Greenhouse gas emissions (GHG), as well as other gaseous emissions and agronomic variables were continuously measured for three years (2011/2012 – 2014/2015) at eight experimental field sites in Germany. All management activities were consistently documented. The GHG-DB-Thuenen stores these multi-variable data sets of gas fluxes (CO2, N2O, CH4 and NH3), crop parameters (ontogenesis, aboveground biomass, grain and straw yield, N and C content, etc.), soil characteristics (nitrogen content, NH4-N, NO3-N, bulk density etc.), continuously recorded meteorological variables (air and soil temperatures, radiation, precipitation, etc.), management activities (sowing, harvest, soil tillage, fertilization, etc.), and its metadata (methods, further information about variables, etc.). In addition, NOx data were measured and analyzed. Also available are site-specific calculated C and N balances for the respective crops and crop rotations.

A correction to this paper has been published: https://doi.org/10.1007/s10705-021-10138-5

The aim of this study was to quantify site-specific levels of indirect nitrous oxide (N2O) emissions from oilseed rape (OSR) cropping in Germany, resulting from ammonia (NH3) volatilization after organic fertilizer application and nitrate (NO3-) leaching based on measurement in field experiments and additional simulation modelling. In field experiments in three years (2012/13-2014/15) at five sites representing the main OSR growing areas N fertilizer amount and type of fertilizer (mineral N or digestate (DIG)) were varied. NH3 emissions were measured after application of DIG with the Drager Tube Method and dynamics of soil water and soil mineral nitrogen (SMN) were monitored for three years, besides other parameters influencing the N balance like plant growth. A Plant-Soil-Atmosphere-Model (PSAM) was developed from existing components to calculate site-specific N leaching. Furthermore, long term scenario analyses allowed to simulate site-specific N leaching and to analyze the impact of total N input and fertilizer N form on N uptake of OSR and the subsequent N leaching. Results showed site-specific differences in measured NH3 emissions after DIG application ranging from 7.6 to 18.3 % of total applied N representing a lower volatilization level than the IPCC default emission factor of 20 % for organic fertilizers. PSAM was able to reproduce observed dynamics of soil water and SMN, but with site-specific accuracy. N leaching levels varied site-specifically and were dependent on fertilizer amount, fertilizer type and site conditions (weather, soil), but ranged with 5.0-17.6% also considerably below the default value of 30 % N input used by IPCC. Finally, calculated N2O emissions resulting from measured NH3 volatilization was up to 61 % lower than the default value and N2O emissions from determined N leaching levels were 64-89% lower.

Oilseed rape (Brassica napus L.) is the major oil crop in Europe and Germany but its hydrological functioning is poorly understood. Studies on the interception processes in oilseed rape have been lacking until the present. The interception of rainfall by oilseed rape is expected to vary in response to substantial changes in canopy structure throughout the cropping cycle and fertilization treatment. To determine evaporation of intercepted water, field measurements of a winter oilseed rape crop were conducted for different stages of development and five treatments of fertilization (0, 60, 120, 180 and 240 kg N/ha). Precipitation (P) and throughfall (TF) were measured hourly, along with vegetation structure measurements of the leaf area index (LAI). A range of 0-21% for the percentage of stemflow (SF) of P was estimated from soil moisture measurements. For the vegetation period from March to June the cumulative P of 112 mm was converted into 49 mm TF (44%). The inferred evaporation of intercepted water (I) was 63 mm (56%). There was a gradual and clear increase in I from 45% to 67%, reflecting the increasing fertilization treatments. Hence, less soil water was available with increasing amounts of fertilization, since the water fraction evaporating from the canopy increases. Plant architecture, LAI and meteorological conditions during the cropping cycle appeared to be the main factors determining I. For irrigation planning and water use, studies of the evaporation of intercepted water must be considered.

The influence of the bonding formdistribution of Fe, Ni, Co and Mn and their potential bioavailability during the anaerobic degradation of maize straw was investigated. Two reactors were operated over 117 days at 37 degrees C and different dosage strategies of mineral were studied in reactor (R2). Control reactor (R1) was metal-limited over time. mineral supplementation (1 g L-1) once a week reported the highest methane yield (257 mL g(-1) VS) with 30% of increment. Ni and Co predominated in their oxidizable bonding forms and Fe mainly existed as residual and oxidizable fractions. The potential bioavailability (Mn >> Co approximate to Ni > Fe) of R2 was higher comparing to R1. Metal deprivation in R1 led to depletion of both sequential extraction fractions and total metal concentrations until the end of the process. This study confirmed that the dosage strategy of mineral has a stimulatory effect on methane production from crop maize waste.

Winter oilseed rape (Brassica napus L., WOSR) is the major oil crop cultivated in Europe. Rapeseed oil is predominantly used for production of biodiesel. The framework of the European Renewable Energy Directive requires that use of biofuels achieves GHG savings of at least 50% compared to use of fossil fuel starting in 2018. However, N2O field emissions are estimated using emission factors that are not specific for the crop and associated with strong uncertainty. N2O field emissions are controlled by N fertilization and dominate the GHG balance of WOSR cropping due to the high global warming potential of N2O. Thus, field experiments were conducted to increase the data basis and subsequently derive a new WOSR-specific emission factor. N2O emissions and crop yields were monitored for three years over a range of N fertilization intensities at five study sites representative of German WOSR production. N2O fluxes exhibited the typical high spatial and temporal variability in dependence on soil texture, weather and nitrogen availability. The annual N2O emissions ranged between 0.24 kg and 5.48 kg N2O-N ha(-1) a(-1). N fertilization increased N2O emissions, particularly with the highest N treatment (240 kg N ha(-1)). Oil yield increased up to a fertilizer amount of 120 kg N ha(-1), higher N-doses increased grain yield but decreased oil concentrations in the seeds. Consequently oil yield remained constant at higher N fertilization. Since, yield-related emission also increased exponentially with N surpluses, there is potential for reduction of the N fertilizer rate, which offers perspectives for the mitigation of GHG emissions. Our measurements double the published data basis of annual N2O flux measurements in WOSR. Based on this extended dataset we modeled the relationship between N2O emissions and fertilizer N input using an exponential model. The corresponding new N2O emission factor was 0.6% of applied fertilizer N for a common N fertilizer amount under best management practice in WOSR production (200 kg N ha(-1) a(-1)). This factor is substantially lower than the linear IPCC Tier 1 factor (EF1) of 1.0% and other models that have been proposed.

In this study modeled full scale application of thermobarical hydrolysis of less degradable feedstock for biomethanation was assessed in terms of energy balance, greenhouse gas emissions, and economy. Data were provided whether the substitution of maize silage as feedstock for biogas production by pretreated cattle wastes is beneficial in full-scale application or not. A model device for thermobarical treatment has been suggested for and theoretically integrated in a biogas plant. The assessment considered the replacement of maize silage as feedstock with liquid and/or solid cattle waste (feces, litter, and feed residues from animal husbandry of high-performance dairy cattle, dry cows, and heifers). The integration of thermobarical pretreatment is beneficial for raw material with high contents of organic dry matter and ligno-cellulose: Solid cattle waste revealed very short payback times, e.g. 9 months for energy, 3 months for greenhouse gases, and 3 years 3 months for economic amortization, whereas, in contrast, liquid cattle waste did not perform positive replacement effects in this analysis.

Efficient utilization of lignocellulosic biomass requires pretreatment in order to liberate cellulose from lignin and disrupt its recalcitrant crystalline structure before effective enzymatic hydrolysis can take place. Three different pretreatment methods (pressure cooking with dilute alkali and dilute acid as well as alkaline extraction) to recover the xylooligosaccharides fraction from five different grass silage samples, whole crop rye silage and maize silage were compared. The predominant end products released were xylobiose, xylotetraose, xylopentaose and xylohexaose whereas the xylooligosaccharides release pattern differed with the substrate. Maximum values of xylooligosaccharides was found for grass silage 17.26 g/L, whole crop rye silage 3.06 g/L and for maize silage 5.77 g/L. Results reveal the production of high value by-products from agricultural biomass. Advantages of the green-biorefinery concept include a resulting liquid fraction after pretreatment with very low contents of inhibitors such as furfural, hydroxymethylfurfural (HMF) and phenolic compounds.

The influence of thermobarical treatment on digestibility of cattle manure was investigated in lab-scale experiments. Therefore, solid cattle manure, liquid cattle manure and mixtures of these from different origins were treated in a closed vessel at temperatures of 140, 160, 180, 200 and 220°C for 5 minutes respectively. The pressure was that of the water vapor pressure at the respective temperature. Methane yield could be increased significantly (up to 58% at a temperature of 180°C) by thermobarical pretreatment. Higher treatment temperatures led to a decrease in methane yield compared to untreated material. This effect is caused by the formation of inhibitors and indigestible substances. An extended analysis of the data obtained via batch anaerobic digestion tests demonstrates a correlation between formation rate and methane yield in the acceleration phase predeterminating the methane yield at the end of the batch test after 30 days. A regression of the values from this correlation resulted in the findings of 164°C as optimum and 115°C as minimum treatment temperature.

Lab-scale experiments were conducted to assess the impact of thermobarical treatment of cattle waste on anaerobic digestion. Treatment was at temperatures of 140-220 degrees C in 20K steps for a 5-min duration. Methane yields could be increased by up to 58% at a treatment temperature of 180 degrees C. At 220 degrees C the abundance of inhibitors and other non-digestible substances led to lower methane yields than those obtained from untreated material. In an extended analysis it could be demonstrated that there is a functional correlation between the methane yields after 30 days and the formation rate and methane yield in the acceleration phase. It could be proved in a regression of these correlation values that the optimum treatment temperature is 164 degrees C and that the minimum treatment temperature should be above 115 degrees C. (C) 2013 Elsevier Ltd. All rights reserved.

The hydrolysis of lignocellulose is assumed to be the rate-limiting step in the anaerobic fermentation process. A fungal hydrolytic enzyme mixture was used to assess the enzymatic impact on different feedstocks for biogas production. The optimal conditions for enzymatic hydrolysis of rye grain silage, maize silage, grass silage, feed residues and solid cattle manure were determined in lab-scale experiments. Finally, the effects of enhanced hydrolysis on anaerobic digestion were investigated in batch digestion tests. Enzyme treatment of substrate showed Michaelis-Menten-like behavior and reached maximum values after 3 hours for reduced sugars as a product of hydrolysis. Methane production potential was determined for specific feedstock mixtures without enzyme, with inactivated enzyme and with active enzyme (with and without buffer). The results obtained show a clear increase in methane production after enzyme application for solid cattle manure (165 L N CH 4 ∙kg ODM -1  to 340 L N CH 4 ∙kg ODM -1 ), grass silage (307 L N CH 4 ∙kg ODM -1 to 388 L N CH 4 ∙kg ODM -1 ; enzyme plus buffer), feed residue (303 L N CH 4 ∙kg ODM -1 to 467 L N CH 4 ∙kg ODM -1 ), maize silage (370 L N CH 4 ∙kg ODM -1 to 480 L N CH 4 ∙kg ODM - 1 )and a lower increase for rye grain silage (355 L N CH 4 ∙kg ODM -1 to 413 L N CH 4 ∙kg ODM -1 ). The ratios of heating values from methane yields to heating values from the dry materials ranged between 0.3 and 0.7 for the untreated feedstock and increased to levels between 0.6 and 0.9 after the different forms of enzyme application.

Continuous bio-methanization of different feedstocks (rye grain silage, maize silage, feed residue (mix of silages), solid cattle manure, and grass silage) was investigated in a long-term laboratory-scale experiment with and without enzyme application. Ten-liter reactors were operated simultaneously in a two-step digestion mode for the continuous production of biogas from different feedstocks over 354 days. One set of reactors was operated as main digester, while the second set was used for the second step. The daily input of feedstock was increased from an organic loading rate of 1 to 3 kg ODM.m(-3).d(-1). All digesters were run under stable conditions, indicated by the ratio of volatile fatty acids to the total inorganic carbon, ranging around 0.2 in the first step and 0.15 in the second step. The hydraulic retention time was maintained between 80 and 90 days during the experiment. The application of enzymes was able to enhance biogas production by 10-15% and increase the methane content of biogas by an increment of 5-10% for the investigated materials except for feed residue. The increase in biogas yields was also reflected in the change in the ratios of heating values of the methane produced to the dry materials. These ratios ranged between 0.43 and 0.71 for the untreated feedstock, increasing to 0.44-0.88 after enzyme application.

A yeast-like fungus producing a large amount of extracellular polysaccharide was isolated from the biogas reactors at North Wyke Research, UK (latitude, 50°46′29″N; longitude, 3°55′23″W). This strain was identified as Aureobasidium pullulans based on nucleotide sequence of the D1/D2 domain of the large-subunit (LSU) rRNA gene. Extracellular polysaccharide or pullulan, produced from this new strain of A. pullulans in shake flasks and a stirred tank fermenter was investigated. A maximum polysaccharide concentration of 40.1gl−1, and productivity of 12.5gl−1 per day was obtained in a batch culture from stirred tank fermenter. The optimal cultivation conditions for pullulan production for this strain in 250ml shake flask containing 100ml of sucrose medium were observed at 28°C and with 200rpm. The effect of different sugars and nitrogen sources on pullulan production was investigated. It was found that more pullulan was produced when the strain was grown in the medium supplemented with NaNO3 than when it was cultivated in the medium supplemented with C5 and C6 sugars and other nitrogen sources.

The composition of feedstock for biogas plants has changed during recent years. There has been an increase in the share of energy crops and residue from agriculture. As a consequence the contents of digesters are less fluid and hence, the effort for mixing has increased. Applying enzymes seems to be a promising way of improving fluidity. In this study the effects of enzyme application were investigated for a set of materials – grass silage, feed residue, maize silage, and rough-ground rye as feedstock for anaerobic digestion. After enzyme application these materials were mixed with cattle slurry and the probable effect was assessed with three different apparatus – fluidmeter, rotation rheometer, and torquemeter. The instruments proved applicable, in general, whereas grass silage could only be measured with the torquemeter. Fluidity of untreated material increased in the following row: grass silage