The stability and size distribution of soil aggregatesisprofoundly affected by land use, but the influencingmechanisms of land use are not clear. Astudy wascarried out to investigate and attempted to interpret the effects of land use on soil aggregates from types of land use and soil properties in soil samples and size fractions of soil aggregates. Soil samples were taken from 9 sites under paddy, forest, and upland in southern China. Thewet-sievingmethod was used to obtain 6 size fractions of soil aggregates: >5, 5~2, 2~1, 1~0.5, 0.5~0.25, and <0.25mm. The stability and size distribution of soil aggregates was measured as mean weight diameter (MWD),the percentage of water-stable aggregate (WSA) and the percentage of each size fraction (PSA). The quantities of soil organic carbon (SOC), humic substances, dithionite-citrate-bicarbonate (DCB) and oxalate extractable iron (Fe) and aluminum (Al) oxides were also measured. The results showed that types of land use solely explained66.6% variation of soil aggregates;SOC, DCB-extractable Fe and Al oxides, and oxalate-extractable Al oxide caused 84.3% variation, in which SOC contributed29.0%, Fe and Al oxides contributed33.8%, and their interactions contributed 21.4%. The multiple linear regression and partial correlation analysis showed that soil organic matterandFe and Al oxides had significant effects but played different roles on the stability and size distributionof soil aggregates. The study suggests that land use affects the stability and size distribution of soil aggregates through the integration of soil organic matter and Fe and Al oxides.

Commonly consumed honeys from sixteen different single floral sources were analyzed for their in vitro antioxidant capacities by several methods including DPPH, ABTS, FRAP, SASR and MDA assays. The total polyphenol contents varied among the tested honeys and were highly correlated to their antioxidant capacity values. The antioxidant capacity of Chinese milk vetch flower honeys was significantly higher than those of other flower honeys. All honeys tested were active in inhibiting the browning of apple homogenate and linden honey displayed the highest inhibition rate as 85%. When the antimicrobial activity of the investigated honeys was screened using Gram-positive bacteria (Staphylococcus aureus) and Gram-negative bacteria (Escherichia coli), clover honey exhibited the strongest antibacterial activity as 2.2 mg mL(-1) kanamycin equivalent inhibition.

Core Ideas Litter addition increased C decomposition. Litter properties were more important than abiotic soil properties in controlling C decomposition. N addition would increase decomposition of SOC with added litter and decrease SOC accumulation by altering litter quality. In grassland ecosystems, nitrogen (N)‐induced changes in plant community often affect grassland soil organic carbon (SOC) decomposition and accumulation. However, there is no consensus on the biological and chemical mechanisms that underlie the response of SOC decomposition to N‐addition. In this study, we did a litter addition experiment to study the decomposition of SOC with added litter of six dominant plant species collected from N alone or N combined with phosphorus (N+P) fertilization treatments in a 7‐yr field experiment. The experiment showed that there were no consistent responses of plant chemical properties to N alone or N+P addition. Fertilization altered plants species' dominance in community, in particular the grass Elymus nutans. Litter addition significantly increased C decomposition, with the highest decomposition rates of SOC with added litter of all six plant species in N+P treatment. In general, both plant litter properties of organic C, total N (TN), lignin concentrations, and soil properties of SOC and TN, but not soil microbial biomass C, were the main factors determining cumulative decomposition of SOC with added litter. Litter properties were more important than abiotic soil properties in controlling C decomposition. This study indicated that fertilization with N alone or N+P can increase decomposition of SOC with added litter and lower SOC accumulation through changes in plant species' dominance and chemical properties of litter. In terms of maintaining high SOC and increasing soil C, N fertilization, whether in N alone or N+P, should not be used in these alpine meadows.

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