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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    Klassenindelingen voor de fosfaattoestand van de bodem, ten behoeve van de afleiding van fosfaatgebruiksnormen
    Oenema, O. ; Mol, J.P. ; Voogd, J.C.H. ; Ehlert, P.A.I. ; Velthof, G.L. - \ 2016
    Wageningen : Alterra, Wageningen-UR (Alterra-rapport 2743) - 39
    bodem - fosfaten - graslanden - bouwland - akkergronden - graslandgronden - soil - phosphates - grasslands - arable land - arable soils - grassland soils
    In 2006 is het stelsel van gebruiksnormen voor stikstof en fosfaat ingevoerd in de Nederlandse landbouw om de uit- en afspoeling van stikstof en fosfaat vanuit de landbouw naar grondwater en oppervlaktewater te verminderen. In 2010 zijn de gebruiksnormen voor fosfaat gedifferentieerd naar de fosfaattoestand van de bodem. Daarbij worden vier klassen voor de fosfaattoestand van de bodem onderscheiden, namelijk arm, laag, neutraal en hoog. De grenzen tussen de klassen worden bepaald via een bepaling van het Pw-getal (voor bouwland) en het P-AL-getal (voor grasland). In 2015 heeft de Commissie Deskundigen Meststoffenwet (CDM) voorgesteld om de fosfaattoestand te bepalen op basis van een gecombineerde indicator, namelijk P-CaCl2 en het P-AL-getal, omdat een gecombineerde indicator in theorie een betere voorspelling geeft van de fosfaattoestand, en de gecombineerde indicator reeds in de praktijk en voor de bemestingsadviezen van grasland en maisland wordt toegepast. Ook speelt een rol dat het Pw-getal door verschillende analyselaboratoria niet meer wordt bepaald. In onderhavig rapport worden voor de gecombineerde indicator klassengrenzen afgeleid voor de fosfaattoestand van de bodem. Daarbij is gebruikgemaakt van een grote database (ruim 55.000 monsters) en van statistische analyses om een klassenindeling gebaseerd op het Pw-getal voor bouwland en op het P-AL-getal voor grasland om te rekenen naar een klassenindeling voor de gecombineerde indicator P-CaCl2 en het P-AL-getal. Verschillende varianten zijn voorgesteld. Effecten van de varianten op fosfaatplaatsingsruimte zijn verkend.
    Bodemkwaliteit op veengrond : effecten van drie maatregelen op een rij
    Eekeren, N.J.M. van; Deru, Joachim ; Lenssinck, F.A.J. ; Bloem, J. - \ 2016
    Driebergen : Louis Bolk Instituut - 32
    biologische landbouw - bodemkwaliteit - veengronden - graslandgronden - melkveehouderij - organic farming - soil quality - peat soils - grassland soils - dairy farming
    Deze brochure behandelt de bodemkwaliteit van veengrond. In Hoofdstuk 2 worden de zes elementen van bodemkwaliteit besproken. Hoofdstuk 3 gaat over meten en beoordelen van bodemkwaliteit. In Hoofdstuk 4 worden drie praktijkmaatregelen in het veenweidegebied behandeld. Onderdeel van deze brochure is een checklist voor bodemkwaliteit die elke melkveehouder op veen kan doorlopen.
    Vegetatie-, beheer- en habitattypen van Het Nationale Park De Hoge Veluwe in 2014
    Bijlsma, R.J. ; Janssen, J.A.M. ; Weeda, E.J. ; Griffioen, A.J. - \ 2015
    Wageningen : Alterra, Wageningen-UR (Alterra-rapport 2616)
    vegetatiemonitoring - habitats - vegetatietypen - nationale parken - heidegebieden - eolisch zand - graslandgronden - natuurgebieden - inventarisaties - veluwe - vegetation monitoring - habitats - vegetation types - national parks - heathlands - aeolian sands - grassland soils - natural areas - inventories - veluwe
    In 2014 is een vegetatiekartering uitgevoerd van Het Nationale Park De Hoge Veluwe uitgaande van een luchtfoto-interpretatie uit 2013 en kleurenfoto’s uit 2010. Het Park bestaat voor ruim 30% uit Natura 2000-habitattypen, verdeeld over 12 typen en draagt belangrijk bij aan oppervlakten habitattype van de Veluwe, met name voor Zandverstuivingen (848 ha), Stuifzandheiden (270 ha), Zure vennen en Heideveentjes (16 ha), Vochtige heiden (27 ha), Heischrale graslanden (189 ha) en Oude eikenbossen (240 ha). Ten opzichte van de kartering in 2007 zijn er op hoofdlijnen de volgende ontwikkelingen: de oppervlakte zandverstuivingen is met maximaal 10% afgenomen, vooral door successie naar Stuifzandheiden; Stuifzandheiden zijn afgenomen ten gunste van Droge heiden; de oppervlakte Heischrale graslanden is praktisch gelijk gebleven; vergrassing met Pijpenstrootje is voortgeschreden; de oppervlakten Vochtige heiden en Zure vennen zijn niet wezenlijk veranderd; habitattype Zwakgebufferde vennen is nieuw onderscheiden met een zeer klein oppervlakte; de oppervlakte Heideveentjes is toegenomen door betere inventarisatie; Jeneverbesstruwelen en Oude eikenbossen zijn in oppervlakte gelijk gebleven; het weinig voorkomende type Beuken-eikenbossen met hulst is uitgebreid met een deel dat in 2007 ten onrechte niet was onderscheiden. De vegetatietypen zijn toegekend aan 11 natuurbeheertypen waarvan N16.01 Droog bos met productie 48% van de oppervlakte inneemt, gevolgd door N01.01 Droge heide met 22% en N07.02 Zandverstuiving met 14%. De overige typen beslaan elk minder dan 5% van de oppervlakte. Vooralsnog is alleen het landschapsbeheertype L01.07 Lanen onderscheiden.
    Strategisch stikstof bemesten op melkbeebedrijven : welke bemestingsadvies gebruik je als stikstof knelt?
    Curth-van Middelkoop, J.C. - \ 2015
    melkveebedrijven - stikstof - dierlijke meststoffen - consultancy - graslandgronden - maïs - bemesting - dairy farms - nitrogen - animal manures - consultancy - grassland soils - maize - fertilizer application
    Dit is een flyer met bemestingsadvies met betrekking tot stikstof. Gebruiksnormen voor stikstof (N) zijn voor gras en snijmaïs lager dan N-bemestingsadvies, met name op zand en löss. Normen gelden op bedrijfsniveau, u heeft de verdeling van de N in eigen hand over: Gewassen; (Groepen van) Percelen en eventueel grondsoorten; Tijd in het uitrijseizoen.
    Production-ecological modelling explains the difference between potential soil N mineralisation and actual herbage N uptake
    Rashid, M.I. ; Goede, R.G.M. de; Brussaard, L. ; Bloem, J. ; Lantinga, E.A. - \ 2014
    Applied Soil Ecology 84 (2014). - ISSN 0929-1393 - p. 83 - 92.
    winter-wheat fields - nitrogen mineralization - organic-matter - food webs - grassland soils - forest soils - community - manure - earthworms - management
    We studied two different grassland fertiliser management regimes on sand and peat soils: above-ground application of a combination of organic N-rich slurry manure and solid cattle manure (SCM) vs. slit-injected, mineral N-rich slurry manure, whether or not supplemented with chemical fertiliser (non-SCM). Measurements of field N mineralisation as estimated from herbage N uptake in unfertilised plots were compared with (i) potential N mineralisation as determined from a standard laboratory soil incubation, (ii) the contribution of groups of soil organisms to N mineralisation based on production-ecological model calculations, and (iii) N mineralisation calculated according to the Dutch fertilisation recommendation for grasslands. Density and biomass of soil biota (bacteria, fungi, enchytraeids, microarthropods and earthworms) as well as net plant N-uptake were higher in the SCM input grasslands compared to the non-SCM input grasslands. The currently used method in Dutch fertilisation recommendations underestimated actual soil N supply capacity by, on average, 102 kg N ha-1 (202 vs. 304 kg ha-1 = 34%). The summed production-ecological model estimate for N mineralisation by bacteria, fungi, protozoa, and enchytraeids was 87–120% of the measured potential soil N mineralisation. Adding the modelled N mineralisation by earthworms to potential soil N mineralisation explained 98–107% of the measured herbage N uptake from soil. For all grasslands and soil biota groups together, the model estimated 105% of the measured net herbage N uptake from soil. Soil biota production-ecological modelling is a powerful tool to understand and predict N uptake in grassland, reflecting the effects of previous manure management and soil type. The results show that combining production ecological modelling to predict N supply with existing soil N tests using aerobic incubation methods, can add to a scientifically based improvement of the N fertilisation recommendations for production grasslands.
    Innovatieve maïsteelt op veengrond in Noord-Holland : jaarrapportage 2012
    Schooten, H.A. van; Deru, J.G.C. ; Parmentier, F. - \ 2013
    Lelystad : Wageningen UR Livestock Research - 16
    zea mays - strokenteelt - graslanden - graslandgronden - veengronden - bodemdaling - grondbewerking - drainage - grondwaterstand - melkveehouderij - noord-holland - zea mays - strip cropping - grasslands - grassland soils - peat soils - subsidence - tillage - drainage - groundwater level - dairy farming - noord-holland
    In de proef op veengrond in Noord Holland is het effect op het grondwaterpeil onderzocht van maïs versus grasland, waarbij de maïs met de strokenfrees is ingezaaid of traditioneel (spitten), zowel ongedraineerd als met onderwaterdrainage. Ook opbrengsten en opbrengstkwaliteit zijn gemeten. De resultaten van het eerste jaar (2012) - waarbij het een heel nat jaar betrof - laten zien dat het grondwaterpeil bij maïs hoger blijft dan bij grasland, en dat het peil onder maïs in stroken hoger is dan bij spitten. Samen met het feit dat bij strokenfrezen ca. 90% van de bouwvoor ongestoord blijft, wordt verondersteld dat het effect van maïsteelt in stroken op bodemdaling gering is. Spitten gaf duidelijk hogere opbrengsten dan strokenteelt, en drainage had een grote positieve invloed op de opbrengst zowel bij spitten als bij strokenteelt. De oogst verliep met duidelijk minder structuurschade bij de strokenfrees ten opzichte van spitten.
    Reducing phosphorus loading of surface water using iron-coated sand
    Groenenberg, J.E. ; Chardon, W.J. ; Koopmans, G.F. - \ 2013
    Journal of Environmental Quality 42 (2013)1. - ISSN 0047-2425 - p. 250 - 259.
    treatment residuals - agricultural land - waste-water - grassland soils - flooded soils - phosphate - drainage - groundwater - reduction - removal
    Phosphorus losses from agricultural soils is an important source of P in surface waters leading to surface water quality impairment. In addition to reducing P inputs, mitigation measures are needed to reduce P enrichment of surface waters. Because drainage of agricultural land by pipe drainage is an important pathway of P to surface waters, removing P from drainage water has a large potential to reduce P losses. In a field trial, we tested the performance of a pipe drain enveloped with Fe-coated sand, a side product of the drinking water industry with a high ability to bind P, to remove P from the drainage water. The results of this trial, encompassing more than one hydrological season, are very encouraging because the efficiency of this mitigation measure to remove P amounted to 94%. During the trial, the pipe drains were below the groundwater level for a prolonged time. Nevertheless, no reduction of Fe(III) in the Fe-coated sand occurred, which was most likely prevented by reduction of Mn oxides present in this material. The enveloped pipe drain was estimated to be able to lower the P concentration in the effluent to the desired water quality criterion for about 14 yr. Manganese oxides are expected to be depleted after 5 to 10 yr. The performance of the enveloped pipe drain, both in terms of its ability to remove P to a sufficiently low level and the stability of the Fe-coated sand under submerged conditions in the long term, needs prolonged experimental research.
    Direct zaaien van maïs in bestaande zode
    Schrauwen, R. ; Eekeren, N.J.M. van - \ 2011
    Royal Haskoning [etc.]
    teeltsystemen - maïs - direct zaaien - rijenbemesting - graslandgronden - zaaien - bemesting - cropping systems - maize - direct sowing - band placement - grassland soils - sowing - fertilizer application
    Met de techniek direct zaaien van maïs wordt maïs in doodgespoten bestaand grasland of groenbemester ingezaaid zonder te ploegen, maar door smalle banen te frezen van 12 cm. Tegelijkertijd wordt de drijfmest in de gefreesde rij toegediend.
    Predicting soil N mineralization: Relevance of organic matter fractions and soil properties.
    Ros, G.H. ; Hanegraaf, M.C. ; Hoffland, E. ; Riemsdijk, W.H. van - \ 2011
    Soil Biology and Biochemistry 43 (2011)8. - ISSN 0038-0717 - p. 1714 - 1722.
    nitrogen mineralization - microbial biomass - chemical methods - grassland soils - forest soils - indexes - availability - carbon - respiration - temperature
    Distinct extractable organic matter (EOM) fractions have been used to assess the capacity of soils to supply nitrogen (N). However, substantial uncertainty exists on their role in the N cycle and their functional dependency on soil properties. We therefore examined the variation in mineralizable N and its relationship with EOM fractions, soil physical and chemical properties across 98 agricultural soils with contrasting inherent properties and management histories. Mineralizable N was determined by aerobic incubation at 20 °C and optimum moisture content for 20 weeks. We used multivariate statistical modelling to account for multi-collinearity, an issue generally overlooked in studies evaluating the predictive value of EOM fractions. Mineralization of N was primarily related to the size of OM pools and fractions present; they explained 78% of the variation in mineralizable N whereas other soil variables could explain maximally 8%. Both total and extractable OM expressed the same soil characteristic from a mineralization perspective; they were positively related to mineralizable N and explained a similar percentage of the variation in mineralizable N. Inclusion of mineralizable N in fertilizer recommendation systems should be based on at least one OM variable. The most appropriate EOM fraction can only be identified when the underlying mechanisms are known; regression techniques are not suitable for this purpose. Combination of single EOM fractions is not likely to improve the prediction of mineralizable N due to high multi-collinearity. Inclusion of texture-related soil variables or variables reflecting soil organic matter quality may be neglected due to their limited power to improve the prediction of mineralizable N.
    Nitrogen mineralization: a review and meta-analysis of the predictive value of soil tests.
    Ros, G.H. ; Temminghoff, E.J.M. ; Hoffland, E. - \ 2011
    European Journal of Soil Science 62 (2011)1. - ISSN 1351-0754 - p. 162 - 173.
    available organic nitrogen - stabilization mechanisms - microbial biomass - matter fractions - chemical methods - grassland soils - land-use - indexes - plantations - management
    Accurate estimation of mineralizable nitrogen (N) from soil organic matter is essential to improve fertilizer management in agricultural systems. Mineralizable N refers to the amount of N in soil that is released during a certain period (ranging from 1 week to the length of a growing season). It has been estimated from increases in inorganic N during incubation or from N uptake by plants grown in a greenhouse or field. Many chemical soil tests measuring extractable organic N (EON) fractions have been proposed to predict mineralizable N. We evaluated the predictive value of these soil tests, using 2068 observations from 218 papers. Meta-analysis was used to find the best soil test, to analyse differences between field and laboratory experiments, and to determine whether their predictive value is affected by extraction intensity (% of total soil N that is extracted). The concentration of EON was positively related to mineralizable N, explaining on average 47% of the variation. It did not, however, explain more of the variation than total N. Best predictions (57%
    Estimation of plant-available nitrogen in soils using rapid chemical and biological methods
    Velthof, G.L. ; Oenema, O. - \ 2010
    Communications in Soil Science and Plant Analysis 41 (2010)1. - ISSN 0010-3624 - p. 52 - 71.
    potentially mineralizable nitrogen - organic-matter - n-mineralization - drying temperature - grassland soils - extraction - fractions - electroultrafiltration - prediction - quality
    The relationships between potential laboratory indices for plant-available nitrogen (N) and the plant N uptake in a pot experiment with ryegrass were assessed for 13 mineral soils and 2 peat soils. The methods included aerobic soil incubation, soil incubation in a bioreactor, hot potassium chloride (KCl)-extractable mineral N, 0.01 M calcium chloride (CaCl2)-extractable N, and N loss at heating. The indices for total plant-available N accounted for 63-93% of the variance in N uptake in a statistical analysis with all soils (n = 15) and 27-89% for the mineral soils (n = 13). Most indices were not a direct quantitative measure of the plant N uptake. The N mineralization indices accounted for 57-86% of the variance in N mineralization for all soils and 5-50% for the mineral soils. Hot KCl-extractable mineral N and 0.01 M CaCl2-extractable N were the most promising rapid indices for plant-available N.
    The nitrate response of a lowland catchment: on the relation between stream concentration and travel time distribution dynamics
    Velde, Y. van der; Rooij, G.H. de; Rozemeijer, J.C. ; Geer, F.C. van; Broers, H.P. - \ 2010
    Water Resources Research 46 (2010). - ISSN 0043-1397 - 17 p.
    nitrogen mineralization - grassland soils - organic-matter - groundwater - transport - scale - model - texture - uncertainty - netherlands
    Nitrate pollution of surface waters is widespread in lowland catchments with intensive agriculture. For identification of effective nitrate concentration reducing measures the nitrate fluxes within catchments need to be quantified. In this paper we applied a mass transfer function approach to simulate catchment-scale nitrate transport. This approach was extended with time-varying travel time distributions and removal of nitrate along flow paths by denitrification to be applicable for lowland catchments. Numerical particle tracking simulations revealed that transient travel time distributions are highly irregular and rapidly changing, reflecting the dynamics of rainfall and evapotranspiration. The solute transport model was able to describe 26 years of frequently measured chloride and nitrate concentrations in the Hupsel Brook catchment (6.6 km2 lowland catchment in the Netherlands) with an R2 value of 0.86. Most of the seasonal and daily variations in concentrations could be attributed to temporal changes of the travel time distributions. A full sensitivity analysis revealed that measurements other than just surface water nitrate and chloride concentrations are needed to constrain the uncertainty in denitrification, plant uptake, and mineralization of organic matter. Despite this large uncertainty, our results revealed that denitrification removes more nitrate from the Hupsel Brook catchment than stream discharge. This study demonstrates that a catchment-scale lumped approach to model chloride and nitrate transport processes suffices to accurately capture the dynamics of catchment-scale surface water concentration as long as the model includes detailed transient travel time distributions
    Van schraal naar rijk zand : onderwijsdag
    Hanegraaf, Marjoleine - \ 2009
    soil - soil quality - organic matter - crop yield - grassland management - grassland soils
    Contributions of woody and herbaceous vegetation to tropical savanna ecosystem productivity: a quasi-global estimate
    Lloyd, J. ; Bird, M.I. ; Vellen, L. ; Miranda, A.C. ; Veenendaal, E.M. ; Djagbletey, G. ; Miranda, H.S. ; Cook, G. ; Fraquhar, G.D. - \ 2008
    Tree Physiology 28 (2008)3. - ISSN 0829-318X - p. 451 - 468.
    soil organic-matter - carbon-isotope discrimination - precambrian shield region - eastern lowland bolivia - gap ratio c - brazilian cerrado - moisture gradient - grassland soils - south-america - national-park
    To estimate the relative contributions of woody and herbaceous vegetation to savanna productivity, we measured the (13)C/(12)C isotopic ratios of leaves from trees, shrubs, grasses and the surface soil carbon pool for 22 savannas in Australia, Brazil and Ghana covering the full savanna spectrum ranging from almost pure grassland to closed woodlands on all three continents. All trees and shrubs sampled were of the C(3) pathway and all grasses of the C(4) pathway with the exception of Echinolaena inflexa (Poir.) Chase, a common C(3) grass of the Brazilian cerrado. By comparing the carbon isotopic compositions of the plant and carbon pools, a simple model relating soil delta(13)C to the relative abundances of trees + shrubs (woody plants) and grasses was developed. The model suggests that the relative proportions of a savanna ecosystem's total foliar projected cover attributable to grasses versus woody plants is a simple and reliable index of the relative contributions of grasses and woody plants to savanna net productivity. Model calibrations against woody tree canopy cover made it possible to estimate the proportion of savanna productivity in the major regions of the world attributable to trees + shrubs and grasses from ground-based observational maps of savanna woodiness. Overall, it was estimated that 59% of the net primary productivity (N(p)) of tropical savannas is attributable to C(4) grasses, but that this proportion varies significantly within and between regions. The C(4) grasses make their greatest relative contribution to savanna N(p) in the Neotropics, whereas in African regions, a greater proportion of savanna N(p) is attributable to woody plants. The relative contribution of C(4) grasses in Australian savannas is intermediate between those in the Neotropics and Africa. These differences can be broadly ascribed to large scale differences in soil fertility and rainfall.
    Elevated CO2 does not favor a fungal decomposition pathway
    Groenigen, K.J. van; Six, J. ; Harris, D. ; Kessel, C. van - \ 2007
    Soil Biology and Biochemistry 39 (2007)8. - ISSN 0038-0717 - p. 2168 - 2172.
    atmospheric co2 - grassland soils - amino-sugars - nitrogen - carbon - responses - agroecosystems - limitation - bacterial
    We examined the effect of prolonged elevated CO2 on the concentration of fungal- and bacterial-derived compounds by quantifying the soil contents of the amino sugars glucosamine, galactosamine and muramic acid. Soil samples were collected from three different terrestrial ecosystems (grassland, an aspen forest and a soybean/corn agroecosystem) that were exposed to elevated CO2 under FACE conditions for 3¿10 years. Amino sugars were extracted from bulk soil and analyzed by gas chromatography. Elevated CO2 did not affect the size or composition of the amino sugar pool in any of the systems. However, high rates of fertilizer N applications decreased the amount of fungal-derived residues in the grassland system. We suggest that these results are caused by a decrease in saprophytic fungi following high N additions. Furthermore, our findings imply that the contribution of saprophytic fungi and bacteria to SOM in the studied ecosystems is largely unaffected by elevated CO2.
    Chemical characterization of manure in relation to manure quality as a contribution to a reduced nitrogen emission to the environment
    Stelt, B. van der - \ 2007
    Wageningen University. Promotor(en): Willem van Riemsdijk, co-promotor(en): Erwin Temminghoff. - [S.l.] : S.n. - ISBN 9789085046301 - 152
    dierlijke meststoffen - ammoniak - vervluchtiging - dieet - stikstofkringloop - graslandgronden - organisch bodemmateriaal - samenstelling - voer - animal manures - ammonia - volatilization - diet - nitrogen cycle - grassland soils - soil organic matter - composition - feeds
    Keywords:manure composition, ammonia volatilization, free ions, Donnan Membrane Technique, manure additives, dietary changes, nitrogen dynamics,grasslandsoils.

    More insight in manure composition, ammonia (NH 3 ) volatilization, and into relationships between soil organic matter (SOM) content and nitrogen (N) flows in grasslands is needed to improve the nutrient use efficiency of manure as fertilizer for plants and concomitantly to reduce the environmental impact of agricultural activities.

    Additives are often added to improve manure quality ( e.g. reduce NH 3 volatilization). Laboratory studies showed that additives used in this study did in general not affect manure characteristics or NH 3 volatilization, when manure was incubated at three temperatures and either regular mixed or not mixed. Only when Agri-mest ® and Effective Micro-organisms ® were both added and the manure was incubated at 4 °C without mixing, NH 3 volatilization was reduced by 34%.

    To study manure composition in more detail, a DMT-manure cell was developed, which either measures 'free' dissolved cation or anion concentrations in manure. Dilution studies showed that total nutrient concentrations and monovalent 'free' dissolved cation concentrations decreased proportionately with increasing dilution, whereas 'free' dissolved divalent cation concentrations were buffered upon dilution. The buffering of divalent cation concentrations is probably the result of the release of these ions from organic matter, or it is the result of the dissolution of certain phosphate minerals ( e.g. struvite and whitlockite). Only a small part of the total phosphorus (P) content (<1%) and the total sulphur content (<13%) was present in a 'free' dissolved ionic form.

    A feeding trial with non-lactating cows showed that the total N and P content and the total ammoniacal nitrogen (TAN= NH 3,aq + NH 4+ ) content of manure increased when the dietary protein or energy content was raised, whereas the 'free'-to-total ratios of Ca and Mg in the manures were not affected by dietary changes. Ammoniavolatilization from manure increased with an increase in dietary protein content and decreased with an increase in dietary energy content, although the TAN content of manures produced from diets with a higher dietary energy content werehigher.

    A field trial, in combination with incubation studies, was carried out in the VEL-VANLA area to study how N dynamics was affected by SOM content. Incubation studies showed that potential N mineralization rates (measured at 20 °C and 60% water holding capacity) of eighteen grassland soils were related to the initial dissolved organic nitrogen content and to the dissolved organic carbon content of the soil, as measured in 0.01M CaCl 2 extracts. During the growing season, two peaks in total soluble N content were observed, which could not be related to the time of manure application, but were both preceded by a period of draught. Maximum total soluble N and nitrate content were higher in soils with a lower SOM content. This is probably caused by faster water depletion of soils with a lower SOM content during drought periods, which will hamper N uptake by plants.

    Concluding, adjusting diets seems to be a more promising way to reduce NH 3 volatilization than the use of manure additives, especially since adjusting the diet will reduce NH 3 volatilization at any time of manure handling (housing, storage, and during manure application), which is not always the case for other NH 3 volatilization reduction techniques. A proper estimation of N mineralization during the growing season can help to improve the nutrient gift (via manure) in order for plants to grow with limited risks to the environment. Dissolved organic N might be a promising parameter to estimate N mineralization.

    Quantitative description of soil organic matter dynamics - A review of approaches with reference to rice-based cropping systems
    Shibu, M.E. ; Leffelaar, P.A. ; Keulen, H. van; Aggarwal, P.K. - \ 2006
    Geoderma 137 (2006)1-2. - ISSN 0016-7061 - p. 1 - 18.
    long-term experiments - microbial biomass - lowland rice - carbon sequestration - simulating trends - grassland soils - modeling carbon - yield declines - winter-wheat - great-plains
    This review paper presents a historical overview of quantitative approaches used in describing soil organic matter (SOM) dynamics, with the objective of identifying processes relevant in describing long-term carbon and nitrogen dynamics in rice-based cropping systems. A number of existing SOM models have been evaluated based on their objectives and underlying concepts. Models are grouped into two broad classes of analytical and simulation models, and within the latter comprehensive and summary models, based on the level of detail in process descriptions. Most of the existing SOM models have been developed for aerobic, upland conditions and describe the processes of decomposition of organic matter, growth and death of microbial biomass, nitrification, immobilization, denitrification, NH4+-volatilization, leaching of NO3¿, crop uptake, erosion and runoff. However, in anaerobic lowland conditions, the rates and relative importance of the processes are different. This paper evaluates the suitability of existing models for application under alternate flooded and non-flooded conditions, corresponding to rotations of rice-upland crops. Since no existing SOM model describes the processes for such conditions and their effect on SOM quantity and quality, a simulation model is yet to be developed, including these processes, which can satisfactorily describe the changes in SOM and crop yield. This paper also identifies the processes to consider in developing a long-term simulation model for alternate flooded and non-flooded conditions.
    Oscillating dynamics of bacterial populations and their predators in response to fresh organic matter added to soil: The simulation model 'BACWAVE-WEB'
    Zelenev, V.V. ; Bruggen, A.H.C. van; Leffelaar, P.A. ; Bloem, J. ; Semenov, A.M. - \ 2006
    Soil Biology and Biochemistry 38 (2006)7. - ISSN 0038-0717 - p. 1690 - 1711.
    belowground food webs - protozoa-induced mineralization - habitable pore-space - winter-wheat fields - wave-like dynamics - nitrogen mineralization - grassland soils - short-term - microbial biomass - n-mineralization
    Recently, regular oscillations in bacterial populations and growth rates of bacterial feeding nematodes (BFN) were shown to occur after addition of fresh organic matter to soil. This paper presents a model developed to investigate potential mechanisms of those oscillations, and whether they were initiated by bacteria¿substrate interactions or by predatory regulation of bacteria. The model was also used to investigate mineral nitrogen release during short-term organic matter decomposition. Experimental data originated from several microcosm experiments with a sandy soil amended with clover¿grass mixture. Numbers of bacteria and BFN, and nitrate and ammonium content in soil were measured daily during about a month, whereas protozoa were counted occasionally. A substrate-based food web model was constructed with 3 plant residue and 5 soil organic matter compartments, 3 trophic groups of bacteria (copiotrophic, oligotrophic and hydrolytic), and two predatory groups (BFN and protozoa). Both carbon and nitrogen flows between these compartments were modelled. Fluctuations in microbial populations in soil after plant residue incorporation could be reproduced with and without participation of predators. The first two peaks in bacterial numbers were mainly related to bacteria¿substrate interactions, while predators (particularly protozoa) influenced bacterial dynamics during later stages of bacterial community development. Oligotrophic bacteria had a stabilizing effect on fluctuations of other trophic groups, and were the main source of nutrients for predators. A peak in soil ammonium occurred within 1 week after residue incorporation. Nitrate increased sigmoidally after a short lag phase. The final nitrate concentration was primarily determined by bacterial dynamics, and to a lesser extent by protozoa and nematodes. This model indicates the importance of substrate¿consumer relations for regulation of populations at different trophic levels and nutrient release from fresh organic matter added to soil.
    Precise soil management as a tool to reduce CH4 and N2O emissions from agricultural soil. III. A preliminary study on grassland soils
    Mosquera, J. ; Huis in 't Veld, J.W.H. ; Beek, C. ter; Hol, J.M.G. - \ 2005
    Wageningen : Agrotechnology & Food Innovations (Rapport / Wageningen UR, Agrotechnology & Food Innovations 569) - ISBN 9789067549868 - 17
    bodemverdichting - broeikasgassen - emissie - grondbewerking - graslandgronden - methaan - distikstofmonoxide - hulpbronnenbeheer - soil compaction - greenhouse gases - emission - tillage - grassland soils - methane - nitrous oxide - resource management
    Development and application of a selective pcr-denaturing gradient gel electrophoresis approach to detect a recently cultivated Bacillus group predominant in soil
    Tzeneva, V.A. ; Li, Y. ; Felske, A. ; Vos, W.M. de; Akkermans, A.D.L. ; Vaughan, E.E. ; Smidt, H. - \ 2004
    Applied and Environmental Microbiology 70 (2004)10. - ISSN 0099-2240 - p. 5801 - 5809.
    16s ribosomal-rna - molecular microbial diversity - in-situ detection - grassland soils - sp nov. - dna - bacteria - identification - netherlands - drentse
    The worldwide presence of a hitherto-nondescribed group of predominant soil microorganisms related to Bacillus benzoevorans was analyzed after development of two sets of selective primers targeting 16S rRNA genes in combination with denaturing gradient gel electrophoresis (DGGE). The high abundance and cultivability of at least some of these microorganisms makes them an appropriate subject for studies on their biogeographical dissemination and diversity. Since cultivability can vary significantly with the physiological state and even between closely related strains, we developed a culture-independent 16S rRNA gene-targeted DGGE fingerprinting protocol for the detection of these bacteria from soil samples. The composition of the B. benzoevorans relatives in the soil samples from The Netherlands, Bulgaria, Russia, Pakistan, and Portugal showed remarkable differences between the different countries. Differences in the DGGE profiles of these communities in archived soil samples from the Dutch Wieringermeer polder were observed over time during which a shift from anaerobic to aerobic and from saline to freshwater conditions occurred. To complement the molecular methods, we additionally cultivated B. benzoevorans-related strains from all of the soil samples. The highest number of B. benzoevorans relatives was found in the soils from the northern part of The Netherlands. The present study contributes to our knowledge of the diversity and abundance of this interesting group of microbes in soils throughout the world.
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