Biogaserzeugung im viehlosen Betrieb: Effekte auf Stickstoffmanagement, Erträge und Qualität

In organic farming systems without livestock some problems arise concerning the nitrogen management: On the one hand, there is a lack of transportable nitrogen fertilisers, on the other hand there is a potential for high losses with the usual management. The biological N2 fixation is decreased, when clover grass is mulched. If the biomass of intercrops and clover grass gets mineralised in autumn, it can be leached in winter. In the trial referred to here, the impact of fermentation of biomass on some agricultural parameters like yield etc. are investigated within a crop-rotation of clover grass, potatoes, winter wheat, peas, winter wheat and summer wheat with undersown clover grass. Intercrops are sown after winter wheat and peas. In the control variant the coupled products (clover grass, straw and intercrops) are left on the field as mulch. In the biogas system this material is harvested for digesting. The remaining products are used as fertilisers. There are liquid products which were used to fertilise the winter wheat and solid ones, which were used for fertilizing potatoes and summer wheat. This system allows a higher efficiency of the nitrogen management: The yield and the content of raw protein in winter wheat increased. The solid material did not mineralise as fast as necessary. It would be better to add this material to the intercrops

Biogaserzeugungspotential aus Gülle und Koppelprodukten in viehhaltenden und viehlosen Betriebssystemen des ökologischen Landbaus

In two agricultural systems with and without animal husbandry the potential to produce renewable energy by digesting slurry and organic residues to biogas were assessed. In comparison to some other methods of energy production by biomass biogas production has the advantage of keeping the nutrients of the substrates within the agricultural system. They can be used as fertilisers. In the investigated system with milk production (0,8 cows ha-1, 8 crops, among them 4 cereals, peas, potatoes and 2 clover grasses with catch crops after winter cereals and peas (see DEUKER et al. 2005), it is possible not only to ferment slurry, but also catch crops and straw of peas and cereals. The methan production potential by digesting only slurry is the equivalent of around 327 l diesel fuel ha-1. By digesting a well developed catch crop it is possible to harvest the equivalent of around 750 l diesel fuel per ha.-1 sown with such crops. Related to the whole system with 4 catch crops within 8 fields it is possible just by including catch crops in the fermentation process with slurry to duplicate the methan harvest of the digesting plant to around 700 l diesel fuel ha-1 a-1. By utilisation of biomass like the straw of peas and other residues it is possible to generate the equivalent of approx. 450 l diesel fuel ha-1. Total biogas production potential by including all fermentable biomass is the equivalent of approx. 1150 l diesel fuel per each ha and year. Usually one third of this energy is necessary to temperate the digester, one third can be converted to electricity and one third can be used to heat buildings in the neighbourhood of the fermentation plant. In a typical stockless organic agricultural system composed of six crops (clover gras, potatoes, winter wheat, peas, winter wheat and summer wheat with undersown clover grass, with catch crops after winter wheat and peas, see STINNER et al. 2005) biomass of clover grass and catch crops will normally be left on the field and incorporated in the soil. By fermentation of clover grass there is a biogas production potential of around the equivalent of 3300 to 4700 l diesel fuel ha-1 a-1. Digesting catch crops allows a methan yield of ca. 650 to 700 l diesel fuel ha-1, digestion of other residues like straw other 1250 to 1350 l diesel ha-1. The total energy production potential of the whole crop rotation system is the equivalent of around 1700 to 1800 l diesel per ha and year. Removal of crop residues is coupled with removal of substantial quantities of nitrogen, reducing the residual mineralisable nitrogen amounts on fields at the end of the vegetation period and the risk of nitrate leaching

Auswirkung der Fermentation biogener Rückstände in Biogasanlagen auf Flächenproduktivität und Umweltverträglichkeit im Ökologischen Landbau – Pflanzenbauliche, ökonomische und ökologische Gesamtbewertung im Rahmen typischer Fruchtfolgen viehhaltender und viehloser ökologisch wirtschaftender Betriebe

Die Effekte der Vergärung von Gülle und Nebenernteprodukten wurden auf der Ebene des gesamten landwirtschaftlichen Systems für einen viehhaltenden Gemischtbetrieb und einen viehlosen Marktfruchtbetrieb untersucht. Dabei wurden die Wirkungen der Vergärung von Gülle und Kleegras auf die Flächenproduktivität, auf die innerbetrieblichen Nährstoffflüsse, auf die Nitratauswaschungsgefahr sowie auf die Gefahr von bodenbürtigen Spurengasemissionen untersucht. Ferner wurde eine ökologische Bilanzierung der Biogasvergärung im ökologischen Landbau mittels Öko-Bilanzierung durchgeführt

Biogas in stockless organic Farming: Effects of Digestion of Clover/grass, Cover Crops and Crop Residues on Nitrogen Cycles and Crop Rotation Productivity

A common practice in stockless organic farming systems is to leave the biomass from clover/grass-ley and crop residues in the field for their residual fertility effect. No farmyard manures for transfer of nutrients within the system are available. Clover/grass-ley biomass and crop residues represents an unexploited energy potential that could be harnessed by the digestion in biogas plants for production of methane, thus replacing ruminants by the biogas digester. In field trials by implementing a whole crop rotation comprehending six crops were carried out in 2002-2005 to evaluate whether the use of N could be improved by processing biomass described above in a biogas digester and using the effluents as a fertilizer, compared to general practice. Results indicate that digestion of crop residues resulted in more efficient manuring systems, not only by the implementation of an additional “product” (power energy), but also by getting more efficient cropping systems with higher DM and N yields of most of the non-legume crops, combined with a reduction of N losses due to denitrification and a reduction of the nitrate leaching risk. The causes were a better and more evenly allocation of nutrients within the whole crop rotation, a higher N input via N2 fixation, lower N losses and probably a higher N availability of digested in comparison to the same amounts of nutrients in undigested organic manures

Effects of Biogas Digestion of Slurry, Cover Crops and Crop Residues on Nitrogen Cycles and Crop Rotation Productivity of a Mixed Organic Farming System

Manures and crop residues can be utilised for digestion, without any significant losses of nutrients. This paper presents the results of field trials about the effects of biogas digestion in a mixed organic cropping systems on nutrient cycling and yield of a whole crop rotation. Digestion of slurry affected yields and N uptake only after soil incorporation. The inclusion of crop residues for digestion increased the amounts of “mobile” manure. N uptake and yield of non-leguminous main crops increased about 10%, due to a more adapted allocation of nutrients within the whole cropping system by reallocation of N towards the crops with higher N needs. Additionally, removing the cover crops in autumn and their digestion increased the fertilizing efficiency of N, lowering the risk of leaching losses

Yield, soil Nitrogen content and weed control in six years of conservation agriculture on-farm field trials in Southwest Germany

Conservation Agriculture (CA) is a farming system that aims to protect soil resources by promoting minimum soil disturbance in combination with the maintenance of a permanent soil cover, and diversification of crop rotation. The aim of this study was to investigate the effects of no-till and shallow conservation tillage using a chisel plough and rotor tiller on loamy soils with high clay contents in combination with cover crop mixtures in rotations with at least three different crops. Crop yield, soil Nitrogen content and weed coverage were the main parameters measured. Experiments were performed in an on-farm approach in southwest Germany on 18 farms and two research stations over a period of 6 years. Yields of cereals, oilseed rape, maize, soybean and peas were slightly lower under no-tillage with 5.8–7.3 Mg grain yield equivalents ha− 1 than under conservation tillage with 6.3–7.8 Mg grain yield equivalents ha− 1. Cover cropping did not affect crop yields. Tillage and cover cropping had no influence on weed control in the subsequent main crop. Soil nitrate contents before winter in November were on average 11 kg N ha − 1 lower in the cover crop treatments compared to the plots without cover crops.This study shows that CA with minimum tillage had slight advantages compared to the no-till system under Southwest Germany farming condition

zur Erlangung des Doktorgrades Dr. rer. nat.

Smart cards are used in security critical applications where money or private data is involved. Examples are the German Geldkarte or new passports with biometrical data. Design or programming errors can have severe consequences. Formal methods are the best means to avoid errors. Java Card is a restricted version of Java to program smart cards. This work presents a logical calculus to formally prove the correctness and security of Java Card programs. The calculus is implemented in the KIV system, and ready for use. First, an operational big-step semantics for sequential Java is presented based on algebraic specifications. All Java language constructs are modeled. Then, a sequent calculus for dynamic logic for Java Card is developed, and the correctness of the calculus is formally proved. The calculus is designed to support libraries, the reuse of proofs, and program modifications. This entails two different notions of type soundness, the standard one, and a weaker version. Furthermore, the calculus is not restricted to Java Card, but can be used for arbitrary sequential Java program. The work ends with some intricate examples. All properties and theorems are formally proved with the KIV system. The resulting verification system is able to cope with real-life e-commerce applications. 3

Fertilizer value and nitrogen transfer efficiencies with clover-grass ley biomass based fertilizers

In temperate regions, legume-based green manures are a key element of organic rotations. However, specialized farms lack sufficient mobile organic fertilizers. To gain a better understanding of the N flows and the nitrogen (N) and phosphorus (P) fertilizer value of different clover-grass-based fertilizers (biogas digestate, compost, silage and fresh clover-grass obtained from clover grass ley biomass), we assessed their fertilizer value. Nitrogen and P offtake by the ryegrass was used to assess the shortterm effects. The data were completed using model calculations to assess the field-to-field N-transfer efficiencies and the overall N-transfer efficiencies. The greatest plant N offtake was achieved with digestates (64%) and the lowest from the compost (6%) and solid farmyard manure (14%). The mineralization rate was positively related to the NH4+– N/total N ratio (P\0.01, r2 = 0.82). The model calculations indicate that the overall short-term N-transfer efficiencies are driven by the field to-field N-transfer efficiency and the field-to-crop transfer efficiency. However, in the long term, model calculations indicate that a high field-to-field N-transfer efficiency is the key strategic approach when aiming to achieve cropping systems with a high overall longterm N-transfer efficiency. Consequently, the results showed that aerobic decomposition (composting) significantly lowered field-to-field as well as field-tocrop N-transfer rates. The relative P use efficiency strongly differed among the fertilizers. In particular, freshly cut clover-grass and solid manure increased P availability and led to an increase of plant P offtake that was higher than the amount of P supplied