Search

The combined application of manure and chemical fertilizers has been recognized as a critical factor driving significant changes in crop yield and nutrient use efficiency, holding the potential to optimize agricultural management to achieve high yields. In this 40-year study, we investigated the effect of manure amendment on soybean and maize yields, water and nitrogen use efficiencies (WUE and NUE), and water and mineral N storage at 0–100 cm soil depths from 2017 to 2018 to explore the optimization of fertilization management strategies for soybean and maize production in Northeast China. To elucidate the impact of chemical fertilizers and manure, twelve treatments—control (CK); single N fertilizer at a low rate (N1) and that at a high rate (N2); N1, phosphorus (P), and potassium (K) fertilizer (N1PK); manure alone at 13.5 and 27 t ha−1 (M1 and M2); and those combined with N, P, or K fertilizer (M1N1, M1N2, and M1N1PK and M2N1, M2N2, and M2N1PK)—were selected and studied. The results showed that long-term amendment with manure significantly increased crop biomass and yield in the soybean–maize–maize rotation system. Combining with manure increased the WUE, the partial factor productivity of N fertilizer (PFPN), and N physiological efficiency (PEN) in both the soybean and maize seasons; conserved soil water (mainly at 40–60 cm); and increased soil N retention (in the upper 60 cm layer), which reduced the risk of N leaching, with a better effect being observed after the application of 13.5 t ha−1 manure. These results provide insight into the potential of using fertilization management strategies that include amendment with 13.5 t ha−1 manure in combination with N, P, and K fertilizer in the maize season and only chemical fertilizer in the soybean season, as these results indicate that such strategies can achieve high yields and be used to implement agricultural sustainable development in brown soil regions in Northeast China. [ABSTRACT FROM AUTHOR]

In this study, we assessed the effects of biochar application for five years on soil phosphorus (P) factions by chemical sequential P fractionation, phosphatase activity, and 31P NMR. Four treatments were included in this research: two biochar (0 and 2.63 t ha−1) levels blended with two P fertilizer levels (0 and 26 kg P ha−1), respectively. We found elevated levels of soil pH, total carbon (C), and total P in soil exposed to biochar. The inorganic (Ca8 – P, Al – P, Fe – P, and Ca10 – P) and organic (LOP and HROP) P fractions were all enhanced by biochar regardless of the application of P fertiliser. 31P NMR spectra further showed that ortho – P, monoester – P, and diester – P levels in the soil with added biochar combined with P fertiliser were 464.5 mg kg−1, 74.3 mg kg−1, and 13.9 mg kg−1, respectively, which were the highest among all treatments. Biochar application increased alkaline phosphomonoesterase activity by 24.4–32.7% and decreased phosphodiesterase activity by 10.2–11.0%. In conclusion, biochar application significantly improves soil P fractions and regulates phosphatase activity. [ABSTRACT FROM AUTHOR]

The northern South China Sea is subject to an increasing influence of aerosol loading, particularly over the past decades owing to the fast economic growth of mainland China. To study the response of the coastal phytoplankton community to atmospheric deposition, we performed onboard microcosm experiments at various coastal regions of the northern South China Sea, including a river plume zone and the two major upwelling zones. We found that the addition of aerosol and rainwater significantly increased the micro‐phytoplankton size‐fraction by 2.3–5.4‐folds regardless of the type of preexisting nutrient limitation in the phytoplankton community. There were three types of distinct responses to the manipulation additions observed: positive, negligible, or even negative effects. A significant inhibition effect (27–74% decrease) in the Qiongdong upwelling zone could be attributed to elevated metal toxicity on the phytoplankton community seeding from the subsurface after it had been brought up to the surface due to an outcrop of the thermocline. While Prochlorococcus growth was uniformly inhibited by the additions, both positive and negative effects were observed for the remainder of the picoplankton community. P‐limited Synechococcus was stimulated by aerosol and rainwater additions (1.2–2.8‐folds increase), whereas N‐limited Synechococcus was inhibited (decreased by 9–28%). Our results suggest that coastal phytoplankton responses to atmospheric depositions are regulated by both the fertilizing effects of aerosol nutrients and the toxic effects of aerosol metals. Our findings highlight the critical role of atmospheric depositions on spatial change of phytoplankton biomass and community structure in the coastal ocean, which could greatly affect ecosystem dynamics and biogeochemical cycles of the shelf sea. [ABSTRACT FROM AUTHOR]

Objective: The present study aims to isolate and identify actinobacteria associated with the soft coral Nephthea sp., and to isolate natural products from these actinobacteria under the guidance of PCR screening for polyketides synthase (PKS) genes., Methods: Eleven selective media were used to isolate actinobacteria associated with the soft coral Nephthea sp. collected from Yongxin Island. The isolated actinobacteria were classified on the basis of phylogenetic tree analysis of their 16S rRNA genes. Degenerated primers targeted on conserved KS (ketoacyl-synthase) domain of type I PKS genes were used to screen for potential isolates. The positive isolates were cultured in three different media to check their producing profiles. One bioactive strain that is rich in metabolites was subjected to larger scale fermentation for isolating bioactive natural products., Results: A total of 20 strains were isolated from Nephthea sp., and were categorized into 3 genera including Streptomyces, Dietzia and Salinospora, among which 18 strains were positive in screening with type I PKS genes. Two bioactive compounds rifamycin S and rifamycin W were isolated and identified from Salinospora arenicola SH04., Conclusion: This is the first report of isolating indigenous marine actinobacteria Salinospora from the soft coral Nephthea sp. It provides an example of isolating bioactive secondary metabolites from cultivable actinobacteria associated with Nephthea sp. by PCR screening.

Objective: To investigate the chemical constituents of an endophytic fungus, Nodulisporium sp. A4, from the medicinal plant Aquilaria sinensis and search for antitumor natural products., Method: The fungus was cultured in liquid medium and extracted with EtOAc. The compounds were isolated by various chromatographic methods (silica gel, reverse silica gel, Sephadex-LH20, preparative TLC and so on) and recrystallization. Structural elucidation was conducted by extensive analysis of spectroscopic data as well as by comparison with literature reports. The antitumor activity of isolated compounds was tested by MTT method in vitro., Result: Seven compounds were isolated and identified from the broth culture, their structures were determined to be 5-methyl-2-vinyltetrahydrofuran-3-ol (1), 6-methyl-2-(5-methyl-5-vinyltetrahydrofuran-2-yl) hept-5-en-2-ol (2), 6alpha-hydroxycyclonerolidol (3), rel-(1S,4S, 5R,7R,10R)-10-desmethyl-1-methyl-11-eudesmene (4), tyrosol (5), 8-methoxynaphthalen-1-ol (6), and 1,8-dimethoxynaphthalene (7). Three compounds were isolated and identified from the mycelia as ergosterol (8), ergosterol peroxide (9), and cerevisterol (10). The in vitro pharmalogical evaluation results displayed that compounds 3 and 4 showed 89.1%, 44.2% and 82.3%, 79.8% inhibition against tumor cell lines SF268 and NCI-H460 at 100 mg x L(-1), respectively., Conclusion: Compound 1 was a new natural product, compounds 2, 3, 7 and 10 were reported from the genus Nodulisporium sp. for the first time. Compounds 3 and 4 exhibited weak inhibitory effects on the proliferation of tumor cell lines SF268 and NCI-H460.