Soil organic carbon (SOC) sequestration impacts on food security and climate change and may be affected by soil microbes in fertilized croplands. A 12-year field experiment under the rice–wheat system was used to evaluate the effect of the long-term fertilization on the SOC accumulation, culturable soil microbes, and their interaction in purple paddy soil. Results showed that varied fertilizations resulted in a significant increase of the SOC content and stock in the plow layer, as well as rise in populations of major soil microbes, including bacteria, actinomycetes, and fungi compared with no fertilization. Soil with combined application of chemical NPK fertilizer and organic amendment (pig manure or rice straw return) on average had the highest organic carbon content and stock, amounts of bacteria, actinomycetes, and fungi, which were 7.8%, 5.8%, 75.8%, 130.5%, and 16.2% higher than the NPK fertilization alone. Fertilization differentially altered populations of the functional anaerobic bacteria in paddy soil. With the combined application of chemical NPK fertilizer and organic amendment, soil displayed higher amounts of anaerobic cellulolytic bacteria, anaerobic fermentative bacteria, hydrogen-producing acetogen, methanogenic bacteria, denitrifying bacteria, and sulphate-reducing bacteria than that with the NPK fertilization alone or no fertilization. Populations of all three major soil microbes showed significantly positive correlations with the SOC content, indicating their interaction was of mutual promotion. Data suggest that the combined application of the NPK fertilizer with organic amendment especially by the rice straw return is recommended to sustain the soil biological fertility and mitigate the emission of the greenhouse gas by the SOC sequestration in purple paddy soil. 相似文献
Objectives: In this study, we sought to accomplish the following objectives: to (1) calculate the percentage of children considered appropriately restrained across 8 criteria of increasing restrictiveness; (2) examine agreement between age- and size-based appropriateness criteria; (3) assess for changes in the percentage of children considered appropriately restrained by the 8 criteria between 2011 (shortly after updates to U.S. guidelines) and 2015.Methods: Data from 2 cross-sectional surveys of 928 parents of children younger than 12 years old (n = 591 in 2011, n = 337 in 2015) were analyzed in 2017. Child age, weight, and height were measured at an emergency department visit and used to determine whether the parent-reported child passenger restraint was considered appropriate according to 8 criteria. Age-based criteria were derived from Michigan law and U.S. guidelines. Weight, height, and size-based criteria were derived from typical restraints available in the United States in 2007 and 2011. The percentage appropriate restraint use was calculated for each criterion. The kappa statistic was used to measure agreement between criteria. Change in appropriateness from 2011 to 2015 was assessed with chi-square statistics.Results: Percentage appropriate restraint use varied from a low of 19% for higher weight limits in 2011 to a high of 91% for Michigan law in 2015. Agreement between criteria was slight to moderate. The lowest kappa was for Michigan law and higher weight limits in 2011 (κ = 0.06) and highest for U.S. guidelines and lower weight limits in 2011 (κ = 0.60). Percentage appropriate restraint use was higher in 2015 than 2011 for the following criteria: U.S. guidelines (74 vs. 58%, P < .001), lower weight (57 vs. 47%, P = .005), higher weight (25 vs. 19%, P = .03), greater height (39 vs. 26%, P < .001), and greater size (42 vs. 30%, P = .001).Conclusions: The percentage of children considered to be using an appropriate restraint varied substantially across criteria. Aligning the definition of appropriate restraint use with current U.S. guidelines would increase consistency in reporting results from studies of child passenger safety in the United States. Potential explanations for the increased percentage of children considered appropriately restrained between 2011 and 2015 include adoption of the updated U.S. guidelines and the use of child passenger restraints with higher weight and height limits. 相似文献
Objective: In this study, we assessed the number of child passenger safety technicians (CPSTs) in Michigan over 4 years and characterized the CPST workforce in 2015 to identify factors associated with high productivity and longevity in the field.
Methods: We determined the number of CPSTs and those newly certified using lists from the Michigan Office of Highway Safety Planning (OHSP) from 2012 to 2015. We conducted a statewide survey of Michigan CPSTs in October 2015. Analyses were conducted in 2016. The survey assessed demographic characteristics, reasons to enter the field and maintain certification, and motivations to conduct seat checks. We used CPST-reported time devoted to seat checks and average number of seats checked per month to create a composite “activity level” variable. We examined activity levels across several characteristics.
Results: The number of CPSTs ranged from 941 to 980 over the study period, with approximately 200 new certifications annually. In 2015, surveys were started by 496 of 962 eligible CPSTs and 427 submitted complete responses. CPST-instructors had a higher response rate than CPSTs in general (89 vs. 49%, P < .0001). The majority of respondents were women (71%) and self-identified as white (88%). More than one third were 35–44 years old. Just 7% were comfortable checking seats using a language other than English. “Personal reasons” were most often cited motivation for becoming a CPST and maintaining certification. Natural fit/job enhancement were more common reasons to maintain certification than become a CPST. Time and distance had the greatest influence on seat check participation. Perceived need, appointments vs. drop-in, and employer factors were very influential for 10–15% of CPSTs. Few CPSTs considered free food and payments/giveaways very influential. About 40% of respondents were considered high-activity (>24 seats checked/year), one third medium-activity (5 to 24 seats checked/year), and one quarter low-activity (<5 seats checked/year). High-activity CPSTs most commonly reported both being paid and volunteering their time to check seats, worked with a Safe Kids coalition, worked in law enforcement or social services, and had recertified at least once. Motivation to participate in seat checks did not vary with activity level.
Conclusions: Understanding the demographic characteristics and motivations of CPSTs can help Michigan OHSP recruit and retain a workforce dedicated to increasing the safety of child passengers. Agencies hosting seat checks can use these results to align the strategies they employ to incentivize CPSTs to serve in their communities with the factors that have the greatest influence on CPST participation. 相似文献
