Priming effects on labile and stable soil organic carbon decomposition: Pulse dynamics over two years.

Soil organic carbon (SOC) is a major component in the global carbon cycle. Yet how input of plant litter may influence the loss of SOC through a phenomenon called priming effect remains highly uncertain. Most published results about the priming effect came from short-term investigations for a few weeks or at the most for a few months in duration. The priming effect has not been studied at the annual time scale. In this study for 815 days, we investigated the priming effect of added maize leaves on SOC decomposition of two soil types and two treatments (bare fallow for 23 years, and adjacent old-field, represent stable and relatively labile SOC, respectively) of SOC stabilities within each soil type, using a natural 13C-isotope method. Results showed that the variation of the priming effect through time had three distinctive phases for all soils: (1) a strong negative priming phase during the first period (≈0-90 days); (2) a pulse of positive priming phase in the middle (≈70-160 and 140-350 days for soils from Hailun and Shenyang stations, respectively); and (3) a relatively stabilized phase of priming during the last stage of the incubation (>160 days and >350 days for soils from Hailun and Shenyang stations, respectively). Because of major differences in soil properties, the two soil types produced different cumulative priming effects at the end of the experiment, a positive priming effect of 3-7% for the Mollisol and a negative priming effect of 4-8% for the Alfisol. Although soil types and measurement times modulated most of the variability of the priming effect, relative SOC stabilities also influenced the priming effect for a particular soil type and at a particular dynamic phase. The stable SOC from the bare fallow treatment tended to produce a narrower variability during the first phase of negative priming and also during the second phase of positive priming. Averaged over the entire experiment, the stable SOC (i.e., the bare fallow) was at least as responsive to priming as the relatively labile SOC (i.e., the old-field) if not more responsive. The annual time scale of our experiment allowed us to demonstrate the three distinctive phases of the priming effect. Our results highlight the importance of studying the priming effect by investigating the temporal dynamics over longer time scales

Response of Soil Fungal Community Structure to Long-Term Continuous Soybean Cropping

Long-term continuous soybean cropping can lead to the aggravation of soil fungal disease. However, the manner in which the fungal community and functional groups of fungi are affected by continuous soybean cropping remains unclear. We investigated the fungal abundance, composition and diversity during soybean rotation (RS), 2-year (SS) and long-term (CS) continuous soybean cropping systems using quantitative real-time PCR and high-throughput sequencing. The results showed that the fungal abundance was significantly higher in CS than in SS and RS. CS altered the fungal composition. Compared with RS, SS had an increase of 29 and a decrease of 12 genera in fungal relative abundance, and CS increased 38 and decreased 17 genera. The Shannon index was significantly higher in CS and SS than in RS. The result of principal coordinate analysis (PCoA) showed that CS and SS grouped together and were clearly separated from RS on the PCoA1. A total of 32 features accounted for the differences in fungal composition across RS, SS, and CS. The relative abundance of 10 potentially pathogenic and 10 potentially beneficial fungi changed, and most of their relative abundances dramatically increased in SS and CS compared with RS. Our study indicated that CS results in selective stress on pathogenic and beneficial fungi and causes the development of the fungal community structure that is antagonistic to plant health

Utility of S100A12 as an Early Biomarker in Patients With ST-Segment Elevation Myocardial Infarction

Importance: S100A12 is a calcium binding protein which is involved in inflammation and progression of atherosclerosis. Objective: We sought to investigate the utility of S100A12 as a biomarker for the early diagnosis and prognostication of patients presenting with ST-segment elevation myocardial infarction (STEMI). Design, Setting, and Participants: S100A12 was measured in 1023 patients presenting to the emergency department with acute chest pain between June 2012 and November 2015. An independent cohort of 398 patients enrolled at 3 different hospitals served as a validation cohort. Main Outcomes and Measures: The primary clinical endpoint of interest was major adverse cardiac and cerebral events (MACCE) defined as a composite of all-cause death, MI, stroke, or hospitalization for heart failure. Results: A total of 438/1023 patients (42.8%) in the diagnosis cohort were adjudicated as STEMI, among whom plasma S100A12 levels increased within 30 min and peaked 1–2 h after symptom onset. Compared with high-sensitivity cardiac troponin T and creatine kinase-MB isoenzyme, S100A12 more accurately identified STEMI, especially within the first 2 h after symptom onset (area under the curve 0.963 compared with 0.860 for hscTnT and 0.711 for CK-MB, both P \u3c 0.05). These results were consistent in the 243-patient validation cohort. The 1-year rate of MACCE was greatest in patients in the highest peak S100A12 tertile, intermediate in the middle tertile and least in the lowest tertile (9.3 vs. 5.7 vs. 3.0% respectively, Ptrend = 0.0006). By multivariable analysis the peak plasma concentration of S100A12 was an independent predictor of MACCE within 1 year after STEMI (HR, 1.001, 95%CI, 1.000–1.002; P = 0.0104). Zhang et al. S100A12 as a STEMI Biomarker Conclusions and Relevance: S100A12 rapidly identified patients with STEMI, more accurately than other cardiac biomarkers, especially within the first 2 h after symptom onset. The peak plasma S100A12 level was a strong predictor of 1-year prognosis after STEMI

Two ultraviolet radiation datasets that cover China

Ultraviolet (UV) radiation has significant effects on ecosystems, environments, and human health, as well as atmospheric processes and climate change. Two ultraviolet radiation datasets are described in this paper. One contains hourly observations of UV radiation measured at 40 Chinese Ecosystem Research Network stations from 2005 to 2015. CUV3 broadband radiometers were used to observe the UV radiation, with an accuracy of 5%, which meets the World Meteorology Organization's measurement standards. The extremum method was used to control the quality of the measured datasets. The other dataset contains daily cumulative UV radiation estimates that were calculated using an all-sky estimation model combined with a hybrid model. The reconstructed daily UV radiation data span from 1961 to 2014. The mean absolute bias error and root-mean-square error are smaller than 30% at most stations, and most of the mean bias error values are negative, which indicates underestimation of the UV radiation intensity. These datasets can improve our basic knowledge of the spatial and temporal variations in UV radiation. Additionally, these datasets can be used in studies of potential ozone formation and atmospheric oxidation, as well as simulations of ecological processes

Characterization of carbon and nitrogen distributed in density fractions and humic substances from oxisols under different land uses in the atlantic forest biome in southeast brazil

Foram caracterizados carbono e nitrogênio orgânicos de três horizontes superficiais de latossolos sob diferentes usos no município de Juiz de Fora, Minas Gerais. A metodologia se baseou na extração do carbono usando uma solução de NaI com densidade de 1,8 g.cm-3 para separação das frações leve livre, leve oclusa e pesada. Concluiu-se que o carbono orgânico predomina na fração pesada e que o cultivo diminuiu o carbono orgânico em todos os latossolos estudados. A fração leve livre predominou na mata secundária, destacando essa fração como um indicador ecológico importante. A humina da fração pesada mostrou-se como uma efetiva seqüestradora do carbono orgânico. Palavras chave: carbono orgânico do solo, frações de densidade do carbono, carbono em latossolos

Effect of fertilization on yield of soybean in rotation and continuous cropping in Northeast China

Macro- and micronutrients are both important for growth, nodulation and nitrogen (N2) fixation of soybean, especially when this species is grown under continuous cropping. In China’s continuous soybean systems nutrient uptake and transport as well as diazotrophic N2 fixation had been found to be severely hampered by the incidence of diseases, insect pests or exudates from roots and microorganisms which can be overcome by increased soil nutrient concentrations. In this paper results from a three-year field experiment are presented that was conducted to study the effects of different levels of macronutrients (N, P and K) and micronutrients (Zn, Mn, B, Mo and Mg) on the yield of soybean under continuous and rotation cropping. The results showed that compared to the unfertilized control the application of N fertilizer can increase yields of continuous soybean by 98%, of P by 89%, of K by 26%, and of Zn, Mn, B, and Mg by 17%, 13%, 1% and 15%, respectively

Effect of fertilization on yield of soybean in rotation and continuous cropping in Northeast China

Macro- and micronutrients are both important for growth, nodulation and nitrogen (N2) fixation of soybean, especially when this species is grown under continuous cropping. In China’s continuous soybean systems nutrient uptake and transport as well as diazotrophic N2 fixation had been found to be severely hampered by the incidence of diseases, insect pests or exudates from roots and microorganisms which can be overcome by increased soil nutrient concentrations. In this paper results from a three-year field experiment are presented that was conducted to study the effects of different levels of macronutrients (N, P and K) and micronutrients (Zn, Mn, B, Mo and Mg) on the yield of soybean under continuous and rotation cropping. The results showed that compared to the unfertilized control the application of N fertilizer can increase yields of continuous soybean by 98%, of P by 89%, of K by 26%, and of Zn, Mn, B, and Mg by 17%, 13%, 1% and 15%, respectively

Response of Soybean Yield to Daytime Temperature Change during Seed Filling: A Long-Term Field Study in Northeast China

Daytime temperature during seed filling is a crucial determinant of grain yield in pulse crops. Although there is much research about the effect of daytime temperature during seed filling on soybean yield in temperature-controlled chambers, the effect in the field has been little explored. Long-term manipulative field experiments are important tools to provide accurate information for revealing the impacts of climate change on crop yields. Using the field records of a long-term fertilization experiment conducted in Northeast China, we analyzed the response of soybean yields to mean daily maximum temperature during seed filling over the period 1987−2007. The results showed that there was a clear positive response of soybean yields to increased mean daily maximum temperature during seed filling ranged from 20 to 24ºC. When compared with the average soybean yields over the last two decades, grain yields increased by 6−10% for each 1ºC increase in mean daily maximum temperature during seed filling and more than 22% of yield trends can be explained. These findings provide a direct evidence for the response of soybean yield to climate change in the field study