Sustained rice yields and decreased N runoff in a rice-wheat cropping system by replacing wheat with Chinese milk vetch and sharply reducing fertilizer use.

Pollution from the paddy fields has posed a threat to surface water quality, and the reactive N in runoff has been recognized as the dominant contributor. In the rice-wheat systems of eastern China, replacing wheat (Triticum aestivum) with Chinese milk vetch (CMV) (Astragalus sinicus) is known to reduce total fertilizer N use and associated N losses during winter; however, the function of the rice-CMV system in controlling the N runoff loss was overlooked during the summer rice-growing season. Over 6 years, we monitored soil mineral N, plant N accumulation, rice grain yield, N agronomic efficiency (AEN), and N runoff in rice-CMV fertilizer N rate-response experiments and made comparisons with the conventional N inputs in rice-wheat rotation. Aboveground CMV residues added 65-116 kg N ha-1 yr-1; therefore, by adjusting the fertilizer time, the rice in this system required 44-56% less N fertilizer to produce rice yields equivalent to the 270 kg N ha-1 (district average, C270) used in the rice-wheat system. In all fertilizer N application treatments, 120 kg ha-1 seemed to be the threshold that ensured the soil N supply, the N accumulation at rice critical stages, and consequently, the current level rice yield. The corresponding runoff N averaged 9.3 kg ha-1 season-1, which was 51.8% less than that in C270 (19.3 kg ha-1 season-1). Cumulative N runoff (total N and NH4+-N) correlated strongly with fertilizer N input for any single year (sample size = 108, P < 0.01). Application of 30-120 kg fertilizer N ha-1 gave an equivalent AEN, which indicated that the integration of CMV and fertilizer N could increase the agronomic efficiency of N fertilizer applied to the rice. Rotating paddy rice with CMV instead of wheat, together with the suitable adjustment of N fertilizer, could sustain rice yield and gain the utmost environmental benefits from rice-based agroecosystems.

Arsenic immobilization through regulated ferrolysis in paddy field amendment with bismuth impregnated biochar.

Iron minerals are important for arsenic immobilization in paddy fields; however, intensive ferrolysis causes arsenic (As) release. Bismuth-impregnated biochar derived from wheat straw (BiBC) was synthesized to immobilize arsenic by regulating the ferrolysis process in a paddy field. Further X-ray based analysis (XRD and XPS) results demonstrated that crystal particles of bismuth oxide and bismuth oxychloride were loaded on the biochar surface, helped create additional micropores and improved its specific surface area. The bioavailability of As, as determined via (non)specifically adsorbed As, decreased as the amended dosage of BiBC increased, while wheat straw biochar (WBC) resulted in arsenic release. The presence of biochar caused a faster reduction rate of iron oxides; however, BiBC promoted the sequential co-precipitation of iron and arsenic ions. Adsorption kinetic experiments indicated that ferrous ions facilitated precipitation of As on the surface of BiBC. The XRD analysis of soil samples showed BiBC facilitated the formation/stability of FeOOH. Thus, amendment with BiBC regulated ferrolysis to buffer iron leaching, which contributed to arsenic immobilization under flooding conditions. This study demonstrated the feasibility of As immobilization by metal-impregnated biochar in paddy soils.

Synthesis of mesoporous bismuth-impregnated aluminum oxide for arsenic removal: Adsorption mechanism study and application to a lab-scale column.

High mobility and toxicity of arsenic [As (III)] limit its removal from an aquatic environment and pose a threat to human health. In this work, batch adsorption experiments were conducted to investigate the adsorption capacity of bismuth-impregnated aluminum oxide (BiAl). Continuous application of As (III) removal was achieved via a lab-scale column reactor. Bismuth impregnation decreased the specific surface area of aluminum oxide and affected its pore size distribution. However, because of its abundant and well-proportioned mesoporous character, it also enhanced its adsorption capacity through the surface complexation of As (III). Batch adsorption experiments demonstrated a suitable Freundlich model and a fitted pseudo-second-kinetic model for As (III) adsorption. The main mechanism was chemisorption with both bismuth and aluminum atoms; however, physisorption also contributed to arsenic adsorption at the initial stage of the reaction. The Adams-Bohart model better described the breakthrough curves than the Thomas model. BiAl exhibited efficient As (III) adsorption over a wide pH range and could be applied to As (III) removal from wastewater. A high As (III) removal efficiency (91.6%) was obtained at an initial As (III) concentration of 5 mg L-1 at a flow rate of 1 mL min-1. This study indicates the potential for the practical application of BiAl in As (III) removal.

Assessment of Surgery Resident Competency Provided by Patients.

The objective of this study was to assess the competency of surgery residents from the patient perspective in the current healthcare environment in China. The authors performed an assessment of 508 surgery residents in Liaoning province. Seven patients were as a group to complete the self-administered questionnaires on the survey for each individual corresponding resident. A 5-point rating scale with an unable-to-evaluate category was used to assess surgery resident competency by patients. Reliability and validity were assessed by Cronbach alpha (α) and exploratory factor analysis, respectively. Statistical analysis was performed using SPSS 13.0. The surveys on 421 residents were valid, and the valid response rate was 82.8%. A total of 2947 questionnaires from patients were analyzed in this study. The Cronbach α coefficient was 0.92. The 4 factors emerging in the exploratory factor analysis reached a cumulative contribution rate of 66.98%. The items of "promotes health maintenance (talks about preventive care)" (206/7.0%), "tells me about any side effects of the medicine" (177/6.0%), "spends enough time with me" (189/6.4%), and "answers my questions thoroughly" (168/5.7%) were scored <4 by higher percentage of patients. The instrument provided an acceptable means for patients to evaluate the competency of Chinese surgery residents. Surgery residents should improve their competencies on preventive care, patient safety, and communication skills.

Adsorption of arsenic, phosphorus and chromium by bismuth impregnated biochar: Adsorption mechanism and depleted adsorbent utilization.

Bismuth impregnated biochar were synthesized to deal with wastewater pollution. Nitrogen adsorption-desorption isotherms, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) were used to determine the characteristics of adsorbents and explore the main adsorption mechanism. Results showed that bismuth particle was carried successfully within the biochar matrix, making contributions to creating micropore and boost specific surface area. The loaded bismuth, served as the adsorption site, rather than the specific surface area played an important role in arsenic and phosphorus adsorption. Batch adsorption experiments demonstrated a fit Langmuir model for arsenic (As) and phosphorus (P) and a suitable Freundlich model for chromium (Cr). Thermodynamic parameters depicted the endothermic nature and the spontaneous process for phosphate and arsenic adsorption. Besides, this contaminant-loaded carbon adsorbent was further applied for the removal of methylene blue from aqueous solution.

[Further reduction of nitrogen fertilizer application in paddy field under green manuring of Taihu Area, China].

This study focused on the nitrogen loss via runoff, change of nitrogen in different forms in surface water in paddy field, and grain yield, through further reduction of nitrogen fertilizer application rate under green manuring without basal dressing. Results showed that with 150 kg · hm(-2) inorganic N fertilizer input after return of green manure to soil, no basal dressing could not only sharply reduce N concentration in surface water and decrease 17.2% of N loss, but also increase 2.8% of grain yield in comparison with basal dressing. It was a worthwhile farming method that inorganic nitrogen fertilizer was not used for basal dressing but for topdressing after return of green ma- nure to soil in Taihu Area. However, the grain yield would decrease if the rate of topdressing nitro- gen was excessively reduced or increased. After all, it was feasible to realize harmonization of grain yield and environmental benefits in Taihu Area, with 133 kg · hm(-2) inorganic N fertilizer input after return of green manure to soil as well as no application of basal dressing, which could greatly reduce N fertilizer input and N loss as well as ensure rice yield.

[Effects of nutrient and water regimes on lodging resistance of rice].

A field experiment was conducted to study the effects of nutrient and water regimes on lodging resistance of rice plant by measuring and comparing the morphological and physical traits and the K2O and SiO2 contents of rice basal stems. The results indicated that a combined application of chemical fertilizers and organic materials, especially and rice straw (CS), could markedly increase the diameter, wall thickness and weight of basal stems, but reduce plant height, which resulted in the effective increase of snapping resistance (RS) and marked decrease of lodging index (LI). The effectiveness of the combined application of chemical fertilizers and rice straw (CS) on the increase of lodging resistance of rice plant was greater in alternate wetting and drying (AWD) and controlled irrigation (DRA), compared to continuous waterlogging (CWL). In addition, the combined application of chemical fertilizers and organic sources, especially with rice straw (CS), greatly increased the K2O and SiO2 contents in rice basal stems, especially in alternate wetting and drying (AWD) and controlled irrigation (DRA). Correlation analysis showed that the wall thickness, weight and snapping resistance of basal stems were significantly positively correlated to the K2O and SiO2 contents in rice basal stems (P<0.05 or P<0.01) in alternate wetting and drying (AWD) and controlled irrigation (DRA).