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Water management affects NH 3 emission in complex ways due to its influence on nitrogen transformation and movement. This study aimed to determine the effect of irrigation timing on NH 3 emission from urea at different initial moistures. A pot experiment was conducted based on three typical soils (Fluvisols, Cambisols, and Luvisols) in the North China Plain. Each soil was treated to three levels of initial moisture (5%, 10%, and 15% w/w) and irrigated with 40 mm water 0, 6, and 12 hr after applying urea. The results showed that NH 3 loss ranged from 0.2 to 14.2 kg N ha À1 , with the greatest loss in Fluvisols, followed by Cambisols, and the lowest in Luvisols. The loss of NH 3 increased with initial moisture for all three soils. But there was no significant effect of irrigation time on NH 3 emission, although the contents of NH 4 + in surface soil were higher for delayed irrigation than for immediate irrigation. Additionally, the NO 3 À content was increased in Luvisols with delayed irrigation at a high initial water content, which may have promoted leaching. Therefore, delaying irrigation by up to 12 hr did not cause a significant increase in NH 3 emission. However, fertilization and irrigation should be carried out with lower moisture, especially for Luvisols to prevent ammonia emission or nitrate leaching.

In order to explore a set of summer corn water and fertilizer management scheme suitable for Shandong region. The effects of dry matter, yield and fertilizer partial productivity management of summer maize under different irrigation amount (69.5 mm,120.5mm, recorded as W1, W2), different nitrogen application (143,190,235 kg/hm 2, recorded as N1, N2, N3) and phosphorus (65, 95, 115 as P1, P2, P3) on yield were significant (0.05), among which the comprehensive score of W2N2P2 was much higher than that of other treatments. According to the above analysis, the W2N2P2 treatment can be used as the best water and fertilizer ratio in this study area.

Background: Femoral interlocking intramedullary (IM) nailing fixation is an effective method for the treatment of femoral shaft fractures. Aseptic nonunion of femoral shaft fracture after IM nailing is uncommon. Currently, the treatment for aseptic femoral shaft nonunion is controversial. The aim of this study was to investigate the clinical effect of augmentative antirotational plating plus decortication and autogenic bone grafting for aseptic femoral shaft nonunion after IM nailing failure.Methods: A retrospective study was conducted on 25 cases of aseptic femoral shaft fracture nonunion treated with IM nailing from January 2015 to August 2019. All patients were treated by leaving the nail in situ, debridement of nonunion sites, decortication, autogenous iliac bone grafting, and augmentative antirotational plating fixation. The time to fracture union and complications were recorded.Results: All patients were followed up for 12-18 months. The union rate after revision surgery was 100%. The average union time was 5.5 months (range, 4-10). Subjective pain symptoms had disappeared in all patients. There were no incision infections or internal fixator fatigue fractures. Average scores of the physical function and bodily pain components of the SF-36 were 95.5 (range, 91-98) and 94.1 (range, 90-97), respectively. No other obvious complications occurred postoperatively. Conclusion:Augmentative antirotational plating plus decortication and autogenic bone grafting is an excellent choice for treating femoral shaft fracture nonunion after IM nailing; this approach has an overall high union rate and few complications.

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