Dirk Gericke

Publications (3)3.22 Total impact

• Source

  Available from: Kang Ni

  Dataset: (JPNSS)-Analysis of ammonia losses after field application of biogas slurries by an empirical model

  Kang Ni, Andreas Pacholski, Dirk Gericke, Henning Kage
• Source

  Available from: Andreas Pacholski

  Article: Modelling Ammonia Losses After Field Application of Biogas Slurry in Energy Crop Rotations

  Dirk Gericke, Lüder Bornemann, Henning Kage, Andreas Pacholski
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  ABSTRACT: Over the past few years the number of biogas slurries, which are generally used as nitrogen fertilisers, have seen a steady increase in Germany. A mechanistic ammonia volatilisation model was developed to predict the ammonia losses of these slurries when applied to bare soil, maize, wheat and rye grass canopies. Data for model development were collected from several field measurements carried out at two locations in Northern Germany between the years of 2007 and 2008. Additionally, the behaviour of the slurries on and in the soil was investigated through the use of infiltration pot experiments. The model includes three main compartments: slurry, atmosphere and soil. The soil compartment model is relatively simple, as the slurry infiltration, nitrification and ploughing dislocation into the soil determined in the experiments showed quantitatively no significant differences between the tested slurries (mono-fermented, co-fermented and pig slurry) and soils (sand soil and loamy sand). Hence, instead of a complex soil model, stable reduction factors, as derived from the experiments, were implemented in the model. Simulated ammonia emissions were statistically compared (root mean square error (RMSE), modelling efficiency (ME), linear regression) to the observed emissions. All evaluations showed an acceptable model performance (RMSE = 1.80kgNha−1), although there were a few number of anomalies which could not be modelled in an adequate way. A model sensitivity analysis showed that temperature and slurry pH value are the main drivers of NH3 volatilization in the model. Following a change of +1°C or of +0.1 pH unit ammonia volatilization will increase by about 1% and 1.6% of the applied total ammoniacal nitrogen, respectively. We were able to show that a simple model approach could explain most factors of ammonia volatilization in biogas crop rotations. KeywordsBiogas slurry–Ammonia volatilization–Mechanistic model
  Water Air and Soil Pollution 04/2012; 223(1):29-47. · 1.63 Impact Factor
• Source

  Available from: Andreas Pacholski

  Article: Analysis of ammonia losses after field application of biogas slurries by an empirical model

  Kang Ni, Andreas Pacholski, Dirk Gericke, Henning Kage
  [show abstract] [hide abstract]
  ABSTRACT: Due to energy crises and stricter environmental regulations, renewable energy sources like bio-methane produced by anaerobic digestion (biogas) become increasingly important. However, the application of slurries produced by biogas fermentation to agricultural land and subsequent ammonia emission may also create environmental risks to the atmosphere and to N-limited eco-systems. Evaluating ammonia loss from agricultural land by model simulation is an important tool of agricultural-systems analysis. The objective of this study was the systematical compari-son of ammonia volatilization after application of two types of biogas slurries containing high amounts of energy crops in comparison with conventional animal slurries and to investigate the relative importance of factors affecting the emission process through an empirical model. A high number of ammonia-loss field measurements were carried out in the years 2007/08 in biogas cropping systems in N Germany. The study consisted of simultaneous measurement of NH 3 losses from animal and biogas slurries in multiple-plot field experiments with different N-fertiliza-tion levels. The derived empirical model for the calculation of NH 3 losses based on explanatory variables gave good predictions of ammonia emission for both biogas and pig slurries. The root mean square error (RMSE) and mean bias error (MBE) of the empirical model for validation data were 2.19 kg N ha –1 (rRMSE 29%) and –1.19 kg N ha –1 , respectively. Biogas slurries produced highest NH 3 emissions compared to the two animal slurries. In view of the explanatory variables included in the model, total NH 4 application rate, slurry type, temperature, precipitation, crop type, and leaf-area index were important for ammonia-volatilization losses.
  Journal of Plant Nutrition and Soil Science 04/2012; 175(2):253-264. · 1.60 Impact Factor