Anaerobic digestion (AD) for biogas production leads to several changes in the composition of the resulting digestates compared to the original feedstock (ammonia content, pH, carbon to nitrogen ratio, etc.), which are relevant for the plant availability of macro- and micronutrients after field application. Increased NH4+-N content in digested slurries compared to undigested slurries does not guarantee improved uptake efficiency of slurry nitrogen and increased savings in fertilizer nitrogen. AD of crop residues and cover crops leads to an increase in the total amounts of mobile organic manures within the farming system, resulting in a higher nitrogen use efficiency and an increased scope for target-oriented nitrogen application in time and space, when needed by the crop, as an alternative to the site-bound soil incorporation as green manures. AD of dairy manure appears to reduce the fraction of immediate plant available phosphorus and micronutrients. This does, however, not affect short-term crop availability under field conditions. More studies are needed to improve current knowledge on sulfur losses during AD and fertilizer value of digestates.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/elsc.201100085

Effects of anaerobic digestion on digestate nutrient availability and crop growth: A review

Carbon mineralization from organic wastes at different composting stages during their incubation with soil.

1 Archaeology, archaeological science and microarchaeology 2 Information embedded in the microscopic record 3 Completeness of the archaeological record 4 Common mineral components of the archaeological record 5 Biological materials: bones and teeth 6 Biological materials: phytoliths, diatoms, eggshells, otoliths and mollusk shells 7 Reconstructing pyrotechnological processes 8 Biological molecules and macromolecules: protected niches 9 Ethnoarchaeology of the microscopic record: learning from the present 10 Absolute dating: assessing the quality of a date 11 Reading the microscopic record on-site 12 Infrared spectroscopy in archaeology

Microarchaeology: Beyond the Visible Archaeological Record

Anaerobic digestion is an optimal way to treat organic waste matter, resulting in biogas and residue. Utilization of the residue as a crop fertilizer should enhance crop yield and soil fertility, promoting closure of the global energy and nutrient cycles. Consequently, the requirement for production of inorganic fertilizers will decrease, in turn saving significant amounts of energy, reducing greenhouse gas emissions to the atmosphere, and indirectly leading to global economic benefits. However, application of this residue to agricultural land requires careful monitoring to detect amendments in soil quality at the early stages.

E. Witter

Papers

Composition of fresh, aerobic and anaerobic farm animal dungs