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A field experiment with maize for silage was conducted to assess the effects of mineral nitrogen (N) fertilizer application rates (0, 50, 100, 150 kg ha⁻¹), slurry application rates (0, 20, 40 m³ ha⁻¹) and the use of an understorey with perennial ryegrass on nitrate (NO₃)-leaching losses. Leachate was collected using ceramic suction cups. Soil mineral N (SMN) was determined to a depth of 90 cm at the end of the growing season. Higher levels of N supply with mineral fertilizer or slurry resulted in higher leaching losses. The grass understorey significantly reduced the losses. The amount of N lost to the groundwater was positively related to SMN at the end of the growing season, with leaching losses representing less than 0·45 of SMN on average. Leaching losses were positively related to the N surplus, which was calculated from the difference between N input (N from fertilizer, slurry and atmospheric deposition) and N output (N removed with maize herbage mass and bound in the understorey biomass in spring). In view of the large variation in weather conditions between the experimental years, it is suggested that for the sandy soils in this experiment N-leaching losses under maize can be estimated satisfactorily from SMN and the calculated N surplus.

A field experiment was conducted from 1998 to 2001 to measure the performance and environmental effects of a maize crop (Zea mais L.) in a continuous production system with and without a grass understorey (Lolium perenne L.), with varied N inputs. The experiment was located on a sandy soil in northern Germany and comprised all combinations of slurry application rate (0, 20, 40 m 3 ha )1 ) and mineral N fertilizer (0, 50, 100, 150 kg N ha )1 ). Understorey treatments included maize with and without perennial ryegrass. Net energy (NEL) yield of maize increased with mineral N application rate but reached a plateau at high rates. Increase in yield of dry matter because of mineral N fertilizer was lower with increased slurry application rate. Neither slurry and mineral N application nor a grass understorey affected NEL concentration of maize, whereas crude protein (CP) concentration increased with increase in application of slurry and mineral N fertilizer. Nitrogen supply by slurry or mineral fertilizer had no effect on the amount of N in the grass understorey after the harvest of maize. The average amount of N bound annually in the understorey was 60 kg N ha )1 . The reduced biomass of the understorey because of enhanced maize competition was compensated for by an increased CP concentration in the grass. The grass understorey affected the NEL yield of maize negatively only at very low levels of N input but increased the N surplus at all levels.

Nitrogen (N) fertilizer application and grazing are known to induce nitrous oxide (N2O) emissions from grassland soils. In a field study, general information on rates of N2O emission, the effect of cattle grazing and the type (mineral fertilizer, cattle slurry) and amount of N supply on the flux of N2O from a sandy soil were investigated. N2O emissions from permanent grassland managed as a mixed system (two cuts followed by two grazing cycles) were monitored over 11 months during 2001–2002 in northern Germany using the closed chamber method. The field experiment consisted of four regionally relevant fertilizer combinations, i.e. two mineral N application rates (0 and 100 kg N ha−1 yr−1) and two slurry levels (0 and 74 kg N ha−1 yr−1). Mean cumulative N2O-N loss was 3.0 kg ha−1 yr−1, and the cumulative 15N-labelled N2O emissions varied from 0.03% to 0.19% of the 15N applied. 15N labelling indicated that more N2O was emitted from mineral N than from slurry treated plots, and in all treatments the soil N pool was always clearly the major source of N2O. Regarding the total cumulative N2O losses, differences among treatments were not significant, which was caused by: (i) a high variance in emissions during and after cattle grazing due to the random distribution of excrements and by (ii) high N2 fixation of white clover in the 0 kg N ha−1 treatments, which resulted in similar N status of all treatments. However before grazing started, treatments showed significant differences. After cattle grazing in summer, N2O emission rates were higher than around the time of spring fertilizer application, or in winter. Grazing resulted in N2O flux rates up to 489 μg N2O-N m−2 h−1 and the grazing period contributed 31–57% to the cumulative N2O emission. During freeze–thaw cycles in winter (December–February) N2O emission rates of up to 147 μg N2O-N m−2 h−1 were measured, which contributed up to 26% to the annual N2O flux. The results suggest that N fertilizer application and grazing caused only short-term increases of N2O flux rates whereas the major share of annual N2O emission emitted from the soil N pool. The significantly increased N2O fluxes during freeze–thaw cycles show the importance of emission events in winter which need to be covered by measurements for obtaining reliable estimates of annual N2O emissions.

Sward composition and structure influence herbage intake of grazing animals. We conducted a grazing study to examine how forage mixture complexity affected sward structure. Replicated 1-ha pastures (Hagerstown silt loam soil: fine, mixed, semiactive, mesic, Typic Hapludalf) were planted to either orchardgrass (Dactylis glomerata L.) and white clover (Trifolium repens L.) or a nine-species mixture [orchardgrass, tall fescue (Festuca arundinacea Schreb.), perennial ryegrass (Lolium perenne L.), Kentucky bluegrass (Poa pratensis L.), red clover (Trifolium pratense L.), birdsfoot trefoil (Lotus comiculatiis L.), white clover, alfalfa (Medicago sativa L.), and chicory (Cichorium intybus L.)]. Pastures were stocked rotationally with lactating dairy cows (Bos taurus). Herbage mass, sward height, vertical structure, and nutritive value were measured pre- and postgrazing during four periods in each of 2002 and 2003. Pregrazing sward height was similar between the mixtures. Pregrazing herbage mass and sward bulk density were 30% less in the two-spedes mixture than the nine-species mixture in 2002 but similar in 2003. The nine-species mixture had more herbage dry matter in the upper sward layers than the two-species mixture. Bulk density of herbage dry matter increased and nutritive value decreased from the top to the bottom of both swards. Cattle grazed deeper into the two-species sward (18 cm) than the nine-species mixture (11 cm) in 2003; however, individual botanical components in the upper 25 cm of the canopy were removed similarly between treatments. We conclude that sward structure did not alter the pattern of herbage removal during grazing of simple or complex swards.

After implementation of legislative measures for the reduction of environmental hazards from nitrate leaching and ammonia volatilisation when using organic manures and fertilizers in Europe, much attention is now paid to the specific effects of these fertilizers on the dynamics of global warming-relevant trace gases in soil. Particularly nitrogen fertilizers and slurry from animal husbandry are known to play a key role for the CH4 and N2O fluxes from soils. Here we report on a short-term evaluation of trace gas fluxes in grassland as affected by single or combined application of mineral fertilizer and organic manure in early spring. Methane fluxes were characterised by a short methane emission event immediately after application of cattle slurry. Within the same day methane fluxes returned to negative, and on average over the 4-day period after slurry application, only a small but insignificant trend to reduced methane oxidation was found. Nitrous oxide emissions showed a pronounced effect of combined slurry and mineral fertilizer application. In particular fresh cattle slurry combined with calcium ammonium nitrate (CAN) mineral fertilizer induced an increase in mean N2O flux during the first 4 days after application from 10 to 300 μg N2O–N m−2 h−1. 15N analysis of emitted N2O from 15N-labelled fertilizer or manure indicated that easily decomposable slurry C compounds induced a pronounced promotion of N2O–N emission derived from mineral CAN fertilizer. Fluxes after application of either mineral fertilizer or slurry alone showed an increase of less than 5-fold. The NOx sink strength of the soil was in the range of −6 to −10 μg NOx–N m−2 h−1 and after fertilization it showed a tendency to be reduced by no more than 2 μg NOx–N m−2 h−1, which was a result of both, increased NO emission and slightly increased NO2 deposition. Associated determination of the N2O:N2 emission ratio revealed that after mineral N application (CAN) a large proportion (c. 50%) was emitted as N2O, while after application of slurry with easily decomposable C and predominantly NH 4 + –N serving as N-source, the N2O:N2 emission ratio was 1:14, i.e. was changed in favour of N2. Our work provides evidence that particularly the combination of slurry and nitrate-containing N fertilizers gives rise to considerable N2O emissions from mineral fertilizer N pool.

Nitrogen (N) leaching under grazed pastures can be very high directly under urine spots. The amount of N which is returned by one excretion of urine or dung can locally exceed 1000 kg ha−1 a−1 which is far more than the uptake by surrounding plants during one grazing period. We therefore quantified the contribution of N deriving from urine and dung to the total N leaching under urine and dung patches. Dung N and urine N was separately sampled from a cow feed with 15N labelled grassilage, and were amended on lysimeters in October 2000 and October 2001. Lysimeters (350 mm diameter and 800 mm length) were filled with sand, and an intact grass sod from a pasture, 4 lysimeter each were amended with the 15N labelled dung and urine; 4 lysimeters without an application of dung or urine served as control. During 11 months after dung and urine amendment the amount of leachate was monitored and leachate was analysed for nitrate, ammonium and total N. 15N in these fractions was measured. Dung and urine applications of 1052 and 1030 kg N ha−1 in autumn increased N leaching. Leaching loss of nitrate and dissolved organic N deriving from dung was only 37 kg N ha−1 in both years, whereas under urine patches 447 kg nitrate-N ha−1, 108 kg N ha−1 ammonia-N and 53 kg ha−1 dissolved organic N leached on average of both experimental years. N not deriving from dung and urine exceeded the leached N under the control by about 36 and 136 kg ha−1 on average of both years, suggesting the contribution of different priming processes.

Grassland and its management is central to the productivity of and nitrogen (N) losses from dairy farms in north-west Europe. Botanical composition, production and N surplus of grassland were assessed during five consecutive years. The experiment consisted of all combinations of five defoliation systems: cutting-only (CO), rotational grazing (GO), grazing + one (MSI) or two silage cuts (MSII) and simulated grazing (SG). Four mineral N fertilization rates (0–300 kg N ha−1 year−1) and two slurry levels (0 and 20 m3 slurry ha−1 year−1) were applied. Fertilizer N was more efficient in producing net energy (NEL) in grazing-dominated, low white clover systems (GO and MSI systems: 70 and 88 MJ NEL kg−1 N) than in white clover-rich systems (MSII, CO and SG systems: ≤60 MJ NEL kg−1 N). While sward productivity in system MSI was similar to that in system GO, system MSII benefited from increased N2 fixation at low N rates. There were small differences in NEL concentrations of the herbage between defoliation systems. Crude protein concentration of the herbage increased with increasing N supply from fertilizer, excreta and N2 fixation. N surpluses (−63 to +369 kg N ha−1 year−1) increased with increasing grazing intensity and increasing N fertilization rate. The average response in N surplus applied was 0·81, 0·59, 0·40, 0·33 and 0·24 kg N ha−1 in systems GO, MSI, MSII, CO and SG respectively.

Based on experimental data gathered in a research project on nitrogen fluxes in intensive dairy farming in Northern Germany, an analysis of fossil energy input and energy efficiency in forage production from permanent grassland and maize for silage was conducted. Field experiments comprised different defoliation systems and different rates of mineral N fertilizer and slurry application. Each change from grazing to cutting in grassland systems reduced the energy efficiency. Energy efficiency consistently decreased with increasing rates of mineral N application. In the production of maize for silage, maximum energy efficiency was obtained with an application of 50 kg N ha−1 from slurry only. Net energy yields of maize for silage were much higher than that of grassland when compared at the same level of fossil energy and nitrogen fertilizer input. Considering both nitrate-leaching losses and a necessary minimum quantity of grass herbage in a well-balanced ration, it is suggested that a high proportion of maize for silage in combination with N-unfertilized grass/clover swards used in a mixed cutting/grazing system represents a good trade-off between the leaching of nitrates and energy efficiency.

The aim of this work was to assess the ability of near-infrared reflectance spectroscopy (NIRS) to be a rapid and reliable method for estimating quality variables for forage maize with an extremely wide range of maturity and growth stage, as it occurs, e.g. in experiments dealing with growth analysis. For maximum variability samples for analysis were collected over 4 years from field trials which comprised a wide range of nitrogen (N) fertiliser (0–150 kg N ha −1 ) and slurry application (0, 20 and 40 m 3 ha −1 ) treatments, but one maize variety named Naxos. Phenological variability was obtained by sampling in intervals of 14 days during growth of maize. A total of 6296 samples was collected and 398 samples were selected to calibrate estimated net energy and crude protein contents and validate the equations derived. To increase accuracy separate calibrations were developed for reproductive and vegetative fractions of maize. For both groups NIRS equations were scrutinized by a set of validation samples which were selected from the same sample pool before the samples for calibration were chosen. Predictions of crude protein and net energy contents over a wide range of plant maturity showed satisfactory accuracy. Standard error of prediction was below 0.3 MJ NEL kg DM −1 for energy value and below 123 g kg −1 of dry matter (DM) for crude protein. In the course of 4 years the number of necessary samples to be included in the calibration decreased to between 2.6 and 15% of sample number in the first year and the validity of the equation increased.

Grass from municipal roadside verges is a potential yet largely unused resource for bioenergy recovery, which is mainly due to its unknown elemental composition. Therefore, we measured the concentration of 16 elements (Ca, K, Mg, N, Na, P, S, Al, Cd, Cl, Cr, Cu, Mn, Pb, Si and Zn) in a material from the city of Kassel harvested in different management intensities. The element concentrations were mainly close to reference values of agricultural or nature conservation grassland and usually within the range of literature data. Concentrations of most elements, including heavy metals, were below limiting values. Only N and Cl concentrations in the raw material exceeded the limiting values for combustion, but washing and dewatering of the biomass with the "integrated generation of solid fuel and biogas from biomass" technique resulted in concentrations in the press cake well below the limiting values. Considering the element concentrations of grass from urban roadside verges, utilisation for energy recovery may be possible, provided an appropriate technology is applied.

International audience; A common experimental protocol was followed at 12 sites in Europe to study the development of two clover cultivars (AberHerald and Huia) grown in association with a ryegrass cultivar throughout their annual cycle. The duration of the experiment was between 1 and 3 years at each site. Detailed information about the morphogenesis and carbohydrate reserves of white clover during winter and the subsequent productivity of clover plants during the growing season was collected. Yield of the companion ryegrass was also measured at several harvests during the growing season and grass tiller density was recorded several Limes during winter, There was wide variation among sites and between years in climatic conditions, in the growth characteristics and chemical composition of the two cultivars, and in the tiller density of the ryegrass. The relative performance of the two cultivars varied among sites but AberHerald generally outperformed Huia, Major changes in plant characteristics (morphology, population size. chemical composition, etc,) occurred during overwintering. This paper presents a preliminary analysis of the effects of site. clover cultivar and sward age (years) on various plant characteristics. It is established that the data provide a unique basis for modelling the effects of a wide range of environmental conditions and plant properties on the performance of white clover in mixed swards. A modelling approach that seeks to replace site and year by climatic variables characterizing each site by year combination is developed in two companion papers.

Data on the development of two white clover cultivars (AberHerald and Huia) in mixed clover/ryegrass swards were available at 12 sites in Europe from experiments conducted for several years under a common protocol. Swards were measured up to seven times over winter and up to seven times over the growing season. In the overwintering period, detailed morphological measurements were taken for clover at each sampling time and, during the growing season, the clover contribution to total available biomass was recorded. Detailed meteorological data were available at all sites. The development of these clover/ryegrass communities over time and sites was modelled. The modelling strategy had three main elements: (a) division of the annual growth cycle of the clover/ryegrass community into a number of functional periods; (b) development of relationships within each functional period using models incorporating plotlevel biotic variables characterizing each community at the start of the period and site-level climatic and management variables measured during the period; and (c) introduction of a dynamic element by linking the models across functional periods. The response variable(s) for a functional period was the biotic independent variable(s) of the succeeding period. The object was to produce a dynamic series of models in which community development within and across sites was described as a resultant of the initial state of the community and climatic and other forces acting on it. The analysis used a mixed models technique in recognition of the complex error structure of the data. Various statistical aspects of the modelling are discussed including the models and fitting strategy used, the complexity of the error structure in an experiment that includes sites and years, and the desirability of transforming certain variables before modelling. The issues in presenting the results of a series of complex models are discussed and a graphical/ tabular approach is outlined. © 2001 Annals of Botany Company

The share of electricity produced from renewable energy is constantly increasing in Germany and worldwide. The transformation to an electricity system based on renewable sources is characterised by an increasing need for balancing power in order to compensate power supply from fluctuating sources, such as solar or wind. Biomass, more precisely energy from biogas, has the potential to generate electricity flexible on-demand. A demand-driven biogas production is vital for balancing power generation and can generally be achieved by biogas storing or flexible biogas production concepts. This study analyses and reviews both concepts regarding their ability to facilitate a biogas supply for short-term and long-term balancing power generation. Results show that a demand-driven biogas supply based on a biogas storing concept is, due to the fast availability of biogas (i.e. biomethane), suitable for the generation of positive secondary and tertiary balancing power. Whereas, long-term balancing power can be provided by flexible biogas production as well as by biomethane, which was injected and stored in the natural gas grid. Basically all reviewed biogas supply concepts that facilitate a shutdown of electricity generation by storing or stopping the biogas production can additionally provide negative balancing power.

The integrated generation of solid fuel and biogas from biomass (IFBB) is particularly designed for the conversion of semi-natural and high biodiversity grassland biomass into energy. This biomass is problematic in common energy conversion techniques, e.g. biogas conversion or combustion, because of its chemical composition. The IFFB process separates the material into a fibre rich solid fuel and a fluid, which is rich in minerals and highly digestible constituents and is used for anaerobic digestion. Biomasses from 18 European semi-natural grassland sites have been processed in an IFBB prototype. The impact of different chemical and botanical parameters on mass flow of mineral plant compounds and their concentrations in the fuel has been investigated. Fuel quality was significantly influenced by chemical and botanical parameters and the quality could be significantly improved during processing. Biomass with a high grass proportion and fibre content showed the best fuel qualities after IFBB treatment.

The study aimed at the identification of favourable land use options for semi-natural grassland management and preservation. Economic assessments of energy recovery by the integrated generation of solid fuel and biogas from biomass (IFBB) in comparison with dry fermentation (DF) and hay combustion systems (HC), beef cattle production (BC) and non-refining landscape preservation measures, such as mulching (MU) and composting (CO), were carried out in this study. Energy recovery systems made profitable use of semi-natural grasslands with the highest economic returns attained by IFBB-AO (Return On Investment, ROI: 22.75%) and HC (ROI: 22.00%) systems, followed by the IFBB-SA (ROI: 7.71%) and the DF system (ROI: 6.22%). Animal husbandry (BC) and non-refining management systems (MU, CO) were not profitable considering the current framework conditions. Input parameters critical for profitability were modified in order to identify influences of changing framework conditions.

The study aimed at the identification of favourable land use options for semi-natural grassland management and preservation. Economic assessments of energy recovery by the integrated generation of solid fuel and biogas from biomass (IFBB) in comparison with dry fermentation (DF) and hay combustion systems (HC), beef cattle production (BC) and non-refining landscape preservation measures, such as mulching (MU) and composting (CO), were carried out in this study. Energy recovery systems made profitable use of semi-natural grasslands with the highest economic returns attained by IFBB-AO (Return On Investment, ROI: 22.75%) and HC (ROI: 22.00%) systems, followed by the IFBB-SA (ROI: 7.71%) and the DF system (ROI: 6.22%). Animal husbandry (BC) and non-refining management systems (MU, CO) were not profitable considering the current framework conditions. Input parameters critical for profitability were modified in order to identify influences of changing framework conditions.

Green cut material is a potential source of renewable energy which is not fully exploited through conventional energy recovery systems. A new energy conversion process, the integrated generation of solid fuel and biogas from biomass (IFBB), which includes mechanical separation after hydro-thermal conditioning, was investigated. Ash softening temperature and lower heating value of the solid fuel were increased through the IFFB process in comparison to the untreated raw material. The net energy yield of IFBB at 40 °C conditioning temperature ranged between 1.96 and 2.85 kWh kg−1 dry matter (DM) and for the direct combustion between 1.75 and 2.65 kWh kg−1 DM. Conversion efficiencies for the IFBB system were 0.42–0.68 and for direct combustion 0.42–0.63. The IFBB system produces storable energy from material which is nowadays not used for energy conversion.

Grassland agriculture is an important industry for livestock production and land management throughout the world. We review the principles of nutrient cycling in grassland agriculture, discuss examples of grassland farming systems research, and demonstrate the usefulness of whole-farm simulation for integrating economic and environmental components. Comprehensive studies conducted at the Karkendamm experimental farm in northern Germany and the De Marke experimental farm in the Netherlands have quantified nutrient flows and developed innovative strategies to reduce nutrient losses in grassland farming systems. This research has focused on improving the utilization of manure nutrients on the farm by including grain crops in cropping systems with grassland and by incorporating manure handling techniques that reduce nitrogen losses. Although the information generated in experimental farms is not always directly applicable to other climates and soils, it is being transferred to other regions through computer simulation. A whole-farm model calibrated and verified with the experimental farm data is being used to evaluate and refine these strategies for commercial farms in other areas. Simulation of farms in northern Europe illustrate that on the sandy soils of this region, maize (Zea mays L.) silage can be used along with grasslands to increase farm profitability while maintaining or reducing nutrient loss to the environment. Use of cover crops, low emission barns, covered manure storages, and direct injection of manure into soil greatly reduces N losses from these farms, but their use creates a net cost to the producer. By integrating experimental farm data with whole-farm simulation, more sustainable grassland production systems can be cost-effectively evaluated, refined, and transferred to commercial production.

The effects of grazing regime (cattle, sheep and mixed cattle + sheep) on white clover content (clover dry matter as a percentage of total dry matter) were measured in a permanent pasture over a 7 year period in the west of Ireland (53°17′N 8°47′E). Rotational grazing was simulated by grazing for short intense periods of 3–4 d at 3 to 5 week intervals. In general, cattle grazing resulted in higher clover content (13.5%) compared with mixed (9.5%) or sheep (4.9%) grazing. The ranking of clover contents (cattle > mixed > sheep) which developed rapidly in 1990 persisted until 1996. Clover contents under mixed grazing tracked those under cattle grazing during the first 4 years, and sheep grazing during the final 3 years. Within-year relativities in clover content among grazing regimes that existed at the start of the grazing season persisted throughout the year. There was an indication that differences in clover content between grazing regimes at the end of grazing persisted until the following spring. A regression analysis of clover content in each grazing period showed strong effects of grazing regime, generally positive relationships with mean air temperature in the period and clover content in the preceding period, and an interaction between air temperature and clover content in the previous period. Implications for pasture management and experimentation are discussed.

International audience; In attempting to increase the reliability of clover contribution in clove/ryegrass systems it is important to understand the roles of (1) specific traits of the clover genotype (2) climate and (3) their interactions in determining clover behaviour in swards. Overwintering and spring growth of white clover (cultivars AberHerald and Huia) grown in binary mixtures with perennial ryegrass were measured at 12 European sites ranging in latitude from Reykjavik, Iceland (64 degrees 30' N) to Pordenone, Italy (46 degrees 30' N). In the overwintering period, tiller density of the grass was assessed and detailed morphological and chemical measurements were made on the clover at each sampling time. During the growing season, the clover contribution to total available biomass was recorded, Detailed climatic data were available at all sites. The annual growth cycle of swards was divided into four functional periods (spring, summer, autumn and winter). Within each functional period community responses were modelled. The models incorporated independent biotic variables characterizing each community within each site at the start of the period and independent variables characterizing the climate at each site during the period. The models were linked dynamically by taking, as response variable(s) for a functional period. the independent biotic variable(s) of the succeeding period. In general, the modelling strategy was successful in producing a series of biologically meaningful linked models. Essential prerequisites for this were (a) the establishment of a well-devised common protocol prior to the experiment and (b) the extensive gradients of climatic and other variables obtained by using numerous sites, AberHerald generally performed as well as. or better than, Hula throughout the annual cycle across the range of climatic conditions encountered, and especially under low temperature conditions in winter and autumn. Clover leaf area index appeared to be a key variable in determining clover performance over winter and through the following growing season. Grass tiller density had a strong negative effect on clover content in spring but only at low temperatures, This emphasizes the importance of a high clover leaf area index in autumn as the main biotic factor related to spring clover content in milder conditions. The importance of climatic variables in the models is their use in explaining the reliability of the contribution of clover in clover,: ryegrass systems. Temperature was the primary climatic determinant of clover response in all periods, having a direct effect on clover content and leaf area index or mediating the effect of the associate species. Radiation strongly influenced Clover dynamics during winter and spring but not in the other periods, possibly because it was confounded with the effect of higher temperature. Precipitation was positively related to clover growth during spring and autumn and was related to tiller density in a complex manner during autumn and winter.

A field experiment was conducted over a 4-year period to determine NO3 leaching losses from grassland on a freely draining sandy soil. The experiment consisted of all combinations of five defoliation systems; cutting-only (CO), rotational grazing (GO), mixed systems with one (MSI) or two silage cuts (MSII) plus subsequent rotational grazing, and simulated grazing (SG), four mineral nitrogen (N) application rates (0, 100, 200, and 300 kg N ha−1 year−1), and two slurry levels (0 and 20 m3 slurry ha−1 year−1). Due to the high N return by grazing animals, leaching losses in the rotational grazing systems generally were associated with NO3-N concentrations which exceeded the EU limit for drinking water. NO3 leaching losses in a rotational grazing system could be reduced by lowering the N fertilizer intensity and the inclusion of one or two silage cuts in spring. However, even in the unfertilized mixed systems, N fixation by white clover exceeded the amounts of N removed via animal products, which resulted in NO3-N concentrations well above the EU limit for drinking water. In terms of leaching losses, the cutting-only system was the most advantageous treatment. NO3 leaching losses on grassland could be predicted by the amount of soil mineral N at the end of the growing season and by the N surplus calculated from N balances at the field scale. From the results obtained a revised nitrogen fertilization policy and a reduced grazing intensity by integrating silage cuts are suggested.

Highlights • Biomass is generated during management of low input high diversity (LIHD) landscapes. • Samples of LIHD biomass were subjected to fast pyrolysis. • Demineralization through washing and pressing was associated with higher oil yields. • Oil yields were within the range following fast pyrolysis of Miscanthus and Willow. • Gross estimates of 4 × 105 tonne per year of oil could be displaced using Welsh LIHD biomass., Waste biomass is generated during the conservation management of semi-natural habitats, and represents an unused resource and potential bioenergy feedstock that does not compete with food production. Thermogravimetric analysis was used to characterise a representative range of biomass generated during conservation management in Wales. Of the biomass types assessed, those dominated by rush (Juncus effuses) and bracken (Pteridium aquilinum) exhibited the highest and lowest volatile compositions respectively and were selected for bench scale conversion via fast pyrolysis. Each biomass type was ensiled and a sub-sample of silage was washed and pressed. Demineralization of conservation biomass through washing and pressing was associated with higher oil yields following fast pyrolysis. The oil yields were within the published range established for the dedicated energy crops miscanthus and willow. In order to examine the potential a multiple output energy system was developed with gross power production estimates following valorisation of the press fluid, char and oil. If used in multi fuel industrial burners the char and oil alone would displace 3.9 × 105 tonnes per year of No. 2 light oil using Welsh biomass from conservation management. Bioenergy and product development using these feedstocks could simultaneously support biodiversity management and displace fossil fuels, thereby reducing GHG emissions. Gross power generation predictions show good potential.