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Purpose Charred materials are low in bioavailable nitrogen (N) due to gaseous losses and the formation of recalcitrant structures during pyrolysis. Enriching chars with N from wastewaters offers a possibility to upgrade the agronomic value of the chars and manage the liquids. For assessing the practical feasibility of the approach, more information on the extent of the retention and release of the loaded N is needed. Methods The ammonium-N (NH4-N) retention capacity of chars derived from sewage sludge (SS_A-C), Salix wood (SA), broiler manure (BR) and coal (LG85) was determined via equilibrations in solutions containing 400, 1500 and 5000 mg NH4-N L−1. Plant availability of the loaded N in SS_C, SA and BR was studied in a pot experiment with ryegrass. Results Differences in the total N retention of moist chars were small. The amount of N retained increased with increase in the solution N and was at the highest 2–4 g NH4-N L−1 char. In four consecutive ryegrass harvests, the apparent N recoveries were 67, 47 and 34% for SA, BR and SS_C treatments. No slow release of N was observed. Conclusion Considering crop production, the amounts of N retained within the studied chars in bioavailable form were small. Chars with a higher N retention capacity would be needed for an efficient cascade from water purification to fertilizer use. Graphical Abstract

A substantial percentage of manure nitrogen (N) can be lost as gaseous ammonia (NH

A substantial percentage of manure nitrogen (N) can be lost as gaseous ammonia (NH3) during storage and field spreading. Lowering slurry pH is a simple and accepted method for preserving its N. Efficiency of slow pyrolysis liquid (PL) produced from birch (Betula sp.) as an acidifying agent, and its ability to reduce NH3 emissions following surface application of cattle slurry, was studied in a field experiment. Untreated slurry (US) and slurries acidified with PL and sulfuric acid (SA) were applied to the second harvest of a grass ley. Immediate NH3 emissions, grass biomass, N-yield and possible toxic impacts on soil nematodes and enchytraeids were examined. Furthermore, the effects on soil respiration, nitrogen dynamics and seed germination were studied in subsequent laboratory experiments. In the field, over one third of the water-extractable ammonium-N (NH4-N) applied was lost through NH3 volatilization from US. SA and PL acidified slurries reduced NH3-N emission rate equally from 3.4 to

This study aimed to investigate the fate of faecal indicator organisms and to characterize microbial diversity dynamics in dairy manure and in aerated liquid manure in different treatment reactors in a series of continuously fed aerated tank reactors using low intensity aeration and ammonia-reduced feedback. The bacterial diversity in the treatment reactors was also compared with that in the soil from which the process inoculant originated. The fate of enteric indicator organisms was studied by the enumeration of viable counts. Total bacterial community DNA was extracted, amplified using 16S rRNA primers, cloned, sequenced and identified by comparison to known sequences. At best over 90% reduction was observed in the numbers of enteric indicator organisms. However, the result obtained varied depending on treatment run and indicator organism. Firmicutes were the dominating phyla of the untreated slurry; whereas; Proteobacteria and Deinococcus-Thermus dominated in the treatment tanks. Soil had the broadest phylogenetic diversity: the major phylums were Acidobacteria, Proteobacteri and Gemmatimonadetes. At the genus level, raw manure and treatment tanks shared a number of sequences. Soil, the origin of the inoculant, and treatment tanks did not share any sequence at the genus level, although some was observed at the family level.

Manure constitutes a nutrient resource that should be efficiently recycled in agriculture. We assessed the nutrient cycling properties of three bedding materials (peat, wood shavings and pelleted straw) in horse manure by comparing their compostability, ability to retain nitrogen (N) and phosphorus (P) under rainfall and capacity to release N when mixed with soil. Manure with pelleted straw bedding had superior composting characteristics as it lost half of its dry mass, reached temperatures >60 °C and ended up having a carbon (C) to N (C:N) ratio of