Impacts of abandoned sloping farmland on soil aggregates and aggregate-associated organic carbon in karst rocky desertification areas.

Vegetation restoration after the abandonment of sloping farmland can effectively promote the sequestration of soil organic carbon (SOC), with soil aggregates playing a pivotal role. However, in abandoned farmlands in karst regions with varying degrees of rocky desertification, the relationship between soil aggregates, aggregate-associated organic carbon (AAOC), and total SOC content remains unclear. Taking abandoned sloping farmlands (5 years, 10 years, and 15 years) with different levels of rocky desertification (no rocky desertification, potential rocky desertification, slight rocky desertification, and moderate rocky desertification) in a typical karst area as research objects, this study investigated the dynamic characteristics of the particle size distribution of soil aggregates, total SOC, and AAOC. The results indicated that total SOC content in the 0-20 cm soil layer increased after abandonment in all levels of rocky desertification, peaking after 15 years. The abandoned sloping farmland with moderate desertification showed the best recovery effect. Post-abandonment vegetation restoration increased the content of 5-10 mm soil aggregates, but decreased those of 1-2 mm and < 0.25 mm aggregates. Particularly for 5-10 mm aggregates, the contribution of AAOC to total SOC significantly increased over time. Moreover, a strong correlation was observed between >1 mm aggregates and total SOC (p < 0.05). The increase in total SOC was primarily driven by the growth of AAOC in 5-10 mm aggregates. In general, vegetation restoration is an effective approach for enhancing total SOC content in abandoned sloping farmland with varying degrees of rocky desertification.

[Application of oxytocin antagonists in thaw embryo transfer].

OBJECTIVE: To study the effects of oxytocin antagonists-atosiban on pregnancy outcome after thaw embryo transfer (TET). METHODS: Between Jul. and Dec. 2012, a total of 120 women undergoing TET in Reproductive Medical Center, General Hospital of Tianjin Medical University were randomly allocated into atosiban and control group. They were all transferred 2 or 3 top quality embryos at phase of 7-8 cells . Patients in atosiban group were administered by intravenous administration of atosiban before 30 minutes of embryo transfer with a total administered dose of 37.5 mg. In the control group, no special treatment was given before embryo transfer. All patients in 2 groups underwent progesterone luteal support regularly after embryo transfer, then the clinical rate of pregnancy, implantation and early abortion was compared. RESULTS: The clinical pregnancy rate per cycle and implantation rate per transfer were 60% (36/60) and 30.0% (48/160) in the atosiban group, which were higher than 42% (25/60) and 20.3% (31/153) in the control group (all P < 0.05). Early abortion rate was 6% (2/36) in the atosiban group, which was no statistical difference comapring with control group [16% (4/25), P > 0.05]. CONCLUSION: It was suggested that atosiban treatment before embryo transfer can improve the outcome of pregnancy, and increase clinical pregnancy rate and implantation rate after TET.