach to prioritize conservation efforts for migratory birds
    Xu, Yanjie ; Si, Yali ; Takekawa, John ; Liu, Qiang ; Prins, Herbert H.T. ; Yin, Shenglai ; Prosser, Diann J. ; Gong, Peng ; Boer, Willem F. de - \ 2020
    Conservation Biology 34 (2020)2. - ISSN 0888-8892 - p. 416 - 426.
    bird migration - connectivity - conservation designation - habitat loss - network

    Habitat loss can trigger migration network collapse by isolating migratory bird breeding grounds from nonbreeding grounds. Theoretically, habitat loss can have vastly different impacts depending on the site's importance within the migratory corridor. However, migration-network connectivity and the impacts of site loss are not completely understood. We used GPS tracking data on 4 bird species in the Asian flyways to construct migration networks and proposed a framework for assessing network connectivity for migratory species. We used a node-removal process to identify stopover sites with the highest impact on connectivity. In general, migration networks with fewer stopover sites were more vulnerable to habitat loss. Node removal in order from the highest to lowest degree of habitat loss yielded an increase of network resistance similar to random removal. In contrast, resistance increased more rapidly when removing nodes in order from the highest to lowest betweenness value (quantified by the number of shortest paths passing through the specific node). We quantified the risk of migration network collapse and identified crucial sites by first selecting sites with large contributions to network connectivity and then identifying which of those sites were likely to be removed from the network (i.e., sites with habitat loss). Among these crucial sites, 42% were not designated as protected areas. Setting priorities for site protection should account for a site's position in the migration network, rather than only site-specific characteristics. Our framework for assessing migration-network connectivity enables site prioritization for conservation of migratory species.

    Managing Forests for Both Downstream and Downwind Water
    Creed, Irena F. ; Jones, Julia A. ; Archer, Emma ; Claassen, Marius ; Ellison, David ; Mcnulty, Steven G. ; Noordwijk, Meine Van; Vira, Bhaskar ; Wei, Xiaohua ; Bishop, Kevin ; Blanco, Juan A. ; Gush, Mark ; Gyawali, Dipak ; Jobbágy, Esteban ; Lara, Antonio ; Little, Christian ; Martin-ortega, Julia ; Mukherji, Aditi ; Murdiyarso, Daniel ; Pol, Paola Ovando ; Sullivan, Caroline A. ; Xu, Jianchu - \ 2019
    Frontiers in Forests and Global Change 2 (2019). - ISSN 2624-893X
    Forests and trees are key to solving water availability problems in the face of climate change and to achieving the United Nations Sustainable Development Goals. A recent global assessment of forest and water science posed the question: How do forests matter for water? Here we synthesize science from that assessment, which shows that forests and water are an integrated system. We assert that forests, from the tops of their canopies to the base of the soils in which trees are rooted, must be considered a key component in the complex temporal and spatial dimensions of the hydrologic cycle. While it is clear that forests influence both downstream and downwind water availability, their actual impact depends on where they are located and their processes affected by natural and anthropogenic conditions. A holistic approach is needed to manage the connections between forests, water and people in the face of current governance systems that often ignore these connections. We need policy interventions that will lead to forestation strategies that decrease the dangerous rate of loss in forest cover and that—where appropriate—increase the gain in forest cover. We need collective interventions that will integrate transboundary forest and water management to ensure sustainability of water supplies at local, national and continental scales. The United Nations should continue to show leadership by providing forums in which interventions can be discussed, negotiated and monitored, and national governments must collaborate to sustainably manage forests to ensure secure water supplies and equitable and sustainable outcomes.
    Innovative lateral flow devices for the detection of pesticides harmful to bees
    Xu, Mang ; Hoof, R.A. van; Hamers, A.R.M. ; Rijk, T.C. de; Guo, Yirong ; Bovee, T.F.H. ; Peters, J. - \ 2019
    Conventional instrumental detection of pesticides is complex and time-consuming, and is not realistic at the Point Of Need. In the B-GOOD project, we applied a dual channel lateral flow device (LFD) that is able to detect six out of eight neonicotinoids based on monoclonal antibody interaction and found that these LFDs have strong potential for field application. Additionally, WFSR has developed a LFD prototype that detects fipronil, a pesticide which was responsible for the recent death of hundred-thousands of honey bees in the Netherlands. Other LFDs, for the detection of bee-harming pesticides are also under development. In the near future, B-GOOD is interested in applying the developed LFDs at the point of need.
    Song, Jing ; Xu, Genyan ; Luo, Yongming ; Gao, Hui ; Tang, Wei - \ 2019
    Earth Science Frontiers 26 (2019)6. - ISSN 1005-2321 - p. 192 - 198.
    Bioavailable heavy metals - Criteria for safe utilization of soil - DUMIS - Soil-crop synchronized monitoring - Suitability assessment of soil environmental quality standard

    By compilation of data from field sampling, pot experiment and literature, we evaluated the suitability of the existing national standards (GB 15618-2018 and GB/T 36783-2018) for the classification of soil environmental quality in potato producing areas of Guizhou. The results showed that both soil Cd standards were overly stringent as, for example, these for potatoes grown in mining areas were more likely to exceed food standard. Here, we summarized the inadequacy of the existing sampling methods for soil-crop synchronized monitoring and proposed a sampling theory-based Decision Unit-Multi Increment Sampling method (DUMIS) for soil-crop synchronized monitoring and remediation verification. We proposed that the criteria for safe soil utilization should be derived on a site-specific basis using bioavailable fractions. In order to facilitate the evaluation of soil environmental quality and safety for the agricultural production regions of China, we suggested that further research is needed regarding the use of DUMIS in soil-crop synchronized monitoring and bioavailable fractions based criteria for safe utilization of mild to moderately contaminated soils.

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