RESUMO
Biochar has been frequently suggested as an amendment to improve soil quality and mitigate climate change. To investigate the optimal management of nitrogen (N) fertilization, we examined the combined effect of biochar and N fertilizer on plant N uptake and N2O emissions in a cereal rotation system in a randomized two-factorial field experiment on a sandy loam soil in Brandenburg, Germany. The biochar treatment received 10Mgha-1 wood-derived biochar in September 2012. Four levels of N fertilizer, corresponding to 0, 50%, 100%, 130% of the recommended fertilizer level, were applied in winter wheat (Triticum aestivum L.)) and winter rye (Secale cereal L.) in 2013 and 2014 followed by the catch crop oil radish (Raphanus sativus L. var. oleiformis). Biomass and N uptake of winter wheat and winter rye were significantly affected by the level of N fertilizer but not by biochar. For N uptake of oil radish an interaction effect was observed for biochar and N fertilizer. Without applied fertilizer, 39% higher N uptake was found in the presence of biochar, accompanied by higher soil NH4+ content and elevated cumulative CO2 emissions. At 130% of the recommended fertilizer level, 16% lower N uptake and lower cumulative N2O emissions were found in the biochar-mediated treatment. No significant change in abundance of microbial groups and nosZ gene were observed. Our results highlight that biochar can have a greenhouse gas mitigation effect at high levels of N supply and may stimulate nutrient uptake when no N is supplied.
RESUMO
Feed and food production are inter alia reasons for high greenhouse gas emissions. Greenhouse gas emissions could be reduced by the replacement of animal components with plant components in processed food products, such as pasta. The main components currently used for pasta are semolina, and water, as well as additional egg. The hypothesis of this paper is that the substitution of whole egg with plant-based ingredients, for example from peas, in such a product might lead to reduced greenhouse gas emissions (GHG) and thus a reduced carbon footprint at economically reasonable costs. The costs and carbon footprints of two pasta types, produced with egg or pea protein, are calculated. Plant protein-based pasta products proved to cause 0.57 kg CO2 equivalents (CO2eq) (31%) per kg pasta less greenhouse gas emissions than animal-based pasta, while the cost of production increases by 10% to 3.00 /kg pasta.
RESUMO
Field studies that have investigated the effects of char materials on the emission of nitrous oxide (N2O) are still scarce. Therefore, we conducted a field trial with bio- and hydrochars and measured N2O emissions for one whole year. It was hypothesised that the incorporation of chars reduces the emissions of N2O. Chars were produced by pyrolysis and hydrothermal carbonisation (HTC) using either maize silage or wood residues as feedstock. In addition, after production chars were post-treated with digestate in order to accelerate the ageing process of the chars. Chars and digestate were applied to the soil to raise the C content. Emissions of N2O were measured weekly and soil samples for inorganic nitrogen (N) and soil water-content were taken once a month. Additionally, the abundance of functional marker genes from denitrification (nosZ) was determined in October 2012 and in June 2013. The treatment with pure digestate emitted the most N2O compared to the control and char treatments. However, this was significant only in one case. There were no great differences between the char treatments due to high spatial variability and gene abundance of nosZ did not differ between treatments. Overall, emissions of N2O were relatively low. This was attributed to the heterogeneous distribution of the chars and the sandy soils that did not favour the production of N2O. To conclude, the emissions of N2O were mainly influenced by temperature and precipitation and to a minor extent by the type of char and post-treatment.