农地经营对水稻化肥减量投入的影响

化肥投入过量是中国农业生产中的普遍问题,不仅增加农业生产成本、浪费资源,也造成了严重的环境污染问题,推进化肥减量投入是促进农业绿色、可持续发展的重要举措。本文利用2016年11月—2017年2月长江中下游6省29县的农户调查数据,应用广义有序Logit模型分析了土地经营规模、地块集中程度、土地租金以及地权稳定性等农地经营对农户化肥投入的影响。结果表明：① 土地经营规模、地块集中程度对农户化肥投入有显著的负向影响,土地租金对农户化肥投入有显著的正向影响,地权稳定性对农户化肥投入的影响不显著;② 相对于小户,规模种植户的化肥投入更合理,但随着土地经营规模扩大,农户化肥减量投入的倾向有所弱化;③ 从影响程度看,土地经营规模对农户化肥投入的影响最大,地块集中程度次之,土地租金的影响相对较小。因此,从化肥减量投入的视角出发,政府应鼓励发展适度规模经营,加快促成地块集中连片。此外,完善土地租金的定价机制也有助于化肥的减量投入。     

Declining interest in science in lower secondary school classes: Quasi-experimental and longitudinal evidence on the role of teaching and teaching quality

Although promoting student interest is a pivotal educational goal, student interest in science, and particularly in physics, declines substantially during secondary school. This study focused on the long-term development of interest in physics at the lower secondary level (grades 5–7) and examined the role of teaching and teaching quality on the development. In particular, the study investigated the role of whether or not physics was taught in class and the role of perceived teaching quality for classes' interest trajectories. The results provide evidence of declining interest in physics from Grade 5 to 7, with stronger declines from Grade 5 to 6. Whether classes participated in physics teaching or not neither notably reduced nor increased interest in physics. However, several dimensions of perceived teaching quality (in particular, cognitive activation and cognitive support) mitigated the decline in interest.