ARI Biennial Review for 2018-2019

fertilised soil the emissions were 267.10 μg N/m 2 . On the contrary, the incorporation of chickpea plant residues with low-N content can be an efficient way to minimise the N 2 O emissions at 21.63 μg N/m 2 . The emissions of N 2 O when compost was applied remained relatively low, equal to 5.47 μg N/m 2 , and in comparison to soil without any treatment. Overall, a positive association between NH 4 + , NO 3 − in soil and N 2 O emissions was observed. However, this response was treatment-dependent, and the significant positive correlation between NH 4 + and N 2 O emissions was noticed in soils treated with ammonium nitrate, chickpea residues with low N content, as well as untreated controls. On the contrary, the positive correlation observed between NO 3 − and N 2 O emissions in soils receiving compost and high N chickpea residues suggests that the different treatments are differentially affecting the processes that are contributing to N 2 O emissions in agricultural soils. These findings emphasise that the different nutrient management schemes are differentially affecting the main processes contributing to N 2 O emissions in agricultural soils (M. Omirou, I.M. Ioannides) . Valorisation of agricultural waste could improve soil fertility and mitigate soil direct N 2 O emissions The emerging need for sustainable management of the increasing quantities of urban and industrial organic waste creates opportunities for the development of alternative strategies for the improvement of degraded soils. The current study was performed to examine the effects of agricultural waste application on soil bacterial community as well as CO 2 and N 2 O direct gas emissions. Untreated soils were compared with soils that received the same amount of N (100 μg/g soil) in the form of ammonium nitrate and organic agricultural waste. In particular, soils were incubated with three different types of organic agricultural waste: orange (OP), mandarin (MP) and banana peels (BP) and ammonium nitrate (F) after adjusting soil water at 70% of its holding capacity. In the current study, soil chemical characteristics, quantitative PCR of denitrifiers (nirK, nirS, nosZI and nosZII) and16s rRNA amplicon sequencing were assessed to examine the links between the soil microbial communities and short-term soil direct N 2 O emissions when treated with agricultural waste. The highest soil direct N 2 O emissions were recorded in soils that had received ammonium nitrate while soils that had received agricultural waste exhibited substantially lower soil direct N 2 O emissions. On the contrary, agricultural waste stimulated CO 2 68 AGROBIOTECHNOLOGY