Mown Grassland Research Articles

Tick infestation risk for dogs in a peri-urban park

BackgroundIncreases in the abundance and distribution of ticks and tick borne disease (TBD) within Europe have been reported extensively over the last 10–20 years. Changes in climate, habitat management, economic patterns and changes in the abundance of hosts, particularly deer, may all have influenced this change to varying extents. Increasing abundances of tick populations in urban and peri-urban environments, such as parks, are of particular concern. In these sites, suitable habitat, wildlife hosts, tick populations, people and their pets may be brought into close proximity and hence may provide foci for tick infestation and, ultimately, disease transmission.MethodsThe distribution and abundance of ticks were examined in an intensively used, peri-urban park. First the seasonal and spatial distribution and abundance of ticks in various habitat types were quantified by blanket dragging. Then the pattern of pet dog movement in the park was mapped by attaching GPS recorders to the collars of dogs brought to the park for exercise, allowing their walking routes to be tracked. Information about the dog, its park use and its history of tick attachment were obtained from the dog-owners.ResultsTicks were found predominantly in woodland, woodland edge and deer park areas and were least abundant in mown grassland. Tick infestation of dogs was a relatively frequent occurrence with, on average, one case of tick attachment reported per year for a dog walked once per week, but for some dogs walked daily, infestation 4–5 times per week was reported. All dogs appeared to be at equal risk, regardless of walk route or duration and infestation was primarily influenced by the frequency of exposure.ConclusionsIn peri-urban green spaces, tick-biting risk for dogs may be high and here was shown to be related primarily to exposure frequency. While tick-biting is of direct veterinary importance for dogs, dogs also represent useful sentinels for human tick-exposure.

Joint Production of Food and Wildlife: Uniform Measures or Nature Oases?

Intensive agriculture is often bad for wildlife. Does this imply that a goal to boost wildlife on agricultural land is best met through a general reduction in intensity? We argue that such an approach may not be optimal, since cost functions for provision of wildlife on agricultural land may be non-convex, due to fixed costs associated with such provision. This implies that, even when farms are identical, it may be preferable to split them into groups of high providers and low providers. We test our hypothesis in a study of the optimal management of mown grasslands in southern Sweden, where the two products are silage and successful reproduction of ground-nesting birds, and the variable controlled by the farmer is the date of the first mowing. We show that the optimal solution is likely to involve some farmers maintaining profit-maximizing practices while other-identical-farmers delay their first mowing significantly. The superiority of such split solutions may have major implications for agricultural policy.

Dew, where and when? ‘There are more things in heaven and earth, Horatio, than are dreamt of in your philosophy …’

Dew, where and when? ‘There are more things in heaven and earth, Horatio, than are dreamt of in your philosophy …’

Adaptation of Poa alpina to altitude and land use in the Swiss Alps

Current land use and climate change are prompting questions about the ability of plants to adapt to such environmental change. Therefore, we experimentally addressed plant performance and quantitative-genetic diversity of the common Alpine Meadow Grass Poa alpina. We asked how land use and altitude affect the occurrence of P. alpina in the field and whether its common-garden performance suggests adaptation to conditions at plant origin and differences in quantitative genetic diversity among plant origins. Among 216 candidate grassland sites of different land use and altitude from 12 villages in the Swiss Alps, P. alpina occurred preferentially in fertilized and grazed sites and at higher elevations. In a common garden at 1,500 m asl, we grew two plants of >600 genotypes representing 78 grassland sites. After 2 years, nearly 90% of all plants had reproduced. In agreement with adaptive advantages of vegetative reproduction at higher altitudes, only 23% of reproductive plants from lower altitudes reproduced via vegetative bulbils, but 55% of plants from higher altitudes. In agreement with adaptive advantages of reproduction in grazed sites, allocation to reproductive biomass was higher in plants from grazed grasslands than from mown ones. For 53 grasslands, we also investigated broad-sense heritability H2, which was significant for all studied traits and twice as high for grazed as for mown grasslands. Moreover, possibly associated with their higher landscape diversity, H2 was higher for sites of villages of Romanic cultural tradition than for those of Germanic and Walser traditions. We suggest promoting diverse land use regimes to conserve not only landscape and plant species diversity, but also adaptive genetic differentiation and heritable genetic variation.

Scavenging of dead invertebrates along an urbanisation gradient in Singapore

Abstract. 1. Little is known about the animals that scavenge invertebrates in the tropics and the impact of human activities on such organisms.2. We studied the scavenging process using baits representing five dead invertebrate types in six habitats along an urbanisation gradient in equatorial Singapore: primary forest, old secondary forest, young secondary forest, recreational park, mown grassland and impervious surfaces.3. Ants were the dominant scavengers, except at night in grassland when an earwig (Labiduridae) dominated. In general, the forest sites had more scavenger species and shorter bait survival times than the non‐forest habitats.4. Bait survival time increased monotonically along the urbanisation gradient, suggesting that this parameter could be used as an indicator of habitat quality.

Differences in fungal communities associated to Festuca paniculata roots in subalpine grasslands

Mycorrhizal fungi or endphytes colonize plant roots and their occurrence and composition depend on biotic and abiotic characteristics of the ecosystem. We investigated the composition of these microbial communities associated with Festuca paniculata, a slow growing species, which dramatically impacts functional plant diversity and the recycling of organic matter in subalpine grasslands. F. paniculata individuals from both mown and unmown grasslands were randomly collected and the microscopic observation of the plant roots revealed a difference in fungal colonization according to management. The ITS regions of root-associated fungi were amplified, cloned and sequenced. Bioinformatic analysis revealed a total of 43 and 35 phylotypes in mown and unmown grasslands respectively, highlighting a remarkable difference in the composition between both fungal communities. The phylotypes were assigned to 9 classes in which two classes Eurotiomycetes and Lecanoromycetes were specific to mown grasslands, while Tremellomycetes were specific to unmown grasslands and only five phylotypes were common to both locations. The comparative analysis of fungal lifestyles indicated the dominance of saprobes and a large proportion of endophytes compared to the mycorrhizal fungi (7/1 and 11/2 phylotypes in mown and unmown grasslands, respectively). Endophyte richness was greater in the unmown gassland than in the mown grassland and their relative proportion was twice higher. Our results suggest that endophytes may offer potential resources to F. paniculata and play an important role in the regulation of plant diversity.

Behaviour of male and female parasitoids in the field: influence of patch size, host density, and habitat complexity

1. Two field experiments were carried out to examine the role of patch size, host density, and complexity of the surrounding habitat, on the foraging behaviour of the parasitoid wasp Cotesia glomerata in the field.2. First, released parasitoids were recaptured on patches of one or four Brassica nigra plants, each containing 10 hosts that were placed in a mown grassland area. Recaptures of females were higher than males, and males and females aggregated at patches with four plants.3. In experiment 2, plants containing 0, 5 or 10 hosts were placed in unmown grassland plots that differed in plant species composition, on bare soil, and on mown grassland. Very low numbers of parasitoids were recaptured in the vegetated plots, while high numbers of parasitoids were recaptured on plants placed on bare soil or in mown grassland. Recaptures were higher on plants on bare soil than on mown grassland, and highest on plants containing 10 hosts. The host density effect was significantly more apparent in mown grassland than on bare soil.4. Cotesia glomerata responds in an aggregative way to host density in the field. However, host location success is determined mostly by habitat characteristics, and stronger host or host‐plant cues are required when habitat complexity increases.

Characteristics of feeding‐site selection by breeding Green Woodpeckers Picus viridis in a UK agricultural landscape

Capsule Green Woodpeckers exhibited strong feeding‐site preference, choosing areas based on abundance of ants with additional micro‐habitat effects. Aims To identify the habitat characteristics influencing feeding‐site selection across farmland. Methods A pair of Green Woodpeckers was radiotracked during a breeding season. Habitat and prey abundance variables were compared within the birds’ combined home‐ranges. canoco was used to identify ecological gradients, and logistic regression used to predict feeding‐site use based on ant abundance with resultant residuals correlated to identify habitat features that further influenced site selection. Results Most feeding was done in sheep‐grazed pastures and garden lawns with arable and cattle‐grazed land avoided. Green Woodpecker feeding sites were associated with areas of short grassland with high plant richness and high densities of ants, especially Lasius flavus. Logistic regression correctly classified 98% of cases from ant abundance. The woodpecker pair had a greater probability of feeding in areas with deep leaf litter, high plant species richness, and lower probability if the site had tall or dense vegetation, or heavily compacted soils. Conclusions Structural habitat characteristics were important, with this woodpecker pair foraging in short grazed and mown grasslands. If these results are replicated elsewhere then appropriate farm management may benefit Green Woodpeckers significantly.

Floristic diversity and the richness of locally endangered plant species of semi-natural grasslands under different management practices, southern Kyushu, Japan

Background: The rapid decline of semi-natural grasslands in Japan threatens many relic and endemic plant species. There is insufficient knowledge on how the impacts of land-use changes and management of grasslands have been affecting grassland ecosystems and what conservation measures may be taken to conserve as much of the existing plant diversity as possible. Aim: We assessed the existing management regimes for their suitability for conserving Red Data Book (RDB) species. Methods: We conducted our study in four districts of Kushima, Kyushu, south-west Japan, with different land-use histories. We compared species richness, plant density and abundance in six grassland types: regularly burnt, regularly mown, paddy levee, roadside, landslip and wetland communities in a total of 289 1 m x 1 m quadrats, recorded in172 grassland patches. Species richness plant density and abundance were analysed with special reference to RDB species under different land use history. Results: Species richness of grasslands did not differ across different land use histories, yet our analysis showed that the reduced area of grasslands markedly affected the density of RDB species. Grassland types differed in their ability to support RDB species: regularly burnt grasslands were the richest in RDB species and poorest in alien species, followed by regularly mown grasslands, paddy levees, landslip, wetland and roadside communities. Conclusions: Traditional management regimes, such as regular burning or mowing of grasslands have the best potential for conserving RDB species, and thus should be part of conservation management practices of semi-natural grasslands.

Impact of land use on vegetation composition, diversity and potentially invasive, nitrophilous clonal species in a wetland region in Flanders

In the framework of a nature conservation project in a wetland region of Meetkerke, Belgium, a comprehensive study was conducted to analyse and to compare species composition and diversity among wet grasslands under the six following types of agricultural land use: pastures used at high or low stocking rate, hayfields used at high or low mowing frequency, abandoned hayfields and hay pastures. The focus of the study was on the effects of grassland management on species diversity and on the restriction of occurrence of invasive clonal species. The results show that species importance was strongly related to grassland exploitation parameters and soil hydrological parameters, as shown by the ordination diagram drawn by canonical correspondence analysis (CCA). Species number and importance of non-leguminous dicotyledons were negatively correlated to intensity of use, N supply, water table depth and soil drainage. Phalaris arundinacea, an invasive species which might reduce species diversity, was better suppressed in grazed grassland than in mown grassland. Phalaris arundinacea and Cirsium arvense were most prevalent in abandoned hayfields. Grazing at low stocking rate was the best management technique to maximise plant diversity while restricting invasion by nitrophilous clonal species. Although species-rich and of high complementary value on a landscape scale, haylands mown at low frequency are at higher risk of invasion by clonal species.

Agricultural Land Use and Biodiversity in the Alps

Alpine grasslands are ecosystems with a great diversity of plant species. However, little is known about other levels of biodiversity, such as landscape diversity, diversity of biological interactions of plants with herbivores or fungal pathogens, and genetic diversity. We therefore explored natural and anthropogenic determinants of grassland biodiversity at several levels of biological integration, from the genetic to the landscape level in the Swiss Alps. Differences between cultural traditions (Romanic, Germanic, and Walser) turned out to still affect land use diversity and thus landscape diversity. Increasing land use diversity, in turn, increased plant species diversity per village. However, recent land use changes have reduced this diversity. Within grassland parcels, plant species diversity was higher on unfertilized mown grasslands than on fertilized or grazed ones. Most individual plants were affected by herbivores and fungal leaf pathogens, reflecting that parcels harbored a great diversity of herbivores and pathogens. However, as plant damage by herbivores and pathogens was not severe, conserving these biological interactions among plants is hardly compromising agricultural goals. A common-garden experiment revealed genetic differentiation of the important fodder grass Poa alpina between mown and grazed sites, suggesting adaptation. Pervillage genetic diversity of Poa alpina was greater in villages with higher land use diversity, analogous to the higher plant species diversity there. Overall, landscape diversity and biodiversity within grassland parcels are currently declining. As this contradicts the intention of Swiss law and international agreements, financial incentives need to be re-allocated and should focus on promoting high biodiversity at the local and the landscape level. At the same time, this will benefit landscape attractiveness for tourists and help preserve a precious cultural heritage in the Swiss Alps.

The Effect of Fertilizer Type and Level of N Fertilization Before and After Grassland Renewal on N Leaching Losses

AbstractWhen grassland is ploughed and reseeded this results in an increased mineralization of organically bound nitrogen (N) in the soil. Greater amounts of nitrate in autumn are at risk of being leached during the winter half of the year. In two field experiments, nitrate leaching was measured over 2 years after reseeding of a 9‐year‐old grassland field in spring on a sandy soil in northwest Germany. During the experiments, major management factors that can influence the intensity of mineralization were varied: Type of fertilizer, mineral N fertilizer or organic manure, and the level of fertilization, 0, 160 or 320 kg N ha−1 a−1, before renewal of the grassland, and level of fertilization, 0, 160 or 320 kg N ha−1 a−1 in mineral form, after renewal of the grassland. The type of fertilization as well as the level of N fertilization before ploughing had no significant effect on the soil mineral nitrogen content (SMN) in autumn and N leaching in the year following the grassland renewal. N fertilizer level after sward renovation had a significant effect on the nitrate leaching losses in the two following years. Fertilization at a rate of 320 kg N ha−1 resulted in leaching losses of 7 and 61 kg N ha−1 in the first and second subsequent years, respectively. At fertilizer rates of 0 and 160 kg N ha−1 leaching losses were lower than 5 kg N ha−1. It is concluded that for mown grassland no restriction of the N fertilization before the renovation of the sward is necessary to reduce the nitrate leaching risk as long as the amount of N fertilized does not exceed the N‐uptake by the crop. Similarly, the N fertilization after the sward renewal does not bear a particular leaching risk.

Influence of different vegetation types on saturated hydraulic conductivity in alluvial topsoils

In the Pariž creek catchment (southwestern part of Slovakia), the influence of different vegetation types on selected soil properties in alluvial topsoils was studied. Specifically, the effect on saturated hydraulic conductivity considered as indicator of water transport process and the effect on soil bulk density considered as indicator of soil structure were analysed. Due to the mutual influence of plant roots on soil properties, the root biomass was also estimated and its relationship to the studied soil properties was explored. Reed and tall-sedge wetlands and alluvial wet meadows represented the studied vegetation types. Adjacent arable lands (former grasslands) with corn were included for comparison. In total, 64 samples were used for comparative analysis. A standard methodology for measurement of the saturated hydraulic conductivity, the so-called falling head technique was used on 250 cm3 soil cores. Undisturbed soil samples were taken from the depth of 5 cm. Analysis of variance, mutual comparison of mean values and correlation matrix were used for statistical analyses. Measurements showed significantly higher values of saturated hydraulic conductivity for topsoils in wetlands (6.2 m day−1 on average) compared to mown grasslands (1.47 m day−1) and arable land (0.79 m day−1). The results indicated a specific significance of wetlands in relation to water transport processes in alluvial topsoils.

Variation in organic‐carbon concentration and bulk density in Flemish grassland soils

AbstractThe different management regimes on grassland soils were examined to determine the possibilities for improved and/or changed land management of grasslands in Flanders (Belgium), with respect to article 3.4 of the Kyoto Protocol. Grassland soils were sampled for soil organic carbon (SOC) and for bulk density.For all grasslands under agricultural use, grazing and mowing + grazing led to higher SOC stocks compared with mowing, and grazing had higher SOC stocks compared with mowing + grazing. Overall, 15.1 ± 4.9 kg OC m–2 for the clayey texture, 9.8 ± 3.0 kg OC m–2 for the silty texture, and 11.8 ± 3.8 kg OC m–2 for the sandy texture were found for grassland under agricultural use to a depth of 60 cm. For seminatural grasslands, different results were found. For both the clayey and silty texture, mowing and mowing + grazing led to higher SOC stocks compared with grazing. The clayey texture had a mean stock of 15.1 ± 6.6, the silty texture of 10.9 ± 3.0, and the sandy texture of 12.1 ± 3.9 kg OC m–2 (0–60 cm). Lower bulk densities were found under grazed agricultural grassland compared with mown grassland but for seminatural grassland, no clear trends for the bulk density were found. The best management option for maintaining or enhancing SOC stocks in agricultural grassland soils may be permanent grazed grassland. For seminatural grassland, no clear conclusions could be made. The water status of the sampled mown fields was influencing the results for the clayey texture.Overall, the mean SOC stock was decreasing in the order clay > sand > silt. The higher mean SOC concentrations found for the sandy texture, compared to the finer silty texture, may be explained by the historical land use of these soils.

Bi‐directional soil/atmosphere N2O exchange over two mown grassland systems with contrasting management practices

AbstractNitrous oxide (N2O) fluxes from soil under mown grassland were monitored using static chambers over three growing seasons in intensively and extensively managed systems in Central Switzerland. Emissions were largest following the application of mineral (NH4NO3) fertilizer, but there were also substantial emissions following cattle slurry application, after grass cuts and during the thawing of frozen soil. Continuous flux sampling, using automatic chambers, showed marked diurnal patterns in N2O fluxes during emission peaks, with highest values in the afternoon. Net uptake fluxes of N2O and subambient N2O concentrations in soil open pore space were frequently measured on both fields. Flux integration over 2.5 years yields a cumulated emission of +4.7 kgN2O‐N ha−1 for the intensively managed field, equivalent to an average emission factor of 1.1%, and a small net sink activity of −0.4 kg N2O‐N ha−1 for the unfertilized system. The data suggest the existence of a consumption mechanism for N2O in dry, areated soil conditions, which cannot be explained by conventional anaerobic denitrification. The effect of fertilization on greenhouse gas budgets of grassland at the ecosystem level is discussed.

Nitrogen Use Efficiency and Herbage Production of an Established Grass Sward in Relation to Moisture and Nitrogen Fertilization

ABSTRACT Herbage growth and nitrogen (N) use efficiency in grazed or mown grasslands are generally low, associated mostly with poor response to fertilizer N. The aim of the present investigation was to examine the short-term response of grass to fertilizer N with respect to herbage yield and nitrogen use efficiency (NUE) in order to provide a better basis for improving the efficient use of fertilizer N in grassland ecosystems. Both NO3 − and NH4 + sources of N were applied to an established grass sward with three moisture levels, i.e., natural conditions (63% water-filled pore space, WFPS), near field capacity level (71% WFPS), and slightly wetter than field capacity (84% WFPS). Herbage yield, i.e., dry matter (DM), N uptake, N recovery efficiency, yield efficiency, and physiological efficiency were determined over a 7–28 d period. Addition of N fertilizers significantly increased the herbage yield and N uptake of grass sward over that of the control. In the plots where NO3 −−N was added as the N source, DM yield was between 1760–1870 kg ha−1, N recovery efficiency was between 24%–43%, and yield and physiological efficiency were in the range of 2.1–3.2 and 6.4–8.8 kg DM kg− 1 N, respectively. In NH4 +−N added plots, the DM yield was between 3190–3700 kg ha− 1, N recovery efficiency was between 39%–48% while yield and physiological efficiency were in the range of 3.5–5.6 and 9.0–11.6 kg DM kg− 1 N, respectively. Results indicated that total DM yield, N uptake, and NUE depend on the source of N and the level of moisture in the field. Assimilation of N is also affected by the stage of plant development after N fertilization. About 50%–54% of applied N was recovered in the initial 14 and 21 d after fertilizer application and thereafter translocation of N slowed. A fall in herbage production and minimal response to N fertilizer has been observed at 84% WFPS, while the maximum herbage yield and N recovery efficiency was recorded in soil near or below field capacity. The grass sward with added NH4 +−N produced a larger yield and had higher NUE relative to the sward with NO3 −−N. Results confirm that applied N was not utilized efficiently by grass sward and a decrease in N uptake and its utilization seem to be the key factors responsible for the poor herbage productivity often observed in pastoral agriculture. These results suggest that both moisture and N source have a substantial effect on herbage yield and N utilization by plants and therefore should be considered for efficient management of N fertilization and recommendations for grass sward.

Are ecological compensation areas attractive hunting sites for common kestrels (Falco tinnunculus) and long-eared owls (Asio otus)?

Common kestrels (Falco tinnunculus) and long-eared owls (Asio otus) in intensively farmed areas in Switzerland decreased markedly as a result of declining vole (Microtus spp.) populations. In order to counteract the loss of biodiversity in intensively farmed areas, the Swiss agri-environment scheme stipulates several types of ecological compensation areas, which together should take up 7% of the farmland. Among them are wild flower and herbaceous strips, which are not mown every year and which in summer support up to 8 times more small mammals than ordinary fields and grassland. This study investigates whether kestrels and long-eared owls preferentially hunt on ecological compensation areas and whether preferred hunting areas are related to the density of small mammals or to the density and height of the vegetation. Both kestrels and long-eared owls mainly hunted on freshly mown low-intensity meadows and artificial grassland, despite low densities of small mammals. Therefore, vegetation structure was more important for the selection of hunting sites than prey abundance. However, both predators preferred to hunt on freshly mown grassland and meadows bordering a wild flower or herbaceous strip. Voles from these strips probably invaded the adjacent freshly mown grassland and became an easy prey for kestrels and owls. In intensively farmed regions, ecological compensation areas, particularly those not mown each year, are an important refuge for small mammals, although in summer the small mammals are not directly accessible to hunting birds. Hence, a mosaic of different habitat types with grassland mown at different times of the year together with undisturbed strips is best suited to provide a year-round supply of accessible food for vole hunters.

Small-scale guild proportions and niche complementarity in a Caucasian subalpine hay meadow

Abstract Question: Monocot and dicot perennial herbaceous species can be considered two a priori guilds, which interact in regularly mown grasslands. Complementary resource use in space is important for diversity and productivity of perennial herbaceous communities, yet small-scale spatial patterns of guilds and niche complementarity have rarely been linked explicitly. We ask: 1. Do guild interactions in our community generate small-scale patterns such as guild proportionality? 2. Do these patterns coincide with overyielding of guilds, that is, can small-scale spatial patterns of guilds be experimentally linked to niche complementarity? Location: Georgia, central Caucasian mountains. Methods: We sampled randomly placed small quadrats and used presence-absence data to measure small-scale spatial patterns within plots. We experimentally tested overyielding of monocots and dicots grown separately and in mixtures. Results: We found measurable small-scale pattern of guilds in our community: monocots and dicots showed significant guild proportionality. However, variance deficit in the number of species per small quadrat was stronger in monocots than in dicots. Experiments found considerable overyielding, which was unaffected by water stress. Conclusions: Coincidence of measurable small-scale arrangements of guilds with robust overyielding indicates that spatial arrangement is an important manifestation of niche complementarity. Stronger variance deficit of monocot species at small scale suggests that monocots compete with each other more strongly and, as a consequence, are more regularly dispersed at small spatial scale. Conversely, morphologically more diverse and more plastic dicots may more easily fit within the neighbourhood patchwork created by monocots.

Nitrous oxide emission from temperate meadow grassland and emission estimation for temperate grassland of China

Nitrous oxide emission from temperate meadow grassland was measured using a closed chamber method at two experimental sites in China. In the four-month measurement period, the N O fluxes in mown meadow grasslands 2 22 21 of the Songnen Plain and of the Kerqin Steppe were on average 41.1 and 7.9 mg N O-N m h , respectively. 2 Considering the influence of grassland type and degradation extent, an empirical formula was constructed, with which the annual N O emission from temperate grassland of China was estimated as 40.4 Gg N. Meadow 2 grassland, accounting for 14.0% of the total grassland area, contributed 28.4% of the total N O emission. 2

Process-based modelling of nitrous oxide emissions from different nitrogen sources in mown grassland

The process-based Pasture Simulation Model (PaSim 2.5) has been extended to simulate N2O production and emission from grassland caused by nitrogen inputs from different sources. The model was used to assess the influence of management on N2O emissions, such as the effect of shifts in the amount and timing of fertilizer application. Model performance has been tested against season-long field measurements at two different field sites. Simulation results agreed favourably with measured N2O emission and soil air concentrations, except during an extremely wet period at one site when grass growth was very poor. The results of short-term and long-term simulation runs demonstrated the potential of the model to estimate N2O emission factors under various conditions. During the first growing season, simulated emissions from organic fertilizers were lower than from synthetic fertilizers because more of the nitrogen was used to build up soil organic matter. The relative difference between the fertilizer types became larger with increasing application rate. The difference between fertilizer types was smaller at steady-state when higher soil organic matter content from repeated application of organic fertilizer over time led to enhanced mineralization and N2O emissions. The dependence of simulated N2O emissions on N input was close to linear at low, but non-linear at high fertilization rates. Emission factors calculated from the linear part of the curve suggested that the factors used in the current IPCC method underestimate the long-term effects of changes in fertilizer management. Furthermore the simulations show that N2O emissions caused by nitrogen inputs from the decomposition of harvest losses and from biological fixation in grassland can be considerable and should not be neglected in national emission inventories.