Nitrogen Mineralization as Influenced by Different Organic Manures in an Inceptisol in the Foothill Himalayas

Nitrogen-use efficiency can be enhanced through an understanding of the nitrogen (N) mineralization behavior of organic sources. An incubation study was conducted to assess the impact of organic manures on N mineralization. The manures, farmyard manure (FYM), Leucaena leucocephala, and poultry manure, were applied to the soil alone or along with urea. There was a rapid increase in the amount of mineral N released with a peak appearing either at 14 days (+urea treatments) or 21 days (manure only) of aerobic incubation. Thereafter the net N mineralized decreased gradually and levelled off beyond day 56. Overall the cumulative net N mineralized after 98 days of incubation was in the order urea > Leucaena + urea > poultry manure + urea _> FYM + urea > Leucaena > poultry manure > FYM > zero N. The potentially mineralizable N (N₀) was lower in treatments where urea was not applied.     

Anthropogenically disturbed potentially toxic elements in roadside topsoils of a suburban region of Bishkek,Central Asia

The ecological environment in Central Asia is vulnerable to pressure from human activity due to the physical geography and climatic fragility of this region. A set of indicators suitable for the future assessment of this pressure needs to be proposed. Thirty‐six topsoil samples (0–5 cm) were collected from roadsides in a suburban region of Bishkek, the capital of the Kyrgyz Republic in Central Asia, and a risk assessment of anthropogenically disturbed potentially toxic elements (PTEs) was systematically conducted with classic statistical methods. The results of detrended correspondence analysis and principal component analysis clearly showed that topsoil samples with high contents of PTEs (Pb, Zn and Cu) were strongly affected by traffic within a distance threshold of 200 m and that anthropogenic effects decreased significantly with increasing distance from the highway. The enrichment factor and anthropogenic contribution for Pb were the highest among the three PTEs, with average values of 2.0% and 47.4%, respectively, suggesting enrichment. However, the results of the human health risk assessment also indicated that noncarcinogenic risks did not occur for any of the anthropogenic PTEs. The reported method provides a new systematic pathway to reveal anthropogenic influences on the geochemical composition of soil. The conclusions of this work will be highly valuable as important guidelines for agriculture, and the results of the PTE contents will provide a scientific basis for soil collection in future studies.     

潜在和新发外来入侵物种三维可视化预警监测系统构建与应用

潜在和新发外来入侵物种数据可视化展示是外来入侵物种管理的重要载体。潜在和新发外来入侵物种数据具有混合型(包括结构化和非结构化)和离散性(数据分布在不同的系统或平台)特点。本文在分析这些数据的基础上,以预警监测模型分析与三维可视化集成、多源异构数据融合为切入点,综合运用3D GIS、物联网、大数据等技术手段,研发潜在和新发外来入侵物种可视化系统的关键技术;以潜在外来入侵物种地中海实蝇Ceratitis capitata和新发外来入侵物种番茄潜叶蛾Tuta absoluta为例,构建多源异构数据融合的潜在和新发入侵物种预警监测三维可视化系统,形成了基于GIS技术的典型潜在和新发外来入侵物种可视化平台的解决方案。该系统可为我国潜在和新发外来入侵物种分级控制管理和区域性防控预案制定提供科学支撑。     

蕴含K1，2，3可图序列的最小度和

经典Turan型问题的变形：确定最小的正偶数σ（H，n），使得对于每一个n项可图序列π=（d1,d2,…,dn）,当σ（π）=d1＋d2＋…＋dn≥σ（H,n）时，π是蕴含N可图的．确定了当n≥6时的σ（K1，2，3，n）。     

Assessing long term effects of compost fertilization on soil fertility and nitrogen mineralization rate

Background

Fertilization with organic waste compost can close the nutrient cycles between urban and rural environments. However, its effect on yield and soil fertility must be investigated.

Aim

This study investigated the long-term effect of compost on soil nutrient and potentially toxic elements (PTEs) concentration, nutrient budgets, and nitrogen (N) mineralization and efficiency.

Methods

After 21 years of annual compost application (100/400 kg N ha^–1 year^–1 [100BC/400BC]) alone and combined with mineral fertilization, soil was analyzed for pH, organic carbon (SOC), nutrient (total N and P, N_min, extractable CAL-P, CAL-K, and Mg), and PTE (Cu, Ni, Zn) concentrations. Yields were recorded and nutrient/PTE budgets and apparent net mineralization (ANM, only 2019) were calculated.

Results

N efficiency was the highest in maize and for mineral fertilization. Compost application led to lower N efficiencies, but increased ANM, SOC, pH, and soil N, and surpluses of N, P, and all PTEs. Higher PTE concentrations were only found in 400BC for Cu. Nutrient budgets correlated with soil nutrient concentration. A surplus of 16.1 kg P ha^–1 year^–1 and 19.5 kg K ha^–1 year^–1 resulted in 1 mg kg^–1 increase in CAL-P and CAL-K over 21 years.

Conclusion

Compost application supplies nutrients to crops with a minor risk of soil-accumulation of PTEs. However, the nutrient stoichiometry provided by compost does not match crop offtakes causing imbalances. Synchronization of compost N mineralization and plant N demand does not match and limits the yield effect. In winter wheat only 65–70% of N mineralization occurred during the growth period.     

浙江农业大学1987～1996年间申报国家自然科学基金未获资助项目的落选原因分析

对浙江农业大学在１９８７～１９９６年间申报国家自然科学基金未获资助的项目按２０种原因分别统计各原因出现的频率,通过方差分析和多重比较识别出申报项目落选的主要原因,同时根据相关分析结果探讨了主要落选原因之间的相互关系．     

对一种测定土壤潜在可矿化氮的化学浸取方法的评价

用全氮、有机质、pH、碳氮比及质地不同的12种土壤进行了大麦、燕麦和黑麦等3种作物的盆栽试验,并以KCl煮沸法测定了其可矿化的氮素,以估计土壤潜在的有效氮素。试验表明,KCl浓度及浸取时间长短对NO_3~--N浸出量无明显影响,用1 mol/L KCl煮沸浸取1h之后,NH_4~--N亦增加不多。1 mol/L KCl煮沸1h所释放的氮素与3种作物吸氮量密切相关,证明了这种水解方法能较好地预报盆栽试验条件下不同土壤释放作物可利用氮素的相对能力。一旦包括土壤特性,温、湿度在内的氮素释放模式形成之后,KCl煮沸法有可能用来很好地预报大田条件下作物生长期间转变成有效态氮素的数量。     

成都平原西缘典型水稻土壤风险元素及磷、硒来源解析与评价

为探究成都平原水稻土壤风险元素来源及其风险性,本研究以成都平原西缘某地0～20 cm的水稻土壤为研究对象,以土壤中Ni、Cr、Cu、Pb、Zn、As、Cd、Hg、P、Se这10种元素作为研究要素,借助统计学描述分析、聚类分析、主成分分析和GIS方法对10种元素的主要来源进行解析,并对其中8种重金属元素的污染风险进行评价。结果显示,研究区水稻土壤中Ni、Cr、Cu没有表现出明显的富集特征,Pb、Zn、As趋向于富集,Cd、Hg、P、Se有明显的富集现象。研究区人为活动影响较强的区域主要分布于I河至J河一带和L河沿岸地区。研究区内Cu、Cr、Ni、Se主要来源于成土母岩,Pb、As受磷石膏堆影响,Hg、P受居民生活废弃物影响,Zn、Cd受控于当地化工企业活动。研究区农耕土壤受Cd胁迫,内梅罗综合污染指数为1.20,达到轻度污染程度。     

区域证券市场发展潜力评价模型的建立及实证分析

建立了评价区域证券市场发展潜力的数学模型－定权聚类评估模型，并对河南各地区证券发展潜力进行了实证研究。     

气候变化情景下毛竹潜在分布及动态预测

为探究毛竹的潜在分布及其动态变化,并确定对其分布起主导作用的环境变量,文章基于MaxEnt预测模型,利用环境变量图层及316个毛竹分布点数据研究毛竹地理分布的变化。结果显示：1）限制毛竹分布的主要环境变量为最干月降水量、年均降水量、最冷月最低温、年平均温、温度年较差和海拔;2）当前毛竹的潜在适生区主要位于中国东南部,与亚热带季风气候区大致重叠,高适生区主要位于总适生区的东部和西北部;3）在未来气候情景下,毛竹总适生区面积有所缩减,各不同等级适生区面积变化大,其中高适生区面积大幅度缩减。研究获得的毛竹适生区变化趋势可为毛竹培育、引种以及入侵防治提供参考。