This is the accepted version of the following article: Wang, Chun et al. "Effect of simulated acid rain on CO2, CH4 and N2O fluxes and rice productivity in a subtropical Chinese paddy field".
Industrial wastes and agricultural byproducts are increasingly used in crop production as fertilizers, but their impacts on soil carbon (C) sequestration remain poorly understood. The aim of this study was to examine the effects of applying steel slag (SS), biochar (B), and a combination of these two materials (SS + B) on total soil organic C (SOC), active SOC fractions, and C pool management index (CPMI) in a subtropical paddy field in China. The treatments were applied at a rate of 8 t ha−1 to rice at the two (early and late) crop seasons in 2015. The SOC concentrations in the top 30 cm soils in the SS + B treatments were 28.7% and 42.2% higher in the early and late crops, respectively, as compared to the controls (p < 0.05). SOC was positively correlated with soil C:N ratio across the two crop seasons (r = 0.92–0.97, p < 0.01). As compared to the control, SS + B treatment had significantly higher carbon pool index (CPI) in both early (22.4%) and late (40.1%) crops. In the early crop, the C pool activity index (CPAI) was significantly lower in B and SS + B treatments by over 50% than in the control, while the soil C pool management index (CPMI) in the SS, B, and SS + B treatments was lower than that in the control by 36.7%, 41.6%, and 45.4%, respectively. In contrast, in the late crop, no significant differences in CPAI and CPMI were observed among the treatments. Our findings suggest that the addition of steel slag and biochar in subtropical paddy fields could decrease active SOC pools and enhance soil C sequestration only in the early crop, but not the late crop.
Environmental bacteria have been revealed to be a reservoir of antibiotic resistance genes and a potential pool of novel resistance genes in clinical pathogens. Recently, the soils, which have never been treated with antibiotics before have proved to contain the resistant bacterial strains. In this study, we assessed whether the soil that had not previously been influenced by antibiotics contained super-resistant bacteria or not. We identified super penicillin-resistant strains in four diverse soils containing up to 1000 mg/L penicillin compared to 100 mg/L, but none of super tetracycline resistant strains were detected in four soils containing up to 1000 mg/L tetracycline, which is the highest concentration of exogenous penicillin or tetracycline reported to date. Twenty bacterial isolates were selected, representing a diverse set of species in the genera Pseudomonas (85%) and Variovorax (15%); these bacteria showed multiple antibiotic resistance patterns for four or more antibiotics. Using polymerase chain reaction and sequence, we carefully examined the existence of antibiotic-resistance genes and integron genes in soils and strains. It was observed that the resistance genes tet(C) and blaTEM were fairly widely distributed in these super penicillin-resistant isolates, and 20%-50% of tested genes were found in the study soils. All the study sites provided great opportunities for horizontal resistance transfer. The antibiotic-resistant genes pool, which is potentially large and diverse, may have considerable implications for ecology and health.
In agriculture, synthetic fertilizers have played a key role in enhancing food production and keeping the world’s population adequately fed. China’s participation is essential to global efforts in reducing greenhouse gas (GHG) emissions because it is the largest producer and consumer of synthetic fertilizers. A field experiment was conducted in a Jasminum sambac (L.) field to evaluate the impact different doses of fertilizers (half, standard, and double) and their combination with straw on ecosystem (including crop plants and soil) GHG emissions. The results showed that in comparison with the control or straw treatments, the straw + standard fertilizer treatment increased the soil water content. The fertilizer treatments decreased the soil pH, but the straw and combination treatments, especially the straw + standard fertilizer treatment, had higher soil pH in comparison with the fertilizer treatment. The active soil Fe (Fe2+ and Fe3+) concentration was slightly increased in the straw + standard fertilizer treatment in comparison with the control. Moreover, fertilizer increased the CO2 emission, and we detected a positive interaction between the straw application and the double fertilization dose that increased CO2 emission, but the straw + standard fertilizer treatment decreased it. Fertilizer decreased CH4 and N2O emissions, but when straw and fertilizer treatments were applied together, this increased CH4 and N2O emissions. Overall, considering the soil properties and GHG emissions, the straw + standard fertilizer treatment was the best method to enhance soil water retention capacity, improve soil acid, and mitigate greenhouse gas emissions for sustainable management of J. sambac dry croplands.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.