In order to reduce soil and environmental quality degradation associated with the use of synthetic nitrogen (N), substituting chemical fertilizer with organic or bio-organic fertilizer has become an increasingly popular option. However, components of this fertilizer strategy related to mitigation of soil N-oxide emissions and maintenance of crop yield remain uncertain. Here, we evaluated the effects of three different fertilizer strategies, with equal amounts of N, on nitrous oxide (N 2 O) and nitric oxide (NO) emissions, vegetable yield, and yield-scaled N 2 O and NO emissions under three consecutive cucumber growing seasons. The three treatments were chemical fertilizer (NPK, urea), organic fertilizer (O, composted cattle manure), and bio-organic fertilizer (O+T, O combined with Trichoderma.spp). Results showed that the NPK plot had the highest area-scaled emissions of N 2 O (13.1±0.48 kg N ha -1 yr -1 ) and NO (5.01±0.34 kg N ha -1 yr -1 ), which were 1.3-1.4 and 3.1-3.7 times greater than the O and O+T plots, respectively. The annual direct emission factors for N 2 O and NO were 2.08% and 0.92% for the NPK plot, which declined to 1.34% and 0.09% in the O plot, and 1.12% and 0.03% in the O+T plot, respectively. The annual vegetable yield was 117±2.9 t ha -1 for NPK plot and 122±2.0 t ha -1 for O + T plot, which was higher than 111±1.7 t ha -1 for O plot. The yield-scaled N 2 O+NO emissions differed significantly with fertilization treatment, with the lowest value observed in the O+T plot. We attributed the lower soil N-oxide emissions following organic fertilizer application to the slow release of available N and enhanced denitrification caused by the increase of soil dissolved organic carbon and pH. Compared with the use of organic fertilizer alone, the addition of Trichoderma.spp significantly increased the potential denitrification rate but decreased N 2 O emissions, which

Aims Soil aggregate is the main habitat for decomposition and transformation of soil organic carbon (SOC) and is important to regulate SOC sequestration. The mechanisms of the stability of SOC fractions may vary among different aggregate sizes. The aims of this study were to explore the characteristics of SOC "fractionation" in soil aggregates, and to reveal the mechanisms of carbon (C) sequestration in soil aggregates of mollisols after 31-year changes in vegetation cover. Methods A long-term field experiment with different vegetation cover (grassland, farmland and bareland) was established in National Observation Station of Hailun Agro-ecosystem System. Soil aggregate fractionation, the density and humus fractionation within different aggregate sizes were further carried out. Important findings The results showed that after 31 years of land cover change, the surface SOC and total nitrogen (TN) contents in grassland with higher C inputs increased significantly with time, while the SOC and TN contents decreased significantly in bareland, but with no statistical significance in farmland. The 2-0.25 mm (include 2 mm, the same below) aggregates was the excellent fraction for SOC sequestration under all three land cover. The stability of soil aggregate was in the order of: grassland > farmland > bareland. The mass proportion of

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