Browsing by Subject "Reststoff"

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Ökonomische Bewertung der „Doppelernte“ von Getreidekörnern mit den Reststoffen Spreu und Stroh
(2021) Ortmaier, Jörg; Köller, Karlheinz
Objective of this work is an economic evaluation of new harvesting methods, so-called “dual- harvesting” methods for common harvesting of grains and their residual biomass. In detail, the aim is on the one hand to evaluate the predicted higher quality and quantity per hectare of har-vestable residual biomass such as chaff and straw that can be realized with dual-harvesting technologies, but on the other hand especially their additional income contrasted to the pro-cess costs by proceeding dual-harvesting. For this purpose, combine harvesting with additional chaff or straw harvesting is compared to some dual-harvesting methods, both in terms of process technology and in monetary terms. Dual-harvesting methods are simulated with self-propelled forage harvester threshing, forage wagon windrow harvesting, compact harvesting and harvesting with a tractor mounted stripper header. The comparison includes the required logistic-chains and crop aftertreatment, i.e. sta-tionary separation of grain and biomass for each method. As basis for calculations is done specific modeling, e.g. for chaff yields and crop volumes as a function of grain yield. Parame-ters such as area size are included and also field distance, loss times, e.g. for turning opera-tions in the field, working speeds and road transport speeds. A calculation model developed for this purpose calculates time required for harvesting of one field for all processes with the greatest possible comparability. Based on machine costs stored in databases, e.g. for depreci-ation or wear and repair, which are automatically transferred to their desired process calcula-tion via selection lists, the costs per operating hour and, including area per hour and area size, costs per hectare can be determined for each harvesting process. Since all processes have different levels of grain and biomass losses, the process-specific, total revenues for grain and biomass are calculated accordingly and process costs calculated in each case are deducted from them. The resulting harvest cost free outputs (HCFO) are used as a comparative value. Without taking into account costs of reproducing soil organic matter as long term result, the following HCFO result for the individual methods according to the assumptions are calculated: combine threshing with bale harvesting 1309.93 €/ha; compact harvesting 1285.66 to 1529.53 €/ha depending on the amount of straw harvested; forage harvester threshing 1421.04 €/ha; forage wagon swath harvesting 1429.40 €/ha; tractor-mounted stripper header 1279.58 €/ha. The compact harvesting method thus has an advantage of up to 219.60 €/ha over the estab-lished combine and bale technology with same given assumptions. The other methods are in between or slightly below the combine harvesting. If costs for nutrient removal and soil organic matter reproduction are included for long term perspective, the advantage of compact harvest-ing is up to 143.44 €/ha. Based on literature research and model calculations, it can be assumed with a high degree of probability that dual-harvesting methods actually make residual materials usable in greater quantities with higher quality than it is possible with widely used combine harvesting. Concerns expressed by Buchmann (1961) and Garmasch (1960) regarding the suitability of combine harvesting for an efficient provision of chaff and straw are substantiated when calculation re-sults are taken into account. In addition, agronomic effects of dual-harvesting methods are positive compared to combine harvesting, which was not able to be evaluated in monetary terms and therefore represents a great need for future research. The positive assessment is due to improved field hygiene by removing weed seeds and plant pathogens from the field during dual-harvest. This could re-duce the need for chemical pesticides. Use of cereal residues not only improves resource effi-ciency and "saves" land for cultivation of renewable raw materials, but the carbon contained in chaff and straw remains bound in sustainable products to a greater extent, such as in biochar. Dual-harvesting is an essential tool for cost-effective provision of plant residues required for that purpose and at the same time offers great potential for more environmentally friendly field management and benefits for biodiversity, e.g. through possibility of regular cultivation of plant mixtures instead of individual crops. Digital development up to autonomous field management can be made more rational in dual-harvesting methods through simplified processes in the field, which can be expected to lead to further increases in efficiency of grain and residue har-vesting in the future.
Suitability of recycled organic residues from animal husbandry and bioenergy production for use as fertilizers
(2021) Bauerle, Andrea; Lewandowski, Iris
In recent years, agriculture has been increasingly faced with the acute need to find a more sustainable practice for dealing with nutrient-rich organic side streams. For ecological and economic reasons, pressure is mounting every day to implement an improved utilisation and to close nutrient loops in agriculture to the maximum possible. Pig manure and biogas digestates are suitable as organic fertilisers because they contain essential plant nutrients. They also provide organic matter that contributes to the maintenance of soil fertility. However, their current use is often insufficient. Both residues can be used as fertilisers either directly or following treatment. This can be as simple as solid-liquid separation. A more advanced approach is the precipitation of phosphorus for conversion into phosphate fertilisers ("P-Salts"). The fertilising effect of such innovative P-Salts needs to be investigated in an agronomic context. The same applies for the integration of separated biogas digestates as organic fertilisers into different biomass production systems. The primary objective of this thesis is to establish whether recycled fertilisers from organic residues are comparable to mineral fertilisers and can serve as a suitable substitution. For this purpose, five specific objectives were defined: (1) to determine whether separated biogas digestates can complement or substitute mineral fertilisers and whether/how they affect long-term yield performance in different biomass cropping systems; (2) to ascertain which type of separated biogas digestate is suitable for which biomass production system; (3) to test the effect of two recycled P-Salts on yield and quality of different crops compared to triple superphosphate (TSP); (4) to examine whether the combination of recycled P-Salts with biochar and dried solid digestates results in interaction effects; and (5) to assess whether there are differences in the uptake efficiency of recycled and mineral fertilisers between different crop types. Thus, several experiments were carried out. The fertilising effect of separated biogas digestates on three biomass production systems (perennial grassland, intercropping of triticale and clover grass, silage maize) was investigated in multi-year field experiments in south-west Germany. P-Salt and biochar from pig manure were tested in a greenhouse study with spring barley and faba bean. In a second greenhouse study with ornamentals, the P-Salt from manure, a P-Salt from biogas digestate, and dried solid digestates were assessed. The long-term yield stability of biomass cropping systems fertilised with separated biogas digestates was clearly demonstrated under field conditions. Separated biogas digestates can substitute mineral fertiliser in perennial and intercropping systems. Solid digestates were most suitable for cropping systems with soil tillage where their incorporation into soil is possible. The intercropping of triticale and clover grass was found to be the most stable system, with constantly high biomass yields being maintained using only digestates. For maize, a combined application of digestates and mineral fertiliser proved to be the best option. The P-Salt from manure had the same or even better effects than TSP on spring barley and faba bean. In the experiment with ornamentals, the two P-Salts from manure and digestate had more or less the same effect as TSP on biomass production. These results suggest that both P-Salts have an equivalent fertilisation effect to TSP and can thus replace it as mineral fertiliser. In this thesis, it was possible to achieve competitive yield results with the tested fertilisers, provided that they are integrated in a suitable fertilising strategy. The next step is for the recycled fertilisers to be actually used in agricultural practice - a prerequisite for which being that their implementation has agronomic, practical, ecological and economic advantages. The enhanced use efficiency of N and P already available on farms is challenging but necessary to reduce dependency on both synthesised N fertilisers and imported P fertilisers. This thesis significantly contributes by providing knowledge on the fertilising effect of selected recycled fertilisers necessary for their future implementation in agriculture. Optimised nutrient management and residue treatment using advanced technologies can contribute to the further closing of nutrient cycles. The highest environmental benefits can be realised on farms with excess residues and limited agricultural land. It is therefore highly recommended that these farms improve their current practice by prioritising the implementation of appropriate measures. Sound residue management necessitates strategic planning and capital investments from farmers and companies, but is a crucial step towards the sustainable intensification of cropping systems and resilient future agriculture.
Vorbehandlung lignocellulosehaltiger Substrate zur Steigerung des Biogasertrages
(2019) Baumkötter, Daniel; Jungbluth, Thomas
There are various approaches for the optimization in biogas technology. One possibility is the pretreatment of the used substrates in order to achieve higher biogas yields, open up new substrates and increase the overall economic viability of biogas plants. For this pretreatment, mechanical treatment technologies are used, which are very different in construction. Therefore, a systematic investigation of the mechanical pretreatment by means of impact with regard to particle size distribution, biogas yield and power consumption for different substrates was carried out for the first time. The aim of this thesis was thus to optimize and eva¬luate the technology “impact reactor” for pretreatment of lignocellulosic substrates for use in an agricultural biogas plant. Substrates with a model character were selected for the experiments, which allow the results to be transferred to comparable substrates. These were triticale straw, oat whole crop silage, maize straw and horse manure. In addition, the substrate mixture of a biogas plant, in which an impact reactor is also used for pretreatment, with a high proportion of grass silage (53 % grass silage, 40 % maize silage and 7 % cattle and horse manure) was examined. Pretreatment of all substrates showed a reduction in particle size. As expected, finer particle sizes also required more effort and therefore higher power consumption. However, no direct correlation could be established between a finer particle size and an increased methane yield. Therefore, an increase in the processing intensity does not necessarily lead to an increase in microbial degradation. In addition to the use of alternative substrates, the main objective of substrate pretreatment was to increase biogas yields. Mechanical pretreatment of triticale straw made it possible to increase methane yield by up to 16 %, horse manure by up to 14 % and substrate mixture by up to 10 %. In contrast, no additional methane yields were recorded for oat whole crop silage and maize straw. Apparently short chopped silages are already sufficiently broken down by the silage. To avoid possible losses due to aerobic degradation, the pretreated substrates must be fed directly into the fermenter. Therefore, the pretreatment should ideally be integrated into the process engineering of the biogas plant between storage and the feed system. In order to classify the results with the impact reactor, additional treatment experiments were carried out with an extruder on a laboratory scale. In principle, the extruder was also suitable for all substrates examined, but liquid had to be added to substrates with a high dry substance content (straw). The results for increasing methane yields were comparable. Besides the investment costs, power consumption had the greatest influence on the costs of pretreatment. These varied significantly depending on the selected settings at the impact reactor. With the help of the determined optimal settings, power consumption of 12.9 kWhel/tFM for triticale and maize straw, 2.6 kWhel/tFM for oat whole crop silage, 10.8 kWhel/tFM for horse manure and 6.1 kWhel/tFM for the substrate mixture could be determined. After combining the results on power consumption and additional methane yield, the mechanical pretreatment of triticale straw, horse manure and the substrate mixture resulted in a gain after energetic balancing. From an economic point of view, horse manure and maize straw showed their potential as an alternative substrate compared to silage maize. Due to their residual material character and the associated lack of market value, these two substrates are economically interesting. By contrast, the market value of cereal straw makes triticale straw more economical than silage maize. However, the results may vary depending on substrate quality and biogas plant, which is why an individual consideration is required for each project. The impact reactor as a method of mechanical pretreatment is basically suitable for various substrates. The pretreatment process increases the biogas yield and opens up previously unused residues for the biogas process, which also improves economic efficiency.